Passivhaus Standard in the UK

Passivhaus standard in the UK: Perceptions from the construction industry and end-user experience

by Adomas Novogrodskis

Passivhaus standard in the UK

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Author: Adomas Novogrodskis Supervisor: Dr Zaid Alwan Date: May 2020

Module: KA7013 Student Selected Investigation Student no. 17025893

word count: 9719 Excluding figure captions, tables, footnotes, and the bibliography

Contents 1.0

Introduction .............................................................................................................................. 4

2.1

Literature review....................................................................................................................... 5

2.2

Industry perceptions................................................................................................................ 5

2.3

End-user experience ............................................................................................................... 8

2.4

Gap in the knowledge............................................................................................................. 9

2.5

Research aims and objectives................................................................................................ 9

3.1

Methodology ......................................................................................................................... 10

3.2

Case studies ........................................................................................................................... 10

3.3

Quantitative research ........................................................................................................... 11

3.4

Qualitative research.............................................................................................................. 13

4.1

Case study 1: Forgebank Co-housing............................................................................... 14

4.2

Case study 2: Racecourse Estate........................................................................................ 15

4.3

Case study 3: Goldsmith Street .......................................................................................... 16

4.4

Results: post-occupancy evaluations ................................................................................. 17 Energy savings....................................................................................................................... 18 MVHR, ventilation and air quality ....................................................................................... 19 Living preferences, lifestyle & overall satisfaction ........................................................... 20

4.5

Results: semi-structured interviews .................................................................................... 21 Participant background & experience .............................................................................. 21 Perceptions of zero-carbon and Passivhaus..................................................................... 21

5.1

Discussion: post-occupancy evaluations .......................................................................... 23 Thermal comfort and overheating ..................................................................................... 23 Energy savings....................................................................................................................... 24 MVHR, ventilation & air quality ........................................................................................... 24 Overall satisfaction................................................................................................................ 25

5.2

Discussion: semi-structured interviews ............................................................................. 25 Passivhaus adoption drivers ................................................................................................ 25 Passivhaus adoption barriers .............................................................................................. 26 Passivhaus strengths & weaknesses................................................................................... 27

6.1

Conclusion ............................................................................................................................. 28

6.2

Research limitations and recommendations .................................................................... 28

7.1

Bibliography .......................................................................................................................... 29

7.2

List of figures.......................................................................................................................... 33

8.0

Appendicies ........................................................................................................................... 34

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1.0

Introduction

In June 2019, by the recommendation of the Committee on Climate Change, the UK government signed a legally binding target to reach net-zero emissions by 2050 (1). The pledge necessitates carbon neutrality across all sectors, including power, transport, industry, buildings, agriculture, waste, and fluorinated gases (2). Being responsible for 19% of total greenhouse gas emissions and over 25% of total energy consumption in the UK, decarbonisation of the building sector, especially housing, is crucial in meeting UK’s overarching climate targets (3). To achieve this, the UK government announced a transition towards zero-carbon buildings and launched the Code for Sustainable Homes policy to assess, certify and promote sustainable design and construction in new buildings (4).

However, with the subsequent ‘watering-down’ of the zero-carbon legislation and eventual withdrawal of the Code for Sustainable Homes in 2015, the UK construction industry has started to debate the validity of the zero-carbon concept (5). With some arguing that a ‘fabric first’ approach to building design such as the German Passivhaus standard could be a more efficient way to deliver energy-efficient housing in the UK and meet the set climate targets (5). Unlike the net zero-carbon housing policy which primarily focusses on carbon emissions and offsetting, the Passivhaus standard concentrates on user comfort and conserving energy through a thermally-efficient fabric, passive solar design, airtightness, thermal-bridge-free construction and use of MVHR (4).

Despite being introduced and successfully adopted across Europe since 1997, the Passivhaus standard is presently much less known, accepted or used in the UK (5). This being said, the Passivhaus standard has since started to gain credibility and traction with a small but growing number of early adopters in the UK (5). Since 2009, when the first Passivhaus building was built in the UK, 265 projects and 1244 units have been completed (6). However, the majority of completed Passivhaus projects to date have been either selfbuild private residential or experimental one-off pilot projects with a limited number of larger-scale housing schemes varying in their tenure, building sector or use (7). Even though several studies have indicated that Passivhaus standard performs considerably better compared to both conventional and low-carbon housing in the UK (8), (9), (10) its delivery and adoption in the industry have been somewhat limited: approx. 124 units a year, which is 0.07% of 170,000 new-build homes annually constructed in the UK (11).

Certain studies suggest that slow Passivhaus standard uptake could be a result of a general private housebuilding sector’s reluctance to innovate and voluntarily deliver energyefficient homes (12). Whereas other studies raise concerns with the Passivhaus standard itself- its complexity and higher build-costs as well as issues regarding summer overheating, MVHR and necessary lifestyle changes as a hindrance to its delivery at scale (13), (14), (15), (16). Consequently, this study aims to investigate the current state of the Passivhaus standard in the UK and discuss drivers, barriers and recommendations for its future adoption through the AEC industry’s perception and current end-user experience.

2.1

Literature review

A systematic literature review has been conducted as part of this study to collect, appraise and synthesize the best available data regarding Passivhaus standard in the UK. Primary databases that were used to find the information included Science Direct, Taylor & Francis, Research Gate, Academia.edu, Google Scholar, etc. While main keywords that were used in different combinations to find the results included but were not limited to ‘Passivhaus’, ‘zero-carbon’, ‘perception’, ‘construction industry’, ‘end-user’, ‘occupant’. A total of 4896 results were found in the search; however, only 65 studies have satisfied the inclusion criteria of freely available academic literature published in the last ten years explicitly concerning Passivhaus in the United Kingdom context (17). Selected studies were then categorized based on their subject (Fig. 1) to determine predominant research topics, reoccurring themes and current gaps in knowledge.

Fig. 1- Diagram representing literature review findings and categorisation based on the research subject

2.2

Industry perceptions

While the literature review highlighted there was a notable amount of literature on the Passivhaus standard, there has been relatively limited research on its adoption and construction industry’s perceptions of the standard. The only three relevant studies analyzing the construction industry’s attitude towards the Passivhaus standard and its uptake in the UK were by H. Lynch (5), H. Schoenefeldt. et al. (18) & E. Heffernan, et al. (19).

The first study carried out by Henrietta Lynch in 2014 (5) employed mixed-methods research which was comprised of focus groups, unstructured interviews, and Qmethodology. Opinions from a group of early UK’s Passivhaus adopters, stakeholders and construction professionals were collated and analyzed to identify emerging themes and statements about the Passivhaus standard in the UK. They were later cross-examined in the Q-test were the respondents had to rate the statements by how much they agreed or disagreed with them. Out of the 43 statements that emerged during the focus group discussions, the themes that gained the highest level of agreement in the Q-test included:

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• • • • •

Thermal comfort and MVHR usability Climate, PHPP software and supply chain ‘Fast-buck’ mentality and conflicting legislation UK Passivhaus representation and precedents Financial incentives

There was a consensus among the research participants that the Passivhaus standard delivered high levels of indoor comfort (5). However, there were also concerns relating to air quality and summer overheating as well as UK construction industry’s competence, skills, and knowledge in delivering energy-efficient buildings and correct MVHR installation necessary for Passivhaus performance (5). There were disagreements among the participants in regards to the Passivhaus PHPP software with some believing it provided a more accurate energy modelling than SAP while others were finding the PHPP complex and challenging to use (5). Respondents agreed there was a lack of Passivhaus building precedents in the UK to learn from as well as an inadequate supply chain of certified Passivhaus components preventing effective Passivhaus delivery at scale (5). Most participants believed the UK construction industry had a ‘fast-buck’ approach to business focusing on quick financial returns and thus stifling innovation and uptake of voluntary standards like Passivhaus (5). Moreover, there was a perception that the Passivhaus standard at the time was generally not well understood, was conflicting with Code for Sustainable Homes policy as well as lacking a coherent and robust representation in the UK (5). Finally, participants concluded there was a significant lack of financial incentives supporting Passivhaus and other energy-efficient housing initiatives in the UK, in contrast to countries like Germany where Passivhaus was substantially subsidized and funded (5).

The second study conducted by Henrik Schoenefeldt, et al. (18) utilized mixed-method research comprising thirteen detailed case studies of domestic and non-domestic Passivhaus projects across the UK. The study also incorporated semi-structured interviews with clients, architects, planners, and contractors involved in the project. It investigated how individual project teams have implemented the Passivhaus standard and what technical, economic and cultural challenges they have encountered in the process. The case studies gave detailed insights into each project and its challenges, yet an undertaken cross-case analysis also revealed some broader overarching themes, which included: • • •

Design complexity, creativity, rigour, and evaluation Innovation, collaboration, research, and development Education, skills and construction assurance

Case studies revealed that practically all project teams had to go to great lengths to acquaint themselves with the Passivhaus methodology, which included PHPP software as well as other necessary evaluative tools for testing overheating and thermal bridging (18). It was apparent that the Passivhaus standard had a strong emphasis on energy performance and a requisite for a particular form factor, orientation and glazing ratios that challenged some traditional architectural concepts. While it was found that this did not stifle creativity in general, it did require a good understanding of Passivhaus principles to reconcile demanding energy requirements (18). Conducted case studies highlighted a significant dependency on imported Passivhaus technologies and collaborations with partners in central Europe to gain the necessary experience and knowledge to implement the standard in the UK (18). That said, Passivhaus methodology acted as a significant driver for

research, innovation, skill development as well as facilitated new forms of practice and cross-industry collaboration between architects, contractors, consultants and universities previously unseen in the industry (18). Undertaken case-studies confirmed previous research findings (20), (21) of the skill and knowledge gap in the UK construction industry which was found to be a significant barrier to successful energy-efficient building delivery (18). Practically all analyzed projects faced issues with poor construction skills and quality assurance, and hence required additional training, briefing and supervision of contractors, in some cases necessitating the use of simplified construction methods such as prefabricated timber-frame to achieve the necessary quality (18). Nonetheless, Passivhaus was perceived as a major driver for upskilling the construction industry by introducing contractors to new building products, construction techniques, focus on airtightness and detailing as well as raising higher quality standards more generally (18).

The third and final study on the Passivhaus standard perceptions in the UK was conducted

by Heffernan, Pan, Liang, & Wilde (19) who analyzed the standard in a much larger context of zero-carbon housing. Semi-structured interviews with 34 cross-disciplinary construction industry professionals were undertaken to identify the main perceived drivers, barriers and support mechanisms of energy-efficient housing delivery in the UK. The research findings were then categorized into themes and sub-themes and included: Drivers: • Legislative (Building regulations, Climate Change Act, planning) • Economic (cost of energy, market demand, financial incentives) • Social (fuel poverty, moral drivers, environmental impact) • Individual (energy savings, public awareness, comfort) • Industry (green marketing, fashion, housing associations) Barriers: • • • • •

Economic (capital cost, viability, perceived risk, land values) Skills and knowledge (lack of knowledge, skills availability, poor competency) Industry (supply chain, lack of collaboration, business models, resistance to change) Legislative (current building regulations, policy uncertainty) Cultural (housebuilding industry culture, aesthetic culture)

Support mechanisms: • • • •

Education (public awareness, industry training, design guides, post-build studies) Legislation (building regulations, robust planning policy, cross-party support) Financial (incentives, market demand, funding, mortgage solutions) Industry (collaboration, self-build, off-site construction, standardized specifications)

The research concluded that while there were several energy-efficient housing drivers, the perceived barriers have exceeded them both in number and magnitude (19). The main drivers were identified to be legislative, especially the building regulations, the climate change act as well as economic such as the increasing energy prices (19). Whereas barriers were also primarily economic, i.e. capital cost and scheme viability as well as industrial, namely housebuilding industry culture and resistance to change, lack of public awareness, and poor industry skills and knowledge (19). Finally, the main support mechanisms for energy-efficient housing were identified to be industrial such as the promotion of self-

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build, and legislative, particularly, a robust planning policy framework supporting the delivery of energy-efficient housing in the UK more generally (19).

2.3

End-user experience

When analysing the development and uptake of the Passivhaus standard, the perceptions of not only the construction industry but also the end-users’ and their experiences has to be considered to accurately judge the energy standard’s compatibility with the UK market (5). Literature review revealed six studies that have analysed Passivhaus in either large-scale or social housing context, their occupant behaviour, thermal comfort and overall satisfaction. All six studies (15), (22), (23), (24), (25), (26) found that Passivhaus standard delivered high levels of thermal comfort, however, issues relating to summer overheating, ventilation and necessary behavioural adaptations were also raised.

A study conducted by Zhao & Carter (26) revealed that occupants found their Passivhaus homes to be very comfortable in terms of heat, illumination and air quality. Other positive aspects of Passivhaus included low maintenance, no condensation or mould issues, good layout and furnishing as well as lower heating bills and convenience (23). That said, there has been an increasing amount of research reporting overheating issues in Passivhaus properties. It was found that while highly-insulated and airtight Passivhaus buildings with maximal solar gains did help to reduce energy demand significantly, it also presented a higher risk of overheating in summer (27). Several studies highlighted this was particularly evident in large-scale housing with social tenants, where due to a lack of MVHR maintenance and natural ventilation most properties reported overheating levels greatly exceeding the required criteria (25), (28). A recent study on Passivhaus occupancy concluded that thermal comfort and energy-efficiency was as much dependent on design as it was on the end-users’ understanding of the installed technologies such as MVHR as well as their patience and willingness to learn how to use them (26).

In terms of end-user behavioural patterns, three studies (15), (23), (26) indicated that Passivhaus buildings required a significant behavioural adaptation from its occupants to successfully operate it and ensure the building met the desired comfort levels without undermining overall energy saving principles. Some of the reported new resident habits included checking the weather frequently, different use of appliances, shifting living spaces away from heaters as well as being more aware of internal gains, e.g. cooking or exercising (23). Interestingly, research on private and public Passivhaus housing highlighted that there were two predominant behavioural adaptations among occupants: comfort-driven and energy saving-driven both presenting their unique behavioural patterns (15). Comfortdriven behaviour seen primarily in private housing commonly included a change of attire, new sleeping and social habits, individual room temperature control, learned behaviour in operating MVHR, solar shading and openable windows (15). Energy saving-driven adaptations, on the other hand, included embracing the slow-response heating systems, closely tracking energy use, community-led learning on energy consumption and more efficient use of electrical appliances (15). The research concluded that failing to recognize and account for the occupant behavioural patterns and variation has the potential to undermine the Passivhaus energy-saving principles (15). Otherwise resulting in negative end-user experience, and thus potentially preventing the Passivhaus standard’s wider adoption on large-scale housing in the UK (15).

2.4

Gap in the knowledge

Conducted literature review revealed that while there was a substantial number of studies about Passivhaus in the UK, specific research regarding its uptake and perceptions from the construction industry has been somewhat limited. Furthermore, all relevant studies were undertaken before 2015 when Passivhaus was still a novel and mostly unfamiliar concept in the industry. At the time, the Passivhaus technology was still at its early development and pioneering phase with a small number of accredited Passivhaus buildings, immature supply chain and limited representation from stakeholders (5). More importantly, at the time, the UK was still part of the European Union committed to meeting the Energy Performance in Buildings Directive, and Code for Sustainable Homes was still an active policy. Both of which promoted uptake of energy-efficient housing and voluntary energy standards such as Passivhaus (29). Subsequent withdrawal of the CfSH and the UK’s decision to leave the EU presented both risks and opportunities for further Passivhaus standard’s uptake in the UK, which has not been considered in the previous research (16).

In terms of end-users, on the other hand, there has been a notable amount of research analysing occupants’ perceived comfort, knowledge, behavioural patterns, and overall satisfaction living in Passivhaus homes. However, less attention has been given to largerscale Passivhaus projects, especially social housing, co-housing or housing for special needs. Besides, there has been a significant lack of longitudinal research and repeated observations of Passivhaus properties over a long period to investigate the longevity of its thermal properties as well as evolvement of end-user experience. Therefore, up-to-date research investigating the current construction industry’s perceptions of the standard as well as revisiting occupant experience in large-scale Passivhaus properties to gain deeper understanding is warranted.

2.5

Research aims and objectives

The aim of this research is, therefore, to analyse and discuss the contemporary drivers and barriers of delivering Passivhaus standard in the UK through an investigation of the perceptions from the construction industry professionals involved in the design and procurement of housing as well as end-users living in large-scale Passivhaus properties.

The objectives of this study are: • • • •

Determine perceived drivers and barriers for Passivhaus standard delivery in the UK Identify perceived Passivhaus standard’s strengths and weaknesses in the industry Analyse three distinct large-scale residential Passivhaus developments and compare their occupant experiences, e.g. comfort, energy savings and satisfaction Examine Passivhaus occupants’ behavioural patterns and identify habits/factors that influenced perceived thermal comfort, air quality, and overall energy-efficiency

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3.1

Methodology

Mixed research methods have been used for this research encompassing both qualitative and quantitative methods as the scope and complexity of the phenomenon require data from different perspectives, i.e. occupants and designers (30). Quantitative research in the form of POE (post-occupancy evaluation) was employed as it allowed to gather concrete, factual data on how the completed Passivhaus buildings were being operated and provide a ‘snapshot’ of its users' experience and satisfaction at this particular time (31). In addition, qualitative research in the form of semi-structured interviews was chosen to investigate the construction industry’s perceptions of the Passivhaus standard as the nature of the study was much more subjective yet was suitable for larger cohorts, specifically when trying to identify trends and themes from a variety of cross-comparable accounts (32). Accordingly, using mixed-methods helped to utilize the strengths of both methodologies as well as bridge the gap between quantitative and qualitative research and achieve a sufficient level of generalisation, accuracy, and complexity within the inquiry (33) (Fig. 2).

Fig. 2- Venn diagram with the middle triangle representing the target data to be collected by this research

3.2

Case studies

Three case studies of large-scale residential Passivhaus developments in the UK were conducted to analyse their inception, delivery, and real-life occupancy. The case study methodology was selected for the research as it enabled practical analysis of a broad phenomenon such as Passivhaus standard integration in the UK, which otherwise would have been difficult to examine (34). According to Robert K. Yin, case studies are able to ‘shed empirical light on some theoretical concepts or principles’ (35 p. 133). Just as a laboratory experiment, instead of trying to extrapolate empirical probabilities (statistical generalisation), it allows us to investigate, expand and generalise existing theories (analytical generalisation), e.g., living in a Passivhaus affects occupants’ behaviour and perceived comfort (35).

Passivhaus case studies were chosen based on their scale, time of construction, location as well as the type of tenure, thus aiming to acquire currently lacking typological data identified by the literature review. The Forgebank project in Lancaster was chosen as a case study because it is currently the only certified Passivhaus cohousing project in the UK, hence providing a unique insight into energy use and behavioural patterns in a highly interactive and social co-housing environment. Racecourse Estate project in Houghton-leSpring was chosen because of its specialised design for occupants with mobility needs as well as for having the best co-heating test results among all monitored Passivhaus dwellings in the UK. Finally, the Goldsmith Street project in Norwich was chosen because it is the biggest Passivhaus development in the UK to date as well as the only Passivhaus and social-housing project ever to win Stirling prize for excellence in architecture. Besides, all three case studies were chosen so they would differ from each other in terms of their location, size, completion date, and tenure, therefore allowing to examine the Passivhaus standard under varying conditions. Selected case studies were analysed through desktop reviews as well as subsequent site visits to acquire missing and more nuanced data.

3.3

Quantitative research

As mentioned previously, to assess Passivhaus standard performance and applicability from the end-users perspective, post-occupancy evaluations (POE) were chosen as the preferred method for quantitative data collection. POEs have become the preferred industry method to monitor in-use building performance and assess energy performance and air quality as well as collect feedback on thermal comfort, space use, and overall user satisfaction (36). The questionnaire was prepared following guidelines from the Postoccupancy Evaluation Toolkit (37) as well as specific POE examples (29), (38). The POE was divided into seven sections (1- background; 2- occupancy, building type, and use; 3thermal comfort; 4- energy use; 5- building services and ventilation; 6- air quality and behavioural patterns; and 7- overall impressions) and was comprised of 38 questions in total. Most questions were either a checkbox or multiple-choice; however, a 5-point Likert rating scale was also utilized in questions relating to user satisfaction, perceived thermal comfort, air quality, and energy-savings. POEs were collected between September and December 2019 through door-to-door canvassing, postal surveys as well as invited online questionnaires. A total number of 49 POEs were cumulatively collected across the three case studies including 15 from Forgebank Cohousing, 9 from Racecourse Estate, and 25 from Goldsmith Street- resulting in an average response rate of 29%, Fig. 3 Forgebank Cohousing

Racecourse Estate

Response

16

No response

25

9

15 26

Goldsmith Street

Response

80

No response

Response

No response

Fig. 3- Number of POE responses from the total number of units

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Collected POE questionnaires were then imported into IBM statistical software SPSS for further quantitative analysis. Each POE question and the collected answer was correspondingly coded into either a nominal, ordinal or scale variables and analysed to find frequencies, associations and correlations between the answers. Firstly, the analysis was run on nominal demographic variables such as age, gender, tenure, house type, etc. to identify reoccurring occupant and household types, which were then compared to determine if they presented differences regarding comfort, energy savings and satisfaction. The analysis was then conducted on occupants’ motivations to live in a Passivhaus property, their preferred heating control devices as well as knowledge and operation of MVHR to determine whether it had any impact on perceived thermal comfort, ventilation and indoor air quality. Lastly, collected data were examined to determine perceived behavioural change, living standard improvement and overall satisfaction with the properties across the case studies. As the majority of collected data was nominal, not normally distributed, and the sample size was fairly limited, non-parametric statistical methods had to be used (39). Therefore, depending on the level of measurement, the collected data were analysed using either a crosstabulation test to determine the association; Mann-Whitney U-test to compare differences between independent groups; or Spearman rank-order correlation to measure the relationship between different variables (39). Particular attention was given to ordinal Likert scale questions asking occupants to rate their satisfaction with a particular aspect of their Passivhaus dwellings such as thermal comfort, air quality or energy-savings.

Spearman correlation is typically employed to determine the monotonic relationship between two variables expressed in correlation coefficient, r, which has a value in the range of [-1, 1] (39). The closer r-value is to either -1 or 1, the stronger the negative/positive correlation, whereas a value close to 0 indicates weak or no correlation (40). By extension, the Pearson Correlation also indicates the statistical significance of the correlation between two variables, best represented by Sig(2-tailed) population correlation coefficient, p (‘rho’) (40). A ‘rho’ value that is equal or less than 0.05 typically means statistical significance, whereas a value greater than 0.05 indicates little or no statistical significance (40).

