Passive House Plus (Sustainable building) issue 41 UK by Passive House Plus (Sustainable Building)

INSULATION | AIRTIGHTNESS | BUILDING SCIENCE | VENTILATION | GREEN MATERIALS

S U S TA I N A B L E B U I L D I N G

RECLAIM TO FAME Salvaged timber adds

texture to Enerphit

EMBODIED CARBON SPECIAL Four building case studies & Passive power

The Berkshire passive house that became a power station

Home school

Rural school house retrofitted to passive micro home

Mass timber masterwork Ultra airtight CLT passive house in Cotswolds

Issue 41 £5.95 UK EDITION

11 wall types analysed

EDITOR’S LETTER

PASSIVE HOUSE+

Combing Aereco's expertise in indoor air quality and its industry leading reputation for outcomes in the sector with class leading technology from Wolf. Aereco will be supplying Wolf's domestic range of Heat Recovery Ventilation Units and a select range of commercial products. For more information on the products and service please visit: www.aereco.co.uk

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EDITOR’S LETTER

PASSIVE HOUSE+

Publishers Temple Media Ltd PO Box 9688, Blackrock, Co. Dublin, Ireland t +353 (0)1 210 7513 | t +353 (0)1 210 7512 e info@passivehouseplus.ie www.passivehouseplus.co.uk

Editor Jeff Colley jeff@passivehouseplus.ie

Deputy Editor Lenny Antonelli lenny@passivehouseplus.ie

Reporter John Hearne john@passivehouseplus.ie

Reporter Kate de Selincourt kate@passivehouseplus.ie

Reporter John Cradden cradden@passivehouseplus.ie

Reader Response / IT Dudley Colley dudley@passivehouseplus.ie

Accounts Oisin Hart oisin@passivehouseplus.ie

Art Director Lauren Colley lauren@passivehouseplus.ie

Design Aoife O’Hara aoife@evekudesign.com | evekudesign.com

Contributors

Toby Cambray Greengauge Building Energy Consultants Marianne Heaslip architect Anthea Lacchia journalist Marc Ó Riain doctor of architecture Peter Rickaby energy & sustainability consultant David W Smith journalist

Print GPS Colour Graphics www.gpscolour.co.uk | +44 (0) 28 9070 2020

editor’s letter ISSUE 41

f you find yourself in a hole, stop digging. Or so the expression goes. But some of us simply can’t help ourselves. In preparing this issue of Passive House Plus, I have been tunnelling ceaselessly through an embodied carbon rabbit hole. As disorienting as the experience has been, it’s been fascinating. Much of what I’ve learned is manifest in these pages, in the embodied carbon calculations included in all four case studies, and in the special feature comparing the embodied carbon of no fewer than eleven wall types. The more I’ve learned, the more I’ve come to the conclusion that as an industry, we must grapple properly with embodied carbon as a matter of the utmost urgency. To stretch the rabbit hole analogy to breaking point, we have to stop playing Whac-A-Mole with environmental problems. If we merely attempt to doltishly hammer the proverbial mole of, say, CO2 emissions from heating back into its hole, it may simply pop its head out of an embodied carbon or cost-of-living hole. We must instead seek the solutions that tackle a multiplicity of converging factors. In this task, building life cycle assessment tools – in the hands of specifiers who use these tools to immerse themselves in learning about how to minimise whole life carbon – are essential. One of the main benefits of building life cycle assessment is that it enables us to start thinking about environmental impacts in a more rounded way. It’s true that thinking in whole life carbon terms doesn’t capture every aspect – for instance aspects such as occupant health and biodiversity aren’t explicitly part of an embodied carbon calculation. But it’s remarkable how many environmental impacts can be addressed by this approach. Can is perhaps the key word here, as the scope of building life cycle assessments can vary wildly. Given the industry is still familiarising itself with the rules over LCA in particular areas, the conditions are ripe for cherry picking. The emerging cliché is the architect presenting

calculations on a mass timber building, focusing only on the upfront emissions released in manufacturing the structure, weighed against the carbon sucked out of the atmosphere by trees, and stored in the building’s structure. The logical conclusion to this way of thinking is to fell our way to victory, and cut down as many trees as possible. Sustainably managed forests have an essential role to play in meeting our climate targets, including the supply of low impact building materials, but we must avoid magical thinking. There’s a series of questions we should ask ourselves. Do we need to build new? If so, is the building the right size, and in the right location? Even on the same site, a 100 m2 concrete building would likely be more sustainable than a 200 m2 timber frame building, because the impacts of a building extend far beyond the building structure, and into other materials – and also operational energy use. So it’s important not to obsess over one element of a building, but think about the whole building context – and the building in context in terms of car dependency, infrastructure, etc. By engaging with whole life carbon calculation we can weigh up the impacts of design decisions from pre planning through to detailed design, taking account not just of the emissions released by the point of the building’s completion – but having a good stab at predicting the amount of emissions that may be released during the building’s life, and once it is eventually taken down. Sometimes, as some of the examples shown in this issue reveal, this process can reveal enormous discrepancies in emissions for seemingly similar products. It’s incumbent on anyone procuring or designing a building to learn about these impacts, and use our emerging understanding of these issues to avoid making decisions which may cause needless and irrevocable damage. Regards, The editor

Cover Clifton Place, New York Photo by Emily Dryden

Publisher’s circulation statement: Passive House Plus (UK edition) has a print run of 9,000 copies, posted to architects, clients, contractors & engineers. This includes the members of the Passivhaus Trust, the AECB & the Green Register of Construction Professionals, as well as thousands of key specifiers involved in current & forthcoming sustainable building projects. Disclaimer: The opinions expressed in Passive House Plus are those of the authors and do not necessarily reflect the views of the publishers.

About Passive House Plus is an official partner magazine of The Association for Environment Conscious Building, The International Passive House Assocation and The Passivhaus Trust.

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CONTENTS

PASSIVE HOUSE+

CONTENTS COVER STORY

NEWS The IPCC calls for more efficient use of building floor space alongside energy efficiency and renewables, the UK’s first passive leisure centre opens its doors, and one local authority in Scotland aims to deep retrofit 3,500 dwellings.

COMMENT Architect Marianne Heaslip writes on why we need to make retrofit more people-centred; Dr Marc Ó Riain wonders if the current world energy crisis will prompt a major shift in Europe from foreign oil and gas towards energy efficiency and renewables; and Dr Peter Rickaby asks what the UK government’s plan is to deliver the whole-house, quality-assured retrofits needed to get to net zero by 2050.

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Mass timber masterwork

Ultra airtight CLT passive house This home on the edge of the Cotswolds, built with cross-laminated timber, now holds the distinction of being the UK’s most airtight home, with the client even doing a significant chunk of the airtightness taping himself. What’s more, it demonstrates how passive homes that generate their own renewable power may escape the worst of the energy price crisis.

INTERNATIONAL This issue features a house in Brooklyn renovated to the Enerphit standard, with recycled wood used throughout.

CASE STUDIES

Passive power

The passive house that became a power station A passive house, by its nature, requires a much smaller amount of energy than a typical home, and when its heating demand is met by electricity, and you cover it in solar PV panels, you can start to see the potential for a whole new generation of passive homes that are semi-independent of the electricity grid. This is the case for Carrstone House in Bedfordshire, which generates so much solar energy it had to be registered as a power station.

Home school

Old Leitrim primary school transformed into a timber-based, Enerphit home Rural Ireland has a crisis of dereliction, with numerous government policies aimed at breathing new life into thousands of old, vacant buildings. The careful transformation of one 19th century schoolhouse into a small, beautiful home shows a way forward for the sensitive, climate-conscious renovation of many of these properties.

PASSIVE HOUSE+

CONTENTS

A grid of their own

Irish housing scheme points to a future of decentralised power A new development in County Wicklow demonstrates how typical housing estates might be turned into electricity microgrids through solar power and battery storage, with residents buying and selling renewable energy from each other, helping to insulate them from price spikes and outages.

INSIGHT Up to 11

Embodied carbon of 11 concrete and timber frame wall specs number crunched Last year Passive House Plus published an indepth assessment comparing the build specs including five wall types to a typical Irish house. To enable the industry to fairly compare a broader range of build options, we now expand that analysis with the addition of four timber frame wall types and two insulated concrete formwork systems.

Embodied carbon explained

All this talk of embodied carbon and building life cycle assessment (LCA) can be very daunting, but what does it mean? This is our stab at shedding some light, and explaining the jargon.

MARKETPLACE Keep up with the latest developments from some of the leading companies in sustainable building, including new product innovations, project updates and more.

When will energy efficiency have its day?

In spite of the ongoing global energy crisis, Toby Cambray wonders why energy efficiency seems likely, once again, to be the bridesmaid rather than the bride.

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INTERNATIONAL PASSI VE & ECO BUIL D S F R O M A R O U N D TH E WO R LD

IN BRIEF Building: 226 m2 row house Location: Brooklyn, New York Building method: Timber construction with cellulose insulation Standard: Enerphit certified

NEW YORK

Photos: Emily Dryden

I N T E R N AT I O N A L

CLIFTON PLACE, NEW YORK

lan Solomon, whose company Sawkill Lumber specialises in providing reclaimed timber for construction projects,

be torn out anyway. Alan and the team completely rebuilt the walls, which are

first heard about the passive house standard when supplying

now comprised of timber studs insulated with cellulose. The

salvaged wood to early passive house retrofit projects in the

front façade was clad in Douglas fir that was salvaged from

New York area.

Worcester Sauce tanks, then charred to increase its weather

“Passive house was starting to get a foothold, and I was intrigued without how it could radically cut energy use,” he says.

resistance, giving it a unique take on a traditional row house facade.

So, when Alan and his wife Rebecca bought a row house

The rear façade is more modern, however, and finished with

in the Bedford-Stuyvesant district of Brooklyn that needed

tropical hardwoods salvaged when the boardwalks at Coney

complete renovation, combining passive house design with an

Island and Rockaway were damaged during Hurricane Sandy

emphasis on reclaimed wood seemed the natural approach

in 2012. The window frames were even made from redwood

to take. “It was a good chance to learn about living with these

salvaged from wine tanks.

materials,” Alan says.

Sawkill Lumber also provided reclaimed lumber for the

The house was in poor condition. “The house had been

flooring, internal doors and other finishes. The house is now

patched up in recent decades, but it just needed to be gutted.

heated by two mini split heat pumps, with fresh pre-warmed

There was very little that could be preserved, the walls had to

air delivered by the heat recovery ventilation system. The

be ripped out.”

finished home was certified to the passive house retrofit

Alan brought in architect Paul Castrucci, and passive house

standard, Enerphit, in 2017.

consultant David White, who advised that it would be a good

“For the most part living in the house is really wonderful,” Alan

candidate for passive house, given that it has good exposure to

says,” the space, the air, the sound — the consistent temperature

the south via the rear façade, and that the walls were going to

throughout the house.”

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NEW YORK

I N T E R N AT I O N A L

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NEW YORK

I N T E R N AT I O N A L

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on www.passive.ie

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AECB CARBONLITE RETROFIT COORDINATION COURSE TM

BECOME PROFICIENT IN RETROFIT COORDINATION & RISK MANAGEMENT

• 105 hours of fully online, self-directed learning with 15 module topics and over 100 lessons. • 12 months access to study the e-learning course at your own pace. Clearly track your progress and easily dip in and out of the course, to ﬁt your study around your work and other commitments. • Downloadable lesson booklets for your reference.�� • Variety of assessment types includes multiple choice, numerical calculations and scenario-based exercises.�� The is dedicated student support available, and also an online forum allowing students to discuss topics or post • There questions with other learners.�� • AECB membership is required to take the course. • All students have the option to renew access after 12 months, for an annual renewal fee of £99 (+ VAT).

The AECB CarbonLite™ Retrofit Coordination course is aimed at professionals and contractors in the construction industry; built environment and those involved in the energy efficiency sector who are already familiar with retrofit and project management. It provides background answers and understanding of how the PAS 2035 framework impacts on projects and which key professionals within their organisations need to upskill as defined in the UK Government ‘Heat and Buildings Strategy’. The course provides the in-depth technical detail essential to understanding low carbon retrofit and a working knowledge of the PAS 2035 process and framework. It enables students to become confident and proficient in retrofit coordination and managing risks, to help facilitate PAS 2035 projects and to understand and support the roles within the process. We aim to equip you and your organisation with an understanding of how to provide PAS 2035-aligned retrofit services to clients while giving individual homeowners and tenants an increased level of confidence and protection across the entire retrofit process. This course will not currently provide the Level 5 certification required to become an accredited Retrofit Coordinator, or to register as such with TrustMark. * Introductory prices available until 07/04/22, except for the CarbonLite™ graduate price which is available during 2022.

Find out more and apply: https://aecb.net/aecb-retroﬁt-coordination-course

JOIN AECB TODAY https://aecb.net/join-the-aecb/

NEWS

PASSIVE HOUSE+

NEWS ‘Sufficiency’ key alongside energy efficiency & renewables, says IPCC Latest climate report calls for more efficient use of floor space in buildings ‘Sufficiency’ policies that reduce the need for new building space, and more efficient use of floor area in buildings, will both have a critical role to play in reducing the carbon footprint of the built environment, the latest report from the Intergovernmental Panel on Climate Change (IPCC) has said. As well as stressing the importance of energy efficiency and renewables, the report says that sufficiency — defined as avoiding demand for energy, materials, land and water while delivering human wellbeing — can play a key role in reducing emissions. It gives dense and compact design, multi-functional spaces, shared spaces, and repurposing of existing buildings, as examples of sufficiency-based policies, and says that, “up to 17% of the mitigation potential in the buildings sector could be captured by 2050 through sufficiency”. The report also says that total direct and indirect emissions from residential buildings increased by 50 per cent between 1990 and 2019, and that this was “mainly driven by the increase in floor area per capita”, as dwelling size has increased while the number of occupants per household has decreased. It says that more efficient use of both floor space and energy will be important to reducing emissions. The document, ‘Climate Change 2022: Mitigation of Climate Change’ was published on 4 April. It is the third and final report published as part of the IPCC’s sixth assessment report. It says that global emissions from buildings could be reduced by 61 per cent by 2050, with the largest share of mitigation potential coming from low carbon new buildings in developing countries, plus the renovation of existing buildings in developed countries. “We see examples of zero energy or zero-carbon buildings in almost all climates,” said IPCC Working Group III co-chair Jim Skea. “Action in this decade is critical to capture the mitigation potential of buildings.” However, the report warns that “low ambitious” policies have the potential to lock-in carbon emissions from the built environment for decades. It also says that “low renovation

12 | passivehouseplus.co.uk | issue 41

rates and low ambition of retrofitted buildings have hindered the decrease of emissions”. But it says that that well designed and implemented new build and retrofit policies have the potential to contribute to the UN’s sustainable development goals while adapting buildings to future climate. “For the built environment, the report revealed some promising information about our sector’s potential to accelerate climate action,” said Cristina Gamboa, chief executive of the World Green Building Council. “Most encouraging is the verdict that net zero buildings can be delivered at scale by 2050, but only if policy packages are effectively implemented and barriers to decarbonisation removed. And these packages must combine a purposeful trifecta of sufficiency, efficiency, and renewable energy measures.” “What we need is the perfect union of political ambition and financial incentives to make this happen at scale. “These mitigation interventions also have significant potential to address wider socio-economic issues, and help achieve the UN Sustainable Development Goals (SDGs)

in all regions, while future-proofing buildings for changing climates. “The challenge of embodied carbon has long been a contention point for our industry,” Gamboa said. “However, this report finds that embodied emissions can be addressed by limiting a new building's required floor space, and reducing the quantity and intensity of material emissions through rigorous efficiency measures. “We know that the solutions already exist to help us achieve net zero buildings, but we need radical, systemic transformation in the way we design, build, operate, deconstruct and value our buildings and infrastructure.” The report also says that the expanded use of wood products from sustainably managed forests has the potential to mitigate emissions if these products are long-lived, recycled or substitute for higher carbon materials, but it stresses that land and forest-based mitigation measures, “cannot compensate for delayed emissions reductions in other sectors.” The full report is available at www.ipcc.ch. •

Global surface temperature (°C) anomaly relative to 1850- 1900 High warming scenario: SSP3- 7, Low warming scenario from SSP1-2.6 Source: IPCC AR6 WG1

PASSIVE HOUSE+

NEWS

UK’s first passive leisure centre nears completion

t Sidwell’s Point Leisure Centre in Exeter, the first passive-certified leisure centre in the UK, is set to open to the public on 29 April. The Passive House Institute has previously certified two swimming pool buildings in Germany, but this is a more substantial building that accommodates not only two swimming pools and a toddlers’ pool but also seating for 100 spectators, a 100-station gym, a spin studio, a dance studio, a health suite with spa facilities and a hydrotherapy pool, plus a café and a creche. Gale & Snowden Architects worked with the institute to agree a bespoke set of technical standards for the building and a certification methodology. Designed for Exeter City Council by Gale & Snowden with SSP Architects, Arup engineers and main contractor Kier, the £42 million, multi-level, multi-zone building stands on a prominent, sloping site in the centre of Exeter. The passive house energy use target of 375 kWh/m2/yr (which the team expects to beat) compares with 1,579 kWh/m2/yr for a typical leisure centre and 737 kWh/m2/yr for a good practice building. There are also component targets for energy use by each item of

major plant, for example 40 kWh/m2/yr for pool filtration. The building is designed to achieve 50 per cent water savings compared with a typical leisure centre, and to be climate resilient up until 2080. Exeter City Council expects 500,000 visitors per year. Gale & Snowden provided passive house consultancy, dynamic thermal monitoring to support the approaches to passive house and climate resilience, building biology consultancy (including selection of materials) and the building envelope design. SSP provided

interior design including the swimming pools. The pools are daylit via split-level, south-facing triple glazed curtain walls to maximise solar gains. Internal brise soleil eliminate reflections and glare from the pool surfaces, which would otherwise interfere with spectators’ viewing. Passive House Plus will feature an in-depth case study of St Sidwell’s Point Leisure Centre in an upcoming issue. • (above) St Sidwell’s Point, the UK’s first passive-certified leisure centre.