3.4

Qualitative research

One of the aims of this research was to analyse the construction industry’s perceptions concerning the large-scale delivery of Passivhaus standard in the UK. Consequently, a series of semi-structured interviews were conducted with several construction industry professionals, including architects, researchers and certified Passivhaus designers.

Purposeful sampling technique was used to identify and select the most knowledgeable yet accessible individuals to have ‘information-rich cases for the most effective use of limited resources’ (41 p. 534). Twelve industry specialists based in the North East region have been identified and individually approached, five of whom agreed to participate.

Interviews were comprised of sixteen open-ended questions about participants’ experience, the UK’s 2050 climate target, zero-carbon housing as well as the pros and cons of the Passivhaus standard and drivers and barriers of delivering it in the UK at scale. All interviewees had some familiarity working with the Passivhaus standard, although at varying degrees, as well as experience working with sustainable housing more generally.

All interviews were conducted in person between November 2019 and January 2020, audio-recorded and transcribed using auto-transcription software Descript. Intelligent verbatim transcription method was then used to remove filler words and repetitions as well as carry out minor paraphrasing to create easy-to-read text document for further data processing (42). Each transcribed interview data was then imported and analysed utilizing the NVivo qualitative data processing software. Following the methodology framework of Heffernan, et al. (19) a combination of thematic analysis, matrix coding and crosstab query were utilised within NVivo to find, filter, sum and group collected data to establish recurring themes concerning Passivhaus delivery in the UK. Thematic analysis was utilised as it is a common method used for qualitative data examination allowing the quantification of qualitative data and identification of recurring themes or patterns within the collected information (43). In this research, the word ‘theme’ refers to a distinct data grouping or category identified by the researcher during the NVivo analysis. For a data grouping to be recognized as a ‘theme’, it had to be independently mentioned by at least two different interviewees. Specific and similar themes were synthesized into broader general themes and divided into sub-themes, e.g. economics: cost, financial incentives, investment, funding, etc. The research themes were identified and developed using theme identification scrutiny techniques set up by G. Ryan and H. Bernard (44) utilising both analysed primary data as well as ‘priori’ approach including themes agreed on and found in literature reviews. Main themes and keywords discovered in the literature review, such as legislation, economics, industry culture, education, etc. formed the initial framework for thematic research. Identified themes were coded in NVivo and analysed through text search within and across the interviews to find similar themes and rate their significance in terms of frequency and the number of respondents who mentioned it.

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4.1

Case study 1: Forgebank Co-housing

Forgebank Co-housing is a 41 dwelling affordable community housing project in Halton, Lancaster built-in 2013. The project comprises a range of house types ranging from flats to two and three-bedroom terraces. 35 of these dwellings are within the co-housing scheme with shared community facilities. All dwellings in the project were designed to Passivhaus, Lifetime Homes and Code for Sustainable homes level 6 standards (45). At the time of its 4.1 Case sForgebank tudy 1: Forg ebathe nk C o-housing construction, was second-largest Passivhaus development in the UK, (46) and it still is the largest and only Passivhaus cohousing project in the UK.project The development Forgebank Co-housing is a 41 dwelling affordable community housing in Halton, went beyond the fabric performance requirements of the Passivhaus standard.

It utilised Lancaster built-in 2013. The project comprises a range of house types ranging from flats ato biomass heating system, solar thermal network asare well a community micro-grid two and district three-bedroom terraces.

35 of these dwellings within the co-housing scheme powered by the hydro-electric scheme and photovoltaic panel array mounted on most 4 .

1 C a s e s t u d y 1 : F o r g e b a n k C o h o u s i n g with shared community facilities. All dwellings in the project were designed to Passivhaus, dwellings’ roof (47).

Lifetime Homes and Code homes level 6 standards (45).project At the time of its Forgebank Co-housing is afor 41Sustainable dwelling affordable community housing in Halton, construction, Forgebank wasproject the second-largest Passivhaus development in thefrom UK, flats (46) to Lancaster built-in 2013.performance The comprises range of house types ranging Review of the building evaluation a(BPE) revealed that energy-performance and it stillthree-bedroom is the largest and only Passivhaus cohousing project in the UK. The development two and terraces.

35 of these within co-housing scheme aspirations and Passivhaus methodology weredwellings adopted are early in thethe project (46). PHPP went beyond the fabric performance requirements of the Passivhaus standard.

It utilised a with shared community facilities.

All dwellings in the project were designed to Passivhaus, software was used to model and test different design options while an airtightness biomass district heating system, solar thermal network well a community micro-grid Lifetime Homes and Code forthe Sustainable level as 6air-barrier standards (45). At the time champion was appointed by contractorhomes to overlook installation and airof its powered by the hydro-electric scheme and photovoltaic panel array mounted onUK, most construction, Forgebank was the second-largest Passivhaus development in the (46)to pressure tests (46). A close relationship between the client and the design team helped dwellings’ roof (47). and it stillcontrol is the largest and only Passivhaus project inclient the UK. The development maintain over the final design qualitycohousing and cost- ensuring expectations have went beyond the fabricOverall, performance requirements ofrevealed the Passivhaus standard.

It utilised a been largely (48). the dwellings were built to a verythat high standard and Review of themet building performance evaluation (BPE) energy-performance biomass district heating system, solar thermal network as well a community micro-grid performed well in co-heating tests, thus practically eliminating the energy aspirations exceptionally and Passivhaus methodology were adopted early in the project (46).

PHPP powered by the hydro-electric scheme and photovoltaic panel array mounted on performance gap (48). software was used to model and test different design options while an airtightnessmost dwellings’ (47). champion roof was appointed by the contractor to overlook air-barrier installation and air pressure (46). A close relationship between(BPE) the client andthat the energy-performance design team helped to Review oftests the building performance evaluation revealed maintain control over the final design quality and cost- ensuring client expectations have aspirations and Passivhaus methodology were adopted early in the project (46). PHPP been largely met (48).

Overall, the dwellings were built to a very high standard and software was used to model and test different design options while an airtightness performed exceptionally in co-heating thus practically energy champion was appointedwell by the contractor tests, to overlook air-barriereliminating installationthe and air performance gap (48). pressure tests (46). A close relationship between the client and the design team helped to maintain control over the final design quality and Fig. 4- Panoramic view of the Forgebank development

cost- ensuring client expectations have been largely met (48). Overall, the dwellings were built to a very high standard and performed exceptionally well in co-heating tests, thus practically eliminating the energy performance gap (48).

Fig. 4- Panoramic view of the Forgebank development Fig. 5- Site layout plan Fig. 4- Panoramic view of the Forgebank development

Fig. 5- Typical one-bed and two-bed dwelling floor plans

Fig. 5- Site layout plan

4.2

Case study 2: Racecourse Estate

Racecourse Estate is a 28 bungalow housing development for elderly residents with mobility needs built-in 2011 as part of a wider Racecourse Estate regeneration masterplan aiming to replace old housing stock with 4,000 sustainable new dwellings (49).

Development is comprised of 25 terraced (Passivhaus certified & CfSH level 4), and 3 detached bungalows (CfSH level 5) designed specifically for mobility-impaired tenants (49). At the time of its completion in 2011, Racecourse Estate was the largest Passivhaus development in the UK, and currently is still the largest Passivhaus development in the North East of England (50)..

Each bungalow was designed to have an open-plan living and kitchen area, two bedrooms and a mezzanine floor which functioned both as plant roof and loft space, with a total floor area of 66 m2 (49). External walls and roof were constructed using prefabricated timber 4.2 Ca se stwith udy 2high : Raclevels ecourof seinsulation, Estate cassettes filled while the ground floor was built using traditional reinforced slab with 300mm insulation and screed residents above (49).

Several Racecourse Estate is aconcrete 28 bungalow housing development for elderly with good areas of practice including careful detailing, mobility needs built-inwere 2011observed as part ofduring a widerconstruction, Racecourse Estate regeneration masterplan fixing damaged areas and use of appropriate gaskets and putty to seal any gaps aiming to replace old housing stock with 4,000 sustainable new dwellings (49). in service penetrations very project architect 4.2 Case (49). stis udcomprised yMoreover, 2: Racecoof ur25 se close Estatecollaboration Development terraced (Passivhausbetween certifiedthe & CfSH level 4), andand 3 the contractor was observed throughout the project with numerous training events and detached bungalows (CfSH level 5) designed specifically for mobility-impaired tenants Racecourse Estate is a 28 bungalow housing development for elderly residents with workshops ensure construction raised airtightness (49).

(49). At theto time of itson-site completion in 2011,met Racecourse Estate wasand thequality largesttargets Passivhaus mobility needs built-in 2011 as part of a wider Racecourse Estate regeneration masterplan development in the UK, and currently is still the largest Passivhaus development in the aiming to replace old housing stock with 4,000 sustainable new dwellings (49).

North East of England (50)..

Development is comprised of 25 terraced (Passivhaus certified & CfSH level 4), and 3 Fig. 6- Racecourse development streetscape view detached bungalows (CfSH level 5) designed specifically mobility-impaired Each bungalow was designed to have an open-plan livingfor and kitchen area, twotenants bedrooms (49).

At the time of its completion in 2011, Racecourse Estate was the largest Passivhaus and a mezzanine floor which functioned both as plant roof and loft space, with a total floor development in theExternal UK, andwalls currently is still the constructed largest Passivhaus development timber in the area of 66 m2 (49). and roof were using prefabricated North Eastfilled of England (50). . cassettes with high levels of insulation, while the ground floor was built using traditional reinforced concrete slab with 300mm insulation and screed above (49). Several Each bungalow was designed to have an open-plan living and kitchen area, two bedrooms good areas of practice were observed during construction, including careful detailing, and a mezzanine floor which functioned both as plant roof and loft space, with a total floor fixing damaged areas and use of appropriate gaskets and putty to seal any gaps in service area of 66 m2 (49). External walls and roof were constructed using prefabricated timber penetrations (49). Moreover, very close collaboration between the project architect and the cassettes filledplan with high levels of insulation, while the ground floor was built using Fig. 7- Site layout contractor was observed throughout the project with numerous training events and traditional reinforced concrete slab with 300mm insulation and screed above (49). Several workshops to ensure on-site construction met raised airtightness and quality targets (49). good areas of practice were observed during construction, including careful detailing, fixing damaged areas and use of appropriate gaskets and putty to seal any gaps in service penetrations (49). Moreover, very close collaboration between the project architect and the Fig. 6- Racecourse development streetscape view contractor was observed throughout the project with numerous training events and workshops to ensure on-site construction met raised airtightness and quality targets (49).

Fig. 6- Racecourse development streetscape view

Fig. 7- Site layout plan

Fig. 7- Site layout plan

Passivhaus standard in the UK

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4.3

Case study 3: Goldsmith Street

Goldsmith Street is a large social housing scheme built in Norwich city centre in 2018 as part of a city council’s wider corporate plan to address increasing social housing needs and tackle fuel poverty (51). The 1.2ha development is comprised of 105 units: 45 two-bed terraces and 60 one-bed flats, and arranged in seven terrace blocks laid out east-to-west emulating the Victorian street layout of the adjacent ‘Golden Triangle’ district (52). In 2019 the Goldsmith Street development was nominated and won the RIBA’s Stirling Prize for excellence in architecture becoming both the first Passivhaus and social housing project ever to win such accolade (53). Moreover, with 105 housing units, Goldsmith Street became the largest Passivhaus scheme in the UK to date.

Unlike many projects of such scale, the project was delivered through a traditional 4.3 Case study 3: Goldsmith Street procurement route which in hindsight allowed the architects to have better control of the Goldsmith Street a large socialand housing scheme builtinitial in Norwich centre in (52).

2018 as build quality, valueisengineering retaining project’s designcity aspirations part of a citythe council’s wider corporate plan to address increasing social housing Throughout project, the design of the buildings took priority: special attentionneeds and and tackle fuel poverty (51).

The 1.2ha development is comprised of 105 units: 45 two-bed care were taken to ensure the Passivhaus standard was working for the design rather than terraces and 60 one-bed flats,to and arranged in seven terrace blocks laidother out east-to-west design becoming subservient make the Passivhaus work (54).

As with case studies, the Victorian streetthe layout of the contractor adjacent ‘Golden districtteam (52).was In 2019 aemulating tight collaboration between architect, and theTriangle’ whole design the Goldsmith Streetthe development was nominated and to won the RIBA’s Stirling Prize for observed right from beginning, largely contributing the project's success (54).

4.3 Case study 3: Goldsmith Street excellence in architecture becoming both the first Passivhaus and social housing project Goldsmith is a large(53). social housing scheme in Norwich city centreStreet in 2018 as ever to win Street such accolade Moreover, with 105built housing units, Goldsmith part of a city council’s wider corporate plan to address increasing social housing needs and Fig. 8Goldsmith St. streetscape view became the largest Passivhaus scheme in the UK to date. tackle fuel poverty (51). The 1.2ha development is comprised of 105 units: 45 two-bed Unlike many of such the project delivered through a traditional terraces and projects 60 one-bed flats,scale, and arranged in was seven terrace blocks laid out east-to-west procurement route which in hindsight allowed the architects to have better control of2019 the emulating the Victorian street layout of the adjacent ‘Golden Triangle’ district (52). In build quality, value engineering andwas retaining project’s design aspirations (52).for the Goldsmith Street development nominated and initial won the RIBA’s Stirling Prize Throughout the project, the design of the buildings took priority: special attention and excellence in architecture becoming both the first Passivhaus and social housing project care ensure (53). the Passivhaus working forGoldsmith the designStreet rather than ever were to wintaken such to accolade Moreover,standard with 105was housing units, design make the Passivhaus work (54). As with other case studies, becamebecoming the largestsubservient Passivhausto scheme in the UK to date. a tight collaboration between the architect, contractor and the whole design team was Fig. 9- Site layoutprojects plan Unlike many of such scale, the project was delivered a traditional observed right from the beginning, largely contributing to thethrough project's success (54). procurement route which in hindsight allowed the architects to have better control of the build quality, value engineering and retaining project’s initial design aspirations (52).

Fig. 8- Goldsmith St.project, streetscape Throughout the theview design of the buildings took priority: special attention and care were taken to ensure the Passivhaus standard was working for the design rather than design becoming subservient to make the Passivhaus work (54). As with other case studies, a tight collaboration between the architect, contractor and the whole design team was observed right from the beginning, largely contributing to the project's success (54).

Fig. 8- Goldsmith St. streetscape view Fig. 9- Site layout plan

Fig. 9- Site layout plan

4.4

Results: post-occupancy evaluations

As mentioned earlier, post-occupancy evaluations were conducted in three different Passivhaus developments varying in their scale, location, typology and ownership (Fig. 10).

There were four main house types identified across the case studies, including flats, terraces, end-terraces, and semi-detached houses; in terms of size, properties ranged from one to four bedrooms. The most common Passivhaus type was found to be a roughly twobedroom (mean, µ = 1.75) terrace house occupied by two people (µ = 2.04). In terms of occupancy, analysis of participants’ demographical data helped to identify five reoccurring household types: single senior, retired couple, single adult, adult couple, and family; out of which families (29%) and retired couples (25%) were found to be the most common.

Case study Forgebank Co-housing, Halton

Region North West, Lancashire

Racecourse Estate, Houghton-le-Spring

North East, Tyne and Wear

Goldsmith Street, Norwich

South East, Norfolk

House Types Terrace, End of terrace Flat Terrace, End of terrace, Semi-detached Terrace, End of terrace, Flat

Ownership/Tenure Co-housing

Construction Type Masonry cavity

Affordable housing

Timber frame

Social housing

Timber frame

Fig. 10- Comparison of conducted case study properties

Thermal comfort and heating habits Collected POE data indicated that all surveyed Passivhaus properties were perceived to be very comfortable during the winter, autumn and spring seasons; however, residents were less satisfied with thermal comfort in the summer months. Eleven occupants (22%) identified they were either less or not pleased with indoor temperatures during the summer season, referring to overheating as the main issue. Such data corresponds with literature review findings where the overheating issue in Passivhaus homes has been highlighted numerous times (14), (25).

Concerning heating, SPSS analysis revealed there were some notable differences between the case studies in terms of heating habits and devices used to control indoor temperature.

Comparison of winter heating patterns (Fig. 11) highlighted that Goldsmith Street had the most habitual residents. They were likely to have the heating on at a predetermined time of day, i.e. mornings and evenings. In contrast, Forgebank occupants could be considered the most ‘reactive’- typically heating their properties only when felt needed. Racecourse Estate residents, on the other hand, were found to be the most energy-conserving, over half of which indicated never needing to have the heating on in their properties.

60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0%

Forgebank Cohousing Throughout the day

Racecourse Estate Mornings/Evenings

Goldsmith Street

Depending on the need

Never

Fig. 11- Comparison of heating frequency during the winter season between case studies

Passivhaus standard in the UK

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In terms of heating control devices (Fig. 12), collected data indicated that Forgebank and Goldsmith St. residents were still heavily reliant on a conventional central heating system (used by >80% of respondents), in contrast to Racecourse Estate were only 44.4% of endusers reported needing the central heating. That said, Racecourse Estate inhabitants were also found to be the most likely needing a portable cooler to prevent summer overheating, as opposed to Forgebank and Goldsmith St. residents which indicated a much lower need for cooling. All case studies indicated a high use of MVHR and operable windows. Yet, notably, fewer Racecourse residents reported using solar shading, which might explain the summer overheating and need for additional cooling.

120.0% 100.0% 80.0% 60.0% 40.0% 20.0% 0.0% Forgebank Cohousing Central Heating

MVHR

Racecourse Estate Windows

Solar Shading

Goldsmith Street Portable Heater

Portable Cooler

Fig.12- Comparison of devices used to control the indoor temperature between case studies

Energy savings In terms of energy savings, Passivhaus residents were asked to recount their monthly heating bills and identify whether they expected such savings and found a notable difference in comparison to their previous house. 71.4% of residents reported monthly heating bills below £50, 28.6% of residents paid somewhere between 50-100£, and no residents reported paying more than £100 (fig. 13). 75.5% of surveyed occupants found this to be a significant saving in contrast to their previous property heating bills, although, only 36.7% of residents indicated expecting such savings. Remaining occupants reported either expecting different energy-savings (16.3%) or not being sure what to expect entirely (46.9%).

90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% Forgebank Cohousing

Racecourse Estate <£50

£50-£100

£100-150

Goldsmith Street >£150

Fig. 13- Comparison of reported monthly heating bills between case studies

MVHR, ventilation and air quality Biggest discrepancies among Passivhaus residents were found in the perceived knowledge and operation of the MVHR (mechanical ventilation with heat recovery). POE data indicated that only a limited number of residents (49%) have had an MVHR induction or possessed a user manual (81.6%); accordingly, only 79.6% of surveyed occupants found MVHR easy to control. Interestingly, a Mann-Whitney U-test indicated that there was a statistically significant difference (U = 41, ρ = 0.000, and r = -0.59), across all three case studies between how easy the residents found MVHR to control and how frequently they had the MVHR turned off. Furthermore, Spearman’s rho correlation indicated that there was a strong monotonic relationship (r = 0.632, ρ = 0.000) between the frequency of having MVHR turned off and the perceived summer comfort (Fig. 14). Similarly, strong relationships were also found between frequency of having the MVHR turned off and a) satisfaction with indoor ventilation (r = 0.606, ρ = 0.000) as well as b) perceived indoor air quality (r = 0.405, ρ = 0.004), Fig. 15. Correlation graphs indicated that frequently turned off MVHR units typically resulted in lower satisfaction with summer thermal comfort, ventilation as well as perceived air quality.

Fig. 14- Graph illustrating the correlation between MVHR use and summer indoor temperature satisfaction

Fig. 15- Graph illustrating the correlation between MVHR use frequency and indoor air quality satisfaction

Passivhaus standard in the UK

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Expanding on perceived air quality, 69.4% of occupants were pleased or very pleased, 12.2% were neutral, and 18.4% of residents reported being less pleased with the indoor air quality. Regarding humidity, more than half of the participants found the air to be pleasant, 34.7% though it was dry while remaining 14.3% perceived it as being very dry, however, it was not indicated whether that was a benefit or hindrance. Interestingly, when asked to compare Passivhaus to their previous home in terms of frequency of experiencing colds, allergies, etc. the majority of end-users (71.4%) perceived Passivhaus to be a healthier indoor environment.

Living preferences, lifestyle & overall satisfaction The last section of the POE focused on occupants’ general perceptions, overall satisfaction and changes to daily lifestyle. Firstly, research participants were asked to identify three main reasons why they chose to live in their Passivhaus property. Radar charts (Fig. 16) showed that ‘sustainability’ was ranked to be the top priority for choosing to live in a Passivhaus across all three case studies (71%). Other top reasons were found to be ‘house type’(47%) and ‘house price’ (43%) while ‘community’ was ranked as a top priority in the Forgebank development.

Forgebank Co-housing

Racecourse Estate

Neighborhood 14 12 10 8 6 4 2 0

Neighborhood 8 Other Sustainability 7 6 5 4 Privacy Security 3 2 1 0 Countryside Community

Other Privacy

Countryside

Sustainability Security

Community

Proximity to work Proximity to friends/family

House type House price

Proximity to work Proximity to friends/family

House type House price

Goldsmith Street

Combined

Neighborhood 20

Neighborhood 20

Other Privacy

15 10

Sustainability Security

Other Privacy

15 10

5 0

Countryside

House type House price

Sustainability Security

5 Community

Proximity to work Proximity to friends/family

0

Countryside

House type House price

Community Proximity to work Proximity to friends/family

Fig. 16- Comparison between different reasons for choosing to live in a Passivhaus property

Research participants were then asked if living in a Passivhaus has caused a change towards a more sustainable way of life. Collected data revealed that the majority of occupants (41 out of 49) believed living in a Passivhaus has influenced them to adopt a more sustainable lifestyle with 33% of participants reporting a significant change, 49% reporting moderate change and 18% reporting a slight but noticeable change. In terms of overall satisfaction with Passivhaus buildings, collected POE data highlighted that surveyed residents were exceptionally pleased with their homes across all three case studies.

Approx. 94% of all participants said they were satisfied or very satisfied with their homes, 6% were neither satisfied nor dissatisfied, and there were no occupants that were dissatisfied with their homes. Furthermore, 65% of residents reported that living in a Passivhaus has significantly improved their living standard, 33% identified a moderate improvement, and 2% found that living in a Passivhaus has not affected their standard of living. In retrospect, 98% of surveyed end-users reported they would recommend it to their friends and family as well as choose to live in a Passivhaus home again if given the opportunity.