Renfrewshire aims for 3,500 whole-house deep retrofits

major new social housing retrofit programme by Renfrewshire Council will see up to 3,500 local authority dwellings renovated to either Enerphit or the AECB Retrofit Standard. Leading low energy and passive house architects ECD have won a £4m design contract to lead the retrofit of between 3,000 and 3,500 dwellings for the local authority — which includes suburbs like Paisley, Linwood and Johnstone to the west of Glasgow — over the next four years. Duncan Smith, former housing strategy and asset manager at the council — who

wrote the specification for the contract — said that it was designed to ensure quality control and a high standard of retrofit. “These retrofits will benefit some of the most vulnerable, some of the poorest people in our communities, those most at risk of the cost-of-living crisis and fuel poverty,” he said. “It’s about reducing energy demand, closing the performance gap, and designing homes that are fit for purpose.” As well as stipulating that all dwellings must be retrofitted to Enerphit, as an ideal target, and the AECB Retrofit Standard, as a backstop, the contract also requires that

retrofits adhere to PAS 2035 principles. The AECB Retrofit Standard is a wholehouse, fabric-first standard that is based on the Passive House Institute’s Enerphit specification, but less onerous, with a space heating demand target of 50 KWh/m2/yr, as opposed to 25 KWh/m2/yr for Enerphit. PAS 2035 is a new process for the energy retrofit of UK domestic buildings. It was developed as part of the ‘Each Home Counts’ process, which was established to tackle the high level of failure in domestic retrofit under government-backed schemes, though widespread adoption of PAS 2035 has been slow to date. PAS 2035 mandates a number of specific roles on retrofit projects, including project designer, project manager, retrofit co-ordinator, and retrofit assessor, with minimum qualifications and/or professional accreditations for each. Renfrewshire’s contract stipulated that RICS professions must be appointed to the key roles of retrofit assessor and retrofit co-ordinator. • (above) A block of flats, built in the 1930s, that Renfrewshire Council upgraded from an EPC D to an A rating last year.

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NEWS

PASSIVE HOUSE+

Creating quality low energy architecture requires a dedicated,

SUSTAINABLE BUILDING MATERIALS FROM FOUNDATION TO RIDGE

knowledgeable team from initial concept right through to finishing touches. Ecomerchant is a key part of that team for Charlie Luxton Design. Our values align, creating good buildings that perform and last whilst respecting our environment. Charlie Luxton

www.ecomerchant.co.uk info@ecomerchant.co.uk +44 1793 847 444 | issue 41 14 (0) | passivehouseplus.co.uk

Principal Charlie Luxton Design

PASSIVE HOUSE+

Max Fordham House verified as UK’s first net zero carbon home

NEWS

Advertising feature

#GoHomeSafe AG Scoops 3 Major Construction Awards

ax Fordham House in North London has become the first residential building in the UK to be verified as net zero carbon. Located in the London Borough of Camden, this certified passive house was designed for, and lived in by, the late legendary engineer Max Fordham. It was profiled in issue 30 of Passive House Plus. Max Fordham House achieved net zero carbon for both operational and construction carbon. Operational verification is based on assessing a year’s actual in-use energy data, while construction verification is based on assessing the emissions associated with the buildings’ materials. The achievement was made in line with the UK Green Building Council’s net zero carbon buildings framework. The RIBA award-winning house was designed by the engineering firm Max Fordham LLP in collaboration with bere:architects and Price & Myers, and built by Bow Tie Construction. Max Fordham himself was an integral member of the design team. "My Dad loved living in this amazing house. It's incredible how it needs almost zero heating,” said Finn Fordham, Max Fordham’s youngest son. “And it's lovely to imagine how he would chuckle and beam at the news of another accolade, now awarded beyond the end of a lifetime. That lifetime was one devoted to beautiful design and engineering. Part of its legacy should be that the principle behind the house is emulated around the world.” To minimise carbon emissions during construction, concrete with low carbon cement replacement was used alongside many natural materials such as timber for the roof structure, window frames, and façade; internal insulation made of wood fibre; and flooring made from cork.

To achieve net zero carbon for the emissions created during construction, an investment in offsetting schemes was made at the voluntary cost of £70 per tonne. This is far higher than the market rate but is recommended by UKGBC and the Treasury to accelerate funding and incentivise reducing emissions first. “Achieving net zero carbon in both construction and in operational energy using UKGBC's framework is not just an industry first for a residential property but for any built asset, making this a truly pioneering project,” said Yetunde Abdul, head of climate action at UKGBC. Retrofit awards Meanwhile, Bow Tie Construction, builders of the Max Fordham House, also picked up the award for retrofit installer of the year at this year’s Retrofit Academy Awards. The company has extensive experience with passive house and low energy retrofit in the London area. “The team at Bow Tie Construction demonstrated fantastic attention to detail and quality that is scalable, with an emphasis on the quality of living for their clients,” said the Retrofit Academy. “The judges’ also commented that it was great to see a new SME contractor bringing a high-quality whole house deep retrofit experience to the social housing sector that can be scaled up.” Other winners at the awards, which were held at Futurebuild in London on 1 March, included Renfrewshire Council for social landlord of the year, Jarrod Green for retrofit assessor, the Northern Ireland Housing Executive for small retrofit project, Melius Homes for large retrofit project, and Barbara Lantschner for retrofit rising star. •

AG, leading paving and building supplies company, has won three major industry awards in quick succession across the UK and Ireland. Established 60 years ago, AG is a 3rd generation family-owned business which now employs more than 230 people at eight locations across the UK and Ireland. The first accolade was winning the Property and Construction Family Business of the Year category at the Energia Family Business Awards. The Energia Awards showcase the commercial success of Irish family companies and highlights the impact their business has on communities. The second award - from The MPA and British Precast for Safer Management of Pedestrian and Transport on its sites – provided positive proof of AG’s excellent work within Health and Safety. Meanwhile, AG received a Distinction Award at the NISO (National Irish Safety Organisation) and NISG (Northern Ireland Safety Group) Safety Awards for 2021. Winning this award demonstrates the dedication of all AG employees and contractors to safety within the company.

To find out more about AG, visit their website: www.ag.uk.com

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MARIANNE HEASLIP

COLUMN

Putting residents at the heart of retrofit We will never scale up retrofit unless we genuinely listen to building occupants and understand their needs, says architect Marianne Heaslip.

he UK government’s lack of ambition around making homes more energy efficient is disappointing. Recent policies, including last autumn’s heat and buildings strategy and the new heat pump grant, are inadequate and disjointed. But given the imperative of the climate emergency, we can’t wait for high level policy to change. We need to get on with improving our homes now and building the infrastructure that will take retrofit to scale. I know from my work with Carbon Co-op on the People Powered Retrofit service — talking to clients and visiting their homes — that many people want to improve their home, but they’re stuck. This is not a problem of technology; the tech we need exists. For many it’s also not a problem of finance, because they have savings or access to finance.

or gaming EPC ratings. It needs to work logically with planned improvements and repairs. We also need to recognise that not everyone wants intimate knowledge of their heating system (though I’m eternally grateful to those who do, because we learn a lot from them). But generally, people just want things to work, to be easy to control and maintain. If we don’t address this as an industry, and make retrofit accessible and attractive, rather than something that is ‘done to’ people, it will never take off. This starts with the retrofit project brief, a welcome focus of PAS2035, and should flow into survey, design, construction and handover. Taking a people-centred approach also improves retrofit quality, through better understanding of the context. Even the most keen-eyed surveyor only visits a home for a

Even the most keen-eyed surveyor only visits a home for a few hours, while the resident lives there. Rather, it’s uncertainty about what to do, fear of getting something wrong, and doubt about who will do it. This uncertainty kills progress. Previous top-down retrofit programmes have taken a ‘one size fits all’ approach, but ended up not fitting anyone. If we’re serious about taking retrofit to scale we need to be equally serious about meeting the needs of those people using the buildings we retrofit. Focusing on people’s priorities makes it more likely that a project will happen and succeed. If a client’s main driver is to improve comfort or energy security, just swapping over their heat source, without addressing draughts and cold spots, won’t do this. This issue will worsen as energy prices soar. Works such as insulation, which mean people need less energy in the first place, must be prioritised. Scaling up and mainstreaming retrofit also needs to be about integrating it with ‘normal’ building work and maintenance. If someone is planning an extension, new kitchen, or loft renovation, the retrofit needs to accommodate this. Phasing of works can’t just be about maximising (notional) cost per tonne of carbon,

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few hours, while the resident lives there. Residents know which rooms are coldest or feel stuffy, where periodic damp and condensation appears, how they control their heating, and where they dry their laundry. Combining this knowledge with professional know-how is invaluable in creating better retrofit designs. If this is also combined with actual energy and other environmental data, so much the better. This people-centred approach doesn’t just apply to owner-occupied housing. Those living in rented homes also deserve not to be ‘done to’ when it comes to retrofit. The Northern Housing Consortium’s Tenants’ Climate Jury, run in 2021, demonstrated that again, the main barrier is not ‘demand’ or understanding something needs to be done. Instead, the concerns are ones anyone might have about a building project: how disruptive and messy it will be, how long it will take, and whether it will achieve its intended outcomes. These concerns can be mitigated by straightforward but often difficult to achieve things (given funding constraints), like good resourcing for engagement, user-friendly information

materials, sensible lead-in times for design and surveys, and practical construction programmes. Aneaka Kellay at Carbon Co-op has done good work in this area (see their ‘Retrofit for All’ toolkit). Last but not least, we need to also be people-centred in our approach to developing supply chains, the people who will actually do this work. Developing good jobs is not something the construction industry has always been good at. Unless contractors are engaged and willing, and can see a future in this work, it won’t happen. This might be about meaningful social value and procurement reform in public sector work. Or, as demonstrated in our work in Greater Manchester with the micro builders who already do lots of local home improvement work, it’s about better understanding their motivations, providing skills support, and contacts to well-informed clients. We can and should campaign for better and clearer central government policy, but we can also take this into our own hands, by improving the services we offer and making retrofit truly people powered. n

Marianne Heaslip is an architect and retrofit specialist at URBED (Urbanism, Environment, Design), an award-winning design and research consultancy based in Manchester.

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DR MARC Ó RIAIN

COLUMN

The world energy crisis 2022 The energy crises of the 1970s did not prompt a major shift in Europe from foreign oil and gas towards energy efficiency and renewables. Will we learn this time around, wonders

Dr Marc O Riain.

n many of my articles I have touched on geopolitical events that have impacted the supply, and therefore the cost, of energy. This has had a direct and consequential effect on the cost of petrol in our cars, and the heating of our homes. Up to 1 April 2022, UK energy costs have already increased by 54 per cent and in Ireland suppliers like Bord Gáis have increased gas prices by 39 per cent, forcing both governments in both countries to give householders a once off energy rebate, which will do nothing to abate demand or reduce energy costs. As I write this article, Russia has invaded Ukraine and Brent crude has just passed $105 a barrel and maintained that level for six weeks. Undoubtedly the ratcheting up of EU sanctions on Russia, the halting of the Nord 2 gas pipeline, and the fact that Nord 1 actually runs through Ukraine from Russia, are likely to result in home energy costs increasing further, throwing more of us into fuel poverty. The number of households in England experiencing “fuel stress” was expected to double to around five million this spring, according to the Resolution Foundation. These are people that will routinely have to decide between food and heating. Soaring inflation and carbon taxes have further increased pressure on household income. You would think that since the first energy crisis of 1974, we would have weaned ourselves off the teat of foreign oil and gas, that we would have transformed our building standards and addressed energy conservation in our existing buildings. Much has been done in terms of the development of renewables and new building standards in response to the Kyoto, and more recently Paris, climate agreements. However, Russia accounts for 57 to 60 per cent of all EU gas, oil and coal imports (REPowerEU 2022) , and accounted for 47 per cent of UK gas imports in 2021. In fact the UK imported 33.7 million megawatt-hours’ worth of liquefied natural gas (LNG) from Russia in 2021, up from 15.6 million in 2018. Russia is trying to force EU countries to pay for gas imports in roubles in order to prop up the value of the currency, and is threatening to turn off the tap. While the EU has been debating the creation

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of a voluntary strategic reserve for natural gas, prices hit record highs in December with gas costing €183 per MWh, an increase of 985 per cent year-on-year, and by 5 April EU gas stocks had fallen to 17 per cent. Wholesale natural gas prices in the EU are at $42.39 per MMBtu, up from $6.127 one year ago, a 690 per cent increase. The EU has struck a deal with the US for about 10 per cent of its gas requirement for the coming winter, but it still faces a major challenge in replenishing its stocks. European Commission president Ursula von der Leyen has stated that the EU wants to diversify away from its reliance on Russian imports and in general pivot towards renewables. But we have not radically shifted, at speed,

must be slashed by 95 percent worldwide, while consumption of oil and gas has to be reduced by 60 percent and 45 percent, respectively, by 2050. We must use this crisis to move our countries towards a faster rollout of renewable infrastructure, offshore wind, micro-solar, solar fields, micro-grids, feed-in tariffs and green hydrogen. We must make grants for elemental and deep retrofit packages simpler and easier to access with low-to-zero cost finance for energy conservation measures. While we think about our own future, energy security, environment and population my heart goes out to the brave people of Ukraine. Solidarnist! n

We have not radically shifted, at speed, toward renewable energy. toward renewable energy, nor have we translated our building stock to low energy demand since the energy crises in 1973 and 1979. Rising environmental concerns have shifted our building energy standards for new buildings since 2010, but this does not address the elephant in the room: we only replace one per cent of our housing stock per year. Since 1974, the UK has aggressively followed an energy independence strategy shifting its energy mix to oil, gas and nuclear, with new reserves in the North Sea and nuclear reactors along the Irish Sea. Indeed, Boris Johnson has just rejected a doubling of onshore wind in favour of seven new nuclear reactors. The percentage of renewable energy generation in the UK in 2021 was 36 per cent whilst fossil fuels represented 45 per cent of total energy demand. Ireland by contrast is more dependent on imported fossil fuels with renewable generation at only 13.5 per cent in 2020 (Source: SEAI). The UN’s Intergovernmental Panel on Climate Change (IPCC) has just published Climate Change 2022: Mitigation of Climate Change, and it has warned that the use of coal

A fully referenced version of this article is online at www.passivehouseplus.ie Dr Marc Ó Riain is a lecturer in the Department of Architecture at Munster Technological University (MTU). He has a PhD in zero energy retrofit and has delivered both residential and commercial NZEB retrofits In Ireland. He is a director of RUA Architects and has a passion for the environment both built and natural.