4.5

Results: semi-structured interviews

Participant background & experience To analyse the construction industryâ&#x20AC;&#x2122;s perceptions of the Passivhaus standard in the UK, five industry specialists based in the North East of England were interviewed for this study.

The surveyed participants included a BIM and digital architecture specialist working in a medium-scale practice with some Passivhaus experience (HT); an associate-level architect and technologist with little Passivhaus experience yet substantial knowledge of delivering CfSH and sustainable housing more generally (MR); architecture professor researching sustainable housing and a current Passivhaus resident (PJ); recently-qualified architect working on an ongoing Passivhaus project (LR); and a Passivhaus consultant with substantial experience in Passivhaus leading a private practice (MS). Fig. 17.

Participant

Position/Role

Sector

Experience

PH Experience

HT

BIM consultant

Private/Public

>15 years

Moderate

MR

Architect/Technologist

Private/Public

>25 years

Limited

PJ

Researcher

-

>20 years

Moderate

LR

Architect

Public

<5 years

Limited

MS

Passivhaus consultant

Private/Public

>20 years

Substantial

Fig. 17- Table showing interview participant categorisation

Perceptions of zero-carbon and Passivhaus In the first part of the interview, participants were asked about sustainable housing more generally as well as about the UK governmentâ&#x20AC;&#x2122;s 2050 zero-carbon target and whether they thought it was feasible. Four out of five participants believed it was achievable, especially regarding the new-build housing; however, all interviewees thought that decarbonising the existing housing was going to be much more challenging. Some participants (MR, PJ, MS) also found a problem with the net zero-carbon definition, claiming it was ambiguous and not particularly useful. Interviewee (PJ) thought it was not clear whether zero-carbon accounted for embodied carbon, how much of it was offset through renewables and how

Passivhaus standard in the UK

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that carbon was calculated. Whereas (MR and MS) believed the term zero-carbon was often used as ‘greenwash’ and did not reflect the actual building emissions. Further, the respondents were asked to identify the main perceived drivers (Fig. 18) and barriers (Fig. 19) for Passivhaus and similar energy-efficient housing development in the UK. Recorded responses have corresponded to the majority of themes identified in the literature review and could be categorised as economic, legislative, environmental, individual & industrial.

Theme Economics

Legislation

Individual Environment Industry

• • • • • • • • • • • • • •

Sub-themes

Sample Quotes

Cost of energy Financial Incentives Investment Building regulations Planning Local authorities Fines & penalties Energy savings Thermal comfort Climate change Fuel poverty Training Education Ethics

‘I suspect increasing fuel prices will push demand for homeowners to go and look at how they upgrade their properties thermally’ [MR] ‘Building Regulations has always been a good driver for improving the thermal efficiency of buildings, and I have seen nothing else that is effective in that way’ [MR] ‘I think pros are very obvious, and it's saving energy’ [PJ] ‘The big driver is the fact that the ice sheets are melting at a quicker rate than we've possibly anticipated’ [PJ] ‘I think in terms of architects (…) RIBA CPDs and having that as part of your training program would be important.’ [LR]

Fig. 18- Identified sustainable housing drivers and their categorization Theme Economics

Legislation

Sub-themes • • • • • •

Industry

Individual

• • • • • • •

Capital cost Perceived cost Supply chain Failed policies Uncertainty with Zerocarbon Retrogressive standards Lack of knowledge Resistance to change Profit-driven system Housebuilding culture Poor competency Public awareness Apprehension

Sample Quotes

‘Even if the clients could recover the cost of the initial investment in a few years, they were still very hesitant to spend extra money initially’ [HT] ‘Code for Sustainable Homes became a tick box exercise (…)

I think we have already proved that that approach doesn’t work’ [MR] ‘The construction industry, more than any other industry that I can think of is incredibly risk-averse, isn't it? We don't like to try new things.’ [MS]

‘People need to understand how to use their homes efficiently and how to get the most out of the technology that they have…’ [HT]

Fig. 19- Identified sustainable housing barriers and their categorisation

The second part of the interviews focused explicitly on the Passivhaus standard and its application in the UK. The participants were asked to describe how familiar they were with the standard and briefly recount the Passivhaus projects that they have been involved in.

Afterwards, they were asked to identify perceived Passivhaus strengths (Fig. 20) as well as weaknesses or the main barriers preventing the adoption of the standard at scale (Fig. 21).

Theme

Sub-themes

Economics

• •

Long-term investment Energy-efficiency

Methodology

•

Fabric-first approach

Quality

• • • •

Quality assurance No performance gap Marketing value Established brand

Brand

Sample Quotes

‘…you need to encourage people and educate them that even if they spend more money on Passivhaus initially, they could be saving money long-term’ [HT] ‘Fabric first is a great way of achieving it (…) where you have to be using better building materials and better building techniques to seal the building.’ [MR] ‘The pros are you end up with a very efficient house that should last for decades…’ [MR] ‘I think a pro is selling something that you can attach a label to like a Passivhaus (…) You’ve got that extra marketing value’[MR]

Fig. 20- Identified Passivhaus standard’s strengths and their categorisation

Theme

Sub-themes

Sample Quotes

Availability

• • •

Capital cost Cost of components Commerciality

Usability

•

Occupant behaviour

Complexity

• •

Certification Bureaucracy

Passivhaus Technology

• •

Insulation MVHR

Design

• • •

Inflexibility Software Climate

Economics

‘They cost a lot more money than a normal house…’ [PJ] ‘Passivhaus- the organisation needs to relax its stance and make it available to everyone in the industry. Whereas at the moment it’s only available to certain few…’ [MR] ‘It doesn't just run itself. If you're somebody who (…) gets a Passivhaus and doesn't engage with it daily, then it will let you down’ [PJ] ‘One of the challenges or the negatives of the Passivhaus is the certification process, and the difficulty in getting the skillset to get it certified’ [LR] ‘To achieve Passivhaus level U-values, you typically need very thick insulation, which is difficult to fit within an existing building without compromising too much internal floor area.’[HT] ‘The difficulty I would say is that it's limiting in terms of design. As a designer, you are not 100% free.’ [HT]

Fig. 21- Identified Passivhaus standard’s weaknesses/barriers and their categorisation

In the last section of the interview, participants were asked about policy changes that would most likely drive Passivhaus or equivalent standard adoption at scale. Three respondents believed Building regulations would be the most significant driver; one interviewee thought it was planning policies while the other participant argued an entirely new overarching policy similar to the Code for Sustainable Homes was needed.

Interviewees disagreed whether the Passivhaus standard was the best approach to be adopted in the UK to meet the 2050 net zero-carbon target. Nevertheless, all participants concluded that Passivhaus standard could help to form a foundation for a more robust zero-carbon policy which was currently lacking. In summary, (HT) believed Passivhaus was the most available and common route to deliver sustainable housing in the UK yet was doubtful if the standard was suitable for warmer climates where active cooling was needed.

(MR) praised the standard for its ‘fabric-first’ approach; however, he was concerned about Passivhaus commerciality believing it had to be fully open-source to be adopted at scale.

(MS) argued that Passivhaus was the only methodology addressing the energy ‘performance gap’ and providing tangible energy-savings and carbon reductions. (LR) found Passivhaus to be a well established and evidence-based standard which focused on user comfort, whereas (PJ) thought that not enough attention was given to occupant behaviour and engagement necessary to operate a Passivhaus dwelling successfully.

5.1

Discussion: post-occupancy evaluations

The three case studies selected for this research were deliberately chosen to vary in their scale, location, construction, ownership, etc. thus allowing to investigate and compare Passivhaus performance under different circumstances. Post-occupancy evaluation data and subsequent SPSS analysis revealed there were significant differences between the case studies in terms of their occupant demographics, household types, occupancy and heating patterns as well as heating and cooling strategies. Nonetheless, the SPSS analysis also indicated a number of commonalities and reoccurring patterns between the case studies regarding thermal comfort, energy savings, ventilation and overall satisfaction.

Thermal comfort and overheating Examined POE data revealed that Passivhaus dwellings across all three case studies were found to be exceptionally comfortable during the winter, autumn and spring seasons.

However, all three case studies were also found to have a consistently lower thermal

Passivhaus standard in the UK

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satisfaction in the summer months due to reported overheating. Out of the case studies, Racecourse Estate was found to have the lowest summer comfort satisfaction with a mean value of (µ = 3.33). Such results confirm previous study findings on the Racecourse Estate, where substantial overheating was recorded (22), (55). Interestingly, cooling habit analysis (Fig. 12) highlighted that Racecourse Estate had the lowest reported use of MVHR, operable windows as well as solar shading which all have contributed to higher internal temperatures and lower thermal comfort. Such a proposition is supported by academic literature, indicating that window purge ventilation, solar shading and correct use of MVHR have a significant effect on preventing overheating in Passivhaus dwellings (56), (57), (58).

Energy savings Despite significant differences in scale, location and occupancy, POEs from three Passivhaus case studies reported fairly consistent energy savings (Fig. 13). Racecourse Estate had the lowest reported heating bills with 77.8% of occupants paying less that £50, however, Forgebank and Goldsmith St. had relatively similar figures of 66.7% and 72% respectively. A non-parametric Kruskal-Wallis test was conducted to test for statistically significant differences between the case studies and reported monthly energy costs. Test results indicated that the mean ranks for variables were similar (26,17; 23,44; 24,86) with p = 0.843, meaning the null hypothesis had to be retained and there was little to no statistical significance between the case studies and reported energy savings. Therefore, it could be argued that based on collected data Passivhaus methodology can deliver notable space heating reduction and energy savings irrespective of building’s location, scale, typology or construction type, thus confirming CEPHEUS research conclusions (59). That said, while the reported average energy savings were in line with other Passivhaus case study findings across the UK (60), (61), (62) a notable segment of properties (28.6%) reported costs in the range of £50-100 which are comparatively higher than the Passivhaus benchmark (63).

MVHR, ventilation & air quality Conducted SPSS analysis indicated that while MVHR was the main ventilation strategy adopted across all three case studies, there were some notable discrepancies in terms of perceived MVHR knowledge and frequency of use. A strong relationship was found between receiving MVHR induction or having a user manual, and how easy occupants found MVHR to control, which in turn affected how frequently they tended to use it.

Literature review suggests this is often the case in Passivhaus dwellings, where a lack of information generates uncertainty in MVHR technology, causing some residents to either switch the system completely off or install additional humidifiers and coolers to achieve thermal comfort (29), (64), (57). Furthermore, analysed results indicated a significant correlation between the frequency of having MVHR turned off and the perceived summer comfort, ventilation and air quality satisfaction, hence making a case that correct commissioning and use of MVHR is essential for Passivhaus operation. This has been confirmed by several studies (64), (65), (66), (67) highlighting that poor understanding of MVHR settings such as the summer bypass mode, lack of filter maintenance as well as its disuse can significantly undermine mechanical ventilation performance, exacerbate summer overheating as well as present indoor air quality problems.

Overall satisfaction In terms of overall satisfaction, collected POEs indicated that very high user satisfaction was reported across all three case studies despite significant differences between the Passivhaus properties. The vast majority of residents identified being either satisfied or very satisfied with Passivhaus thermal comfort, energy savings, building services, air quality as well as the overall effect it had on their standard of living. Such high levels of reported occupant satisfaction confirm previous Passivhaus research findings from both Continental Europe (68), (69) as well as the UK (22) where Passivhaus properties were found to be exceptionally comfortable and energy-efficient.

5 .2

Discussion: semi-structured interviews

Passivhaus adoption drivers Examined interview transcripts revealed that legislation was jointly seen as the most significant driver for Passivhaus adoption and delivery in the UK; identified a total of 23 times (Fig. 22 & 23). Under the legislation theme, a series of subcategories were identified out of which building regulations; specifically, Parts L and F were seen as the most impactful for Passivhaus uptake. The legislation was the only Passivhaus driver theme identified by all interviewees and at least a couple of times in contrast to other themes that were identified only by several participants. The industry theme encompassing aspects like professional training, education and ethics, was recognized as the second most significant driver mentioned a total of 10 times. In contrast, the economics theme covering aspects like financial incentives and cost of energy was the third most considerable driver cited 7 times yet by a higher number of interviewees than the industry. Interestingly, individual and environmental drivers were seen as the least significant for Passivhaus uptake and delivery mentioned only 2 and 3 times, respectively. Such findings confirm previous research results on Passivhaus and zero-carbon housing perceptions in the UK (19) where legislation was also identified to be the most significant driver followed by economics. By contrast, the industry- which was identified as the second most significant Passivhaus driver in this study was deemed to be the least important factor by the mentioned research paper (19).

Participant

Economics

Legislation

Individual

Environment

Industry

Total

HT MR PJ LR MS Total

2 2 2 0 1 7

3 6 2 6 6 23

0 0 1 1 0 2

0 0 2 0 1 3

1 0 0 3 6 10

6 8 7 9 14 45

Fig. 22- Number of Passivhaus driver themes mentioned per participant from Nvivo matrix coding query 25 20 15 10 5 0 Economics

Legislation

Individual HT

MR

PJ

LR

Environment

Industry

MS

Fig. 23- Number of instances Passivhaus drivers were identified for every category by each interviewee

Passivhaus standard in the UK

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26

Passivhaus adoption barriers In terms of barriers, the industry (identified a total of 14 times) was considered to be the most significant barrier for Passivhaus adoption and delivery in the UK (Fig. 24 & 25). The main perceived barriers covered by the industry theme were the industryâ&#x20AC;&#x2122;s resistance to change, volume housebuilding culture and profit-driven business models that stifle innovation and voluntary standards adoption. Many participants expressed strong and definite opinions about the industry more so than with other themes, thus affirming its significance as a barrier not only quantitatively but in terms of semantics as well.

Interestingly, legislation- which was perceived as the biggest driver for Passivhaus adoption was also considered to be its second-biggest barrier. Legislative subthemes included the failure and withdrawal of the Code for Sustainable Homes policy, retrogressive legislation such as the Future Homes Standard as well as uncertainty with the current zero-carbon approach and definition. Individual barriers were considered less significant than legislative yet were identified by a larger number of interviewees and mentioned 8 times in total. A particular noteworthy barrier was the lack of public awareness which was determined by four out of five respondents. Surprisingly, economic barriers such as a higher capital cost and immature supply chain were perceived to be the least significant for Passivhaus standards uptake in the UK. However, this could be partly explained, given that as the Passivhaus standard is becoming more common in the UK, its construction costs would be decreasing (70). A current indicative best practice Passivhaus build cost is just below ÂŁ1500/m2 in contrast to ÂŁ2000/m2 reported back in 2015 when the study was first conducted (70).

Participant

Economics

Legislation

Individual

Industry

Total

HT MR PJ LR MS Total

1 1 0 4 0 6

0 4 3 0 3 10

1 0 2 1 4 8

0 2 7 2 3 14

2 7 12 7 9 37

Fig. 24- Number if Passivhaus barrier themes identified per participant from Nvivo matrix coding query 15 10 5 0 Economics

Legislation HT

Individual MR

PJ

LR

Industry

MS

Fig. 25- Number of instances Passivhaus barriers were identified for every category by each interviewee

Passivhaus strengths & weaknesses In regards to the Passivhaus standard itself, interviewees were divided about its perceived benefits and shortcomings as well as whether it should be adopted at a national scale to achieve UKâ&#x20AC;&#x2122;s climate goals. Nvivo analysis revealed that participants were able to identify more Passivhaus weaknesses than strengths, both in terms of the number of subcategories and the frequency of mentions indicating a leaning towards a wary perception of the standard at present (Fig. 26 & 27). The biggest Passivhaus weakness was seen to be its availability, mentioned 8 times, referring to the standardâ&#x20AC;&#x2122;s commerciality, associated software, training and certification costs as well as not being a UK native brand. The second biggest weakness was perceived to be Passivhaus standardâ&#x20AC;&#x2122;s complexity, mentioned 5 times yet by a higher number of respondents. The Passivhaus complexity comprised aspects such as the certification process, associated paperwork and bureaucracy as well as practical issues relating to detailing or building material selection and sourcing. Another noteworthy weakness identified by the respondents was the actual design process referring to the complexity of the SPSS software, limitations in terms of building form, glazing and choice of products as well as its suitability for different climates. On the other hand, Passivhaus greatest strength was perceived to be its quality, both in terms of quality assurance, minimising the performance gap as well as delivering definite energy savings and carbon reductions. The other key strength of the standard was perceived to be the Passivhaus brand itself, referring to its well-established methodology, internationally recognized name, environmental credentials and additional marketing value.

Participant

Availability

Complexity

Design

Economics

Technology

Usability

Total

HT MR PJ LR MS Total

0 7 0 0 1 8

1 1 1 2 0 5

5 0 0 1 0 6

0 1 1 0 0 2

1 0 1 0 0 2

0 0 4 0 0 4

7 9 7 3 1 27

Fig. 26- Number of Passivhaus weakness themes mentioned per participant from Nvivo coding query 9 8 7

6 5 4 3 2 1 0 Availability

Complexity

Design HT

MR

Economics PJ

LR

Technology

Usability

MS

Fig. 27- Number of Passivhaus weaknesses identified for every category by each interviewee

Passivhaus standard in the UK

27

28

6.1

Conclusion

The aim of this study was to analyse the Passivhaus standard in the UK in its present condition through the construction industryâ&#x20AC;&#x2122;s perceptions as well as current occupant experiences. Forty-nine post-occupancy evaluations conducted in three separate case studies across the UK revealed that occupants were generally very pleased with their Passivhaus dwellings. Residents reported high levels of satisfaction with both internal thermal comfort, monthly energy-savings as well as acoustics, air quality and perceived impact on health. Some of the reported issues with Passivhaus were regarding overheating in the summer months and poor ventilation. However, research findings indicated this was primarily due to incorrect operation of the MVHR units and disuse of natural ventilation and solar shading. Subsequent statistical analysis suggested that in large part this could be attributed to a lack of end-user inductions and limited information regarding MVHR. In general, research results were consistent with previous literature findings and the hypothesis that Passivhaus methodology can deliver highly comfortable homes and substantial energy savings regardless of buildingâ&#x20AC;&#x2122;s location, occupancy or construction.

In terms of industry perceptions, conducted semi-structured interviews with five construction industry professionals indicated conflicting views regarding the Passivhaus standard and its effectiveness in the UK. While more drivers than barriers were identified for Passivhaus delivery in the UK, highlighting a suitable market environment for energyefficient housing, the standard itself was perceived with wariness. The principal Passivhaus drivers were identified to be legislative, namely Building Regulation Parts L and F, and local authority frameworks as well as industrial such as professional training, education and ethics. The primary barrier, interestingly, was also identified as being industrial, referring to the industryâ&#x20AC;&#x2122;s resistance to change, volume housebuilding culture as well as profit-driven business models. The second biggest barrier was perceived to be legislative encompassing the past failures of the Code for Sustainable Homes policy, retrogressive legislation as well as uncertainty with the current zero-carbon approach. In terms of the Passivhaus standard itself, its main strengths were perceived to be its quality, focus on energy-efficiency as well as an established brand with strong marketing value. In contrast, its biggest weakness was considered to be its accessibility as well as complexity in terms of design, detailing, required training and certification. Nonetheless, participants believed that the Passivhaus standard had the potential to form a foundation for a more robust sustainable housing policy which is currently lacking in the UK. 6.2

Research limitations and recommendations

The conducted research was based on relatively limited data samples collected from three case studies and five semi-structured interviews. Hence it is questionable if the study findings can provide a generalisation of all Passivhaus dwellings across the UK, and thus further research is warranted. That said, the study did provide informative insights into existing large-scale Passivhaus developments and their occupant experiences as well as currently held perceptions on the Passivhaus standard from the industry specialists, specifically in the North East of England. Further research would benefit from revisiting examined case studies, especially Goldsmith Street in Norwich to test if user experiences have changed over time. Whereas subsequent research on industry perceptions would require a larger sample size, especially including interviewees from different backgrounds such as contractors, developers, engineers and local authorities.

7.1

Bibliography

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18. Schoenefeldt, Henrik, et al. Interrogating the technical, economic and cultural challenges of delivering the PassivHaus standard in the UK. Centre for Architecture and Sustainable Environment, University of Kent. Canterbury: Kent School of Architecture, 2014.

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20. Feasibility of zero carbon homes in England by 2016: A house builder’s perspective.

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455–472.

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26. Perceived Knowledge in Operating a Passivhaus. Zhao, Jing and Carter, Kate. Genova: The Architectural Science Association & Genova University Press, 2014. Architectural Research through to Practice: 48th International Conference of the Architectural Science Association 2014. pp. 139-150.

27. An empirical evaluation of temporal overheating in an assisted living Passivhaus dwelling in the UK. Fletcher, M J, et al. 15, Leeds: Elsevier Ltd., 2017, Building and Environment, Vol. 121, pp. 106-118.

28. Overheating investigation in UK social housing flats built to the Passivhaus standard.

Sameni, Seyed Masoud Tabatabaei, et al. Coventry: Elsevier Ltd., 2015, Building and Environment, Vol. 92, pp. 222-235.

29. Improving passive house certification: recommendations based on end-user experiences. Mlecnik, Erwin. 4, s.l. : Taylor & Francis, 2007, Architectural Engineering and Design Management, Vol. 9, pp. 1752-7589.

30. Revisiting the Quantitative-Qualitative Debate: Implications for Mixed-Methods Research. Sale, Joanna E M, Lohfeld, Lynne H and Brazil, Kevin. 2002, Quality & Quantity, pp. 43–53.

31. Fellows, Richard and Liu, Anita. Research Methods for Construction. Oxford: John Wiley and Sons Ltd., 2015.

32. Lucas, Ray. Research Methods for Architecture. London: Laurence King Publishing Ltd, 2016.

33. Bridging the chasm between survey and case study research: Research methods for achieving generalization, accuracy, and complexity. Woodside, Arch G. 1, Chestnut Hill: Elsevier Inc., 2010, Industrial Marketing Management, Vol. 39, pp. 64–75.

34. Feagin, Joe R, Orum, Anthony M and Sjoberg, Gideon. A Case for the Case Study.

London: The University of North Carolina Press, 1991.

35. Yin, Robert K. Case Study Research and Applications: Design and Methods. Los Angeles: SAGE Publications, 2018.

36. Post-Occupancy Evaluation: An Inevitable Step Toward Sustainability. Meir, Isaac A, et al. 1, s.l. : Taylor & Francis, 2009, Advances in Building Energy Research, Vol. 3, pp. 189219.

37. HEFCE. Post Occupancy Evaluation Toolkit. Space Management Group. [Online], 2006. http://www.smg.ac.uk/supp_occupancy.html.