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DR PETER RICKABY

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Punk retrofit: fighting the lack of vision on energy upgrades In the aftermath of COP26, Dr Peter Rickaby asks what is the government’s plan to deliver the deep, whole-house, quality-assured retrofits needed to get us to net zero by 2050?

n the disappointing aftermath of COP26, I was part of a WhatsApp group called ‘Punk Retrofit’. Members were professionals disgruntled that despite the UK’s commitments, insufficient progress is being made with domestic retrofit, on which achieving our ‘net zero carbon’ target depends. They were also disappointed by an apparent loss of commitment to the quality assurance process developed after the Each Home Counts review. At the beginning of the last decade domestic retrofit was placed in the hands of an installation industry that was untrained, with little understanding of building physics, moisture risks or retrofit risk management, and which was fragmented into ‘silos’ around individual measures. Retrofit professionals, with more knowledge (learned from Retrofit for the Future, CoRE, RE:NEW, the STBA and elsewhere) had been excluded from The Green Deal and ECO. It is not surprising that much retrofit went horribly wrong, damaging public and government confidence in the industry. Potential funding bodies were not impressed. The Each Home Counts review was established in 2014 to protect people’s homes and health against poor retrofit and to restore confidence in the industry. The report was published in December 2016, and government recently reaffirmed its commitment to implementing the recommendations in full, but it appears to have lost its way.

information and advice hub to inform the public and industry. The implementation board was clear that the hub must be authoritative, independent and publicly funded. The hub is needed without delay – it is the only recommendation of Each Homes Counts that has not been implemented. Another view of the Each Home Counts implementation board was that the recommended retrofit quality mark should be public-facing (part of the process of restoring confidence) and that it should have the ‘teeth’ to curb poor practice. The role was given to TrustMark, which has no public profile, and which is funded via the certification bodies to which retrofit installers belong. How can a gamekeeper be funded by the poachers? The funding arrangements for TrustMark create a conflict of interest that does not help with its mission of protecting homes and occupants’ health. Another recommendation of Each Home Counts was to move away from measures-based incremental retrofit towards more robust whole-dwelling retrofit, a change that removes many risks to people’s homes and occupants’ health. During the development of PAS 2035 it was acknowledged that many owner-occupiers and landlords cannot afford to improve their homes all at once, to the extent needed. In response, PAS 2035 requires a retrofit process in substantial stages, using the ‘fabric first’

We will not achieve net zero carbon without inspiring leadership, a clear strategy and courageous policy.

We know how to do safe, healthy retrofit. Knowledge has been embedded in the BSI Retrofit Standards Framework, including Publicly Available Specification (PAS) 2035, that was developed in response to one of the Each Home Counts recommendations. But that knowledge is not being adequately disseminated. A key recommendation of Each Home Counts was the establishment of an

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approach, and based on a whole-dwelling assessment, an improvement option evaluation and a medium-term improvement plan. ‘Substantial stages’ means, first, improvement of the whole building fabric (plus ventilation), then decarbonisation of building services (heating and hot water); and then the use of renewable energy systems to top up to zero carbon if necessary. Yet govern-

ment continues to promote measures-based retrofit funding programmes involving pre-determined measures, and although packages of measures are encouraged, the funding caps are inadequate and the timescales are often unachievable. A programme with a funding cap of £15,000 should support, as first priority, building fabric retrofit (and ventilation), and leave decarbonisation to the next stage. Mixed messages about ‘step by step’ retrofit are confusing and unhelpful. Participants in the Punk Retrofit discussion complained that installers, not retrofit professionals, have the ear of BEIS when it comes to standards and quality assurance in domestic retrofit. This is despite the evidence from Each Home Counts that installers are part of the problem, not part of the solution. The BSI Retrofit Standards Task Group now plans to change the focus of PAS 2035 from professionals and installers to professionals and contractors. In this context it is time for the government to listen to experienced individuals and organisations who know what they are doing, rather than to inexpert and differently motivated trade groups and certification bodies who make the most noise. All low carbon heat options (heat pumps, heat networks, hydrogen, renewables) require demand reduction. They are also surrounded by uncertainty that will not be resolved for years, so today the only ‘no regrets’ strategy is demand reduction through retrofit. However, the UK government appears to be ducking the challenge. We will not achieve net zero carbon by 2050 without inspiring leadership, a clear strategy and courageous policy. Unfortunately, too little, too late, with no sense of urgency and a reluctance to communicate inconvenient truths, seems a good characterisation of current policy. n

Dr Peter Rickaby is a retrofit consultant with Savills social housing team, and chairs the BSI Retrofit Standards Task Group. The views expressed in this article are his own, and not necessarily those of Savills or of BSI.

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MASS TIMBER MASTERWORK ULTRA AIRTIGHT CLT PASSIVE HOUSE This home on the edge of the Cotswolds, built with cross-laminated timber, now holds the distinction of being the UK’s most airtight home, with the client even doing a significant chunk of the airtightness taping himself. What’s more, it demonstrates how passive homes that generate their own renewable power may escape the worst of the energy price crisis. By John Cradden

IN BRIEF Building: 162 m2 detached house Method: Cross-laminated timber Location: Upper Quinton, Warwickshire Standard: Passive House Classic Energy bills: £240 profit/year on energy bills prior to recent price spikes. Predicted net cost of £230/year post price spikes.

£19

per month (2022) vs £20 per month profit (2021) 22 | passivehouseplus.co.uk | issue 41

CASE STUDY

The builders have ‘accidentally’ created the UK’s most airtight house.

Photos: Mark Siddall and Regen Media

his modest, single-storey three-bed home in the northernmost tip of the Cotswolds has been singled out for the kind of praise and awards that will warm the hearts of both passive house advocates and fans of precision-built timber — not least because its builders have ‘accidentally’ created the UK’s most airtight house. Larch Corner’s record-breaking airtightness result of 0.048 air changes per hour (at 50 Pascals pressure) is some 12 times higher than that required by the passive house standard, and 244 times more than that required by UK building regulations. The project also represented an early attempt to calculate the embodied carbon of a building in the UK, before standard tools for doing so were widely available. The site in Warwickshire had planning permission for a passive house before its owner, Mick Woolley, bought it at an auction in 2018. Woolley, a software engineer, was attracted to the scientific approach of the passive house standard. But even to his untrained eye, the original design needed work, so he commissioned architect Mark Siddall, one of the UK’s leading authorities on passive house design, to come on board. Siddall identified a number of issues straight away. “The design was based on socalled passive house principles, but it was heavily flawed,” he says. “There was way too much glazing, too much shading in other locations, and the form factor was worse than it is now.” Planning permission limited the height of the house to one storey, but the

LARCH CORNER

form factor [the ratio of the surface area of the building to the floor area] was measured at over 3.9 and was unnecessarily complex. “There were lots of jagged edges and things that together just would’ve really undermined the ambition, and would’ve led to additional costs.” Siddall wasn’t a big fan of the floor plan either, particularly in terms of the relationship between public and private areas. Part of Woolley’s brief was also for a space that was fully accessible for his sister-in-law’s wheelchair, for when she comes to visit. However, Siddall was happy to work within the limits of the existing permission rather than go back to the drawing board. “I don’t get wrapped up in being creative for the sake of it,” he said. “It’s a case of understanding the constraints and working within them. We didn’t want to put in a new planning application. We had to work with the one that was granted already, so we could tidy it up, but not in ways that were going to be a concern from the planning perspective.” The excessive glazing of the original design added to the costs because, after all, windows cost more than walls, but also because it created overheating risks that the design tried to compensate for with shading. Furthermore, it also created a bit of a goldfish bowl effect because of the corner site’s exposure to a moderately busy road and footpath. Using the AECB’s daylighting tool, Siddall was able to cut down on the glazing to still provide good levels of daylight but without the need for shading devices. The front

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LARCH CORNER

CASE STUDY

The finished building is held together by 21,000 screws.

façade was retained because it worked well in articulating the sweeping corner plot, but the northern and western façades were manipulated a little and refined. “Reappraising glazing areas, removing eight corners and reducing the form factor were all part of a value engineering strategy which avoided complexity, improved buildability and reduced costs, without compromising the home that Mick wanted,” Siddall says. “It’s the strive for optimal value, achieving more with less, that underpins every project I work on.” Further evidence that whoever created the original blueprint didn’t fully understand passive house design was the lack of provision in the space for an MVHR [mechanical ventilation with heat recovery] system, which Siddall also addressed with his revised plan. While Siddall and Woolley struck up a good working relationship, one aspect they differed on was the exact type of timber construction to be specified. Woolley was keen to use cross-laminated timber (CLT), a mass timber method more commonly used for multi-storey buildings, mainly because he

WANT TO KNOW MORE? The digital version of this magazine includes access to exclusive galleries of architectural drawings. The digital magazine is available to subscribers on passivehouseplus.ie & passivehouseplus.co.uk

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really liked the range of options from CLT manufacturer Novatop that provide a good quality timber finish on the inside, including the roof. “I ended up deciding that the ceiling should be timber as well,” he says. Siddall felt that using engineered timber I-beams would have been more cost-effective and would have reduced the overall carbon footprint of the project (CLT is a wood panel product which is made by gluing together layers of solid-sawn lumber. As such it is heavier, more resource hungry and more carbon intensive when compared to a structure built using engineered timber I-beams). Woolley insisted on CLT, but admitted that Siddall’s focus on resource efficiency and embodied carbon has finally rubbed off him. “I’ll have to hold me hand up now and say, having built it, if I did it again… that you could build a stud version of the house and still finish it internally with timber,” he says. “At the time it wasn’t something that occurred to me, particularly. I was thinking, well, I like this. But I must admit I’m probably more thoughtful now about what the embodied carbon might be of various products, which has made me think a lot about possible other options if I did something like this again.” It was at this point that Swiss-trained carpenter Andy Mackay of Mac Eye Projects got involved because of his experience building with CLT. He installed the superstructure and later became the main contractor, and by all accounts was instrumental in delivering the project’s high-quality finishing and superb airtightness result. Mackay had recently qualified as a certified

passive house tradesperson and brought a lot of enthusiasm to the project, says Siddall. “The detail that he goes to, the accuracy, the precision, the quality of workmanship is just really, really up there,” he said. “For instance, where we’ve got electrical cables routed into the CLT, he’s cut into the CLT, he’s then matched a piece of wood over the top in such a way that the grain matches in with other bits of the CLT around it. So, you don’t even know it’s there. Just excellent.” The finished building fabric is comprised of 35 CLT panels held together by 21,000 screws, which means it can be more easily disassembled and reused at the end of its life. Mackay also added his own small contribution to reducing the embodied carbon of the

CASE STUDY

LARCH CORNER

project by making bespoke furniture from CLT off-cuts, including the dining room table, integrated window seats, an oversized sliding door, and hidden guest bed. He also built the single interconnected engineered oak floor throughout the entire house, and describes working on the project as “one of the highlights of my career thus far”. The build itself progressed very smoothly with few issues, and Woolley and Mackay ended up becoming a bit of a tag team, with Woolley on site pretty much full-time, rolling up his sleeves and getting stuck in. One of the big jobs he contributed to was the airtightness taping. “He showed me what to do, and then I just got on with it,” Woolley says. In fact, the two worked together so well that later on Mackay got him involved in a couple of other local builds as an assistant. “I did some of the airtightness taping on that one and it got 0.1, so again, I just don’t think it’s hard to do if you just do it properly,” said Woolley. Getting involved also allowed him to appreciate how building a passive house is all about the attention to detail. “With the right amount of insulation, the right design, and then the execution to build, it’s just all about care. It’s not about doing anything completely bizarre and impossibly difficult. It’s just about taking care of things.” Siddall says the amazing result of the airtightness test, conducted by Paul Jennings, was a “nice surprise” and something the team could be really proud of — but it also confirmed that if you “design it properly, make sure it’s buildable, you can get a crazy result without trying — just by accident”. He continues: “When we had the initial blower door test we were at 0.09, so we knew were in a good position. It was a case of, ‘well, we don’t need to get better than that — if we can maintain it, that would be amazing’. We were never pursuing something so ridiculous that the leakage fits on a one penny coin. “I think that different things might have helped to support or improve the performance, such as the consistency in the workmanship. Then when we added on blown [wood fibre] insulation and the wind barrier on the outside. It seems all that just helped ratchet it down a little bit further.” Larch Corner is also notable for Siddall’s efforts at calculating its embodied carbon, at a time when there were no standardised tools available for doing so (see ‘Embodied car-

Design it properly, make sure it’s buildable.

ph+ | larch corner case study | 25

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1 The Novatop cross-laminated timber system arriving on site; 2 & 3 the first CLT panels being fitted into place; 4 Green Building Store Ultra timber triple glazed windows and Pavatex DSB2 airtight roof sheathing membrane, 5 installation of the Steico Zell blown wood fibre insulation, with 80 mm Pavatherm Combi wood fibre insulation fitted externally to the wall; 6 & 7 this is followed externally by a Pavatex ADB wind barrier and finished with 22 mm larch cladding; 8 formation of a hipped, shallow pitch, ventilated roof void in preparation for the installation of ply boarding, and above that, the roofing membrane and green roof, 9 & 10 airtightness taping was one of the important jobs on the build that owner Mick Woolley contributed to; 11 electrical services do not penetrate through the CLT, which acts as the air barrier, and in some cases electrical conduits were used, as seen here; 12 large radiators, served by an air source heat pump, are the primary mechanical means of space heating.

26 | passivehouseplus.co.uk | issue 41

bon’). This was one facet of the project that helped it to win the small projects category at the 2021 UK Passivhaus Awards, not to mention commendations and shortlistings for several other awards. Woolley was initially hoping to achieve passive house plus certification but because of the poor ratio between the (already large) PV array and the large projected building footprint, it did not satisfy the criteria of the ‘plus’ standard. But he’s happy that the team achieved the best possible result within the constraints they had to work with, and qualified for passive house ‘classic’ certification. In terms of its visual and visceral impact, Larch Corner is certainly a “timber triumph”, to borrow the Passivhaus Trust’s description of it. Clad in Siberian larch cladding and insulated with wood fibre, it all works really well in articulating the sweeping corner site. It’s also no surprise to learn that, after three years of living here, Woolley is delighted with it. “I love the fact that it’s very, very relaxing to be in,” he said. “And I think it’s partly because of the MVHR and the fact that it gives you this really comfortable even temperature. But I also think that the timber is a factor. I’ve certainly had people come over to the house and say to me, after a few hours, you know, ‘this is so relaxing’. They quite often say they can smell the timber, which I’m surprised about after three years.” One of the more interesting visual details is the roof ’s rainwater drainage, which is notable for not featuring any kind of conventional gutters or downpipes. “It was about trying to do something interesting with the rainwater,” says Siddall. “There’s a sedum roof, which will attenuate a lot of the water coming off the roof, and during heavy rain we didn’t have the same rainwater cascade that you might get in a lot of instances. Obviously rainwater does come off the roof, so it was then a case of do we put little down pipes on there or do we want to kind of try and keep the facade a bit cleaner. So, we thought these kind of gargoyles, as I think of them, we’d just give them a go.” As projects go, there’s much to talk about with Larch Corner, whether it’s the record airtightness, the superb timber construction and detailing inside, the unusual form factor (for a passive house) or the embodied carbon calculation. The house also demonstrates

The air leakage fits on a one penny coin.

LARCH CORNER

CASE STUDY

Monthly Import/ Export

SELECTED PROJECT DETAILS

how passive dwellings that generate renewable power and heat on site may be better insulated from the worst of the current energy price crisis. Mick currently makes almost £200 per year profit on his energy bills when you factor in his solar export and renewable heat incentive payments. And while the price he pays for electricity, and his standing charge, were set to double at the time of writing, even this should only bring his annual bill to about £230. For his part, Woolley gets plenty of com-

Client: Mick Woolley Architect: LEAP (Mark Siddall) M&E engineer: Alan Clarke Main contractor: Mac Eye Projects Blower door test: Paul Jennings Cross-laminated timber: Novatop System Timber engineered I-beams: Steico Wall insulation: Pavatex, via Soprema Additional wall insulation: Steico Roof insulation: Steico Additional roof insulation: Pavatex, via Soprema Airtightness products: pro clima, via Green Building Store & Pavatex Roof lights: Passivhaus Store Entrance doors: Green Building Store Heat pump: Mitsubishi MVHR: Green Building Store

ments from passers-by, and regularly takes the opportunity to educate them. “I’ll be out there trying to do a bit of gardening and quite regularly people stop and have a chat, because one of the footpaths paths goes sort of along the lane here, past the house. And so, you get a lot of walkers for instance, coming past and they tend to stop and ask you questions about the house. So, I sort of immediately launch into why everyone needs to have a passive house.”

Monthly Import/ Export

Imported Elec.

PV Eported

1500

1000

kWh

500

-500

-1000

-1500

p-1

t-1

v-1

c-1

n-2

b-2

r-2

y-2

n-2

l-2

-20

g Au

(above) Electricity imported and exported at Larch Corner over a 12 month period

ph+ | larch corner case study | 27

LARCH CORNER

CASE STUDY

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28 | passivehouseplus.co.uk | issue 41

CASE STUDY

LARCH CORNER

EMBODIED CARBON AT LARCH CORNER

Substructure

Frame, internal walls and partitions

External walls

Building services Windows and external doors

Roof

(above) Embodied carbon by building element 500

400

300

PV AND HEAT PUMP IMPROVEMENTS

kgCO2e/m2 Gross Internal Floor Area

200

100

Composite Concrete Copper

-100

Inert Mineral wool Oil-based PV Steel

-200

Timber Timber-based Store Co2: Timber Store Co2: Timber-based

-300

Transport to site Construction Use (maintenance/ replacement Demolition & Disposal

-400

Life cycle assessment (LCA) calculations by Tim Martel using PHribbon showed a cradle-to-grave embodied carbon figure of 473.2 kg CO2e/m2, comfortably beating the RIBA 2030 Climate Challenge target for dwellings of 625 kg CO2e/m2. (Check out the embodied carbon calculation explainer on page 67 for a simple explanation of the embodied carbon calculations published in Passive House Plus.) The analysis includes full build ups for the external and internal walls, roof and foundations, along with windows, doors, roof lights, heating system, ventilation system and large PV array. In this case timber flooring, kitchen units, electric wiring, and bathroom fit-out were omitted. Wherever possible, emissions data was derived from valid Environmental Product Declarations (EPDs) for products used on the build, or from generic industry association EPDs or Product Environmental Passports (PEPs) applicable to the products in question. Where this was not possible, values from EPDs or PEPs for comparable products were used, or from default data such as the Inventory of Carbon and Energy (ICE). Given the substantial use of timber at Larch Corner, the total amount of 300 kg CO2e/m2 stored CO2e is almost equivalent to the 323 kg CO2e/m2 of upfront emissions – though Siddall is careful to warn against “magical thinking” that the decision to opt for mass timber and timber-based insulants led to a net reduction in carbon being released into the atmosphere. These stored emissions are regarded as being released back into the atmosphere in the end-of-life phase of the LCA, and applying this assumption to the sheer amount of timber and timber-based materials in the building is the main reason why the module C total is so large. If the building lasts longer – and data on UK housing stock replacement rates indicates a 200year lifespan could be expected, then these emissions would be significantly delayed – although a longer lifespan would mean more replacement and repair emissions during the building’s use phase, module B.

Module A Stored CO2 Module B Module C

Lifecycle stage

(above) Embodied CO2e: As built

The specified Mitsubishi Ecodan QUHZ air-to-water heat pump uses CO2 as a refrigerant. Up until this point, PHribbon calculations in Passive House Plus have tended to rely on an industry association Product Environmental Passport for an air-to-water heat pump, based on averaged emissions of two conventional refrigerants, R410A and R407C, which respectively have a global warming potential (GWP) of 2,088 and 1,774. Each kilogram of these refrigerants is equivalent to 2,088 and 1,774 kg of CO2e, respectively. CO2 by comparison, has a GWP of 1. In one fell swoop, this specification has effectively solved the refrigerant leakage issue. Refrigerant leakage from the heat pump (and assumed replacements over the 60-year design life specified for LCAs in the UK) add up to a rounding error: just 0.4 kg of CO2e. Meanwhile, some recent EPDs on solar PV arrays are showing dramatic reductions in embodied carbon, likely due to a combination of lighter materials, lower emissions manufacturing processes, and dramatic improvement in the efficiency of PV arrays over the last decade or so – an important consideration as EPDs for PV arrays are expressed in CO2 emissions per kilowatt peak. One interesting footnote is that Mark Siddall built his own embodied carbon calculator for Larch Corner in 2018, with Siddall spending a significant amount of time hunting down EPDs for products not included in the ICE (Inventory of Carbon & Energy) database. Siddall’s calculations were tested against a beta version of PHribbon. “It was a painful but valuable learning experience, but now that the PHribbon plugin for PHPP exists for calculating the embodied carbon of passive house buildings, I can firmly say that I will always use it in preference to any other tool,” says Siddall. “This is because it saves so much time and because it integrates so smoothly into the normal workflow.”

ph+ | larch corner case study | 29

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CASE STUDY

LARCH CORNER

IN DETAIL Building type: 162 m2 detached cross-laminated timber dwelling.

foundation. Reducing the timber fraction by using engineered I-beams.

Site & location: Upper Quinton, Warwickshire

Ground floor: 22 mm timber floorboards, followed underneath by 213 mm reinforced concrete, 260 mm Jackon Jacodur Plus XPS insulation, sand blinding. U-value: 0.07 W/m2K

Completion date: April 2019 Budget: £448,000 (excluding cost of plot) / £2,685 per m2 Passive house certification: Passive House Classic certified Space heating demand (PHPP): 14 kWh/m2/yr Heat load (PHPP): 8 W/m² Primary energy demand non-renewable (PHPP): 66 kWh/m2/yr Primary energy demand renewable (PHPP): 26 kWh/m2/yr Renewable energy generation: 38 kWh/m2/yr Heat loss form factor (PHPP): 3.9 Overheating (PHPP): 5 per cent assuming night vent at 0.1 ACH. Measured: 5.5 per cent. Number of occupants (PHPP): 3.0 for passive house assessment (actually one). Airtightness (at 50 Pascals): 0.041 m3/hr/m2 at 50 Pa / n50 of 0.048. Measured energy consumption: 4,723 kWh (avg. over 3 years). Thermal bridging: Default building regulations assumptions (Y-value 0.15 W/m2K) would mean 60 per cent of all heat loss goes through thermal bridges. Vigilant design and attention to building physics reduced this by 90 per cent (Y-value 0.015 W/m2K). Insulated raft

Walls: 22 mm larch cladding, followed inside by ventilated cavity, Pavatex ADB wind barrier, 80 mm Pavatherm Combi wood fibre insulation, 360 mm JJI-Joist with Steico Zell wood fibre insulation, 84 mm Novotop CLT (taped and sealed for airtightness). U-value: 0.09 W/m2K Roof: Green roof, followed underneath by ventilated air gap, Pavatex ADP underlay, Pavatherm wood fibre insulation, Pavatex DSB2 air barrier, Novatop hollow CLT panel filled with Steico Flex wood fibre insulation between the ribs, 70 mm service void/air gap, 14 mm Novatop acoustic panel. U-value: 0.12 W/m2K Windows & external doors: Green Building Store Ultra timber triple glazed windows. Passive House Institute certified. Overall U-value of 0.74 W/m2K Roof window: Lightway Crystal 300 HP Blue Performance. Overall U-value: 0.6 W/m2K Heating system: Mitsubishi QUHZ air source heat pump, heat distributed via oversized radiators at low flow temperature. Ventilation: Paul Novus 300 mechanical ventilation with heat recovery (MVHR) system. Passive House Institute certified heat recovery efficiency of 93 per cent. Wellness: BS 8206-2 was used to assess daylight

provision and avoid oversizing windows. This means rooms are well lit, minimise the use of artificial lighting, reduce overheating risks and minimise Seasonal Affective Disorder (SAD). Noise from MVHR is unregulated. To avoid sleep disturbance and preserve IAQ, habitable rooms are designed to achieve <25 dB(A). Water: AECB Water Efficiency standard adopted. This has been achieved through the use of low flow fittings, a compact services plan, microbore plumbing (which minimises the volume of dead legs to < 1.0 litre) and a super-insulated storage cylinder. Electricity: 9.3 kWp photovoltaic array. Excess energy is used for electric car charging or grid export. The EPC states household emissions are -2.2 tCO+e/yr. The site used 39 per cent of the electrical energy generated by the photovoltaic array and exported the remaining 61 per cent. Energy breakdown for a typical year: PV generated: 8,530 kWh/yr PV used: 1,600 kWh/yr PV exported: 7,200 kWh/yr Electricity imported: 3,123 kWh/yr Total household elec: 4,723 kWh/yr Electricity use of heat pump: 1,343 kWh/yr Space heating: 1,133 kWh/yr Hot water: 210 kWh/yr Other (Household elec.): 3,380 kWh/yr Note: ‘Other’ includes the charging of an electric car which is estimated to use about 1,600 kWh per year.

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CARRSTONE

CASE STUDY

PASSIVE POWER THE PASSIVE HOUSE THAT BECAME A POWER STATION A passive house, by its nature, requires a much smaller amount of energy than a typical home, and when its heating demand is met by electricity, and you cover it in solar PV panels, you can start to see the potential for a whole new generation of passive homes that are semi-independent of the electricity grid. This is the case for Carrstone House in Bedfordshire, which generates so much solar energy it had to be registered as a power station. By David W Smith

IN BRIEF Building: 230 m2 detached house Method: Timber frame Location: Bedfordshire, England Standard: Passive house plus Energy bills: £46 per month for all energy including running an electric car (estimate, including April 2022 price hike.) Compared to £8 per day profit from March 2021-2022.

£46

per month (2022) vs £8 per month profit (2021)

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CASE STUDY

Carrstone House has so many PV panels that it had to be registered as a power station.

s energy prices soar to all-time highs, the thought of living in a house that generates much of its own power sounds appealing. This is the case for Carrstone House, in Bedfordshire, which has 91 solar PV (photovoltaic) panels providing 24 kW peak of electricity, enough to meet the equivalent of all the house’s power and heating needs, with excess to run a powerful electric Tesla Model X car and export surplus electricity back to the grid. Carrstone House has so many PV panels that it has had to be registered as a power station. The owners, Paul and Belinda Wilson,

moved into the house in 2017 after an eightmonth build. Their new home was constructed in the one-acre garden of their old house and achieved the passive house ‘plus’ standard, only just falling short of the passive house ‘premium’ benchmark. These additional certification categories reward passive houses that produce renewable energy. The couple decided to build their own home after their three children had grown up. They sold their old house and half the garden, and the new owners moved in just weeks after Paul and Belinda had left. Paul and Belinda are very satisfied with the comfort and heat-efficiency of their passive house. “To date we have been paid more than we pay out by a few hundred pounds... in the winter it has cost us more to use electricity than we create, but in the summer we have made a significant surplus,” says Paul. “We have a 4 kW air source heat pump, which provides the heat. As part of the project, we bought a Tesla Model X including free supercharging… we’ve done 65,000 miles in five years and, with negative costs for electricity at home and free Tesla charging on the road, it hasn’t cost us a penny for fuel.” The average annual amount of electricity generated by the panels, he says, is 19,500 kilowatts, or 1,625 kilowatts per month. But in practice it ranges widely between 200 and 3,575 kilowatts monthly. The couple’s feedin-tariff pays them about £1,500 per year. Their electricity bills were averaging about £1,320 per year, but the rate they pay for electricity is now set to increase to 29p per

CARRSTONE

unit, which will push their annual bill up to over £2,000, meaning for the first time they will pay more for buying electricity than they earn for generating it. It is a sign of just how much energy prices have risen that a house with such a large solar array will now have an annual bill of about £800 (See ‘In detail’ for more on these figures). The surface of the roof uses an integrated PV system, with PV panels supported on an aluminium railing system. Glass was used for the perimeters to limit the amount of PV electricity provided to 24 kW peak, because the network operator said the grid could not take any more. Because the home has so many PV panels, the couple had to obtain a licence to be classified as a power station. Restricting the peak to 24 kW left the house slightly short of the passive house premium standard, but they cannot imagine living in a more comfortable home. “The main lesson we’ve learned is we wouldn’t want to go back to living in an ordinary house. Our ambient temperature is 21 degrees and, generally, any house we visit feels cold and draughty. We’ve got used to an absolutely constant temperature,” says Paul. “We have the heating on for about 20 per cent of the time through the winter. Heating is provided by underfloor heating installed in the slab. The foundation contractor offered it for an extra £1,200 so it was too good to miss. The other thing is we often make the mistake of going out inappropriately dressed, especially in spring. Belinda has headed off a few times in her flip-flops when it’s been

ph+ | carrstone case study | 33

CARRSTONE

CASE STUDY

cold outside.” The couple are horrified by the quality of construction of some of the new builds springing up locally. “You think it’s going to be phenomenal to heat these new homes with so little insulation and poor detailing. It’s like our home is hermetically sealed with a constant source of fresh air being pumped into us inside the pod. You have to live in it to believe it.” Belinda and Paul bought their old house 15 years ago and in 2014 began to think about building a house in the garden, then selling the first home. An initial design was rejected by local planners based on a rule that new builds had to be either in the style of “country houses” or have something special about them. The couple immediately thought of building an environmentally efficient home. When Belinda chanced upon a YouTube video with Alan Budden of Eco Design Consultants demonstrating the care required to ensure airtightness when building a passive house, the pair were curious. The high standards of passive house appealed to Paul, who was sceptical about what he called “cosmetic” add-ons to houses. He had worked in the construction industry as a quantity surveyor and ended up running UK operations for a major contractor. “I’d seen work on buildings with tiny windmills, wood pellet boilers and ground source pumps, but I wanted us to go much further and get the house to pay for itself,” he says. Paul was also reluctant to build a prefabricated “kit house”. The manufacturers, he said, could not confirm whether they would reach passive house standards until the design was complete, nor would they commit on price.

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CASE STUDY

The couple spoke to their existing architect about designing a passive house and he advised them to find a specialist architect. They approached Alan Budden, from Eco Design Consultants, in Milton Keynes. The couple already had some clear ideas about what they wanted design-wise. The old house had far too much circulation space and they wanted to minimise it in their new home. One feature they opted to keep was a downstairs bedroom. Meanwhile, they asked for the kitchen-diner to have the best views during the day as opposed to the lounge, which was where they would put their feet up in the evening. “When planning was [initially] refused the house design was quite tall and didn’t fit into the environment, blocking views from the old house due to the bulk and scale,” says architect Alan Budden. “We designed Carrstone House to look a little like an outbuilding down the side of the garden with a lower pitched roof, hunching down into the environment. We also dropped it into the ground to enhance the views from the former property. At the same time, Paul and Belinda liked the old house’s extension which had a vaulted ceiling. So, those two things came together to create the overall effect.” Paul and Belinda helped to check that the new roof designs allowed good views. They conducted experiments with poles and ropes in the garden to test how obtrusive the new roof would be. They looked across from the patio and kitchen window in their old house, and were happy with the lines of sight. “We’ve enjoyed those views for years and it is no different now to what we could see before,” he says.

Photos: Alistair Nicholls

Their new home was constructed in the oneacre garden of their old house.

There was some concern when they put in for planning for the second time that the application would be refused on the grounds of “garden grabbing”, rumoured to be a significant local problem. But the council planning team said it was not yet an official policy. “They’d debated it many times, but when the planning officer checked, it turned out there was currently no rule,” says Paul. “Alan prepared an extensive document with pictures showing the advantages of the build and the planner said they’d given permission for buildings ‘nothing like as interesting, beneficial, or sustainable’, as ours.” The builder, Nick Hull, and sub-contractors, began on site in May 2016 and had completed the work by January 2017 when the couple moved in. In the meantime, the couple had sold their old house and the new owners arrived in February 2017. Gloucester-based MBC Timber Frame not only put up the frame, but also did all of the foundation work. “In three weeks, they had completed nearly all the work. They went away and we had the windows delivered and installed and then they came back a week later

CARRSTONE

and did the air test. At that point we had a watertight, airtight building to passive house standards,” he says. Paul’s extensive experience in construction helped to make it a smooth process. He opted to be the project manager and took on the role of principal designer, giving him responsibility for ensuring that health and safety were managed properly. He took a one-day construction, design and management course to make sure he understood the role fully. He also enforced some basic rules – every person on site had to wear a hard hat, high visibility jacket and protective boots, and everyone entering the site was inducted. Belinda also did a four-day first aid at work qualification along with the builder. There was a first aid presence on site at all times. The finished house has large open-plan living spaces downstairs. This necessitated extra insulation in the building envelope as it made the form factor of the house worse, increasing the surface area from which heat can be lost. The single-storey living area has a sloping roof that provides one to 1.5 storey height rooms. The interior hall has views through to the living space and garden beyond. “Belinda was keen on the idea of ‘borrowed landscapes’ so the garden in the background feels part of the living space,” says Paul. Carrstone House has Internorm triple glazed timber aluminium windows and sliding doors. The sliding doors were chosen instead of bifold ones because of their superior airtightness. “There are two large glazed units in the sliding doors, which each weigh about a quarter of a tonne. But they slide across when pushed by one finger. So, the quality is

ph+ | carrstone case study | 35

CARRSTONE

CASE STUDY

1 The insulated foundation system features 300 mm of Kore EPS; 2 installation of underfloor heating pipework, DPM and reinforced steel mesh, to be followed by concrete slab; 3, 4 & 5 erection of the MBC timber frame system underway, which is insulated with Warmcel, and the SmartPly ProPassiv panels fitted to the inside delivering outstanding levels of airtightness; 6 & 7 breather membrane and Aquapanel render board fitted to the external side; 8 a section of the 91 panel roof-integrated PV system, with PV panels supported on an aluminium railing system, and glass to perimeter; 9 & 10 airtightness taping to ProPassiv panels and ductwork for MVHR system; 11 & 12 the roof light seen here was formed on site with a triple-glazed panel in the PV curtain-walling system, while exposed MVHR ducting is also visible here.