38. Steen, Ole P. Sustainable Social Housing Performance and Adoption of Energy Efficient Technologies- Empirical evaluation of occupant behaviour and home energy use in lowcarbon affordable housing schemes in South Tyneside and Hebburn in the United Kingdom. Issue. [Online] 16 January 2015. https://issuu.com/olepettersteen/docs/steen__ba_disstertation_2015_print.

39. Morgan, George, A, et al. IBM SPSS for Introductory Statistics. London: Routledge, 2011.

40. Bryman, Alan and Cramer, Duncan. Quantitative Data Analysis with IBM SPSS 17, 18 &19: A Guide for Social Scientists. London: Routledge, 2011.

41. Purposeful sampling for qualitative data collection and analysis in mixed method implementation research. Palinkas, Lawrence A, et al. 5, s.l. : NCBI, 2015, Administration and Policy in Mental Health and Mental Health Services Research, Vol. 42, pp. 533–544.

42. Salonga, Sophie. Types of Transcription Explained: Verbatim vs Intelligent vs Edited Transcription. Globalme Language & Technology. [Online] 19 July 2019. https://www.globalme.net/blog/verbatim-vs-intelligent-vs-edited-transcription.

43. Smith, Jonathan, A. Qualitative Psychology: A Practical Guide to Research Methods.

3rd. London: SAGE Publications Ltd, 2015.

44. Techniques to Identify Themes. Ryan, Gery W and Bernard, H Russell. 1, Gainesville: Sage Publications, 2003, Field Methods, Vol. 15, pp. 85–109.

45. Passivhaus Trust. Lancaster Cohousing Project. Passivhaus Trust. [Online] 21 January 2020. http://passivhausbuildings.org.uk/viewproject.php?id=325#description.

46. Technology Strategy Board. Building Performance Evaluation. s.l. : Technology Strategy Board, 2013.

47. Lancaster Cohousing. About us. Lancaster Cohousing. [Online] 21 January 2020. https://www.lancastercohousing.org.uk/About.

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32

48. Eco Arc. Lancaster Cohousing Project: Design Philosophy & Innovation Report For The Passive House Trust Awards 2013. Ecological Architecture Practice. [Online] 10 May 2016. https://ecoarc.co.uk/wp-content/uploads/2016/05/Lancaster-Green-Building-MagazineArticles.pdf.

49. Technology Strategy Board. Racecourse: Building Performance Evaluation. London: Good Homes Alliance, 2014.

50. Passivhaus Trust. UK Passivhaus Trust Awards 2013: Racecourse Estate Passivhaus.

Passivhaus Trust. [Online] 2013 b. http://www.passivhaustrust.org.uk/UserFiles/File/UK%20PH%20Awards/2013/Posters/UKP HAwardsPoster_social%20housing_Racecourse(1).pdf.

51. Priest, Isabelle. The morality tale of Norwich’s social housing. RIBA Journal. [Online] 20 August 2019. https://www.ribaj.com/buildings/mikhail-riches-goldsmith-street-socialhousing-norwich-passivhaus-stirling-prize.

52. Waite, Richard. RIBA Stirling Prize 2019 goes to Goldsmith Street council housing scheme. Architects' Journal. [Online] 8 October 2019. https://www.architectsjournal.co.uk/news/riba-stirling-prize-2019-goes-to-goldsmithstreet-council-housing-scheme/10044745.article.

53. Passivhaus Trust. Goldsmith Street crowned prize-winning Passivhaus. Passivhaus Trust.

[Online] 9 October 2019. https://www.passivhaustrust.org.uk/news/detail/?nId=859.

54. Greengauge. Ambitious M&E Design for RIBA Stirling Prize Winning Housing- UK's Largest Passivhaus Social Housing Development. Greengauge. [Online] 23 January 2020. https://ggbec.co.uk/portfolio/ambitious-me-design-for-uks-largest-passivhaus-socialhousing-scheme.

55. An empirical evaluation of temporal overheating in an assisted living Passivhaus dwelling in the UK. Fletcher, M, J, et al. 15, Leeds: Elsevier Ltd., 2017, Building and Environment, Vol. 121, pp. 106-118.

56. An investigation into future performance and overheating risks in Passivhaus dwellings.

McLeod, Robert S, Hopfe, Christina, J and Kwan, Alan. Cardiff: Elsevier Ltd., 2013, Building and Environment, Vol. 70, pp. 189-209.

57. Do passive houses need passive people? Evaluating the active occupancy of Passivhaus homes in the United Kingdom. Zhao, Jing and Carter, Kate. Edinburgh: Elsevier Ltd., 2020, Energy Research & Social Science, Vol. 64.

58. Overheating investigation in UK social housing flats built to the Passivhaus standard.

Sameni, Seyed Masoud Tabatabaei, et al. Coventry: s.n., 2015, Building and Environment, Vol. 92, pp. 222-235.

59. CEPHEUS – measurement results from more than 100 dwelling units in passive houses.

Schnieders, Jürgen. s.l. : ECEEE, 2003. ECEEE 2003 Summer Study – Time to Turn Down Energy Demand. pp. 341-351.

60. Passivhaus Trust. Passivhaus social housing: Cost research. Passivhaus Trust. [Online] 29 June 2017. https://www.passivhaustrust.org.uk/news/detail/?nId=712.

61. Price, Sarah and Brown, Helen. Whole-life costs of a Passivhaus: Sensitivities of wholelife cost analysis for domestic Passivhaus buildings. Passivhaus Trust. [Online] 20 February 2014. https://www.passivhaustrust.org.uk/UserFiles/File/Technical%20Papers/TechnicalInsight-February-2014-Whole-life-Costs-of-a-Passivhaus%20by%20Encraft.pdf.

62. Bere, Justin. An Introduction to Passive House. London: RIBA Publishing, 2013.

63. Jennifer, Hardi and Chris, Parsons. Cost of delivering to Passivhaus Standard.

ResearchGate. [Online], 2013.

https://www.researchgate.net/publication/275020729_Cost_of_delivering_to_Passivhaus_ Standard.

64. Indoor air quality investigation in code for sustainable homes and passivhaus dwellings.

McGill, Grainne, Oyedele, Lukumon O and Keeffe, Greg. 1, s.l. : Emerald Insight, 2015, World Journal of Science, Technology and Sustainable Development, Vol. 12, pp. 39-60.

65. Overheating risk in Passivhaus dwellings. Mitchell, Rachel and Natarajan, Sukumar. s.l. : SAGE Journals, 2019, Building Services Engineering, Research & Technology, pp. 446-469.

66. A case study investigation of indoor air quality in UK Passivhaus dwellings. McGill, GrĂĄinne, Qin, Menghao and Oyedele, Lukumon. Belfast: Elsevier Ltd., 2014, Energy Procedia, Vol. 62, pp. 190 -199.

67. Climate Resilience in New-Build Social Housing: Challenges, opportunities and unintended consequences. Gupta, Rajat, Kapsali, Mariam and Gregg, Matt. Sheffield: The School of Architecture, University of Sheffield, 2015. Architecture and Resilience on the Human Scale. pp. 497-506.

68. Cutland, Neil. Lessons from Germanyâ&#x20AC;&#x2122;s Passivhaus experience. Milton Keynes: NHBC Foundation, 2012.

69. Mlecnik, Erwin. Innovation development for highly energy-efficient housingOpportunities and challenges related to the adoption of passive houses. Amsterdam: IOS Press, BV, 2013.

70. Passivhaus Trust. Passivhaus Construction Costs. London : Passivhaus Trust, 2019.

7.2

List of figures

Fig. 4- Pitt, Vern. Lancaster Cohousing. [internet]. 2013 [cited 01 May 2020]. Available from: https://www.building.co.uk/news/lancaster-cohousing-tales-from-the-riverbank/5063953.article Fig. 5- Eco Arc. Lancaster Cohousing Project. [internet]. 2013 [cited 01 May 2020].

Available from: https://ecoarc.co.uk/wp-content/uploads/2016/05/Lancaster-GreenBuilding-Magazine-Articles.pdf Fig. 6- Siddall, Mark. Racecourse: Passivhaus Estate. [internet]. 2012 [cited 01 May 2020].

Available from: http://leap4.it/filter/LEAP/Racecourse-Passivhaus-Estate Fig. 7- Gentoo Homes. 28 Bungalows at Racecourse Estate, Houghton-le-Spring. [internet].

2009 [cited 01 May 2020]. Available from:https://www.insidehousing.co.uk/news/news/ first-uk-homes-meet-german-eco-standard-13745 Fig. 8- Crocker, Tim. Mikhail Riches- Goldsmith Street. [internet]. 2019 [cited 01 May 2020].

Available from: http://www.mikhailriches.com/project/goldsmith-street/#slide-2 Fig. 9- Mikhail Riches- Goldsmith Street. [internet]. 2018 [cited 01 May 2020]. Available from: https://ukphc.org.uk/wp-content/uploads/2017/09/Achieving-Passivhaus-at-ScaleDavid-Moorcroft-Norwich-City-Council-James-Turner-Mikhail-Riches.pdf

Passivhaus standard in the UK

33

34

8.0

Appendicies

8.1

Appendicies- Post-occupancy evaluation example Department of Architecture and Built Environment Architecture (MArch) inProgramme terview eofxaStudy: mple Supervisor: Dr Zaid Alwan Researcher: Mr Adam Novogrodskis

8.2

Appendicies- Semi-structured

8.3

Appendicies- Transcript from an interview with HT

Sustainable Homes for the Future: Goldsmith Street, Norwich Passivhaus as a route to achieving net-zero carbon new-build housing in the UK by 2050

8.4

Appendicies- Transcript from an interview with MR

Purpose of the Study This survey is a post-occupancy evaluation of your building to analyse how well it performs

8 .5its occupants.

AppendThe iciestudy s- Traaims nscrto iptassess fromresidentsâ&#x20AC;&#x2122; an intervthermal iew witcomfort, h PJ for energy savings,

and overall experience living in a low-carbon home. Data collected in this research will be used to identify areas of improvement, provide feedback for similar buildings, compare Passivhaus to conventional new-build homes, and help to get a better understanding survey research at North8 .6 of sustainable Appendihousing cies- Trin anthe scrUK. ipt This from an inwill terbe vieused w wiin thongoing LR umbria University in Newcastle with the intent to publish it in a post-graduate dissertation next year. This questionnaire takes about 7 minutes to complete.

Consent

8.7

Appendicies- Transcript from an interview with MS

If you are interested in taking part, please read the participant information sheet and keep a copy for your records. Feel free to discuss it with others and ask any questions.

If you agree, please tick the boxes below, sign and turn the page to start the survey.

8.8 I have App endand iciesunderstand - SPSS anathe lyspurpose is data of the study, and agree to participate read 8.9

I have had the opportunity to ask questions and discuss this study and I have received satisfactory answers

Appendicies- Nvivo analysis data

I understand I am free to withdraw from the study at any time, without having to give a reason for withdrawing, and without prejudice I am aware that my name and details will be kept confidential and will not appear in any printed documents I consent to the retention of this data under the condition that any subsequent use also be restricted to research projects that have gained ethical approval from Northumbria University.

I agree to the University of Northumbria at Newcastle recording and processing this information about me. I understand that this information will be used only for the purposes set out in the information sheet supplied to me, and my consent is conditional upon the University complying with its duties and obligations under the Data Protection Act 2018 which incorporates General Data Protection Regulations (GDPR)

Name Signature

Date

If you prefer doing the survey online, please visit: www.surveymonkey.co.uk/r/PYPW5H7

1. Background What is your age? (please check box that applies) <18

18-30

31-50

>50

What is your gender?

Female

Male

Other

Prefer not to say

How many years have you lived in this house?

Less than 1 year

1-2 years

3-4 years

5 years or more

Are you the tenant or the owner of the house?

Tenant Owner

2. Occupancy, Building Type and Use What type of house do you live in?

Detached

Semi-detached

Terrace

End of terrace

Flat

Other

How many people currently live in this house?

1

2

3

4

5

6 or more

How many bedrooms do you have?

1 Bedroom 3 Bedrooms

Passivhaus standard in the UK

2 Bedrooms 4 Bedrooms

35

36

Why did you choose to live in this house? Please check three most important factors Neighbourhood

Sustainability/Energy savings

Safety/Security

Community

Proximity to work/school

Proximity to friends/family

House price

House type/size

Countryside/Green space

Other

When is your house typically occupied? Check all that apply Daytime

Weekends

Evenings

Not often

3. Thermal Comfort How pleased are you with the indoor temperature during winter? Check box that applies Very Pleased

Pleased

Less Pleased

Neither

Not Pleased

How pleased are you with the indoor temperature during autumn/spring?

Very Pleased

Pleased

Less Pleased

Neither

Not Pleased

How pleased are you with the indoor temperature during summer?

Very Pleased

Pleased

Less Pleased

Neither

Not Pleased

When do you typically have the heating on during winter season? Check all that apply In the morning

In the evening

Throughout the day

At night

Depending on the need

Never

Goldsmith Street Passivhaus Post-occupancy Evaluation

Which of the following do you use to control the indoor temperature? Check all that apply Central heating (boiler, radiators, etc.)

Mechanical Heat Recovery Ventilation

Windows (open/close as necessary)

Blinds, shutters or solar shades

Air conditioner

Fireplace or stove heater

Portable heater (fan, convector, etc)

Portable cooler (evaporative fan, etc.)

Ground/air source heat pumps

Other

4. Energy Savings After moving into this house, have you noticed a difference in your heating costs?

Significant reduction in bills

Same as before

Slight reduction in bills

Increased heating bills

What are the combined average monthly heating & hot water costs in your house? <£50

£50-£100

£100-£150

>£150

Did you expect such heating costs in this house before moving in?

Yes

I was not sure what to expect

No (please see the question below)

Overall, how pleased are you with the cost of heating your house?

Very Pleased

Pleased

Neither

Less Pleased

Not Pleased

Considering Passive House costs/price against the provided energy savings, thermal comfort and other benefits, do you think it offers good value for money?

Yes No

Goldsmith Street Passivhaus Post-occupancy Evaluation

Passivhaus standard in the UK

37

38

5. Building Services and Ventilation What building services do you have installed in your house? Check all that apply Mechanical Heat Recovery Ventilation

Ground/air source heat pumps

Gas/electric heating system

Biomass heating system

Solar panels (photovoltaic)

Solar water heating (thermal)

District heating/cooling system

Solar shading

Energy monitoring system (smart meter)

Programmable thermostat

Occupancy sensors (motion detector)

Air conditioner

Fireplace/wood burning stove

Other

From selected services, how pleased are you with their quality and performance?

Very Pleased

Pleased

Neither

Less Pleased

Not Pleased

â&#x20AC;˘ If less/not pleased, could you please specify why?

Overall, how pleased are you with ventilation in your house?

Very Pleased

Pleased

Neither

Less Pleased

Do you have a heat recovery ventilation (MHRV) unit in your house?

Yes No (please skip the next 4 questions)

Do you find heat recovery ventilation unit easy to control/understand?

Yes No

Were you briefed on how to use the heat recovery ventilation unit?

Yes No Goldsmith Street Passivhaus Post-occupancy Evaluation

Not Pleased

Do you have the user manual for the heat recovery ventilation unit?

Yes No

How often do you shut down the heat recovery ventilation?

Never

Rarely

Sometimes

Often

Always

How pleased are you with the indoor acoustics/sound of ventilation in your house?

Very Pleased

Pleased

Neither

Less Pleased

Not Pleased

6. Air Quality and Behavioural Patterns How pleased are you with the air quality in your room? (stuffy/stale/bad odour, etc.)

Very Pleased

Pleased

Neither

Less Pleased

Not Pleased

In terms of humidity, how do you experience the overall air quality?

Very Dry

Dry

Pleasant

Humid

Very Humid

In comparison to your previous home, how often do you experience colds & air borne infections/allergies/wheezing/chest pain/dry throat/fatigue, etc.?

Never

Rarely

Sometimes

Often

Always

Goldsmith Street Passivhaus Post-occupancy Evaluation

Passivhaus standard in the UK

39

40

Has living in this Passivhaus caused a change towards a more sustainable way of living?

Yes No

To what extent have you experienced a behavioural change and awareness towards your energy consumption and carbon emissions?

Significant

Little

Moderate

None at all

7. Overall Impression Overall, did living in a Passivhaus improve or reduce your living standard?

Significantly Improved

Moderately Improved

Same as before

Somewhat Reduced

Significantly Reduced

All things considered, how pleased are you with your current house?

Very Pleased

Pleased

Neither

Less Pleased

Not Pleased

All things considered, would you ever choose to live in a Passive House again?

Yes No

Knowing what you know now, would you recommend it to your friends or family?

Yes No

This is the end of the survey. Thank you very much for your participation!

Once completed, could you please post this survey using the pre-paid envelope.

Once again, thank you for taking the time to complete this survey. I truly value the information you have provided. Your response will contribute greatly to the ongoing research on sustainable housing in the UK.

8.1

Appendicies- Post-occupancy evaluation example

8.2

Appendicies- Semi-structured interview example Department of Architecture and Built Environment (MArch) anProgramme interviewofwStudy: ith HArchitecture T Supervisor: Dr Zaid Alwan Researcher: Mr Adam Novogrodskis

8.3

Appendicies- Transcript from

8.4

Appendicies- Transcript from an interview with MR

Sustainable Homes for the Future:

Passivhaus as a route to achieving net-zero carbon new-build housing in the UK by 2050

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Appendicies- Transcript from an interview with PJ

Introduction My name is Adam. I’m a post-graduate student from Northumbria University at Newcastle, com-

8 .6 my Ap pendicdegree ies- TrinaArchitecture. nscript from n intervwriting iew waithdissertation LR pleting master’s I’macurrently on the Passivhaus

standard where I’m analysing whether Passivhaus could be used as a way to achieve net-zero carbon housing in the UK. My research aims to examine the government’s newly announced 2050 zero-carbon target and analyse whether it is feasible in terms of housing; identify current drivers and and 8 .7 barriers Apof pezero-carbon ndicies- Thousing ranscriuptake pt from andelivery intervin iethe w wcurrent ith MSUK’s construction industry as well as discuss existing and former zero carbon housing policies and their success. Most specifically, the study aims to examine the Passivhaus standard in the UK context, its relation to the zerocarbon target as well as potential challenges and opportunities in adopting it on a national scale.

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Appendicies- SPSS analysis data

Conflicts of Interest Statement Apart from Northumbria University, I have no affiliations with or involvement in any organization or entity with any financial or non-financial interest in the subject matter or findings of this interview.

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Appendicies- Nvivo analysis data

Purpose of the Study As part of the wider research, I am conducting a series of semi-structured interviews with a range of construction industry professionals such as architects, contractors, planners, developers, etc. where I am aiming to collect their expert opinion on the Passivhaus standard as well as zero-carbon housing generally and discuss its delivery, challenges and opportunities within a UK context.

The interviews seek to collate respondent’s thoughts on the newly announced 2050 net-zero carbon target and its feasibility, main drivers and challenges facing the UK’s construction industry to deliver it nationwide as well as Passivhaus standard specifically as one of the possible routes to achieve it. Interviewed professionals will have a chance to share their experience of zero-carbon homes and express their views and recommendations on how to improve their quality, delivery, and adoption on a large scale. Interview takes about 30 minutes to complete.

Consent I have been briefed about this research project and its purpose and agree to participate I have discussed any requirement for anonymity or confidentiality with the researcher I agree to be audio recorded during this interview for the purpose of transcription Specific requirements for anonymity, confidentiality, data storage, retention and destruction

Name Signature

Date

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Background 1.

• • •

To start things off, could please describe your work experience in the construction industry?

What is your education/occupation/professional training?

How long have you been working in the industry?

Where do you specialise in?

2. Could you tell me about your experience working with zero or low-carbon housing?

• What specific projects did you work on? Where? When?

• What was your role in these projects?

Zero-carbon Housing 1. Have you heard about the government’s recent target to achieve net-zero carbon by 2050?

• What do you personally think about it?

2. Do you personally think it’s feasible in terms of housing? Existing and new-build?

• If yes/no, ask to elaborate on why they think so?

3. What do you think are the biggest drivers or support mechanisms for zero-carbon housing and its uptake/delivery? (Legislative, economic, social, individual and industrial) 4. What do you think are the biggest barriers or challenges in delivering/adopting zero-carbon housing? (Legislative, economic, cultural, skills and knowledge, industrial)

Passivhaus Standard 1. Have you heard of the Passivhaus standard?

2. How familiar would you say you are with the standard?

3. Have you ever worked with Passivhaus buildings in the UK? • If yes, ask to briefly talk about their experience?

4. In your professional opinion, what would you say are the pros and cons of the Passivhaus standard? (Complexity, quality, PHPP, skills and knowledge, training, cost, certification, quality assurance, perceived risk, legislation, funding, market demand, supply chain) 5. Do you think the UK industry could achieve Passivhaus or equivalent standard nationwide by 2050 in response to the government’s zero-carbon target?

• Could you please elaborate on why you think so?

6. What are the biggest challenges/barriers in adopting the Passivhaus standard?

7. What policy changes do you think would most likely drive Passivhaus or equivalent standard at scale? (Building Regulations Part L & F, punitive measures- energy performance bonds, government procurement, financial incentives- CIL rebate, other incentives- planning gain 8. In your professional opinion, do you think Passivhaus standard could be used as a possible route to achieve the net-zero carbon housing? In what capacity?

9. Alternatively, do you think Passivhaus could help form a foundation for a more robust zero carbon housing policy in the UK? 10. In your personal opinion, what do you believe would be the best way to achieve the set target for net-zero carbon housing by 2050?

Before we conclude the interview is there anything else you would like to add?

Maybe I’ve missed something you think is important or might be relevant to the study?

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Appendicies- Semi-structured interview example

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Appendicies- Transcript from an interview with HT

AN: First of all, just as a background question, could you please talk a bit about your experience in the construction industry? Briefly mentioning your education, professional how the 8training, .4 Aand ppe ndilong cies-you've Transbeen criptworking from aninin teindustry? rview with MR HT: I graduated in Sudan in 1999, then I came to the UK, where I did a Master's degree in something called Digital Architecture.

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Appendicies- Transcript from an interview with PJ

AN: Digital?

HT: Yes, which is dealing with BIM and 3D modelling with software like ArchiCAD and Revit

8and .6 howAto ppuse ensuch dicietechnology s- Transcriinptorder fromtoaenhance n interviyour ew wdesign? ith LR AN: And was this in the 90s, the Master's degree?

Master's 8H.T7: The A ppenddegree icies- Twas ranin sc2002. ript frIocame m anhere inte(the rvieUK) w win ith1999, MS did two years of volunteering in a company, and then started my Master's degree straight after that. I was learning how to work with ArchiCAD and similar programs to design more sustainable buildings. I did two or three Passivhaus buildings, actually. They were not certified, but I 8.8 Appendicies- SPSS analysis data was doing the details towards achieving the Passivhaus standard. It was new at the time, so it was actually a bit awkward to achieve the standard, at least in the UK.

8A.N 9 : DidAyou ppqualify endicias esan - Narchitect? vivo analysis data HT: I have qualified as an architect, yes. I have a full registration in Sudan. But when I came here, the ARB stopped recognizing architects from Sudan just one or two years before I came. So, the ARB said to me, 'No, you can't register in here, unfortunately.'

AN: So, when did you start working?

HT: In 2002, but I started working while I was studying at university. I have done a five-year architecture course. It is not like in the UK, where it is a three-year course. I started working when I was in my second year in Sudan and worked for four years. Two years after the qualification and four years before the qualification.

AN: That's great. Where would you say you specialize in?

HN: When I started working in the UK, we used to do a lot of house extensions, small to medium size projects, not big. Some of them were cultural buildings as stuff like that- that's the top one, but normally we just did (house) extensions. And when I joined AK Architects, I started to do more veterinary work, hospitals but still some house extensions and big residential buildings.

AN: Could you briefly talk about your experience with sustainable housing or zero or lowcarbon housing?

HT: I've done a fair amount of sustainable design; that was one of our aims in the first company that I worked for. I believe when you start designing a sustainable building, you need to think about the construction materials first. How are you going to get those materials, and from where? And is it green or not? And even if it's green, usually that's not enough. You need to think about how do you actually get that material, what sort of energy

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is involved in making that material. Only after you have considered such issues you can say that's actually a green product that I can use in the building. Normally, we would try to use local materials from the area, that would be one of the first things we would consider when starting a project. One example could be a project we did in Northumberland; it was a Wildlife Discovery Centre for Northumberland Wildlife Trust in the Hauxley Nature Reserve.

It was a building designed for observing wildlife, especially birds. For that particular project, we decided to use straw-bale, which was sourced locally from the area and came from the same type of land it was built on. In order to construct the building, we used local people and volunteers. That meant we had to design the building to be suitable for simple construction where potentially anyone could work on it â&#x20AC;&#x201D; thus making it greener in comparison to something more complicated, where you need a lot of technical and highly skilled people to be involved.

AN: Okay. That's great. Now I will ask you some questions about zero-carbon housing and then about Passivhaus. Firstly, have you heard about the recently announced UK government's target to be zero carbon by 2050?

HT: By 2050? Yes, I have.

AN: And what do you think about it? Just in general.

HT: I think it's a good idea because even if the UK government doesn't achieve it, at least they are going in the right direction. I know that they (Building Regulations) have started to ask for improved U-values. For example, the newly built houses are better in terms of their U-value then they used to be. Also, the government is trying to encourage people to do that by giving them tariffs, among other things. Have you heard of the feed-in tariff proposed by the government where people can get payments from their energy suppliers for generating their own electricity, e.g., with solar panels or wind turbines and selling the energy back to the grid?

AN: Back to the grid?

HT: Yes, back to the grid, thus helping them to generate additional income, which I think is a good way to encourage people to live in a sustainable way.

AN: Do you personally think the 2050 target is achievable in terms of housing, specifically existing and new-build residential housing?

HT: What do you mean by achievable? Do you mean to actually achieve zero-carbon or to strive towards that?

AN: To actually achieve carbon neutrality. The target sets out that the UK has to be net zero-carbon by 2050.

HT: Has to be? What about if they couldn't achieve it? What would happen, then?

AN: That's the goal of the target, whether they achieve it or not. As far as I understand, net zero-carbon means that we would still be emitting carbon; however, all generated carbon would be balanced out and offset with renewables or allowable solutions. And the

government wants to achieve that in all sectors, including transport, housing, industry, etc.

Now we are talking specifically about housing and whether you think it's possible to achieve net zero-carbon in this sector.

HT: I think yes, but it will not be easy, especially dealing with existing housing based on the current situation. I think it will be difficult, but in terms of new-build, the government could pass new laws and push people towards the set target.

AN: What would you say are the biggest drivers or support mechanisms for zero-carbon housing? These could be economic, social or cultural, etc. What do you think is pushing or could be pushing zero-carbon housing?

HT: All of the ones you mentioned. In terms of housing, for example, the government needs to push for better U-values, lower carbon footprint, greener construction materials, all of these things would push the industry towards the set target. But then again, you also need to educate people about how to build more sustainability, how to use less energy, how to control the energy, how to deal with the materials, etc. The zero-carbon footprint, in my opinion, is not just related to how you build the house but how you use the house long after it has been constructed. People need to understand how to use their homes efficiently and how to get the most out of the technology that they have in their homes.

AN: Okey, and what do you think are the biggest barriers or challenges in delivering zerocarbon houses, or adopting zero-carbon housing, especially on a large-scale.

HT: Cost, based on my experience. I remember when we first started pitching the Passivhaus idea to clients, the first thing they would be asking about was cost. Even if they could recover the cost of the initial investment in a few years, they were still very hesitant to spend extra money initially. I think that's partly because green materials are typically more expensive than standard ones.

AN: Apart from the cost, are there any other barriers stopping the adoption or delivery of zero-carbon housing? Whether it's the knowledge, software, complexity or policies, etc.

HT: Probably knowledge, because if the client is educated about sustainability and what he is going to get out of it, he might be more willing to accept the extra cost associated. Of course, education, legislation, and other elements are important as well and must to go hand in hand if we really want to solve this problem. Because if you got the right materials and design, but you don't have the right client, or if you have the right materials and client, but you don't have the right occupants using the building, you start losing that a zerocarbon footprint.

AN: Okey. Now let's talk about Passivhaus. First of all, have you heard of the Passivhaus standard?

HT: Yes AN: How familiar would you say you are with the standard?

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HT: It's a tricky question because when I started learning about it was fairly new at the time, and there wasn't as much information about it as there is now. As I mentioned, we did two or three houses and then stopped. We couldn't achieve the Passivhaus certification, but we did manage to get the right information and use the right tools.

AN: Have you worked with any Passivhaus buildings in the UK? I mean, you have already mentioned that you have, so could you briefly talk about them in more detail?

HT: I did two or three Passivhaus buildings. The first one was an extension in a residential building, but as I mentioned earlier, it wasn't fully certified. The problem was that we were dealing with an existing building, and even though we managed to get the extension to a Passivhaus level, the rest of the house was not, hence we could not get a fully Passivhaus building, but the client was happy with that. I remember we used insulated blockwork technology because we were dealing with curved geometry. When you do curves, it's very awkward to fit the insulation, but with this technology, the insulation was built into the object itself, and that helped us to achieve a good U-value. It also helped with airtightness because the joints between the blocks were really thin. Looking back, I think it helped with cold bridging as well. I think that the project won a prize in the North East for the best construction of the year.

AN: That extension?

HT: Yes, the extension.

AN: Oh, that's great! Okey HT: If you want to know more about the extension, I can give you more details after the interview.

AN: Yes, that would be great. I would love to know the name of the project and a bit more about it.

HT: So, that's the first project. The other project was a scheduled monument, so another existing building. It was when I worked in the previous office. We tried to achieve the Passivhaus for a scheduled monument, but it was very difficult because you have an existing structure that you cannot touch. The project involved expanding the monument by building two stories on top of the existing structure. The two additional stories were fairly easy because we could use the construction that we wanted to get the right U-value, airtightness, ventilation system, etc. The awkward part was dealing with the existing structure on the ground floor because we could not do anything to the original walls. We ended up creating a cavity to ventilate the existing walls and only then adding the new structure, insulation, etc. It was quite difficult, but we managed to get the right construction to deal with the old walls. We used ArchiCAD to deal with the cold-bridging in all the details. ArchiCAD highlighted if there was a cold-bridge in detail and we could sort it out within the software until we cold a fully cold-bridge free structure. That helped us a lot.

AN: And the third one? Or were these two the main ones?

HT: These two were the main ones; the third one was probably another extension we did. I didn't work on a full house or a new build Passivhaus. We did have courses and stuff and knew how to do them, but we just didn't have the chance to work on any such projects.

AN: Now, in your opinion, what would you say are the pros and cons of the Passivhaus standard? Some of the talking points could be the complexity of the standard, its quality, software, skills and knowledge, training, the cost, the certification, the risks, funding, etc.

HT: About each one?

AN: No, these are just some examples. I would like to hear your opinion on which ones do you think are the most important ones: the pros and cons, the best things about Passivhaus and the difficulties or challenges of Passivhaus.

HT: The good thing about the Passivhaus standard is that it ensures you deliver healthy, economical, and thermally efficient buildings, that's the first thing. Secondly, I believe it's a better alternative for the environment in comparison to the standard practices. The difficulty I would say is that it's limiting in terms of design. As a designer, you are not 100% free; for example, it limits the amount of glazing you can have in a building. I mean, that's not necessarily a bad thing because it might be more sustainable, but it is limiting in a sense.

AN: Do you think the UK industry could achieve Passivhaus or equivalent standard nationwide by 2050 in response to the government's zero-carbon target?

HT: Yes, I think so. It's has been achieved in other countries. I don't see why it couldn't be achieved in the UK. AN: Yes, but on a nationwide scale, though.

HT: The main problem with achieving Passivhaus nationwide in the UK, in my opinion, is that you've already got a lot of existing buildings which would have to be improved. How are are you going to do this? I think that is the main issue. With new buildings, you could do that easily because there are no pre-existing conditions, you start with a new slate. With existing buildings, it's much more complicated.

AN: So you think it's achievable with a new build?

HT: Yes AN: But not so much with existing housing?

HT: Yes. The first thing you need to do is convince people who own existing homes to go towards Passivhaus. The second thing you need is the right technology, for example, insulation because the floor area is going to be an issue with existing homes. To achieve Passivhaus level U-values, you typically need very thick insulation, which is difficult to fit within an existing building without compromising too much internal floor area. So, you have to look for thinner insulation alternatives or new insulating technologies.

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HT: Going back to the pros and cons question, I think the software is another challenge because it's not that easy to use. It's not straightforward. You need to fill in a lot of information, and all of it has to be detailed and accurate; otherwise, the software does not produce the necessary results. At least that's what I found with the older versions of the PHPP software; I am not sure about the newer versions; maybe they've improved it.

AN: So you think the software is quite complex?

HT: That's my opinion. When I've tried to use it, I found it difficult. You really need to understand how to use it first, and you have to make sure that the information you are providing is correct; if not, there is no point in using the software.

AN: What do you think are the biggest challenges or barriers in adopting the Passivhaus standard?

HT: Do you mean to push the standard nationwide?

AN: Yes, in the whole UK. Currently, Passivhaus is a voluntary standard, you can adopt it if you want, but you don't have to. I'm asking about making the standard mandatory or at least a common practice for all new buildings.

HT: If someone wants to push that nationwide, it would have to part of the building control or some other legislation; otherwise, you will not force people to use it because it's expensive. But you have to balance that; you need to encourage people and educate them that even if they spend more money on Passivhaus initially, they could be saving money long-term.

AN: As you mentioned legislation, what policy changes do you think would most likely drive Passivhaus adoption at scale. Would it be Building Regulations Part L and F, punitive measures like energy performance bonds, government procurement, financial incentives, etc.?

HT: Building Regulations would definitely drive it because people would trust it more if it's coming from the government. Once it's in the building regulations, you could enforce both people and the architects to comply. I don't think most architects take Passivhaus very seriously at the moment. They are primarily concerned with costs and saving money, but if Passivhaus standard was in the building regulations that would compel them to take notice.

AN: Coming back to the 2050 zero-carbon target, do you think Passivhaus could be used as a way to achieve it?

HT: It could be one of the ways, yes.

AN: I mean, there is no one prescribed way how you design a zero-carbon building. You could design it without Passivhaus if you wanted. But do you think Passivhaus can be a way?

HT: I think it's the only available way now or the most common way, at least. Yet if there are other ways, I don't see why you shouldn't use them too. Because in terms of Passivhaus, the standard is primarily focused on European countries and climate because if you think about it, the main objectives are to make the building warmer, airtight, and simplify its ventilation. But what about hot climate, would the same strategy work in that situation? I don't know to be honest with you. Could the same system work for all climates, or would you need different systems for different climates? I guess that's a thing to think about.

AN: I agree with you. I mean, I've read that Passivhaus can be adapted to different climates where the building's heating demanding would be replaced with cooling demand. So instead of heating systems, you could use air conditioners and other things to regulate the indoor temperature.

HT: But would that be sustainable? In most hot climates, you need very good air circulation, but you don't need to use air conditioners that much sometimes you could just rely on the natural ventilation and that would cool the building. Is that considered in Passivhaus?

AN: I don't know if I'm honest.

HT: Passivhaus is concentrating on keeping the indoor and outdoor environments separate and maintaining an even comfortable temperature all the time. Yet in hot climates, if you want to keep the indoor temperatures cool all the time, that will require more energy as you will have to keep the cooling constantly on, whereas you could just open the window or use a way of ventilation that would automatically do that.

AN: Do you think Passivhaus could help to form a foundation for a more robust zerocarbon housing policy in the UK? HT: I think so, yes. I mean, that's the only option we have at the moment anyway. I think you could build on it, but you shouldn't be limited by it.

AN: And the last question: 'in your personal opinion, what do you believe is the best way to achieve the net-zero-carbon housing target of 2050?

HT: Don't rely on one system. Read, study, and educate your clients. Try to find what works for you. You can use Passivhaus as a base, but it doesn't have to be the only system you can follow. If you are struggling to make something work with Passivhaus, you don't have to use it. Don't be afraid to look elsewhere. I know it's a certified system that has been developed throughout the years, but you find it doesn't work for a particular case or climate; you don't have to follow the Passivhaus system.

AN: What about in the UK specifically?

HT: I think, in the UK, it would work about 80% of the time.

AN: Do you mean that the system has to be flexible?

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HT: Yes, flexible enough, so there are many different ways you could achieve the target, and allow people to add to the system rather than control them with the system.

AN: Finally, before we conclude this interview, is there anything else you would like to add?

Maybe I've missed something important, or you remembered something you wanted to say?

HT: Not really. I just want to say thank you for the interview invitation.

AN: You're welcome, and thank you for doing the interview.

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Appendicies- Transcript from an interview with HT

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Appendicies- Transcript from an interview with MR

AN: To start things off, could you please describe your work experience in the construction industry?

8M.5R: I have Apbeen pendworking icies- Tin raarchitecture nscript from an interview with PJ for 30 years. I have worked for local practice that deals mainly in volume housebuilding for 18 of those years, and my entire career has primarily been involved in housebuilding in one form or another. In terms of projects I have 8done, .6 some Appof enthe diclarger ies- Tones ranscare ripStt fPeters rom aBasin n inteurban rviewregeneration with LR scheme in Newcastle; Staithes South bank scheme in Gateshead; Westoe Crown Village, which is another urban regeneration scheme in South Shields, and Vista in Peterborough, which is one of the HCA carbon challenge sites, which, as I understand it, is the UK's largest zero 8carbon .7 Append icies- TranscI believe ript frofrom m anmemory interviethere w wiwere th Mabout S housing development.

300 properties on there. I can give you the exact number if you need it. So yes, I have various levels of experience working on various levels of delivering housing from social housing to private housing, from volume housebuilding clients to small developers to private individuals.

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Appendicies- SPSS analysis data

AN: That's great. Could you please talk a little bit about your work experience with sustainable or zero-carbon housing? before, 8M.9R: Yes.AAs ppI ementioned ndicies- N vivo aInwas alysinvolved is data in the delivery of HCA carbon challenge

development in Peterborough. That was one of six carbon challenge projects identified by the government's HCA department. That scheme was intended to prove that code for sustainable homes level 6 housing was deliverable on a volume housebuilder basis to encourage that sort of development throughout the UK. It was the second of six schemes to take off but there were issues in the first scheme, which was Hanham Hall in Bristol, the second scheme which was ours in Peterborough with regards to the delivery of heat and power throughout the site. There were issues with regards to how could this be delivered to get the effective off-grid solutions to cover the code for sustainable homes level 6 required. Because our's broke down, we agreed with the HCA that we would deliver the housing up to the equivalent code for sustainable homes scoring, which I believe was in excess of 90 at the time but we would only ever achieve code level 5 because we could not resolve the district heating issue and I believe that on the back of that it led to the code for sustainable homes being dropped and the whole carbon challenge initiative being dropped as well. So that is kind of the high-end experience I have had. In terms of lowerend, obviously, the mid-90s and early-2000s code for sustainable homes was a bit of a buzz thing and looked at various developments we were ort of delivering code 3 through to code 6 primarily for social housing because their funding was granted on the back of it.

What I found with social housing projects, before it was all deregulated, I think is probably the right word, before it was all deregulated and it was when social housing was built by resident social landlords, their funding was a good driver in changing policy, and that is as I understand what led to a lot of things like secure by design and initiatives like that being introduced.

AN: Now in terms of zero-carbon housing, have you heard of the government's recent target to reach net-zero by 2050?

MR: I am aware of it. I am aware there have been various announcements, especially with the election; however, I have seen no substance to it. I am a bit worried at the moment we are going to see a repeat of the code for sustainable homes again. But I can see why that is. Code for sustainable homes became a tick box exercise of: 'have you got a bit of paper?', 'yes, I have got a bit of paper', 'tick-there is a point' and that's, I think we have

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already proved that that approach doesn't work. So, I'm interested to find out the detail behind delivering this. I presume it will be done through changes to Building Regulations as these things always seem to be. Part L of the Building Regulations has always been a good driver for improving the thermal efficiency of buildings, and I have seen nothing else that is effective in that way because housebuilders obviously work to price so they will, sort of, unless they have to they won't do it.

AN: That actually answers one of the questions I had, but I'll get back to it later on. So, personally, do you think it is feasible in terms of housing? To achieve net-zero carbon by 2050, specifically talking about existing housing and new-build housing?

MR: I think the delivery of new build housing by 2050 is very achievable. 30 years, we're kind of, we've been doing it. But we've been doing it on individual schemes. There were various research houses I did that achieved code level 6 because we put enough solar panels on the roof. If you look at plot M at Hampton Vale Western Peterborough, that was our research house. So, it can be done, that's a net-zero-carbon building -quite easy to achieve. What needs to be brought into line is how you do it on a big scale and the infrastructure behind servicing the properties needs to brought into question. Things like the provision of electricity, for example, we are only using more and more and more electricity but how can that be produced efficiently and in a carbon zero way? There are ways of doing it, but it's how you do that but keep the open market nature of the current service provision in the UK. AN: And what about the existing housing?

MR: Existing housing stock I think is a much bigger problem because no matter how many grants and things you throw at peopleâ&#x20AC;Ś There is a lot of housing in the UK that has to be upgraded massively to make it zero-carbon. There are 150-year-old houses quite happily functioning as homes in the country with no need to do anything to them to make them habitable because they are habitable, people are living in them. So to go to a homeowner and say, 'right, you need to add insulation on to your house to make this carbon zero', 'alright so how does that work?', 'well you can put it on to the outside of the building', 'but I like the look of my house', 'well you can put inside then', 'yes but my rooms will get smaller, why would I do that?'. To me, it's more efficient to accept the fact that you have the existing housing that's lived in and it's not doing the work for the sake of doing the work; there has to be a reason behind it. I suspect increasing fuel prices will push demand for homeowners to go and look at how they upgrade their properties thermally, but there is a limit to how much you can actually do to an existing property, and I think there is very few that will ever become net-zero because the practicalities of doing it are just very very difficult.

AN: Yes. Now, what would you say are the biggest drivers and support mechanism for zero-carbon housing, its uptake and delivery? Whether that's legislative, economic, social, individual, industrial, etc.

MR: I think the main drivers in this are- it's financial because we are all on limited resources financially so the ever-increasing gas and electric prices, that's kind of if someone says, 'if you change your boiler you will save that money per year'. I looked at this recently by changing my heating system at home. It was going to cost something like ÂŁ5000 to change my heating system and that would put a solar hot water panel on the roof, pressured cylinder and keep the boiler I have now but to do that meant I had to run a 22 mm pipe

right through the house from the ground floor up to the second floor which meant hacking out bits of wall and a lot of builder work to do that, so that was added cost to get payback of that work over a 25-year period. That's not incentive enough there to go and pull my house apart to do it.

AN: Diminishing returns.

MR: Yes, and I would love to do it, I would love to that particular project, but for the cost of it, it's just, there's no incentive for me to do it. And there's certainly no incentive to convince my wife it needs to be done because her approach was, 'why are we spending five grand to not change anything?'. I said, 'Well, we are changing things', but shed replied, 'No, we're not because we'll still get hot water out of the tap and we'll still get hot radiators'. Fair enough. I think to save us something like, whatever it works out at, but it was some like ÂŁ200-ÂŁ150 a year or something like that, it was just, what's the point?

AN: Right, that's great.

MR: Oh sorry, the other thing that will drive it is building regulations because I think that's the only thing that will effectively force people to do it.

AN: Yes, I agree. So, now in contrast to that, what would you say are the biggest barriers or challenges in adopting and delivering zero-carbon housing?

MR: In some ways, it's a change for change's sake. As I was saying, why do you want to go and change something that works for something that's going to be slightly more efficient?

It's educating people as well, the term being carbon-zero doesn't really mean anything because I don't think people are wholly convinced by the phrase carbon-zero and what that really means. I think a better approach would be to say 'if your monthly bills get expensive you can have more money in your pocket if you do this'.

AN: Yes, it's a bit of jargon.

MR: Yes. For years when even when I was studying there was a term used that was 'greenwash' and that's what we are getting again. It's a carbon-zero, must be carbon-zero, must be net-carbon-zero. What's the target? It's every industry will be net-zero-carbon by 2050?

AN: Net-zero-carbon, yes.

MR: How? How can you do that? It doesn't mean anything. What does being carbon-zero mean?

AN: Yes. Well, one of the things I was looking into was the actual definition of zero-carbon.