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CASE STUDY

As the ducting was so neatly done, it was left exposed.

superb,” Paul says. The MVHR (mechanical ventilation with heat recovery) unit is on the ground floor in the utility room. As the ducting was so neatly done, it was left exposed to improve route efficiency and to show a key part of the passive house philosophy. Air is distributed to the bedrooms, living room and study via ducts in the first floor, and exposed ducts in the study and pantry. The air is then transferred under doors and through the hall to the kitchen and bathrooms. When the district network operator limited the licence for electricity to 24 kW peak, other options were considered in order to reach the passive house premium standard.

The couple could have bought shares in a renewable energy scheme, for example. They rejected this solution in the end, but may explore it again in the future. Direct electric heating was also assessed, but using an air source heat pump provided much greater efficiency and could also heat the domestic hot water supply. The air source heat pump and hot water cylinder supply the underfloor heating downstairs, as well as towel rails in the bathroom. Belinda and Paul thought about using battery power, but this was difficult to do at the time as their three-phase installation would have required three different battery systems. However, Paul says the recent spike in energy price means he is now thinking again about getting a battery, and Tesla now supply a three-phase version. The couple’s experience has been so positive that they have been happy to advise people thinking of going down the same route. “We’ve sat down with quite a few people to discuss their plans and talk about how they can achieve what they need,” says Paul. For Belinda, there is even the enticement of building another passive house. “It’s tempting to buy a plot in Norfolk, and have another go,” she says.

CARRSTONE

SELECTED PROJECT DETAILS

Architect & passive house design: Eco Design Consultants Main contractor: Nick Hull Builders Timber frame: MBC Timber Frame Structural engineering: South Stoke Structures Passive house certification: Etude Building services design: Williams Energy Design Building control: JHAI Airtightness test: Melin Consultants SAP assessment: Eco Energy Environmental Power connection: UK Power Networks Thermal breaks: Compacfoam, via Green Building Store Windows & external doors: Internorm, via Footprint Homes MVHR: Touchwood Building M&E contractor: Teckos Tesla connection: Mark Cawood Lighting: National Lighting

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CARRSTONE

CASE STUDY

Dream to Reality

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MBC Timber Frame is a long established company that specialise in the production of super insulated, precision engineered, energy efficient timber frame and passive standard homes throughout the UK. We are a registered Gold member of the Structural Timber Association and are quality accredited with an outstanding reputation. At MBC our experience and continuous focus on quality enables our team to satisfy the specific needs and requirements of each individual project, while at the same time provide outstanding service and support to our clients.

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38 | passivehouseplus.co.uk | issue 41

info@mbctimberframe.co.uk

facebook.com/mbctimberframe

CASE STUDY

CARRSTONE

EMBODIED CARBON

Substructure

External walls

Ceiling finishes Windows and external doors

PV roof

Floor finishes

Wall, floor & ceiling finishes

(above) Embodied carbon by building element Building services, FF&E (fixed) & refrigerant leakage

400

Wall, floor & ceiling finishes Internal walls, partitions & upper floor

300

Windows for External Doors External Walls

kgCO2e/m2 Gross Internal Floor Area

The building’s embodied carbon emissions were calculated by Tim Martel using PHribbon. (If you’re new to embodied carbon, see the explainer on p67 to make sense of what you’re about to read). The scope focuses on the house only – without the separate garage building – and included the substructure, superstructure, finishes, FF&E and building services, albeit with some items omitted. Facilitating works were not included, nor were external works. While the MVHR unit and heat pump were included – based on industry association PEPs in both cases – the associated services such as ducts, pipes and heat emitters were not, and nor were any of the electrics, with the exception of the PV array. The EV charger, solar inverter and battery, stairs, carpets and paints weren’t included. Tiles were included, along with all bathroom fittings – but the kitchen sink was not. The biggest ticket item by far is the home’s 93-panel building integrated photovoltaic (BIPV) array, which stands at 150.3 m2 of modules, with 36 m2 of single glazed curtainwalling to the perimeters to make up the remainder of the roof. In the absence of verified embodied carbon values for the PV panels, default data for monocrystalline panels from the ICE database was used. If we stop short of the PV + perimeter glass roof, the building total stands at a cradle to grave figure of 316 kg CO2e/m2 – a highly creditable score bearing in mind the RIBA 2030 Climate Challenge target for dwellings is 625 kc CO2e/m2 GIA. But with the PV roof included a different picture emerges. Based on a default value from the ICE Database of 242 kg CO2e per m2 of module area, the total rockets to 809 kg CO2e/m2, though the reality could in fact be worse still. Passive House Plus found a valid EPD for a different brand of monocrystalline PV module available on the UK market with independently verified embodied carbon results worse than the ICE default data, including a cradle to factory gate (A1-A3) total of 276 kg CO2e per m2. This module would bring the building’s total up to 859 kg CO2e/m2. But if PV modules like Sunpower’s Maxeon 3 was used instead, the total would drop to 490 kg CO2e/m2. The Maxeon 3’s impressively low embodied carbon score appears to be due to a number of factors, including their use of thin wafers from Nowegian supplier NorSun, who have taken efforts to reduce their own carbon footprint. What’s more the Maxeon 3 boasts a market-leading output of 226 Wp per m2, as compared to a still respectable 205 Wp score by the brand with the higher embodied carbon EPD score. It was assumed the array would last for

PV roof

200

100

-100

-200 Module A

Stored CO2

Module B

Module C

(above) Embodied CO2e: As built 25 years, meaning the calculations allow for two full replacements of the array within the 60-year design life specified for building LCAs in the UK. But this exercise has shown that the impact of PV module choice can be stark. For an array of this size, the embodied carbon of the modules alone could vary from 35 tonnes for an array with higher output, to over 125 tonnes for an array with a lower output, which would be over 61 per cent of the whole building total. A health warning must be applied here: as no EPD or PEP was available for the modules used in Carrstone House, it’s not possible to determine whether the default values used reflect the actual system installed. One factor which helped reduce the building’s embodied carbon score was the decision to opt for a heat pump which uses CO2 as its refrigerant, a Mitsubishi Ecodan QUHZ. The global warming of R410A – a refrigerant which dominated the market when Carrstone House was under construction – is 2088, meaning each kilo in the machine

represents 2.088 tonnes of CO2e. According to CIBSE TM65, a document which defines how to calculate the embodied carbon of building services, a leakage rate of 2 per cent is assumed per annum, and a further 1 per cent leakage at the building’s end of life. While Mitsubishi has completed TM65 calculations of its outdoor units, the absence of calculations for the indoor unit led to data for air source heat pumps from French industry association Uniclima being used, albeit with the refrigerant substituted out for CO2 – meaning a kilo of refrigerant only contains a kilo of CO2e. The total is also reduced by the build system – Larsen Truss timber frame filled with cellulose insulation, and with an Aquapanel render board externally. In spite of the use of 28/35 reinforced concrete made with CEM I, the insulated foundation system likely helped reduce the embodied carbon too, by reducing concrete use compared to conventional foundations.

ph+ | carrstone case study | 39

CARRSTONE

CASE STUDY

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40 | passivehouseplus.co.uk | issue 41

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CASE STUDY

CARRSTONE

IN DETAIL Building type: 230 m2 detached two-storey timber frame house. Location: Bedfordshire Completion date: July 2017 Budget: £528,000 including fees. Passive house certification: Passive house plus certified Space heating demand (PHPP): 16 kWh/m2/yr Heat load (PHPP): 10 W/m² Primary energy demand (PHPP): 83 kWh/m²/yr Heat loss form factor (PHPP): 3.09 Overheating (PHPP): 4 per cent Airtightness (at 50 Pascals): 0.27 ACH Energy performance certificate (EPC): A 136 Energy use & generation: Paul and Belinda’s energy consumption of grid electricity has averaged approximately 7,500 kWh per year. However, their 24 kW peak solar PV array has generated, on average, 19,500 kWh per year, about 2.5 times what they import. Energy bills: Paul and Belinda's average annual energy bill has increased from approximately £1,125 in 2017 to an anticipated £2,156 for the next calendar year (inc VAT and standing charges), as their electricity rate has increased from 15p per kWh in 2017 to 27p in 2022. Their standing charge has also increased from 19p per day to 36p per day (or from £69 to £131 per year).

The couple recieves an annual fee for generating electricity of approximately £1,600 per year, comprised of both a feed-in-tariff and an export allowance. This means that, with the recent hike in energy prices, the couple will soon make a net loss on their annual energy bills of approximately £556 per year, or £46 per month, after five years of making a net positive on their bills. They will continue to make a significant surplus in summer due to high power generation, but will incur the total cost of their power during winter months. Thermal bridging: Use of the MBC timber frame with Larson truss to reduce thermal bridging in wall and at foundation, additional Compacfoam used at door thresholds. Additional insulation around window frames to reduce thermal bridging. SVP vent pipes eliminated by venting manhole. Ground floor: Hardcore and sand blinding, followed above by DPM, 300 mm EPS100 (λ=0.036), separating layer, 100 mm reinforced concrete slab with underfloor heating pipes (thicken to 200 mm x 600 mm wide at perimeter, and load bearing walls). Power-floated finish. U-value: 0.117 W/m2K Walls: K-Rend external render on Aquapanel render board, followed inside by 50 mm ventilated void with battens, 12.5 mm Medite Vent panel board, 300 mm Larsen Truss timber frame by MBC with plywood gussets and Warmcel insulation between, 12.5 mm SmartPly Propassiv

board internally taped with Siga tapes to form airtightness layer, 38 mm service void formed with battens, 12.5 mm plasterboard plus skim. (One external elevation render board replaced with 150 mm stone blocks). U-value: 0.12 W/m2K Roof: 80 mm PV curtain walling system externally, with aluminium rails supporting PV panels, and glass to perimeter, followed underneath by 35 x 50 battens and counter battens, Amacol Areo Plus breather membrane, 400 mm MBC Larsen Truss roof panel, with plywood gussets and filled with Warmcel insulation, Siga airtightness membrane, 38 mm service void formed with battens, 12.5 mm plasterboard plus skim. U-value: 0.11 W/m2K Windows & external doors: Internorm HF 310 from Footprint Homes. Sealed with Siga tapes. Roof windows: Formed on site with triple glazed panel in PV curtain walling system and insulated kerb. Heating system: Mitsubishi Ecodan PUHZ-W50VHA-5KW, with integral hot water tank – 170 litres ErP class C. Feeding underfloor heating on ground floor, and heated towel rails in bathrooms on first and ground floors. Ventilation: Paul Novus 300 with summer bypass. Water: Restricted waterflow showerheads. Water from roof to water butts, then overflow into pond and then second soakaway pond in garden.

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LEITRIM SCHOOLHOUSE

CASE STUDY

IN BRIEF Building: 52 m2 detached schoolhouse from 1870 Method: Retrofit with internal timber frame Location: County Leitrim Standard: Enerphit (uncertified) Energy bills: €20 per month for space heating (estimate). See ‘In detail’ for more.

€20 per month

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CASE STUDY

LEITRIM SCHOOLHOUSE

HOME SCHOOL OLD LEITRIM PRIMARY SCHOOL TRANSFORMED INTO A TIMBER-BASED, ENERPHIT HOME

Rural Ireland has a crisis of dereliction, with numerous government policies aimed at breathing new life into thousands of old, vacant buildings. The careful transformation of one 19th century schoolhouse into a small, beautiful home PRODUCED BY AN AUTODESK STUDENT VERSION shows a way forward for the sensitive, climate-conscious renovation of many of these properties.

PRODUCED BY AN AUTODESK STUDENT VERSION

By John Hearne

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LEITRIM SCHOOLHOUSE

CASE STUDY

It’s warm, it’s quiet and the air quality is perfect.

eán Breathnach’s deep retrofit of a 19th century schoolhouse offers an insight into what might be done with Ireland’s extensive stock of empty stone-built buildings. Working almost singlehandedly, Seán converted a drab ruin into a high comfort home, which is beautiful both inside and out. He estimates that the entire project, including the purchase of the site, cost about €95,000 (though he stresses this is a rough estimate). When Breathnach returned to Ireland from Canada in 2017, the carpenter and newly qualified passive house designer had a very clear idea of what he wanted to do: find a small, dilapidated structure in the west of Ireland and bring it up to Enerphit standard (the passive house retrofit standard). He found the perfect candidate in a schoolhouse perched at the top of a hill in north Leitrim. “It dated from 1870, and it was very cheap, which was great because my budget was tiny. I got it for €33,000,” he says. “What made it perfect was the fact that somebody had already started renovating it around

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2006. They’d cleared out all the old fixtures and fittings. They also re-roofed it, put on new skylights and replaced the lintels in the stone walls.” The most surprising thing about the building was that it was bone dry inside. “The first time I walked in with a friend who lived up there, we couldn’t believe how dry it was. You’d expect everything to be covered in mould. But the roof was sound, and all the windows were broken, so there was plenty of air circulating through it.” In addition, well-draining soil and the elevated location meant that moisture tended to fall away from the site. Breathnach had left Ireland for Canada in 2006, served an apprenticeship as a carpenter and in time became an expert in post and beam construction – what’s known simply as ‘timber framing’ in Canada. He subsequently developed an interest in alternative building systems like straw bale and other natural materials. “The problem was that these projects could be very badly detailed. The concept could be great, but the detailing, particularly in relation to airtightness, tended to be quite poor,” he says. It was in order to redress this deficiency that Breathnach began researching the passive house standard, and ended up taking a passive designer course in Vancouver in 2017, the same year he decided to return to Ireland. Because the Leitrim schoolhouse was technically derelict, he was granted a planning exemption and was cleared to begin work. The school’s outhouse hadn’t formed any part of the aborted 2006 refurbishment and was effectively a shell: four walls but no roof. Breathnach rebuilt the walls of the outhouse, put on a roof, insulated it and moved in. This tiny (nine square metre) building would be

his home for the coming months as he began work on the schoolhouse itself. The plan was to build a new house inside the shell of the old building; a box-within-abox. The exterior walls function as a cladding material, then you have a 40 mm air gap and the interior shell is built out from there, beginning with a weather membrane and 40 mm Gutex woodfibre insulation, while 150 mm of cellulose in the stud takes care of the bulk of the insulation. “Because this kind of build is rare, it’s difficult to know exactly how big that air gap between the stone and interior shell should be, or how many ventilation holes you need,” he says. When insulating internally, there is always a greater risk of creating a dew point for condensation, where the temperature drops suddenly between the new insulation and the old wall. So, Bob Ryan of Earth Cycle Technologies was hired to run a WUFI condensation analysis, which confirmed the integrity of the build-up. In addition, Breathnach, who is studying civil engineering in Sligo IT, plans to conduct a full moisture assessment of the walls as part of his final year dissertation. He also deliberately avoided using concrete as much as possible to reduce the embodied carbon of the build. There is no concrete slab, for example, and instead the beams are supported with a combination of small concrete pads and Mannok Aircrete thermal blocks. Breathnach was able to complete the build with very little help. “You’d be surprised how much you can do on your own if you’re used to it,” he says. “I didn’t have any concrete pours, those pads were small, and it turned out that there was no roofing required at all, which was amazing. I upgraded the glass in the skylights, but that could be done from the inside. In terms of other