What I found in my literature review was that one of the big issues with zero-carbon is the actual definition itself because it's changing. And because it's changing it's really hard to tie any policy to it because it has to be quite clear what it means. Initially, the term zerocarbon, as far as I am aware, in code for sustainable homes meant including regulated energy and unregulated energy, which is plug loads, cooking, etc. Later, they have changed the definition so it's just regulated energy and now, as far as I'm aware, they've changed it where you have the fabric efficiency, the carbon compliance and a thing they also introduced called allowable solutions, which is basically government schemes whether that's tree planting or other things where you make up the difference between what you've designed andâ&#x20AC;Ś

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MR: Yes. It weakens it. It's a bit like 'We want you to become zero-carbon, so you need to do that', 'I don't want to do that, can I plant a tree instead?', 'Yeah, go on then'. I mean, when I did Peterborough I've been saying 'carbon-zero, carbon-zero, carbon-zero' and it was like 'well no, it's net-carbon-zero'. And I was, 'what does net-carbon-zero mean?', 'Oh, well, it's when you give back as much as you use'. 'Okey, that makes sense, so how do we that then?'. It became a different question. It suddenly wasn't about what's being independent of the grid; it was about how do we give back as much to the grid as we take from the grid.

AN: It's just balancing it out like a balance sheet.

MR: Yes, and it became a bit of a, once you understood that, it was very easy to work around the design problems. Just to get the point across, as architects we were looking for the design problems to work and solve them, but when you got a volume housebuilder client who's interested is profit, and the kudos that comes from delivering a scheme like that they wanted a little bit more, he still has a financial limit, he has to; otherwise, it's not commercially viable, and the whole point about carbon challenge was to be commercially viable. So, when you say, 'we've got a problem, we propose this', they respond with, 'there has to be another way of doing it'. So they would bring in another expert who says, 'well an allowable solution would be to do that'. The term net-carbon-zero needs to be clearly defined, and once that's happened people will be able to start making clear routes to it, and at the moment it's a bit of a greenwash, which is helpful for an election coming up.

AN: Yes, I agree. Now let's move on to the Passivhaus standard. You are obviously aware of the standard, yes?

MS: I am aware of it, yes.

AN: How familiar would you say you are with the standard?

MR: Not very. I have, in the early days when it was coming out, referenced it for various projects, and worked with extracts from it but as the Passivhaus organization got a bit more commercially savvy, they restricted access to their publications, so I've lost touch with it.

And that's how I found out about needing to be a certified Passivhaus designer to be able to get the standards because you need to be a certified Passivhaus designer to actually call it a Passivhaus. So yes, I'm aware of them and I'm aware of the principles of them, and nothing wrong with having a trademark name, I have no problem with that but it's not a beall and end-all solution. It's a good sound approach, but the stuff in there which I would say is a good design we get taught in architecture school anyway, things like what's the orientation of the building, how do you maximize the solar gain, how does your passive ventilation work? Things like that which we should be all doing as a matter of course anyway, it's good design.

AN: In your professional opinion, what would you say are the pros and cons of the Passivhaus standard, so just a few points to mention could be the complexity, quality, software, skills and knowledge, training, costs, certification, risks, funding, market demand, supply chain, etc. Or the most important ones.

MR: Well, obviously, the pros are you end up with a very efficient house that should last for decades. If the standard lifespan of a house is 60 years, I'd be expecting Passivhaus to still be a Passivhaus standard house, to still be functioning for it occupants very well beyond that sort of time scale. The climate only changes so much over a period of time. So in that

regard, I would expect them to perform very well. I also think a pro is selling something that you can attach a label to like a Passivhaus or zero-carbon. You've got that extra marketing value. So, there are pros for developers for adopting it in that way. The problem with the Passivhaus is that it has become a very niche standard for private one-off dwellings. I haven't seen a commercial developer take it up as a whole scale solution. I don't know whether that's just a perception or the complexities of dealing with the standard itself or some of their detailing is way over what's needed to satisfy building regulations if you think building regulations part L and any parts in it is a minimum standard. Robust details, accredited details are quick wins by housing developers. You have to remember that those systems were brought in by the housing corporation or the housebuilding recognized bodies basically with a view to delivering something that the housebuilders could just build it and avoid to do any pressure testing or acoustic testing because it has all been one before, so you don't have to do it again. Whereas I believe with Passivhaus, you have to go and test every time.

AN: Yes. MR: So, it's things like that. In some ways, I was quite disappointed when they relaxed the need for pressure testing houses because that meant that that level of control and concentration had gone.

AN: I guess, not to expand to long, you could argue whether that's a good thing or a bad thing? Because when you have systems in place where you don't need to test it makes everything much quicker and efficient but whether the quality control and assurance is still there, and people are not looking for shortcuts?

MR: What I've noticed, as soon as you tell as housebuilder that the properties are going to be tested for acoustics or for pressure testing or whatever, as soon as you tell them that, they immediately become a lot more considered in their approach to the job, and they are a lot more careful, and the build quality is so much better. So as soon as that was relaxed, I started to see things like mortar pointing in party walls wasn't quite as neat, so it's things as that disappointed me that those standards like Robust details were great because people were taking care. Sorry, acoustic testing was great because people were taking care, but as soon as they brought Robust details in and you didn't have to test them anymore, it was like, 'let's just throw these up', 'yeah, come on'.

AN: Okey, let's move on. So, apart from the standard itself, what would you say are the biggest challenges and barriers in actually adopting the standard nationwide? Because I think that is one of the issues.

MR: In adopting Passivhaus as a standard nationwide?

AN: Yes, at scale, because as you said that at the moment, it's usually only used for private schemes because it's a voluntary standard.

MR: It's financial. It's the developers who pay for the building. Developers pay for buildings and look for maximum profit. Why go and pay for something you don't actually need to have? If you have to have it, they will pay for it. If somebody said, 'right, in order to beâ&#x20AC;Ś all buildings have to be carbon-zero and comply with building regulations, but to be carbonzero you have to have Passivhaus, but to be Passivhaus you have to pay for certification', they will do it. But the problem there is you then got one standard that has a monopoly on the UK market, so I'm sure the not pleased emerges, people would get very interested in

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that. The only way that you'd be able to do that would be if you took everything out of Passivhaus standards and implemented that into building regulations. So, if you did that, then you'd end up with a Passivhaus design building to Passivhaus standards that you can't call a Passivhaus because it's not Passivhaus certified.

AN: Right. Yes, that makes sense. It actually ties in with one of the questions I had further on which is: do you think Passivhaus could help to form a foundation for a more robust zero-carbon policy?

MR: It definitely could, but as I said Passivhaus- the organization needs to relax its stance and make it available to everyone in the industry. Whereas at the moment it's only available to certain few, which is fine because its a commercial project but it could only work as a wide route to net-zero-carbon, globally in fact, if they are prepared to say 'right, we've got a robust set of standards', they go local governments everywhere and say, 'you can have them for your building regulations and policies'. If they do that, then that I'd say can be the only way to achieve it unless they went, 'actually, we're a totally voluntary organization now, anyone can design to our standard'. They may have people testing it, who verify it at the end of the job like they do with the energy assessors. They may go round and sort of say, 'there you are, yes, you've ticked every box on the Passivhaus standard, it's a certified Passivhaus' and if that certificate could be given to building control instead of the energy performance certificate or SAP rating certificate, if that could be done instead then it might be adopted.

AN: That's a really interesting point because I think at the moment there's a bit of a conflict.

As far as I'm aware, when I was reading about it, I think initially in Germany, it started out as an open-source thing where they wanted, the guy who invented it just wanted a lot of energy-efficient houses.

MR: Well, that's, that's how I knew about it in the first place, because when you could just go and have a look and work to it.

AN: Yeah. But as you said, I know there are courses, quite expensive actually, where you become a certified designer, and there's a software. You need to use it. I think it's not very cheap either. And, so yeah, I'll look into it. That's, that's really interesting actually. Just a few more questions. That's, so again, sort of going back to the zero-carbon, policies and targets, do you think Passiv house could be a route to achieve it and in what way, or in what capacity it could or couldn't.

MR: Well, no, it can, but it's a difficult thing to do when it's a commercial standard.

AN: Right.

MR: As you said, as an open-source product, yes. I think it would be very achievable because you could then get building control authority, building regulations to get around the fact of achieving carbon zero. Route one- fabric first, route two- passive house, route three- something else. And that way you've got the option of going for that standard, and that would encourage its use, but that would only work if it was freely available, which as you said yourself by, you know, the fact, the software is expensive, the training is expensive it's actually a very, very niche fit.

AN: Right, yeah.

MRS: And as a commercial, as a commercial product, I don't think it would ever achieve wide-scale net-zero, which is what I think you're asking.

AN: Why is that?

MR: Just because of the restrictions and the commerciality of it. Because obviously, they want to make money out of it. If they can find a different way of funding it and making it more available, you know, any designer can follow a set of standards, a design guide.

AN: Well, it's quite interesting because as I was reading that in Germany, especially in Australia, there's a lot of government incentives where, if you build this to Passivhaus, then I think it's easier in terms of mortgages and funding and other things. So, it's like financial incentives for developers and for people to build it.

MR: Which basically offsets the cost.

AN: Yes, the extra cost that's associated with it.

MR: But does Germany have a policy of encouraging people to adopt Passivhaus? Is that their government policy?

AN: I think it's a bit similar to the UK where they have building regulations and then they have Passivhaus. It's a voluntary standard- the Passivhaus, in Germany as well. I think a lot of, councils, local councils adopt it similarly to London. Where they would have... Well, we have London plan, and we build to a higher spec. We expect higher spec then the national standard. So, I think a lot of local councils in Germany said, 'well, we're only going to build to Passivhaus', but it's their decision. It's like a local thing rather than nationwide. Right. So the final question I would ask is, just in your personal opinion, what would you think is the best way to achieve net zero-carbon by 2050?

MR: How to achieve zero-carbon, right?

AN: Housing, or new build housing.

MR: Well, I think the question of existing housing stock- I don't think it's possible. That's all.

You might get the odd one done as a research project, but with current technology, I don't think it's possible to convert an existing house sufficiently to make it net-zero. Which forces you to into new build, and I think the technology, the technologies are there. I think it has to be driven through some regulations to get wide adoption of it. Fabric first is a great way of achieving, of getting towards achieving it where you have to be using better building materials and better building techniques to seal the building. I keep talking to other people on projects, I support the best experience I've had of it, but there we proved that modern methods of construction weren't as efficient as traditional cavity masonry walls, because of the problems we found. Which, I mean, it shocked me at the time. And that was part of the thing with the code for sustainable homes, just for your own information, where you're getting points for using modern methods of construction and also construction, which we looked at, but then we realized we could actually deliver more efficient buildings by using traditional construction on site. So, why would you go down the modern methods of construction when you don't have to?

AN: So, it's a bit of a tick box exercise?

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MR: Yeah, and that's why I'm suspicious of things like, if you use MMC (Metal Matrix Composite), you'll get the point, but MMC is not as good as fabric first. So, put your fabric first, please. I think there also needs to be an understanding of the way building fabric functions. I don't know if you have a come across the term slow response and fast response buildings?

AN: I think I have, a little bit, yes.

MR: And that's, I think if we understand things like thermal mass and using solar gain properly instead of, at the minute we all seem to go, 'South- lets put a big window in- it will get solar gain'. Well, I mean, you've just overheated it there. But it's things like that; we need to understand the environments we create better as designers I feel. We all know the theory, but we don't test the theory. South-facing windows for solar gain, yes- tick, but then it overheated, so you're cooling- cross. At what point does that balance out? At what point do you use material within the space that's facing South that absorbs enough heat to dissipate that back out overnights so you don't need the heating on. It's that sort of, we know the theory, but we don't know the numbers and the technical backup to the theory.

And I think as designers, we've got to get better at that, especially as architects. Best way to do it is by pushing the volume housebuilders into it. Every time new standards come out, they all complain, they all get together and they all find a way around it. It's about pushing housebuilders down the route to achieving it. Nobody will ever voluntarily put something in like an air source heat pump. I'm not saying air source heat pump is the best way to achieve it or the right approach for achieving billing services but nobody will ever push numbers enough to warrant that at a volume scale. Similarly, as I said, we've got to get our services infrastructure better, if we can make our services infrastructure net-zero that solves a big problem of having to have houses micro-generating. Don't get me wrong, microgeneration is great and frees up people from national grids and things like that, but it's not possible to be wholly independent without taking on a naturalist lifestyle. But you do, if that can be done in a way that alleviates the problem for the housebuilders because they're still plugged into the grid, then great. That'll do it. Things like- Byker has district heating, you know, it's very expensive to try and tap into that. I looked at, again in Peterborough we looked at district heating and district electricity, and we've got into problems with competition and markets commission because you're forcing three hundred homeowners to buy all their heating and power from one source. They're not in the open market. You can't do that. So, maybe nationalization of services, maybe Jeremy Corbin's right. Maybe that is the way forward, but I'm not sure I truly believe that. So, fabric first is a definite approach. Also doing something about service infrastructure has to be the main thing. And then it's the production of materials as well because there's a lot of embodied carbon in things like concrete and brick manufacturing, and things like that.

Bricks are fired in a big gas-powered kiln in one of the hundreds of brick manufacturing factories around the country. Well, that's not efficient.

AN: So, before we conclude this interview, is there anything else you would like to add?

Maybe I've missed something you think it's important that might be relevant to this study?

MR: I think I said enough.

8.4

Appendicies- Transcript from an interview with MR

8.5

Appendicies- Transcript from an interview with PJ

PJ: The problem with all these things is that nobody knows what any of these definitions mean.

So what does zero-carbon mean? What is carbon-neutral, what is carbon-positive, carbonnegative?

What just that bureaucrats 8.6 Ap pendo dicthey ies-mean?

TransIt's crip t frnonsense. om an inIt's teravword. iew wIt's ithaLphrase R latched onto and then started using it, as a sort of, without actually really understand what that means. So, zero-carbon. It's impossible to have zero-carbon. What are they talking about? Is it zero-carbon over its lifetime? And that's through offsetting the carbon (the operational 8energy) .7 Apterms pend iescarbon, - Transversus cript fthe rom an interenergy view wwithin ith Mthe S construction. Is that in oficthe embodied what they mean? Zero-carbon, is it zero-carbon in terms of its usage, i.e. it's autonomous and doesn't; therefore, it doesn't need any energy input because it generates the heat through the cottar's 8cooking, .8 Abody, ppenwhatever? dicies- SItPisSSasavague nalysias sd ata terms.

AN: Yeah. So, what I'm trying to do, as part of the research, is to talk about the definition, and what it actually means.

8.9

Appendicies- Nvivo analysis data

PJ: I reckon you can ask a dozen people and everybody would have a different definition of what they think that means. So, if it's zero-carbon, it usually means in terms of. Well, how I think, how I understand zero carbon is in the energy usage of a building. So if you're Passivhaus then you shouldn't have to heat it, it shouldn't need to be heated, it should be able to stay around 17-18 degrees all year round, and you shouldn't have to cool it. So in that regard, it could be zero-carbon, but if you talk about carbon from the point of view of its embodied and operational energy, well, you need a definition of what actually is because I've heard it used in several different ways. I think that confusion actually allows people who want to use it, as a sort of means, to provide false claims. Whatever, it's like using a stat: you can use it whatever way you want, positive and negative, that's kind of how they're using it. So, anyway, that's probably not what you're asking.

AN: Well, it is. So, could you briefly describe your work experience?

PJ: In terms of Passivhaus or in terms of?

AN: Just in general.

PJ: Well, I'm an architect and academic, and a professor in architecture. I do real projects as well as theoretical ones. So do theoretical research but also make practical applications where I apply that research to the practical application.

AN: That's good. And what about zero-carbon or low-carbon, or sustainability?

PJ: So, at the minute, I'm doing 12 houses in Sunderland which have been designed to Passivhaus standards.

AN: Is that Humbledon Hill?

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PJ: Yes, and I did my own house which is an ultra-low energy house, and I am currently working on a range of council houses for the 21st century (Old House, New Home) with George Clarke, the architect on the television. So, I've got quite a lot of experience. I've written papers on energy efficiency and carbon and things like that.

AN: Great. Have you heard about the government's recent target of 2050?

PJ: I know that they're trying to work towards a zero-carbon position but as I said I don't think they know what they mean by that and I don't think they understand enough about the difficulties in actually achieving that. It's just political confetti.

AN: What I wanted to ask is whether you think that it is actually achievable? Do you think? All houses zero-carbon by 2050, existing and new build, or maybe one is, and one isn't.

PJ: Well, everything's got to have some kind of energy input to get down to, if you're not heating a house, you still going to have to be using electricity in some shape or form whether through the heat recovery unit, light fittings, cooking, all that kind of stuff. So, what are they talking about? They are talking about the prime energy use for heating or was its heating and power?

AN: I think they use the definition by the zero-carbon hub and they only look at related energy, so they don't look at embodied energy, and not plug loads. It's only regulated energy. And they, I think, allow for allowable solutions, as they call them, which is.

PJ: It could mean anything.

AN: Planting trees, all kinds of schemes of offsetting.

PJ: So if you can offset the carbon by, if you can get down to new houses being zero carbon, I work to Passivhaus standard, well, yes that's achievable because if you can achieve one, you can achieve a million. But even Passivhaus buildings still have to have energy input to enable them to be Passivhaus. So if you are going to then say, well, we can offset that energy use by planting trees well again you can achieve, that so it's achievable. Because if you've achieved it once you can achieve it multiple times. Because these cost a lot of money, they cost a lot more money than a normal house, standard building. You have to input more plant; the windows have to be triple glazed, argon filled so they are going to be more expensive than standard PVC double-glazed units. You know the typical HVAC system with, heat recovery system would probably be somewhere in the region of three and a half thousand pounds per house. So are they going to add that up? While, while housing is a profit-driven system, which it currently is, they haven't got a chance of achieving it because the big house-builders will always find a way around why they shouldn't do it. And the politicians would just capitulate just because they've got no backbone. So you can have whatever targets you want.

AN: So, theoretically, it is achievable?

PJ: Theoretically, it's achievable; culturally, it's not because we haven't hit one of the targets that we said we're going to achieve from Kyoto 15 years ago.

AN: Well, this actually ties in really nicely with the question I had. What are the biggest drivers for zero carbon and enables things and is pushing forward, and things that are barriers or challenges?

PJ: Well, the big driver is the fact that the ice sheets are melting at a quicker rate than we've possibly anticipated, so five years ago, we thought that the rates they are currently melting would not be seen for 25 years, we're seeing them now. So, there's, I forgot what the theory is called, but it's a resistance theory around the idea that the system of many different inputs will be stronger than any one of those things on its own. And the earth should be underwater by now by what we've done to the planet, but the resilience in the system actually enabled us to stay would slow the rate of impact down immeasurably. From this, now they think that we may have actually snapped, that we've gone beyond those baseline forecasts where now the system's no longer working for us, the systems is now broken, so we will see in the next 10 to 15 years a rapid change in the way in which the planet's currently operating. So, the impetus to do anything is basically because we're living on borrowed time and we're now starting to see droughts in areas which were relatively affluent like Australia, America. When you start to see superpowers starting to be affected, their weather patterns affected which is then having an effect on their prosperity, that's when they'll start to take notice. So the impetus or the imperative, if you like, is to do with the environment, the impediment to doing anything about it is greed, collective greed. And people not seeing enough consequences of their waste. So, we are already seeing; literally, we're seeing weird weather events. Probably for three or four times a year now. Whereas it needs to be happening every day for them to realize. The problem is that when we get to that situation, we can't turn the clock back. We can't then just start. Even if we go down to zero-carbon, it will be hundreds of years before we'd see the benefit. We would be in this exaggerated landscape for several hundred years to come because of the way we've wasted energy in the last, principally, the last fifty years.

AN: So would you say the barriers are then collective greed, and then you also talked about the cultural things?

PJ: Cultural things, yes. While we see this problem as a profit. As the opposite side of profit, and profit will always win out because, it's what Chomsky refers to as the industrial and commercial feudalism- the big business own government. While the big business owns government then nothing will change, we'll only ever skirt around the edges. We won't get ahead. We won't make anything radically different. So even if the UK goes after it, we have a change of government, and we go after significant environmental targets, it would make no difference because the two big, the two most profligate countries in the world are China and America. And they'll just carry on although China does actually try and make a difference.

AN: I've heard about their renewables.

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PJ: Yes, they've got a lot of interest in renewables because the most polluted ten cities on the planet are in China. So they may be doing some things, but they're not doing others.

AN: Yes, right. Well, let's move on to Passivhaus then in more detail. So how familiar would you say you are the standard?

PJ: Pretty familiar.

AN: Right, and in your professional opinion, what would you say are the pros and cons of Passivhaus, so that could be the complexity, the skills or knowledge, availability, the cost, certification etc.?

PJ: I think pros are very obvious, and it's saving energy, I mean, that's great. The cons are that you really struggle to model Passivhaus building in energy terms, and all the other things that go around with it. So, if you have somebody who's sort of evangelical about it, who sees it as a kind of hobby to how you operate your Passivhaus, then it's probably quite good, but you've got put a lot of investment into running it. It doesn't just ruin itself. So, if you're just somebody who likes the idea of it or likes the sound of it and then gets a passive house and doesn't engage with it on a daily basis, then it'll let you down. So, for instance, we get overheated in the summer.

AN: Yes, that's what I found.

PJ: And in the winter it's too cold. So, even with people who say, 'that people have a heat threshold', so, my heat threshold, I like to be around about 19 degrees internally whereas my wife would much prefer over 21. So, if in the summer you get overheated then you have to turn the heat recovery unit off, and then open the windows, you get dead spaces in the house, and even with the fans running. My living spaces is 50 square meters; it's got my kitchen, my living, and my dining all in one place. We only have one input and one output in that space.

There are parts of that room which are a little stale. So, I find that when we got the heat recovery unit working, and we've got the sun shining onto the house, it gets really stuffy. We can't deal with that; we have to turn the machine off and then open the windows. And that's not even a Passivhaus, that's probably twice as inefficient as a Passivhaus. So, if you were working around point three or point four air change in an hour, I think it would not be a nice place to live in. So, and going back to the people who are, if you like, are passive to the passive house, i.e. if you are creating social housing or council housing which is to Passivhaus standards. I don't think they know enough about how to use it or care enough about it. So, it's always going to fail; it's always going to let them down.

AN: Yes, I've read that there is a lifestyle change.

PJ: A massive lifestyle change AN: That's associated with living in a Passivhaus.

PJ: Absolutely AN: And until you know how to operate the heat recovery and when the windows should be opened, and all that stuff.

PJ: Yes, and how you use your trickle vents, all those sorts of things. People are just; clearly, you can see that when you go down there, and all the windows are open. It's not operating like a Passivhaus because the windows are supposed to be sealed. In most passive houses they actually don't have opening windows, they have sealed window units, and they rely entirely on the fans.

AN: So would you say then that's a lack of awareness?

PJ: It's a lack of awareness. So, I think it's also that people like to have an opening window and get a blast of cool air on the face. Having this recirculated air, it's just not the way people live.

It's like being in an air-conditioned office. It's air conditioning; however, you set it up. When the heat recovery unit is air conditioning- you're taking moisture out of the air, and you're taking the heat out of the air and then put it through a heat exchanger to put it back in- that's air conditioning. And I don't think people live like that. I spent much more money on my fabric. I had fabric-first principles rather than airtightness because it's like having another blanket on your bed at night; it just makes the heat that you have got to stay in there longer.

Obviously, it's a balance between that and, but also another thing that's hard about of the Passivhaus is that you're testing the house at 50 Pascal's, well we don't live in 50 Pascal's, we live at normal background leakage. So, when you start putting the house in an artificial environment, then some houses would start to draw air out of cracks that ordinarily they wouldn't be drawing the air out. So, that doesn't work either.

AN: I wouldn't say that is Passivhaus specific though. I think SAP and others use that standard (pressure testing at 50 Pascal's).

PJ: Yes. AN: Alright, let's move on, just a few more questions. Do you think Passsivhaus or equivalent standard could be adopted nationwide?

PJ: Well, only for new houses. But I think we'd have to put a lot of money into it. The problem with our system is it's not interested in returns. If all these houses were in some kind of public ownership and we then saw the value of not having operational energy being used to heat over a 20-year term, then you would have pension funds and stuff signing up for that. But that's not how it works. You have somebody who puts money into the building of a house and wants an immediate return. So, the fact you get no immediate return, I would argue, unless there's a huge cultural change, well, we can't speculate it being used as a national standard.

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AN: Right. In terms of policies, there is a question. What policy change would most likely drive Passivhaus? There's a couple of examples: building regulations, Part L and F, punitive measures like energy performance bonds or government procurement, or financial incentives, planning incentives. What do you think would have the biggest impact?

PJ: Well, government legislation to make big house-builders, the mass house-builders, to engage with it would be the only way to do it. But even then, it becomes a black market.

Because I know that, I've actually seen it in practice. What companies do is they pay off the assessors because they can't reach the standards they need. So, they just pay him off, and he writes whatever he wants. So, that would be, almost without exception, that's the way that would work because it's profit-driven. So, the only way you could do it is significant fines and legislating that if you don't do it if you don't get permission to build. The problem is that most of the land is now land banked. So, you would say to a house-builder, 'right, you're not allowed to build on that land', and then they're sitting with all this land that's tied up so, you can't, the government needs houses to be built. But that's not working in the opposite direction to the legislation that they could then use to get to Passivhaus standards. That would massively slow things down while the government has a huge imperative to build.

AN: Right, two more questions. Alternatively, if Passivhaus, you know, we don't look at it specifically. Could it help form a foundation for a more robust zero carbon housing policy?

Because I think, at the moment, now that the code for sustainable homes was withdrawn there's not really any specific policy in place. Should it be fabric first approach?

PJ: For me, for instance, I never set out to reach Passivhaus standards, but I was aware what a Passivhaus standard was, and I was aware of what you have to do to get towards that. So, when I was actually building my house after the builders had gone, I would go round taping joints of the insulation, and I'd fill in with foam around openings and things. Things that they just wouldn't ordinarily do. So, having the Passivhaus as a sort of ambition isn't a bad thing.

Because even if you don't get to a Passivhaus standard, you are saving a considerable amount of money that you otherwise wouldn't be if you were just looking at meeting building regulations. So, I think it's a good thing to have as a guide. But the problem with the country is if it's just a guide it will never be used.

AN: If it's voluntary?

PJ: If it's voluntary. It's like we have the same voluntary codes for things like waste management. If we just say to the builders, 'oh well, you know, it'll be good if you did this'.

They just don't care. You have got to hit them in the pocket, you've got to find them. You've got to make it so it's impossible for them to build and only then would they start taking note of it. But it's no more useful than Code for Sustainable Homes because if nobody's going to follow it, then why bother? Code for Sustainable Homes was probably a better measure than Passivhaus because it had multiple inputs, not just necessary energy saving. One of the reasons why I didn't go for Passivhaus was because it's a lot of paperwork. You have to prove

that you haven't brought materials from beyond five miles of the site, and stuff like. Five miles around my house is pretty much countryside; I wouldn't be able to build the bloody thing. I think Passivhaus has some good parts to it, but I think a much better one was the Code for Sustainable Homes. I think that was a more generous interpretation of the environment. And you could build and offset things based on your approach to it rather than kind of fascist sort of energy-driven system that you find with Passivhaus.

AN: Well, okay, we can wrap it up here.

PJ: Is that it?

AN: Yes. That's great.

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Appendicies- Transcript from an interview with PJ

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Appendicies- Transcript from an interview with LR

AN: So, I'll just go through the questions if that's okay. So, could you describe your work 8experience .7 App ndconstruction icies- Transindustry? cript froLike m an inteducation, erview witprofessional h MS inethe your training, etc.

LR: So, I'm qualified as of September last year. Before that, I studied at Northumbria University and Manchester University. And in terms of work experience. My first insight into practice was 8.8 Appendicies- SPSS analysis data in 2012. I did some work experience at Edwards Architecture in Newcastle and then moved on to Butterfield Architecture, which is in Manchester, which was mainly residential and smallscale commercial work. And then, my post Part 2 work was with Ryders in Newcastle, which 8covered .9 A pendrange icies-ofNsectors vivo an alyprojects sis dataand different sorts of tasks and roles. ap broad and AN: Great. Let's talk a little bit about your experience working with sustainable housing, zerocarbon, or anything related.

LR: So, probably my main experience would be when I was working at Ryders. I was working on; I was the lead architect in a project called Future Homes, which was a social housing project based in Newcastle. In that project, there were a number of engagement sessions with different industry professionals and the public to come up with key principles and objectives to design those social houses. And one of them was low-carbon, low-energy design.

Obviously, it makes it better for the user and probably helps the developer and council. So, that project ran from stage one to stage three while I was there. And that's probably my main insight into working on low-carbon housing.

AN: Have you heard about the recently announced zero-carbon target of 2050?

LR: Yes, yes, I have. Yes, I have heard of that.

AN: Not a lot of people have, actually. But it's just something that was announced; I think Theresa May might have announced it in Spring.

LR: Yeah, I can't remember why I've heard of it, but obviously, I think, when I was working, I knew about 80 percent carbon target by 2050, and then obviously that has increased. So, I must have just heard it through like Dezeen and various websites just through work and people talking about.

AN: And do you think it's achievable in terms of housing? So, to actually have net-zero-carbon.

Both looking at the existing and new build housing?

LR: I think. My gut feeling is the new build is more likely because you can implement that and have more control. Existing housing stock I think is a difficult thing just in terms of the people, the social aspect of it and technology and things that are available. It's a lot of upheavals to try and change the existing housing stock. Whether that's private or whether that's. So, I don't know whether you're talking about specifically private or social.

AN: Just overall.

LR: Just in general? I think social is probably easier to manage because the council still has some involvement with some of the developers of social housing. Privately I think it would be more of a struggle. Still, overall I think there is a general move towards that, and from my work experience that is what people seem to be pushing and moving towards generally so if that can increase that speed up then I would say,' yes, it could be realistic more so for a new build.

But you'd still like improvements to existing.

AN: What would you say are the biggest drivers or support mechanisms for zero-carbon housing or low-carbon housing?

LR: I would say from my perspective working on social housing; it would be policy and frameworks. So, in order for the social housing development to meet the government's standards, they should have to include things like low-carbon housing or a percentage of that as part of the development. So, I think if councils have that or developers have that on their framework, then it makes it necessary, and you have to, you can't really avoid it. And if everything moves towards that and there's a policy like really clear policies in place, I would say that would probably be the biggest driver.

AN: Okay. So, on the opposite, what would you say are the biggest challenges in delivering sustainable housing? Whether that's economic, cultural, etc.

LR: I would say economic but also knowledge and skills. I think practices are getting up today, but I think there's still a bit of a knowledge gap.

AN: Designers or people actually on-site?

LR: Both. I would say both. Yeah, and projects that are available. I think there's a bit of a gap in the knowledge in there as well. From my experience, I was introduced to low-carbon housing through university. So, I think if you're already working in the industry, depending on the kind of practice that you're at, and I'm more inclined to say if you're in a small practice. You'd just be less aware of it, less knowledge. So, I think to have that as part of your RIBA training, CPD, and all that kind of thing. I think that would help, but I think knowledge is a bit of a challenge.

And then economic as well. I think there is this kind of idea that low-carbon design is more expensive because the products you buy in are more expensive, you have to train up the labour and workforce and that kind of thing. Possibly only have specific contractors on site. So, that will get more expensive as well. There needs to be a cultural shift as well as an industrial shift to make that more commonplace in which case they'll be cheaper, and we'll overcome those economic challenges. But everything needs to happen hand-in-hand. In terms of social and cultural, I would say it is largely just the idea that it's expensive. So, if you're a homeowner trying to upgrade or a new build, you would have the idea or impression that it's more

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expensive. And because it's less common, there is less knowledge about it people don't know; people don't see that sustainable design every day.

AN: So, like a lack of awareness?

LR: Yeah, yeah. Lack of awareness. Exactly. And I would say, well, I'm not sure, but I think the lack of awareness is probably another challenge.

AN: Right, okay. Now, let's move to the Passivhaus standard more specifically. So, have you heard of the Passivhaus standard?

LR: Yes. AN: How familiar would you say you are with the standard?

LR: Reasonably familiar with it. I'm not certified, I've never developed a Passivhaus. But I have had some training and worked on projects that were moving towards Passivhaus standard.

AN: Could you briefly talk about the training?

LR: So, it was a day-long training course, and it was held at Ryders. It was to introduce professionals to the Passivhaus standard design principles. And then the second workshop which I couldn't attend was about the technical design, and the calculations, and the software programs they need to become certified. So, it's kind of in two segments, and I would say that the first segment about the design and the principles that I feel quite comfortable with. The technical and the software aspect I'm less experienced in.

AN: Do you know whether they use the software at Ryder? Do you have the software?

LR: No, they don't. And to be honest, the only reason I was on this Passivhaus course was because it was being held in the office and so they offered someone a free space on the training course. So, I took it as a project I was working on was relevant to that. Yeah, they're not investing in it as far as I'm aware.

AN: In your professional opinion, what would you say are the pros and cons of the Passivhaus standard? So, whether that's the complexity, or the software, or cost, certification, training, etc.

LR: Pros, I would say they are the design principles and aspirations of Passivhaus. I think a lot of them are steeped in the user's comfort and I think that's really important in housing. And then I would say in terms of ease of understanding the Passivhaus principles are quite easy to understand. They're quite clear and quite strong, and it's concrete. And that's like a concrete name to put towards it. So, like Passivhaus is a concrete name that people can research and

learn about, and it's something tangible that you can design because of those guidelines and the certification. But what I would say is a negative thought is the certification itself. I think it's quite difficult to get certified. And I think a lot of people or a lot of architects aspire to meet Passivhaus standards, and they might almost meet it, but it's not certified. And from what I learned in this course is that you need this program to be able to have a certified Passivhaus. I think that there's a bit of a disconnect between practices actually investing in the program and the skills to use that program to get a certification. So, I think that it can seem quite complicated as well. The technical side of it and the calculations that you need to do. I think that would put people off.

AN: Do you think the UK could actually achieve Passivhaus or equivalent standard nationwide by 2050? For new build housing?

LR: For a new build, I would say yes. And I'm not sure whether that I would be Passivhaus or whether it would be a standard implemented by the legislative policy.

AN: Let's say equivalent. So, meeting the U-values, etc.

LR: For a new build, I don't see why not. I think it's policy led. And legislation will help to drive that. I mean, from my work, I've already seen that the social housing providers are pushing towards that. Again, I think it's just the knowledge, and the cost implications would be a challenge to that.

AN: You were talking about policy. I will briefly ask what policy changes do you think would most likely drive Passivhaus? I have a couple of options which were presented at the Passivhaus conference that I went to in Manchester. So, they are building regulations Part L or punitive measures, procurement, financial incentives, etc.

LR: Definitely building regulations because I mean Part L is relatively new and how that was implemented on old projects. So, I'd say that would have a huge impact. And procurement definitely so like frameworks and things like. That would have a huge impact because it's a requirement, and people and practices surely would want to be on large frameworks and procurements. What else could it be? I do agree that policy and things like building regulations would change the system.

AN: I mean, at the conference about 60% of people said it's Part L. LR: Oh, really? Why would people say it wasn't Part L? Why do people disagree with that?

AN: It wasn't that they disagreed. It was just like, which one do you think would drive the most?

LR: Have the largest impact.

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AN: Yeah, so other people thought maybe it's planning gain, etc.

LR: Yeah, I think that would bring up a lot of issues with planning because I think people would use it to build on the green belt, etc. I feel like it could have some negative impact if it was a planning condition.

AN: A few more questions. In your professional opinion, do you think Passivhaus could be used as a way to achieve the zero-carbon target, where they want all buildings to be net-zero?

Do you think Passivhaus could be one of the ways to achieve it?

LR: For housing?

AN: For housing.

LR: Yeah. I don't see why not. That is one of the principles of Passivhaus. It's already established as a standard, and we are seeing more and more Passivhauses designed, and built, and certified. I think there should be a push to try and create more and use not as a tangible standard. I think there's already been an investment in the Passivhaus standard as well. So, it already exists. It's just training within practices for the construction industry.

AN: Because the thing at the moment is. Now there's a lot of talk about zero-carbon, net-zero.

But what does it actually mean? Is zero-carbon the same as net-zero-carbon? There are all kinds of ways to achieve it. Do you do it through a lot of renewables? That's why I was researching this subject and whether Passivhaus could be one of the ways to achieve it.

LR: Whether it's over the lifetime of the building? Whether it balances out or whether it's immediately net-zero?

AN: It's like if you told someone, 'could you please design me a zero-carbon house.' Well, how would you go about it? There is no handbook specifically. Everyone is doing it in their own way, and some are doing better than others. So, there's no prescribed route on how to actually achieve it. There was Code for Sustainable Homes, which was scrapped. So, there's nothing now that is concrete and tangible standard to meet. And some people said well, we don't know how to achieve zero-carbon specifically, but we know how to Passivhaus. And if you achieve Passivhaus with a couple of renewables, it actually meets the zero-carbon.

LR: Yeah, exactly. It's already been established as a standard. It's tangible; it can be certified.

So, why wouldn't you strive to use that, and implement that? It is a bit of a grey area in terms of saying, 'could you design a zero-carbon house?'

AN: Few more questions. So, alternatively, if Passivhaus cannot be would be adopted, do you think it could form a foundation for a more robust policy? So, let's say a government comes up with a new policy on their own, but they take some of the principles of the Passivhaus, do you think that would be a good idea?

LR: I think, yes, because one of the challenges or the negatives of the Passivhaus is the certification process, and the difficulty in getting the skillset actually to get it certified but if you take in the principles and striving to those you still should be achieving the same thing without that barrier of certification.

AN: And the last question. In your personal opinion, what do you think would be the best way to achieve the zero-carbon target? What do you think are the most important things or the changes that need to happen?

LR: I would say legislative would be the main driver. I think that could push the whole construction industry to change and move towards it. I think in terms of architects, myself personally RIBA CPDs and having that as part of your training program would be really important. I know a lot of practices in the North East that are investing in themselves to become Passivhaus certified and specialize in that. And that's really important as well. So, I think some of the larger practices could maybe lead by example. Although they are a small practice that I know is doing this, so anyone can do it. It's really positive to see small practices invested in that. But I think to have it as part of your RIBA membership and CPDs and that kind of thing that can be widely accessed by young professionals like myself and you and like established professionals. That covers all bases, but then in terms of the whole construction industry, I would say policy and building regulations, and procurement, and frameworksâ&#x20AC;&#x201D; things like that.

AN: Right, fantastic. Thank you very much!

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Appendicies- Transcript from an interview with LR

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Appendicies- Transcript from an interview with MS

AN: To start things off, could you please describe your work experience in the construction industry?

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Appendicies- SPSS analysis data

MS: So, I used to work for larger architectural practices in Newcastle. It was in 2006, as I mentioned that I started to get, I've got to a position whereby I was looking increasingly in more depth into sustainable design and construction. By around about 2011, 2012, it was 8clear .9 to A ppthat end icies- Nwork vivo in anaaregular lysis daarchitectural ta me I couldn't practice anymore because I couldn't support or endorse the practices of a typical architectural practice that was driven by a lot of the standard commercial pressures just to put food on the plate. And the quality of work was just not something that I could longer tolerate. I had to either leave the industry or leave the practice. So, I ended up setting up my practice in 2011. There was a parallel global kind of challenge going on at the time, and the writing was on the wall, and I left the practice at the right time. Should we say? So, I then went to work for Northumbria University while starting with practice part-time. Yeah, and for anyone who understands, working for the university and running a practice at the same time, it's never a part-time in either case. So, I'm still running my practice as a sole practitioner, though it does occupy all of my time. I don't really deliver any university, kind of tutoring, and things at this particular point anymore. It's been 12 months since I have done anything like that. I do deliver training courses though for architects, engineers, and anybody else that's wanting to get involved with Passivhaus. And tradespeople as well. So, I happen to support the growth of that. And we've got a course taking place in February and March in Newcastle where we've got 21 people coming already. But it's taken 12 years to get to that point. We've tried courses in the North East multiple times, of course, but they've never quite kicked in. So, it's interesting that something's finally taking place. So, that's a bit of background and context. So, yes, I'm a sole practitioner. The work that I do predominantly is with people that are looking to build our own homes and, more recently, people that are looking to retrofit. I do advise on larger scale projects as a Passivhaus consultant as well. So, that's another part of the work that I provide.

AN: While talking about the background, could you briefly talk about maybe a few projects you've done?

MS: Okay, so purely Passivhaus related?

AN: Or low-carbon, or sustainable housing, etc.

MS: Yeah. Well, the first practice I worked at, I was involved in a BREEAM assessed project at the NET park Institute over in County Durham. That was the first sustainable, the first real project I was working on out of university on a sustainable project as a BREEAM assessed project. I do recognize now that my aspirations were higher than the client's aspirations in terms of what its sustainable potential could be. And, also, I had a learning curve to go through, and I was still going through it at that point. So, there's a lot of things that I'd do differently now, albeit we were trying to do something sustainable. From there on out, there were a number of other projects that I've got different degrees of involvement with that were doing things sort of different. Some of which were really parallel to the things that I was researching at the time. The milestone in my view is the Racecourse Passivhaus estate, which is 25 Passivhauses in Houghton-le-Spring, Sunderland. And then there were three very low energy homes on that site as well. In 2011, they were the largest Passivhaus development in the UK for a period of time. And then other people obviously surpassed that, and it's great its progress. What was interesting about that project is that it's not just

that they were built, they were also assessed externally, not just from a certification perspective, but Leeds Beckett University actually did measure tests on the properties to see whether they really worked in practice. Because I don't know whether you're aware, but there is a huge performance gap. There is how we might think we design things, and what we sell to our clients, what we persuade them that we're doing, and then there's the realityand the reality is quite significantly different. Whereby, a lot of the data is based on domestic information because the scale of the buildings means we can do affordable tests.

Large non-domestic buildings become more complicated and costly. But the evidence suggests that exactly what goes on in domestic properties is the same problems you'll see in not domestic, but it's just not as catalogued as clearly. So, Leeds Beckett University has developed what they've called a co-heating test process, and they measure the absolute heat loss of the property independent of how it's lived in. So, this is a bit like putting a car up on in the garage and testing the emissions from it and see whether it's really working, and what are the emissions. The difference is that in the garbage, it's on the chocks, and it's not moving anywhere in the building, it's physically connected to the environment. So, it's a real dynamic test, so what you're doing is you're holding the building or the house at 25 degrees Celsius, or as close to and measuring the amount of heat loss or energy used to maintain that property at that temperature at a cold period of the year. Most studies undertaken by Leeds Beckett University have shown that most properties consume more energy than was expected. And the more ambitious the target, the wider the performance gap. So, basically, we- the industry and I'm not segregating now architects from engineers, from building contractors. We, the industry, sold our clients properties that were going to be a certain energy performance, and in practice, they were using 200% to 300% more energy than predicted because of failures in the design and construction process. This is not about how people live in buildings. This is not a performance gap due to our failures to understand how people live in buildings. This is a fundamental performance gap in how we design and construct, and that is something that architects, in my opinion, choose to be often ignorant about. And I say choose because, well, 'oh, but then I'd have to change the way that I design,' yes, you would. For me, it's a fundamental ethical issue that you design things with integrity, and that means that they should work as predicted. It's not just a case of, 'well, the client was fairly happy.' No, they should do what they said. And if there are failings, then you should be able to go back and learn from them to try and eliminate them in future projects. Because who's to say whether we can't close the gaps. Going back to Houghton-le-Spring, Leeds Beckett University did two co-heating tests, and they were the first two tests that they'd ever done that were within the predicted measurement error of test process itself. They performed as predicted, not only that; the energy use was significantly reduced compared to predictions. So, they use less energy, and they performed as predicted. In terms of the fabric heat losses. So, those gaps, those failures that are not supposed to be there are because of design process problems that I had worked very hard to eliminate. So, that told me that it could be done on my projects in certain circumstances. Not necessarily always. Luckily, two houses got tested for, and they worked. I got quite a lot of confidence that the other ones were all done to the same standard on that site. You go to a different site with different construction technologies, does it absolutely translate? Well, Leeds Beckett University has done co-heating tests on other properties. And other people at other universities and academic institutions have done co-heating tests on other Passivhaus properties, and we've had the same kind of results, whether it's timber frame as Racecourse, masonry builds, etc. They come back with the same kind of results. So, that gave me an awful lot of confidence that Passivhaus can

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deliver. We've also gone back five years later to see whether the airtightness was still there.

You know, the airtightness is shocking. The airtightness target is 0.6 air changes per hour at 50 Pascals, not quite, but broadly speaking, that is, 16 times better than UK building regulations. But does that last, will it degrade over time? So, we went back five years later, not funded by anybody, apart from the curiosity and did some blower door tests. We put a fan in the door to measure the air leakage. There was some uncertainty because of some differences in testing regimes because we couldn't access all the properties, but as far as we can tell, they were fully as predicted as they had been five years ago. No degradation. It works. So, these things can have longevity for them as well. So, that's one detailed case study. Then there were other residential projects that I've been involved with. There is Steel Farm over in Hexham; there's a documentary if you haven't seen it, called, ' Passivhaus Secrets' there's a three-part documentary series about that. There is Larch Corner, a more recent project, which is down in Warwickshire. That's again, a Passivhaus with some photovoltaics on it, built using CLT, cross-laminated timber, so again, different kinds of construction, but that's the UK's most airtight house. So, the air leakage from that fits; if you gathered all the holes in the property into one place, then the total area of those holes is smaller than one penny coin. Whereas in a normal Passivhaus, it's about the size of a letterbox. And if you look at Canada, where they build to an airtightness of 3, which is tighter than the current Building regulations here in the UK, then they reckoned that they have a half the door missing from the house. So, there's sort of scales of examples. There's a couple of other Passivhaus projects, and there's more recently a retrofit. I say retrofit; it's a barn conversion. We basically put a timber frame inside a barn. So, it's different from how you'd retrofit a house, but I've got a number of residential retrofits that are now on the books. So, hopefully, that gives you enough of a perspective about my case studies.