CASE STUDY

contractors, I had a guy do the driveway, I had an electrician do his stuff, and I had help with insulation pumping and the heat pump installation.” Breathnach especially praises Roman Szypura of Clíoma House, who installed the cellulose insulation, for his workmanship, and the guidance he provided on airtightness. While the house is not Enerphit-certified, it does meet the requirements of the standard in PHPP, the passive house software. You can use one of two methods to qualify for Enerphit: either by meeting energy performance targets for the individual elements of the building (the component method), or by meeting overall space heating targets for the building. Breathnach chose to go the component route. While in a retrofit this only requires internally insulated walls to achieve a U-value of 0.35, he chose to aim for the higher target of 0.15. This move alone cut the modelled heat demand of the building by almost half, from 48 to 26 Wh/m2/yr. The downside was that the additional insulation thickness reduced available space in what is already a small house. Breathnach also makes a point about form factor in small buildings. Form factor refers to the shape of the building. It’s the ratio of the external surface area to the usable internal floor area, or treated floor area. It can also be measured by the ratio of the external surface area to the internal volume (SA/V). Heat loss form factor, to give it its full title, is essentially a measure of how dispersed the design is. In essence, a simple, quadrilateral design is easier to heat than one which is more spread-out. However, form factor can

Photos: Stefan Hoare / Sheelin Photography

He deliberately avoided using concrete as much as possible.

penalise small housing units, no matter how otherwise compact. This is from The Passivhaus Designer’s Manual edited by Christina J Hopfe and Robert S McLeod: “...buildings can have identical U-values, air change rates, window areas and orientations yet feature very different heating and cooling demands simply because of their SA/V ratio. Very small buildings (such as detached bungalows) have an inherent high surface area to volume ratio compared to larger buildings.” Breathnach says this can make it harder for small buildings to achieve passive house certification. It can also make it harder to achieve airtightness targets, because air changes per hour — the way in which airtightness is evaluated under the passive house standard — is a measure of the proportion of the interior volume of the building passes that through the surface area in one hour. It’s not hard to see why a smaller volume could yield more air changes. Airtightness in the walls comes via an Intello membrane, while 18 mm Smartply tongue and groove board provides airtightness in the floor. Breathnach says his de-

LEITRIM SCHOOLHOUSE

tailing philosophy was based on simplicity. “I tried to keep everything as basic as possible,” he says. “This meant minimising timber build-up at junctions and ensuring insulation in any gaps. A lot of traditional stick-framing techniques overbuild corners and openings resulting in excessive thermal bridging.” He also tried to keep things as natural as possible. The stick-framing in the walls was rough sawn spruce from a local sawmill, the exposed interior frame and trim is Douglas fir, from the same sawmill, while the ceiling is white deal, and the floor is Scots pine. Though he could have fitted a loft, he opted for a single storey with a cathedral roof to give the place a feeling of size and space. Sourcing the heat pump proved one of the biggest challenges. “I had awful trouble getting anyone to even talk to me about heat pumps. I think it’s because I’m based in Leitrim, plus the fact that it was a small project,” he says. He points out that the low number of suppliers is likely to impact the government’s plans to renovate half a million homes in the next eight years. Breathnach subsequently worked with

ph+ | leitrim schoolhouse case study | 47

LEITRIM SCHOOLHOUSE

CASE STUDY

4 1 The 19th century schoolhouse was gutted prior to construction; 2 & 3 Douglas fir for the interior frame was sourced from a local sawmill, while studwork on the inside of the walls and roof was insulated with cellulose and then covered with an Intello vapour control and airtightness membrane; 4 measuring tape showing the depth of the cellulose-insulated stud, with Intello membrane applied to the room-face.

48 | passivehouseplus.co.uk | issue 41

(above) Homeowner and carpenter Seán Breathnach Greentherm in Dublin, installing a Hitachi 7.5 kW heat pump, which works with a radiant tubing system, installed in the walls rather than the floor. According to Enda Ruxton of Greentherm, the heat pump’s large size for such a small, highly insulated house was about ensuring hot water supply at all times. “People are forgetting that if you empty a 300-litre tank and fill it with cold mains water, it’s going to take you almost 15 kWh to bring to 60C.” Ruxton adds that inverter-driven heat pumps will tend to modulate down to about half of their output. “A 7 kW would modulate down to about 3.5 kW, which is just bigger than an electric immersion. And people forget about hot water recovery. If you have a few people taking showers it could take a couple of hours to heat back up. It’s the battle between energy efficiency and practicality.” With everything specified, the construction phase proceeded remarkably smoothly. “I got lucky,” says Breathnach, “really lucky, first of all with the state of the building when I bought it, and also I didn’t hit any major snags that I couldn’t figure out. I’ve worked on so many buildings and something always goes sideways, and you go, ‘Oh right here’s another five grand down the hole because I didn’t see this coming’. That didn’t happen here, and it was down to pure luck.” The timing of the build was also fortunate. Everything was done before the current phase of building materials inflation kicked in. Breathnach moved in in October 2019, when the house was just about liveable, and continued to work on it through the summer of 2020.

“It’s been brilliant,” he says, “compared to a lot of rental houses in Ireland which are hard to heat and can have mould issues. The temperature is perfect. It’s warm, it’s quiet and the air quality is perfect.” Including the purchase of the site, Breathnach estimates his project cost about €95,000. He can’t quite put a value on his own labour, but estimates it at something around €50,000. As such, this is probably one of the most cost-effective projects that Passive House Plus has ever featured. Between December 2020 and December 2021, his total electricity bill came to €1,099. “A lot of people when they look at renovation, they think in terms of payback times. Maybe that makes sense with a rental property, but if it’s your own home, you’ve got to think about it as investing in your own comfort and well-being. That’s something that you can’t put a number on,” he says. It’s interesting to note too that because the schoolhouse was originally a public building, the quality of the stonework is superior to what you usually find in dwelling houses of the same period – an important consider-

You’ve got to think about it as investing in your own comfort and well-being.

CASE STUDY

ation for someone looking for a renovation project. Breathnach points out too that very many of our run-down town centres feature period stone buildings. In the context of Ireland’s various town centre regeneration plans, not to mention the housing crisis, his ‘box-within-a-box’ approach could offer an excellent template for refurbishing stonebuilt buildings. “Builders often shy away from stone because it’s awkward,” he says. “But approaching the project in this way makes it far more doable, and offers a way of renovation which meets NZEB standards.”

He opted for a cathedral roof to give the place a feeling of space.

LEITRIM SCHOOLHOUSE

SELECTED PROJECT DETAILS

Client & builder: Seán Breathnach Passive house consultant: Earth Cycle Technologies WUFI analysis: Earth Cycle Technologies Heating & plumbing contractor: Ribbit Engineering Electrical contractor: Shay Boylan Timber (framing): Brooks Group Cellulose insulation: Clíoma House Wood fibre insulation: Gutex, via Ecological Building Systems Airtightness products: Ecological Building Systems Windows and doors: Munster Joinery Roof windows: Velux Entrance doors: Munster Joinery Timber (fit-out and trim): McHale’s Sawmill Flooring: McHale’s Sawmill Heat pump: Greentherm MVHR: Paul Scotland

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LEITRIM SCHOOLHOUSE

CASE STUDY

50 | passivehouseplus.co.uk | issue 41

CASE STUDY

LEITRIM SCHOOLHOUSE

EMBODIED CARBON

Windows and external doors

Substructure

External walls

Wall finished Frame, internal walls & partitions

Building services

Roof

Ceiling finishes

Furniture, fixtures & equipment (fixed)

Temporary enabling works Floor finishes

(above) Embodied carbon by building element 500

400

300

kgCO2e/m2 Gross Internal Floor Area

200

100

Composite Concrete

-100

Copper Inert Mineral wool Oil-based Steel

-200

Timber Timber-based Store Co2: Timber Store Co2: Timber-based Transport to site

-300

Construction Use (maintenance/ replacement Demolition & Disposal

-400

Module A

Stored CO2 Module B Module C

Lifecycle stage

(above) Embodied CO2e: As built

The embodied carbon of the house was assessed by John Butler Sustainable Building Consultancy using PHribbon. The scope was in accordance with the requirements of the RIAI 2030 Climate Challenge embodied carbon reporting (See our explainer on what we include in embodied carbon calculation on page 67). In this case, the calculation included virtually all works done since Breathnach acquired the property, which therefore excluded works done before Breathnach’s time, such as a new roof membrane and slates, roof window frames, and with an empty shell inside. The total came in at 26.8 tonnes – or 415 kg CO2e/m2 gross internal area, comfortably inside the RIAI 2030 Climate Challenge target of 625. While the total may seem high given that this project is a retrofit, there is one mitigating factor in particular: the house’s very small size and high surface area to volume ratio means that each square metre of floor area carries a higher proportion of the total. If floor area is ignored, the result looks very different: the score of 26.8 tonnes is the second lowest of the four retrofit projects assessed in Passive House Plus case studies to date. Notably, the only retrofit to post a lower score, an Enerphit to a far larger house by Ruth Butler Architects in New Forest, did not include interior finishes or fitted furniture – which in Breathnach’s house make up 11.9 per cent of the total – and did not involve installing a new heating system. As if to emphasize that point, by far the single greatest contribution to the embodied carbon score of the building is the building services, which represent 48.8 per cent of the total emissions. The vast bulk of this total comes from the heat pump, which is taken to represent over 8.7 tonnes, roughly a third of the total. (It’s important however to emphasize that even when heat pumps come with a significant embodied carbon impact, this tends to be paid back many times over in terms of emissions reductions from operational energy use.) The heat pump data was derived from a Product Environmental Passport (PEP) by the French industry association Uniclima, a generic certificate applicable to specific air-to-water heat pump models from a number of leading heat pump brands. A health warning here: strictly speaking these values don’t apply in this case, as the manufacturer and model in question wasn’t referenced in the PEP, but the data in the PEP seemed a close analogue for the installed heat pump. As per the PEP, the heat pump was projected to have a 17-year lifespan, meaning two replacement heat pumps were included to cover the projected 50-year lifespan of the building, with both replacement units assumed to have very low global warming potential (GWP) refrigerants, given the expected impact of the EU F-Gas Regulation and Montreal Protocol. The refrigerants in the PEP were substituted for the refrigerant used in the heat pump – R410A, which has a relatively high GWP of 2088. Breathnach’s heat pump includes 2.4 kg of R410A – as the much lower GWP R32 wasn’t yet available on the market – representing over 5 tonnes of CO2e. As per TM65.1 the refrigerant leakage in the first heat pump adds up to a total of 1.75t of emissions. The house’s Munster Joinery Passiv Aluclad windows – which have an Environmental Product Declaration (EPD) showing a 50-year lifespan – added 2.97 tonnes, while the frames of the roof windows – which were installed prior to Breathnach acquiring the property – were not calculated. The triple glazed units Breathnach fitted into the existing roof window frames added a quarter of a tonne. In line with the RICS Whole Life Carbon guidance, emissions associated with the construction process itself were estimated based on the value of the project. Sean Breathnach, who did most of the construction himself, estimated that the total build cost would have been circa €140,000 if he had paid contractors to do the work instead, rather than the actual build cost of €62,000. The difference added almost a tonne of embodied CO2e. In line with LETI’s embodied carbon guidance, the construction process totals were divided out among the building elements according to their A1-A3 embodied carbon scores. As per the RIBA & RIAI 2030 Climate Challenge targets, external works were calculated but not included in the main totals. If included, they would have added an estimated 3.3 tonnes of embodied CO2e.

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LEITRIM SCHOOLHOUSE

CASE STUDY

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52 | passivehouseplus.co.uk | issue 41

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CASE STUDY

LEITRIM SCHOOLHOUSE

IN DETAIL Building type: 52 m2 detached schoolhouse from 1870. Enerphit refurbishment to near-derelict building without extension. Location: Rural site, Co Leitrim Completion date: September 2020 Budget: €95,000 including cost of land and property and all materials. Majority of labour not included except for electrical, groundworks, insulation and installation of heating system (though homeowner helped with these too to keep costs down). Homeowner’s labour estimated at an extra €50,000. Passive house certification: Meets Enerphit criteria via component certification but uncertified. BER (after): TBC Space heating demand: 26 kWh/m2/yr Heat load (PHPP): 10 W/m2 Primary energy demand (PHPP): 106 kWh/m2/yr Primary energy renewable demand (PHPP): 61 kWh/m2/yr Heat loss form factor (PHPP): 2.24 (surface area to volume) Overheating (PHPP): 8%. Number of occupants: 1 Energy bills (after): €1,099 spent on electricity (Dec 20 – Dec 21) including all charges. Using

final energy demand figures in PHPP, Bonkers. ie suggests a cheapest available annual space heating & cooling bill for this property of €236 for this property (17.32 cent per kWh plus 13.5% VAT). Exclusive of annual standing charge of €184 and PSO levy of €52. Airtightness (after): 0.7 ACH Ground floor Before: Uninsulated dirt floor. After: Suspended timber floor insulated with 425 mm cellulose insulation. U-value: 0.09 W/m2K Walls Before: Solid stone wall. After: Stone wall externally, followed inside by air gap, weather membrane, 40 mm Gutex woodfibre insulation, 150 mm cellulose in stud cavity, Intello airtight membrane and vapour control layer, 100 mm Rockwool, 12 mm plasterboard. U-value: 0.13 W/m2K Roof Before: Roof slates on strapping with weatherproof membrane over rafters. After: Slates on wooden strapping over weatherproof membrane (all retained). Existing rafters as air space. Breathable membrane, 300 mm cellulose insulation in stud framed cavity, Intello air barrier, 100 mm Rockwool insulation in stud framed cavity, 19 mm wooden ceiling. U-value: 0.10 W/m2K

Windows & doors Before: Single glazed, timber windows and doors. Overall approximate U-value: 3.50 W/m2K After: New triple glazed windows: Munster Joinery triple glazed PassiV Future Proof timber aluclad windows and doors. Overall U-value of 0.80 W/m2K Roof windows: Velux triple glazed roof windows with thermally broken timber frames. Overall U-value: 1.0 W/m2K Heating sytem Before: Open fireplace. After: Hitachi Yutaki-M 7.5kW monobloc air source heat pump, heating via wall and floor mounted radiant heating pipes. 200L split tank for domestic hot water. Ventilation Before: No ventilation system. Reliant on infiltration, chimney and opening of windows for air changes. After: BluMartin FreeAir decentralised heat recovery ventilation system with extract duct from bathroom. Passive House Institute certified to have heat recovery rate of 86%. Water: Low flow fixtures throughout. Green materials & measures: Retention of original walls and existing roof; avoidance of concrete where possible; cellulose and wood fibre insulation; timber construction and finishes.

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TINAKILLY

CASE STUDY

A GRID OF THEIR OWN IRISH HOUSING SCHEME POINTS TO A FUTURE OF DECENTRALISED POWER A new development in County Wicklow demonstrates how typical housing estates might be turned into electricity microgrids through solar power and battery storage, with residents buying and selling renewable energy from each other, helping to insulate them from price spikes and outages.

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8 .94

0 . 69

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CASE STUDY

TINAKILLY

IN BRIEF Building: Scheme of 365 A-rated dwellings (phase one) Method: Timber frame with block/brick outer leaf Location: County Wicklow Standard: NZEB

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TINAKILLY

CASE STUDY

n Ireland’s east coast, just north of Wicklow town and a few hundred metres from the sea, a new residential development by D-RES Properties is taking shape. Nestled between the Wicklow mountains and the Irish Sea, within easy commuting distance to Dublin, these homes-to-be are within easy reach of many amenities. The 365 units of Tinakilly Park, comprising 3, 4 and 5-bed family homes and duplexes, get their name from the estate of Tinakilly Country House, a Victorian home constructed in the mid 1800s, on which they are located. The first phase of the development, which includes 125 properties, launched on 24 February, with the first 27 homes to be completed in June. But a total of 700 homes is expected, pending planning permission for future phases. The scheme is aimed at first-time buyers and families.

We wanted to create a kind of mini power station in the house.