AN: Alright, now could we focus a little bit more on the policies and the zero-carbon?

MS: Okay.

AN: So, the recently announced 2050 net-zero target, do you believe it's achievable for new build housing?

MS: Who's 2050 target?

AN: UK's.

MS: Okay. So, the reason for that level of inquiry is simply that there are different ways of looking at what 2050 targets can be. If it's, as you would say, the RIBA and their particular sets of goals or the UK's ambitions and things like that. So, I understand what you're saying now. I know, that's why I was inquiring. Okay, so in terms of the UK's 2050 target. What are my feelings about that? I'd like it to be sooner. But I think that there are some very significant challenges to make it sooner. And I think that people that want to get everything to zero by, yeah, I have problems with zero, but that's another thing we'll get to. I think that trying to get to a target of 2030, 'we'll do it all by 2030!' It is not realistic either. I like the sort of war mentality that people describe it as. That whole frame of mind whereby, 'make it happen!' We've seen that kind of behaviour in a set of dire circumstances in the past, and we need to have that galvanizing spirit and just do it. And we should be able to implement things a lot quicker than we'd otherwise think, or we're not treating things like our house is fire, if we can use this phrase. I think as soon as possible, and we need to mobilize to do that. I think that net-zero is something that I have a lot of problems with. I think that I mean, I can't speak to net-zero at the level of a nation because it gets too complicated when I'm

an architect. Because then we can go and talk about flights and do they count? And lots of other things which are not in the built environment and which are not relevant to a net-zero conversation. But when we start to focus on buildings, I can more comfortably speak my role; then, I think it's still nonsense. I think that Net-zero buildings. I mean, there's a whole load of papers on it. Nick Grant- an engineer and a friend of mine has written about netzero, previously. I contributed to the thinking that went into that, a little bit, but basically, it's, as I mentioned before, you get the building right, reduce your energy use, and then call it, why not just call it a tax? Your new building tax. And then you go and spend that money to deliver a better grid with better electrons, that's one way of describing it, that is actually meaningfully making an impact. Or maybe that money should just be a new building's tax and they're going to say right, 'We've got this money, we'll invest that in insulating existing properties because we've done an awful lot to decarbonize the grid already. Heat is the problem. And if you look at the data, it shows that the carbon emissions from dwellings haven't reduced in the last ten years for heating. That's where we need to place the attention. You have 50% of the carbon emissions from a house or space heating, another 17% for domestic hot water. So, we've got 67% of our carbon emissions basically related to comfort in some degree or another, we've got to focus on addressing that. So, I think that net-zero is not a useful frame of reference because it creates- it's a tax dodge for one way of describing its accountancy. And accountancy is not strategic thinking. So, I think that net-zero games from that perspective are not useful. If we then start to think about embodied energy. So, that's energy use, and I think that it doesn't work. So, then you start to get the conversations about, reducing the embodied energy or embodied carbon. And you can play games with that as well. The RICS has a process whereby if you build a building for timber, then you can play the net-zero game, 'Oh, we expended this energy here and trapped carbon emissions because it's made out of wood, this miracle material, and therefore it locks up CO2, so therefore we can do a numbers game, and we can subtract one from the other, and we get a tiny number, maybe it's even negative. It's amazing!' That's true, but you could have just left the tree standing up. It would have still sequestered all that carbon, assuming it didn't blow over. For the industry to then start to make these claims is preposterous. I think that there are all sorts of other things about when you start to get into forestry and the impact that you do, it's not just chopping down a tree. It's the impact on the soil carbon and the roots, and all sorts of other secondary things that are not in our heads because we are not foresters. It means that there are boundary conditions that we can't speak confidently about. Never mind the fact that most of these international codes related to reducing carbon emissions have a date associated with them. When was that tree planted? Was it before or after that green? Because that's going to change the nature of how you calculate your numbers. So, there's uncertainty, and I don't think that we can play a net-zero game with that. I think both numbers are useful, but they're more like guidelines than anything real. And I think that we could easily suffer from an 'emperor's new clothes scenario' if we started using the net-zero approach to any of these things because they don't reflect the realities. Interestingly on social media the other day there was Oliver Wainwright from Guardian, he'd written about how the construction industry's responsible for very large carbon emissions, a lot of material waste, et cetera, et cetera. And, you know, this whole conversation about reducing net-zero embodied energy. Well, with net-zero, you can play that game. You know, we've made it net-zero, but we're still consuming far more materials that our planetary resources can support. So, we've got to actually become more resource-efficient in our approach to things as a way of reducing carbon emissions. It's not just a case of making things zero.

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AN: Well, the reason I was asking about net-zero was because at the moment, Passivhaus is a voluntary standard, and there is no legislation that requires to use Passivhaus, but there is legislation that talks about net-zero. Even though I agree with you about that, because I've read about different definitions of net zero-carbon and how it changed throughout the years and.

MS: Sorry, just to jump in here, Wolfgang Feist, the physicists, like a raw physicist, a nuclear physicist. That's what his background was happened to get involved in buildings through the quirk of faith. He was like, 'how can you redefine zero in physics? Zero is absolute; it's unquestioned, you can't redefine zero. It's not a political football. Zero is zero.' If we look at things climatologically, for example, if I emit a ton of carbon right now, did that warm the atmosphere, yes or no? Yes, absolutely. Well, it has contributed to that frame of reference.

If I then go plant a tree, has it cancelled that out? No, it'll take time to do that. There's the global warming potential to that emission. These net-zero games have failed to account for the global warming potentials and all sorts of other things as well. So, I think that's another element of that context of rant.

AN: So, now more in terms of the Passivhaus, what would you say are the pros and cons of the Passivhaus standard in the UK in terms of, for example, the software, the knowledge, the training required, perceived risks, market demand, supply chain, things like that.

MS: Oh yeah, okay, multiple. If you've got a list of those things, we'll come back to each one of them, because each one requires different perspectives.

AN: What about the main ones, which ones would you say?

MS: They are multiple should we say. I think there is a broader awareness of Passivhaus obviously that it has been at some point in the past. There are architects that are aware, you know, and I'm thinking now to an industry level because I think as architects, we have the role of helping to support and educate clients. And therefore, we can help introduce these things to conversations, which could then capitalize on actual action in some form or another. So, we have marketing; all architects are marketing for sustainability. So yeah, in terms of trying to deliver something, we could discuss whether it's Passivhaus or not. I'll keep to that. So, I think there's a growing awareness. I was involved in this before there were any Passivhaus buildings in the UK, so I've seen it evolve over time, and there is a certain maturity in the marketplace right now in terms of the, you know, the industry, that hasn't always been there. I think that there are more people aware of performance gaps, and more people are conscious that they are problematic. Ethically, as much as anything else, I think there is more talk about that. And I think that that started to lead people towards focusing on what are the solutions to these performance gaps. That's, that's where my sentiment comes from. It's not that I want to build Passivhaus; it's that I want to build buildings that don't fail to perform properly. And it happens to be Passivhaus. The same questions I ask about why my buildings might not perform properly were asked by a physicist 28 years ago and resolved. And every time I tried to challenge the Passivhaus standard, 'is this particular target good? Is it useful?' I keep coming back with the answers of- yes, it is. So, I think there's a convergence when we start to look at closing performance gaps, that we're moving towards these kinds of solutions. So, I think that that's its own right is building a certain kind of momentum. So, why do people not want to build Passivhauses left, right, and centre? I think that's apprehension. As I say very rarely have, I had a client

that starts off in the first conversation that they absolutely want a Passivhaus. I might help educate their thinking about that is possible, and some of them might change their mind progressively over time as we're working together. Because they start to realize that it is possible. But it's the one where often there's an apprehension about what's the financial implication of this, which actually goes back to not knowing enough about it. It's uncertainty, list of uncertainties. And we all have these aversions; we're all risk-averse. And there's nothing that involves more risk than buildings in terms of financial outlays and livelihoods and all sorts of things like that. It's a very, very risky thing. And the construction industry, more than any other industry that I can possibly think of is incredibly risk-averse, isn't it? So, we don't like to try new things. The industry suffers from what the energyefficiency guru Amory Lovins calls 'infectious repetitus.' It's kind of a disease that the industry has where we just like to copy the same thing again and again and again, and not question. And I think it's that cultural malaise which is actually a large part of the problem.

And even though that you see in certain large organizations, you see a willingness from time to time to engage with, 'well, we'll try this, we'll try that, we'll try to build some Passivhauses or whatever that might be. But it's often fleeting and, you get the 'oh, we tried it once' as opposed to 'what lessons did we learn, how do we do it again?' You can't make an omelette without breaking eggs. In the same way that you've got to get involved, you've got to go through the process as painful as it may be, deliver a Passivhaus project. My learning curve was like a cliff face. I think through the education process, I've now got it to something more like a 45-degree slope, but it's still a scramble uphill because you could sit at a room, you can learn things, but applying it is very different. But it's easier now than it has ever been, but there's still a big learning curve. But once you've got to that level. It's like fitness. You know, you can get your fitness up to a certain level, and you can maintain that level, but you've got to keep practising. If you go up there and run a marathon once, but then you're back to 20 stone again, it really didn't help. So, it's the same kind of thing, you've got, to keep the dexterity and then you develop. Well, I think that people treat these as experiments. We'll try this; we'll try that. As opposed to becoming clear about something and then moving forwards. So, spend more time getting the ground rules right and then move forward and don't just experiment willy-nilly. You've got to be more definite and confident in the approach, which is where I've come from. As I say, I didn't start with Passivhaus in mind. I was looking at how architects can engage with sustainable design and construction. And performance gaps, they sound worrying. I started reading about those in the UK separately to anything else. Then I was looking at Passivhaus. Then the question was, doing with Google translate, 'does that close before those gaps, and if it does, then we're maybe on the right road. Yeah, and I told you the rest. So, if that's how I converged on it, I think the other people could go down that route as well. You know that you've got parallel threads, but it has closed performance gaps reduced to use the environmental impact, and you kept to that certain sweet spot.

AN: Right, okay. Do you think the UK industry could achieve a Passivhaus or equivalent standard nationwide by 2050?

MS: By 2050?

AN: Yeah, for new builds. Because I remember there was a similar question, in the, I went to the Manchester Passivhaus conference 2019, and I think there was a similar question where they were asking people to stand up, whether they've believed it can and by when and there was a mix of opinions. So, what's your opinion, do you think?

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MS: I think that all things are possible. I think that it's a question of impetus. If you look at Canada, more specifically Vancouver, and you look at some of the things that are going over there right now, they are undergoing fantastic rates of change, and Passivhaus is growing exponentially in terms of the numbers of projects that are on the books and everything else. And that's because of a certain set of circumstances that they have created that are incentivizing and enabling Passivhaus to take hold. Well, they've got different setups but parallel setups in a sentence. So, you are getting planning permission.

Okay. There they have plot ratios- your building should not fil more than a certain ratio of a plot for a certain area, e.g., city centre, suburban, wherever. Well, they recognize that if you build your Passivhaus, then you've got your fatter walls; therefore, you end up losing more floor space. So, they changed the plot area ratios or offered relaxations to this kind of thing. So, therefore, people were not penalized for doing these kinds of things. They've created other little relaxations, which create opportunities for developers to make money doing these buildings. Not necessarily more money but make money. As opposed to, we in the UK seem to always go in with a big stick, you know, and there are fine reasons to beat the developer and the big housebuilders up, but we don't just have to beat them up, we can incentivize them to do the right things, and they will do it because it makes good commercial sense to them. Because I think that we could actually go in with a more positive frame of mind that could help support these changes in transition. It's about education. I'm running a little education program right now. I'm not sure how many people we train a year, but we'll say 200 people a year. But we've got an industry of thousands, including trades, it's tens of thousands. We need to be able to upscale that training and that needs the right kind of resources and support, and the UK approach to things is- 'well, we'll just say what we'd like, and the market will sort itself out.' It's wrong thinking. It needs something more joined-up than that. If we look at Belgium, in Brussels, they have from 2016 basically building Passivhauses as standard.

AN: As a standard?

MS: As a standard.

AN: So, every new building?

MS: Every new building.

AN: Wow! MS: But what they did, is they, first of all, ran a program that said, 'well, we ought to build buildings more sustainably, more environmentally-friendly, whatever we call that and then they set up a program and they created some funding and said, 'if you get to build sustainably, we'll give you some money, somehow, some sort of framework. They then looked at what the marketplace delivered and realized, 'oh, most people are building this Passivhaus thing, that's obviously what the market wants.' Okay. This is savvy thinking.

Yeah. So, then they said, right, well, in that case, we're going to go with Passivhaus. That's obviously the thing that the market wants and not because of any other perverse incentives. Anybody could bring any kind of sustainable targets to the table. So, then they started to create a program that supported educating architects about Passivhaus and how to deliver Passivhaus buildings. So, if a client wants to build a Passivhaus building, your architects will get free education. The architect goes on a two-week course, learns about

Passivhaus. Why not incentivize that? Instead of, 'here's some cheap materials and bolt-on panels for a roof' and paying for that. No, you pay for the skills because the skills will be used for the rest of the career. So, then you've got the one whereby every architect is educating the contractor on how to do it. Why do you need to do it? And they're creating a secondary education system, which can be supported over time. So, it's about education and how we incentivize and support the right kind of education system to enable these things, and this transition. The was a great quote from a university lecturer in Australia somewhere, and it was basically 'the frontiers of knowledge of behind us,' and I think about that every now and again. Because we know everything that we need to know, we just need to implement it. We as the human race, we know it, we just need to implement it, and therefore it's a disseminating the right bits of knowledge to the right people, and then that's passed that process of delivery. So, it's primarily about education. If most people knew that the quality of the work that they were getting was very poor, they would not be happy with that, certainly at a professional level. I think a lot of tradespeople will then say, 'but we're not paid to do that.' And that is another dynamic. But that's because we haven't established the quality in the first place. We've not known what the quality is, so we've just kept undercutting, and the quality of the workmanship got worse and worse and worse. As well as quality design has got worse and worse and worse because we haven't secured ourselves to a 'that's what it is, and if you want it at a lower cost, you can't have it.' So, the free market has some problems. It's not to say that we shouldn't have a free marketplace or go back to the old percentage-based fees and things, but there's, there are definitely problems. At an institutional level, it's a problem, which then makes it hard to deliver projects.

AN: So, I think that ties in quite nicely with the next question I had, which was, 'what do you think are the biggest challenges and barriers at the moment in adopting Passivhaus at scale? For example, what are the biggest things preventing it?

MS: I think that the biggest barrier for scale is going to be. Well, it depends on what scale. I think in a sense there's a certain supply chain side of things, like if we pushed the button tomorrow and said, 'every building is going to be Passivhaus' and nobody had any awareness to it, then you've got manufacturing of triple glazed windows and ventilationheat recovery unit systems and all the rest of it. Where are they going to come from? The demand would outstrip the supply, and prices would go through the roof, and everyone would go, 'see, I told you it was too expensive.' But these things can be done with the right approach. Again, in Canada, what they've created is a step code. So, Passivhaus is what they know they're going for. They've created a framework whereby they're incentivizing it.

The industry knows that that's where they're going and they're incentivizing it. But then they said, 'we're going to get there over these years, and these are the targets, and we're going to get there following these steps. So, therefore the industry knows what the end destination is; you go straight to it if you want. It's like monopoly board, you can go straight to 'Go' and collect your 200 pounds by building a Passivhaus and making the profits now and equipping yourself with the knowledge and skills in the process, or you're going to be forced to go through these steps over a period of time to get to the same place. But that creates a sense of clarity and confidence for the construction industry. And it also allows the construction industry to start to mobilize and prepare, and for innovative and entrepreneurial people to start to build a business around where it's all going to get to, so over time, as that marketplace grows, it's done in a more sustainable fashion. So, I think that's part of it. In terms of?

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AN: The biggest challenge?

MS: Yeah, I think that supply and demand are going to be a critical part if we were to make those sorts of demands overnight. So, that would be a very top-down government says everything's got to be Passivhaus. However, I don't think the government is going to say, 'everything's got to be Passivhaus' because, first of all, it's German. Current circumstances would suggest that it could create tension among certain members of the populace. So, first of all, it's not invented here, and it's also the one whereby it's perceived to be a commercial standard, which in some respect it is, but it's also open-book. Not every Passivhaus building has to be certified. It's not something commonly talked about. You can have certified buildings, declared buildings, and then stuff. So, the Steel Farm project in Hexham, for instance, was a declared Passivhaus. I did all the quality assurance myself; I got all the numbers and everything in place, but no one could pay for certification. The client didn't want to pay for it, I haven't had the opportunity or finance to pay for it, so it wasn't certified. So, I declared it as a Passivhaus- that's allowed by the rules. And then, over a period of time, I worked something out, and the project was certified. So, there is that open-book approach. The PHPP software is an Excel spreadsheet. Yeah. It costs 180 pounds or something like that. It's not a lot of money, really. Especially if you do a number of projects over a period of time. So, there are no considerable expenditures apart from going on the course and getting the education. So, I think that if Passivhaus was deemed to satisfy the UK's building regulations. Sort of saying, 'it goes beyond, but it's acceptable,' and you don't need to go through some of the other assessment procedures associated with building regulations. That would be a real boon. And that's part of the clearing the way and making it easier. Why do we need that log jam in the play? We could make the process easier because we know that it's better than everything else that's going on. And the Future Home Standards, it's retrogressive. LETI, the London energy transformation initiative, basically helped demonstrate that their proposed building regulations will have less demanding fabric standards than the current ones... What's going on there? So, the intergovernmental panel for climate change, they've identified that there's a thing called 'lock-in,' which is that if you initially spend a certain amount of money on something but it then becomes not cost-effective you're still not likely to abandon the project or products because of the initial investment you made, so you get locked-in. So, you want to do it once and do it right. So, Passivhaus pretty much gets there- you're not going to need to put more insulation in. And in terms of how to make a living out of this, so marketing, and profits, and business, and things like that. Well, for the houses that I've designed, I've done my details. I probably won't have to assume all things being equal; I don't have to change those details until the end of my career. Things like, 'here are your 300 millimetres of insulation in the wall, this is how you reduce thermal bridging by 90%', something a lot of architects, don't worry about, but it makes a big difference in terms of the actual energy performance- so those details are done. For residential, I can build up a portfolio of details, out to them progressively build up my vernacular, in house. So, the building will look different from the outside because of the proportions and all sorts of other things. But the way it's assembled, it's same again, same again. Refined if I found that there's a detail that's more practical and pragmatic to do, but otherwise, it doesn't necessarily have to change. So, then you can just focus on reducing costs, not on whether it works or not. I'm not reinventing the wheel. So, there are those kinds of things as well, which can start to streamline it as well. But you'll get that only if you've gone through that learning curve and you start to do the rinse and repeat benefit of that.

AN: Okay, just a few more questions. So, you were talking about that it's unlikely that the government is going to declare that all houses need to be Passivhaus, as you mentioned because it's German and whatever. So, alternatively, for example, if Passivhaus cannot be a national standard, do you think it could help form a foundation for a more robust zerocarbon policy?

MS: Yes, oh, certainly yes. I mean, I'd love to see Passivhaus become the standard one day but for now I think that it's most certainly something that could provide a foundation for thinking about how to deliver buildings that close performance gaps and reduce environmental impact in doing so, and deliver the energy savings that these properties are meant to deliver. Because it closes the performance gap, which is a quality assurance system, more than anything else, and we have to learn from it. And then we can debate whether it's 15 or 25 degrees or something else. We could debate the numbers and about the absolutes even though there are reasons why Passivhaus has got those targets the way it has. We can debate those absolutes, but we can't debate whether the quality assurance works or not. There will be people that will say, 'oh, 0.6 airtightness is hard'. Well, I got 244 times better than building regulations on one house, and it was, I don't know, 60 times better than Passivhaus, if you will, better than, whatever that is. It's within the constraints of what delivers a Passivhaus. I think that if you understand how to deliver airtightness- it's easy. You design for zero, and then it's just implementation. Generally, I find that if I designed for zero, you'd get something like 0.3 or less just because they followed the drawings, and everything was documented clearly. The key thing that I kind of got to was that the 0.6 airtightness is actually fundamental in terms of delivering the energy performance- the quality assurance performance. It's not a number out the air. It demands a certain level of attention and quality of workmanship. There's a range of physics for why it's been selected as well, but we don't have to talk about it right now. But if you start asking, 'well, why not 1 or 3?' then you're missing the point. All other building physics converges in that sort of place. The danger is when we start to say, 'oh, well, we want to do something similar but different' well how do you perform that? We've got to focus on closing performance gaps. Does something work? Yes. So, let's just do it.

AN: And the last question will be a bit about the legislation. What policy changes do you think would most likely drive Passivhaus or equivalent standard? For example, Building Regulations Part L and F, punitive measures, e.g., energy performance bonds, financial incentives, or other things? What did you think at the moment would help to drive the Passivhaus or similar standard the most?

MS: I think the planning policy is a good place to start. It would be a good place to start, but I don't think it's going to happen. Because whilst local authorities have the opportunity to set standards for building work happening within their region, they're constrained by the government as to what the targets they can set for new building residential. Having said that, they are not constrained by non-domestic buildings or any buildings built on their land. So, local authorities as a whole can enforce performance targets too. So, I think that there are some huge opportunities for local authorities to take the lead, in the right conditions, and encourage better practice. I think that through the local authorities that have declared climate emergencies, there's an opportunity for those conversations to be held, whether those conversations turn into something that's actually listened to is a different thing altogether based upon my experience. I think that it tends to go back to who's got the most money. Also, you've got councils, I'm thinking of Durham County

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council, you've got people that are in positions that didn't necessarily want to be in that sustainability of the business position. They've got found themselves there, and they're not incentivized in the right way. Their focus is I want business as usual, but green. That can't happen. We've got to change things fundamentally; there's got to be some greater changes that take place before any Passivhaus things or anything else are really going to take place because it's actually about how the cogs are working in our heads, I'm afraid.

AN: Alright, well, thank you very much!

MS: You're welcome.

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