56 | passivehouseplus.co.uk | issue 41

Building a community Robbie McGrath, head of sustainability with D-RES, has been involved with the project for the last seven months. With a background in engineering, he worked in Finland for 13 years as a sustainability consultant on projects ranging from offices, to airports, hospitals and universities. He says that one of the aspects that drew him to D-RES was the company’s focus on community-building, rather than simply house-building. This focus shines through the project, from the layout of the site, to its amenities, and, crucially, to how energy is generated in the homes. “The aim is to have more functional spaces for people, not just a

few benches, but connectivity to green spaces and biophilic design, which was championed by our creative design manager Aideen Leahy. Having that connection to nature for people has been really important, especially in Tinakilly because we have a lot of green space,” he says. At Tinakilly, the community will be able to generate its own energy, reducing demand on the national grid. All homes are A2 energy rated, and have mechanical ventilation with heat recovery, and fully electrical heating via heat pumps. “The heat pumps have been specially selected to communicate with the smart energy management system to maximise energy efficiency,” McGrath says. Residents have the option to upgrade to an A1 building energy rating (BER) by installing six 400W solar PV panels on the roof and generating electricity that can be stored in smart batteries. “We wanted to try and create a kind of mini power station in the house,” McGrath says. On cloudy days, the batteries can charge from the grid at off-peak times. At peak times, battery electricity can be used to reduce the demand load on the national grid. Renewable energy supplier Pinergy is acting as energy partner on the project, helping D-RES to provide the energy upgrade package. Philip Connor, head of energy services with Pinergy, has an eclectic background in law, aircraft engineering, boat building, and professional yacht racing. Since 2015, he has been working in the renewable energy space, and is now leading Pinergy’s energy efficiency and renewable energy solutions. The energy system for the homes works

CASE STUDY

in a “fully optimised fashion”, he says. The homeowners can generate electricity, they can store it, and a cloud-based software system manages the energy for each home. Energy tariffs are cheaper at certain times, and the system takes tariffs into account in making decisions to ensure the homeowner is using the cheapest energy available. The system looks at the amount of energy that is being used and when it’s being used during the day. It then looks at the cost of energy over that period, and at weather forecasts over three to four days, to understand what the solar opportunity is like, explains Connor. It then decides around how much energy to store and when to store it. A home dashboard app shows residents how power is flowing in the household and how much energy is being generated and stored. Although the system’s decisions can be overridden by users, the automated system helps make “sustainability easy for homeowners,” says Connor. It’s up to the homeowners to decide if they want the panels. “In the initial rollout, we’re waiting for the owners to order the systems, and, if they engage earlier in the process, we can install them as part of the construction phase,” says Connor, adding that retrofitting is going to be “very straightforward”, since the space for cables is built into the homes. “The home is basically battery and solar ready,” he says. Connor says that the system has the potential to provide big savings, with optimisation modelling suggesting a reduction in energy costs anywhere from 40 to 60 per cent com-

Having that connection to nature has been really important.

pared to the same homes without this optimisation. This feat is achieved by a system which will run in the background and decide for the occupants when it’s appropriate to use energy generated on site or draw from the grid. Another big advantage of the system is that, in the event of power outages, people can use their own energy, says McGrath. Micro-grid Unused excess electricity can be exported to the national grid or shared with neighbours in a peer-to-peer network, explains McGrath. In the past “you might have knocked on a neighbour’s door to get a cup of sugar, now you’re getting a few kilowatts of energy,” he says. Through this system, residents can set a price and trade with each other. In future, they may also be able to sell energy back to the grid at times when it might be struggling. This payment is enabled by the Irish government’s ‘clean export guarantee’ tariff as part of its microgeneration support scheme, announced at the end of last year, but it is up to the market to decide on a price

TINAKILLY

for the tariff. (In March, Pinergy became the first supplier on the Irish market to announce a clean export guarantee tariff, which will be available later in the year.) “We tried to make it as joined up as possible,” says McGrath. “So, it’s not just individual houses. It’s the whole 300-house community which will be linked together in a two-megawatt micro grid,” he says. Electric vehicle (EV) charging points are another option available to residents, McGrath notes, adding that the battery in EVs may be used effectively as secondary batteries for the houses. According to Connor, at present this will be limited to using the EV batteries to soak up grid or micro-generated energy at the most opportune times, as the functionality of powering houses from EVs will require the development of new standards and will require engagement from the EV manufacturers. McGrath says that by giving residents more control over their energy use, D-RES hopes to empower them to become energy citizens, who play an active role in the transition to a low carbon future.

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TINAKILLY

CASE STUDY

Excess electricity can be shared with neighbours in a peerto-peer network.

Positive living When asked what about Tinakilly Park excites him most, McGrath says it’s “the holistic approach that has been taken to sustainability. It’s not just an add on. D-RES are really interested in putting sustainability at the forefront of everything we do [...], from site selection, to design, construction, down to our waste management.” The company is also interested in how sustainability and ESG (environmental, social and governance) principles can filter down to the process of house building, he says, explaining that ESG principles affect the entire business. McGrath adds: “It’s how we run our business, how we look after the environment, but also how we look at the social side. We pay people on time, we look after our staff, we encourage companies who have apprenticeships, we select local businesses and local materials, and we try to tie in with local sports clubs, to show that we understand the impact we have and the impact we can have for the good.” As well as hiring McGrath as head of sustainability, D-RES has established a company-wide ESG team to drive ESG actions throughout the organisation. D-RES is also listed on GRESB, an international benchmark for sustainability in property and real estate, with chief executive Patrick Durkan driving the company’s overall sustainability goals. “We now have a sustainable purchasing policy,” says McGrath, adding that, going forward, they will be asking service providers to have environmental product declarations for materials. Towards passive house The houses at Tinakilly Park, which are timber framed, have an airtightness of about 1 m3/hr/m2 and were built using passive house, fabric-first principles — an element of the project driven by D-RES development manager Kevin Durkan. However, the price point of the houses meant it wasn’t feasible to adhere to all passive house principles. Triple glazing, for instance, would add a lot of costs, so the windows are double glazed, he says. “If the market changes as the phases go on,

58 | passivehouseplus.co.uk | issue 41

and people say they really would like passive houses, it’s easy for us to just upgrade the house and get it to that level”, he says. Within the homes, the batteries are upstairs in the areas traditionally reserved for a hot press, and the heat pump cylinders are downstairs in utility rooms. The PV panels are made of monocrystalline silicon and are self-cleaning, says Connor. The batteries, which are lithium ion, contain built-in inverters which convert direct current electricity from the panels on the roof into alternating current which can be used in the home. They have a 10-year warranty equivalent to 10,000 cycles, he says. In future, says McGrath, it may be possible to increase the number of solar panels on the roofs from six to eight or ten.

Caring for ecosystems Given climate-change related extreme weather events, rainwater management was a challenge for the site, which currently has attenuation tanks that may be used in rainwater harvesting, says McGrath. Other ideas include allowing playgrounds to turn into wet playgrounds on very rainy days, he says. The houses’ avian names, from kingfisher, to redwing, to guillemot, conjure up images of local wildlife. Right beside the development lies Broad Lough, the largest estuarine habitat in Co. Wicklow and an important area for migratory and resident birds. Working with an ecologist on site, wildflower meadows and about 1,400 trees are being included, he says. “Obviously the site had to be cleared to an extent, so we are try-

CASE STUDY

TINAKILLY

ing to increase the ecological value of the site after we’ve worked on it,” he says, adding that D-RES are trying to reuse felled trees in the playground areas. Other options include installing bee boxes, and including better linkages between ponds and meadows to facilitate movement of reptiles and amphibians. These natural features could tie in with educational events for local schools, where children could come in and see things like frogspawn, he says. Other green infrastructure will include off-road cycleways allowing people to easily travel to and from Wicklow town. McGrath hopes that centralised bike storage facilities with green roofs or solar panels could be added as well. He also wishes to include more facilities for teenagers, such as skatefriendly solar furniture.

1 & 2 Ground floor build-up features a 150 mm reinforced concrete floor slab with a minimum of 50% GGBS, with 150 mm Xtratherm PIR floor insulation underneath and 25 mm upstand perimeter insulation to the edges; 3 the prefabricated attic roof trusses on site; 4 vapour control/airtight membranes to walls and ceiling; 5 & 6 progress continues on the site, which is located close to close to Broad Lough, Wicklow Town and the Irish Sea.

ph+ | tinakilly case study | 59

TINAKILLY

CASE STUDY

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60 | passivehouseplus.co.uk | issue 41

THE STREET

CASE STUDY

TINAKILLY

SELECTED PROJECT DETAILS

EMBODIED CARBON A reference house – a three-bed semi-d with a gross internal floor area of 108 m2 – at Tinakilly Park was assessed by Robbie McGrath using One Click LCA. The scope was as per the requirements of Level(s), including essentially everything in Level(s) scope, with the exception of external works. The PV array and associated equipment – which can represent a large amount of embodied carbon as the two UK case studies in this issue reveal – were also excluded, as PV is an optional extra for purchasers. For some building products, the calculations relied upon default data from One Click LCA, or from generic/industry association Environmental Product Declarations (EPDs) and Product Environmental Passports (PEPs) – in some cases from similar products. As Level(s) specifies a 50-year life cycle rather than the 60 years specified by the RICS methodology used in the UK, the project’s embodied carbon emissions were reduced by assuming fewer prod-

uct replacements across the building’s lifespan. For instance, this led to two replacements of heat pumps, given the 17year lifespan referenced in the PEP used for the calculations. The external render was assumed to need one replacement, while the Munster Joinery windows were assumed to need no replacement, given the company’s EPD contains a life expectancy of 50 years. The house scored a cradle-to-grave total of 439 kg CO2e/m2 – comfortably beating the RIAI 2030 Climate Challenge target of 625 kg CO2e/m2. Some of the key factors which may have contributed to this low score, the omission of the PV system notwithstanding, include the timber frame build system, the 50-year window EPD, the presence of the relatively low global warming potential (GWP) refrigerant R32 in the heat pump, and the specification of 50 per cent Ecocem GGBS in the concrete.

Developer: D-RES Architect: BBA Architects M&E design: PMEP Consulting Civil & structural engineering: CS Consulting Group Project management: D-RES Plumbing contractor: Gaffney Mechanical Electrical contractor: Armour Electrical Build system supplier: FastHouse Attic insulation: Baker & Co Windows & doors: Munster Joinery Fire proofing contractor: Fireseal Heat pumps: Daikin, via Gaffney Mechanical Floor insulation: Xtratherm Roof tiles: Neal Brennan Roofing Ground works: Cowman’s Civil Engineering Brick facades: Likestone Concrete blocks: Dan Morrisey & Co Concrete (50% GGBS): Dan Morrisey & Co Landscaping: SMB Landscapes Solar PV & battery: SolarElectric Lighting: Eurosales

ph+ | tinakilly case study | 61

TINAKILLY

CASE STUDY

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62 | passivehouseplus.co.uk | issue 41

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CASE STUDY

TINAKILLY

IN DETAIL Buildings: Three (112 m2), four (146 m2), and five (207 m2) bed detached and semi-detached timber frame dwellings with exterior block & render. Location: Tinakilly Park, Rathnew, Co. Wicklow Completion date: Phase 1 completed June 2022 Embodied carbon: 619 kg CO2e/m2, for building life cycle stages A1 through C4 (assessment using One Click LCA). Primary energy demand: 37.85 kWh/m2/yr (sample 3-bed dwelling) Energy performance coefficient (EPC): 0.271 (sample 3-bed dwelling) Carbon performance coefficient (CPC): 0.257 (sample 3-bed dwelling) BER: A2 (or A1 with solar upgrade) (indicative BERs only) Airtightness (at 50 Pascals): 1.46m3/m2/h (sample 3-bed dwelling) Thermal bridging: Through using a fabric-first approach particular care was given to design out heat loss through thermal bridges in the external envelope, e.g., the use of blocks with low thermal conductivity at the external wall-to-floor slab detail. All junctions were designed as per the FastHouse thermally modelled suite of junction details. Many of

these are superior to those in the Acceptable Construction Details (ACDs, TGD L), and they are accredited and certified by an NSAI Approved Thermal Modeller. Thermal bridging factor 0.08 W/m2k. Ground floor: 150 mm reinforced concrete floor slab, on 150 mm Xtratherm PIR floor insulation, 25 mm upstand perimeter insulation to the edges with min R-value of 1.0 m2K/W. Blockwork wall on monarflex RMB350 DPM/radon barrier. Floor U-value: 0.12 W/m2K Walls: Facing brick or rendered blockwork externally, on 50 mm ventilated air cavity, on external breather membrane, on 9 mm OSB, on 89 mm timber frame wall panel with Rockwool insulation packed between, on 40 mm PIR insulation, on vapour control/airtight membrane, on 36 mm x 46 mm battens with service void, on 15 mm Type F Fireline board. U-value 0.18W/m2K Roof: Slate tiles on treated timber battens on Siga Majcoat breathable membrane. Attic floor construction comprised of prefabricated attic roof trusses with 400 mm Isover Metal mineral wool laid between and over. Vapour control layer, services cavity and Type F plasterboard beneath. U-value 0.11 W/m2K Windows: Munster Joinery uPVC double glazed, argon-filled, U-value 1.3W/m2K

Heating system: Daikin Altherma 3 range of heat pumps specified throughout. Seasonal coefficient of performance (SCOP) estimated to be 3.8 at the flow temperature of 45 C. These provide heating via radiators and hot water via the integral thermal store. Back up immersion to supply hot water. Motorised valves on the hydronic heating system which separate the ground floor and other floors into two zones. Each zone has a local thermostat, and can be programmed on a separate time schedule via user interface. Ventilation: Vent-Axia Sentinel Kinetic FH heat recovery ventilation system installed in the attic of each home. Integrated humidity sensors. Heat recovery efficiency of 90 per cent. Water: Low flow water fixtures. Basin taps with flow rate of 5 litres per minute. WC dual flush 6/4 litre with effective flush volume of 4.67 litres per flush. Shower flow rate 8 litres per minute. Electricity: Solar PV 6 panels (400kW peak) with output of 2.4 kW. Sonnen 7.5kW battery and smart energy management system. Green materials: FastHouse timber frame structure, all timber is certified sustainably sourced and chain of custody; concrete used in the foundations and ground floor slab have a minimum of 50% GGBS; all lighting is LED.

ph+ | tinakilly case study | 63

ITFMA EMBODIED CARBON REPORT

INSIGHT

Up to 11 Embodied carbon of 11 concrete and timber frame wall specs number crunched Last year Passive House Plus published an in-depth assessment comparing the build specs including five wall types to a typical Irish house. To enable the industry to fairly compare a broader range of build options, we now expand that analysis with the addition of four timber frame wall types and two insulated concrete formwork systems. By Jeff Colley

ssue 38 of Passive House Plus included an article, Six of one, which took a typical Irish house type and analysed the embodied carbon required to build it – assessing a number of variables for wall types and foundations. The house design in question – a 76 m2 end-of-terrace unit provided by Cork City Council – was assessed using the PHribbon embodied carbon calculation tool, in a collaboration between the Passive House Association of Ireland (PHAI), which funded the work, and the Association for Environment Conscious Building (AECB). The analysis included cradle-to-grave calculations for wall types including cavity walls (with rendered block or brick externally), externally insulated blockwork (with either render or brick slip) and an I-beam timber frame wall with cellulose insulation and a render board. While these calculations were an important start – an opportunity to compare apples with apples by assessing the same house against different build approaches – it took in a comparatively small number of variants. The PHAI and AECB therefore agreed to make the calculations available to any third parties who wish to assess other variants against the house type, provided they agree to share the results for further dissemination. The Irish Timber Frame Manufacturers Association (ITFMA) has taken the opportunity to assess four additional timber frame wall variants against the house type – essentially including timber frame with a fire-rated plaster board and either mineral wool or PIR insulation, and in both cases either rendered block or a recycled glass render board and render system. The ITFMA commissioned sustainable building consultant John Butler to produce a report on the different wall type variants – along with an insulating concrete formwork (ICF) system – and provided draft results to Passive House Plus for this article. The wall build-ups were calculated to a U-value of 0.18, the backstop for walls under Ireland’s 2019 Technical Guidance Document for Part L of the building regulations, and the five build-ups from the earlier PHAI/ AECB analysis were adapted to meet the same U-value, to enable fairer comparison. For this article, Passive House Plus commissioned fur-

64 | passivehouseplus.co.uk | issue 41

ther analysis to evolve the ICF analysis into two scenarios – including high and low embodied carbon variants. At the risk of death by tables, the 11 variants are included here, to show the build-ups in each case. While the full ITFMA report will assess wall build-ups to achieve U-values of 0.18 and 0.15, for this article only values of 0.18 were used. Eleven variants may also be a lot to take onboard in one article – let alone 22. As the embodied carbon explainer on p67 reveals, building life cycle assessments typically include three modules – A (cradle to practical completion), B (use phase, typically excluding operational energy and water use) and C (end of life). In this case, two sections of modules have been omitted. Modules A5 and C1 – which respectively deal with emissions released via construction (e.g. onsite activity) and dem-

olition (at end of life), are typically calculated based on the project cost, based on default figures. In the absence of specific costs for the various wall build-ups, these aspects were omitted. Consideration was given to excluding emissions from transporting the materials from factory gate to site (A4) from the calculations for this article, in part due to the difficulty in accurately calculating transport distances for concrete products, in the absence of environmental product declarations (EPDs) for many specific products. (For instance, in the case of a concrete block this would involve speculating on where the cement, sand and aggregate were sourced, calculating distance, freight type – and how heavily laden the vehicle is, including return trips – to and from the blockwork manufacturer, and calculating the ratio of each material used). In the end, transport

ITFMA EMBODIED CARBON REPORT

INSIGHT

Embodied C02e of 11 wall variants Wall type 1 Cavity wall, PIR, rendered block Plaster Blockwork PIR Residual cavity Blockwork Sand / cement render

mm 13 100 110 10 100 19

Total

352

Wall type 4 Externally insulated single leaf block with brick slips mm Plaster 13 Blockwork 215 Sand / cement scratch coat 10 EPS 160 Adhesive 10 Brick slip 20

Total Wall type 7 Timber frame, mineral wool/ PIR, renderboard Fire-rated plasterboard Cavity (with battens) VCL PIR Mineral wool between timber studs OSB 3 Weather tight vapour permeable membrane Cavity (with battens) Renderboard and render system Total Wall type 10 Insulated concrete formwork base case Fire-rated plasterboard EPS Concrete (1% rebar, 28/35 RC, CEM I) Polypropylene webs EPS Render system

Total

428

mm 15 35 30 140 9 50 16 295

mm 15 75 150 75 10

325

default data from the RICS whole life carbon methodology was used, which suggests default distances for locally, nationally, and mainland Europe manufactured products of 50, 300 and 1,500 km by road, and points to UK government data for emissions from a range of road freight scenarios. Where a material was Irish-made – as most materials in the analysis are – it was assumed to travel 300 km nationally by articulated truck, and 50 km locally by rigid truck. With the exception of the OSB and cellulose insulation, the timber and timber-based products were assumed to be from mainland Europe, along with the mineral wool insulation, render board system, EWI silicone render and the adhesive for the EWI brick slip system. Based on 2021 UK averages, the local journeys appear to be circa 50 per cent laden trucks, due to consideration of return journeys, which

Wall type 2 Cavity wall, PIR, brick outer Plaster Blockwork PIR Residual cavity Brick

mm 13 100 100 40 103

Total

355

Wall type 5 I-beam timber frame, cellulose, renderboard Fire-rated plasterboard Battens @ 600C Airtight OSB Cellulose in I-beams WF sheathing Battens, counterbattens Renderboard & render system

Total Wall type 8 Timber frame, PIR, rendered block Fire-rated plasterboard Cavity (with battens) Foil-faced VCL Cavity between timber studs PIR between timber studs OSB 3 Weather tight vapour permeable membrane Cavity Blockwork (medium dense concrete) Sand / cement render Total Wall type 11 Insulated concrete formwork improved case Fire-rated plasterboard EPS Concrete (0.4% rebar, 20/25 RC, CEM III with 70% GGBS) Polypropylene webs EPS Render system

Total

mm 15 25 12 190 22 50 16

303

mm 15 35

Wall type 3 Externally insulated single leaf block, rendered Plaster Blockwork Sand / cement scratch coat EPS Silicone render

mm 13 215 10 160 6

Total

404

Wall type 6 Timber frame, mineral wool/ PIR, rendered block Fire-rated plasterboard Cavity (with battens) VCL PIR Cavity between timber studs Mineral wool between timber studs OSB 3 Weather tight vapour permeable membrane Cavity Blockwork (medium dense concrete) Sand / cement render Total Wall type 9 Timber frame, PIR, renderboard

50 100 19

Fire-rated plasterboard Cavity (with battens) VCL PIR across timber studs Cavity between timber studs PIR between timber studs OSB 3 Weather tight vapour permeable membrane Cavity (with battens) Renderboard and render system

368

Total

50 90 9

mm 15 35 15 30 110 9 50 100 19 383

mm 15 35 25 50 90 9 50 16 290

mm 15 75 150 75 10

325

are presumably largely empty for local trips. This means that the 50 km local trips are effectively assumed to be from depots circa 25 km from the site. The 300 km national and 1,500 km European journeys assume roughly 75 per cent laden artics, reflecting a reduced likelihood of empty return journeys. The timber frame variants tended to include more materials from continental Europe, but this doesn’t come with a significant embodied carbon penalty via transport, due to the lighter material weight compared to concrete products. By way of example, option 5, the I-beam timber frame system with cellulose, generally assumes timber and timber-based products from Sweden, with the exception of Irish-made cellulose and OSB. Much of the imported structural timber used in Ireland comes direct from the south of Sweden by relatively low carbon sea freight, but as the article supposes

1,500 km truck journeys were instead made, with an extra 50 km locally to deliver to site, it would have added 326 kg CO2e, compared to 86 kg based on 300 km national and 50 km local transport. Given the lack of EPDs for Irish concrete blocks, figures for a medium density block from the British Precast Association were used, albeit with national transport assumptions. Also, the concrete mix calculations for the ICF system were done prior to the Cement Manufacturers of Ireland obtaining an EPD for CEM I, and were therefore instead based on an averaged portland cement EPD by the UK’s Mineral Products Association. This meant the cement had a value of 846 kg CO2e/tonne, compared to CMI’s values of 723 kg CO2e/ tonne for CEM I, or 698 kg for CEM II. If the calculations were redone, it’s likely the ICF worst case would have reduced by over one

ph+ | up to 11 insight | 65

A5 Constuct

B1, B2, B3

5: Timber frame (I-beam, cellulose & renderboard)

3.5

-5.4

0.5 Omitted

0.0

7: Timber frame (mineral wool + PIR, renderboard)

4.2

-4.0

0.6 Omitted

0.0

9: Timber frame (PIR, renderboard)

4.4

-4.0

0.6 Omitted

0.0

6: Timber frame (PIR, renderboard)

4.2

-3.3

1.1 Omitted

-0.5

8: Timber frame (PIR, block outer)

4.6

-3.3

1.1 Omitted

-0.5

3: Block on flat (rendered EWI)

6.2

0.0

1.6 Omitted

-1.0

1: Cavity wall (rendered)

6.6

0.0

1.5 Omitted

2: Cavity wall (brick clad)

8.0

0.0

11: ICF (20/25 RC, 70% GGBS, 0.4% rebar)

6.2

0.0

7.9

0.0

1.7 Omitted

11.4

0.0

1.9 Omitted

(above) Results, tonnes C02e

66 | passivehouseplus.co.uk | issue 41

C3/C4 (Incinerated)

C3/C4 (Landfill)

0.1

0.0

5.4

0.1

0.1 Omitted

0.1

0.0

4.0

0.0

5.0

0.0 Omitted

0.0

4.1

0.0

5.2

1.0 Omitted

0.3

0.2

3.3

0.0

6.4

0.9 Omitted

0.3

0.2

3.3

0.0

6.6

0.4 Omitted

0.4

0.5

0.0

0.1

8.2

-0.9

0.9 Omitted

0.4

0.5

0.0

0.1

8.9

1.3 Omitted

-0.5

0.0 Omitted

0.4

0.0

9.8

1.8 Omitted

-0.2

0.0 Omitted

0.5

0.9

0.1

9.9

-1.0

0.4 Omitted

0.5

0.0

0.1

10.0

-0.4

0.0 Omitted

0.5

0.6

0.9

0.1

15.0

0.0 Omitted

Total A-C

C3/C4 (Recycled)

10: ICF (28/35 RC, CEM I, 1% rebar)

C2 Transport

4: Block on flat (brick slip EWI)

the ICF or timber frame variants. The fairest comparison therefore is arguably between the rendered versions of all wall types, including systems with rendered block-clad outer leafs, rendered EWI, and renderboard systems. Secondly, the ICF variants – and to a lesser extent the other concrete-based variants – are to a fairly large extent affected by the assumptions around transport distance: 1.48 and 1.56 tonnes of CO2e are estimated for transporting concrete to site in the low embodied carbon and high embodied carbon ICF variants respectively, assuming 300 km by artic and 50 km by rigid trucks. While these distances may look less far-fetched given that the figures are based on round trips, over a tonne of CO2e is associated with the artic journeys specifically. An ICF project near a cement manufacturer’s factory gate would stand to achieve significant reductions. It’s also important not to take these results out of context, notwithstanding the fact that this article is focused on embodied carbon alone, and ignoring other considerations. External walls can represent a significant proportion of a building’s total embodied carbon, but there are other building elements which may have similar or greater impacts in some cases. The extraordinarily high results for an admittedly unusually large solar PV roof in the case study on p39 are a case in point. Passive House Plus intends to add other build specs to this comparison in future issues, and invites other parties to put forward their build specs for publication. But while analysis like this may serve as useful guidance to inform design specifications, it’s imperative that building designers start either commissioning building LCA consultants or using building LCA tools for themselves – and at the earliest possible stages in the design, in order to inform the specification – and focus the minds of suppliers to find ways to reduce the embodied carbon of their solutions. • C1 Demolition

Wall Types

A4 Transport to Site

A1-A3 Sequestered

external cladding, such as charred timber cladding – which can offer the dual benefit of low upfront emissions and 100-year plus lifespans. The second and third best results go to two timber frame walls with render board finishes, wall type 7 and 9, with the mineral wool/PIR insulated version (5.0 tonnes) scoring better than the PIR-only variant (5.2 tonnes). Wall type 6 – timber frame with mineral wool/PIR and blocker outer – comes in at 6.4 tonnes, while wall type 8, 8 – a PIR insulated timber frame wall with rendered block cladding – comes in at 6.6 tonnes. One point to note here: the timber frame variants 7-9 benefit significantly from the very low emissivity levels assumed for the foil-faced PIR insulation and foil-faced VCLs and membranes, where these materials were facing unventilated cavities, in line with ISO 6946:2017. This meant significantly reduced insulation thicknesses are required to achieve the 0.18 U-value backstop. The cavity wall variants also benefited from this emissivity – with the foil facing on the PIR facing into unventilated cavities. Sixth place and the best result for a concrete-based system goes to wall type 3, the block on flat with EPS external insulation and silicone render, which at 8.2 tonnes adds over a tonne compared to the worst performing timber frame variant – and double the score of wall type 5. Rendered cavity wall (wall type 1) comes in seventh at 8.9 tonnes, with brick-clad cavity wall (wall type 2) at 9.8 tonnes – reflecting the high embodied carbon of brick manufacturing. The low embodied carbon variant of ICF (wall type 11) comes in ninth at 9.9 tonnes, followed by the brickslip-clad externally insulated block variant (wall type 4) at 10 tonnes. The clear outlier from these 11 wall types is the higher embodied carbon variant of (wall type 10) bringing up the rear at 15 tonnes. There are a couple of important observations here. The first is that the brick or brickslip clad variants fare significantly worse than their rendered equivalents. Note that brick or brick slip options were not considered for

A1-A3 Manufacture

tonne of CO2e. A 50-year building design life was assumed, as per the EU Level(s) sustainable building framework. The render board and render system used for three of the timber frame variants was assumed to last for the lifespan of the building – though as the EPD for the system makes clear, this assumption is dependent on the quality of installation, taking account of rainproof connections to other buildings or building parts. Similarly, the silicon render system used on the two ICF variants and on the rendered EWI system were also considered to last for the life of the building, although the EPD in this case listed a design life for the outer layers of the system of 25 to 50 years, depending on location, construction and material quality, while also recommending repainting after 15 to 20 years. Repainting and retouching of render systems was omitted in all scenarios, including the sand/cement render, which was assumed to have a 30-year lifespan. Interior painting and repainting were omitted in all cases. Had a 60-year lifespan been assumed instead, as per the UK RICS methodology, the results may have differed in some cases – depending on what assumptions are made about component lifespan. The five timber frame variants posted the lowest embodied carbon scores, both in terms of the module A (cradle to practical completion) results, and the A-C (cradle-to-grave) results. Wall type 5 – the I-beam timber frame wall with cellulose insulation and a render board – is the clear winner at 4.1 tonnes from A-C. This wall type is also the only variant where more CO2 is sequestered in the walls at the point of practical completion than was released in the manufacture and transport of the wall materials to site. It’s important to note that this sequestered CO2 is assumed to be released at the end of the 50-year design life in the life cycle assessment (LCA), but if the walls were to last in excess of 100 years, this CO2 would remain sequestered for that time. Planners permitting, greater reductions still could potentially be achieved by use of lower embodied carbon

INSIGHT

B4, B5

ITFMA EMBODIED CARBON REPORT

4.1

PASSIVE HOUSE+

EMBODIED CARBON

Embodied carbon explained All this talk of embodied carbon and building life cycle assessment (LCA) can be very daunting, but what does it mean? This is our stab at shedding some light, and explaining the jargon.

hifting the focus from the emissions caused by energy used to heat, cool and power buildings, embodied carbon focuses instead on emissions generated in the construction of the building itself, from extraction of raw materials right through to the building’s eventual end of life. Embodied carbon scores are expressed in terms of CO₂ equivalent, or CO₂e. This is a combined total of CO2 and other greenhouse gases converted into the equivalent amount of CO₂ . The emissions totals are broken down into separate modules – A, B, C and D, which represent different stages of the building’s life. If buildings were living organisms, module A could be thought of as emissions released in gestation. Module B would be emissions released during the creature’s life, and module C would be emissions released when it dies. Module D makes this metaphor a little nightmarish, representing the potential benefits that may be salvaged by the proverbial gravedigging that is future recovery. For the sake of transparency – and just to make a complicated process even more complicated – it is worth pointing out that module A includes two markedly different parts, and where possible we have tried to reflect this in the graphs we publish. Module A (upfront emissions) includes emissions released up to the point of practical completion – including the manufacture of construction materials, transporting materials to site, and the construction process itself. Materials are covered by A1-A3, A4 covers transport to site, and A5 covers the construction process itself. Module A (stored emissions) includes the CO₂e sucked out of the atmosphere by building materials from biogenic sources – such as trees or other plants – and stored for the duration of their use in the building. They’re reported as a minus figure. Stored emissions should be reported separately in this way to discourage accountancy sleight of hand. There is new thinking that biogenic storage should be assessed dynamically, for instance to include sequestration from regrowth in a forest after timber is harvested. But for the sake of simplicity, we’ve chosen not to go there yet. Module B (use-phase emissions) looks ahead at the emissions predicted to be released during the building’s use period. B1 to B5 covers CO₂e that may be released in the maintenance, repair and replacement of

building components across the reference design life of the building, while B6 and B7 include emissions from estimated energy and water use respectively. The Royal Institute of British Architects (RIBA) and the London Energy Transformation Initiative (LETI) in the UK, and the Royal Institute of the Architects of Ireland (RIAI), all exclude B6-B7 from their embodied carbon targets. (All three organisations have standalone operational energy targets, while RIBA and the RIAI also have water use targets.) The length of the projected building lifespan can have a significant impact here. RICS (Royal Institution of Chartered Surveyors) specifies a 60-year lifespan – although there are plans to start adjusting totals based on building type – while the EU Level(s) framework sets the design life at 50 years, which may mean inclusion of fewer replacements of components. RIBA and LETI use the RICS 60-year figure, while the RIAI in Ireland use the EU 50-year figure. Module C (end of life) estimates the amount of emissions released from the building when it is eventually taken down, taking account of demolition, transport, waste processing and disposal. At this point, the CO2e stored in building components is effectively regarded as being released into the atmosphere. In reality, it’s plausible that most of these emissions may not be released for a very long time, if at all, as the fabric of buildings can last for hundreds of years. (Though as high-profile building failures have shown, far shorter lifespans can occur due to defective materials, design or workmanship). Module D (recycling potential) covers the net environmental benefits or loads that may result from reuse, recycling and energy recovery – including the potential reuse or recycling of building components, while potential energy exported into the grid during the building’s life is also crowbarred in here. Module D emissions aren’t included in the RIBA, RIAI or LETI targets, so we’re ignoring them too. It’s also critical to consider what is included within the scope of a building life cycle assessment, aside from taking account of whether modules A, B, C and D are included.

Building elements But where does a building begin and end, and what stuff should you count? Broadly speaking, the elements which can be included in an LCA are similar between the documents which frame the UK and EU approaches, respectively Table 3 in the RICS document, ‘Whole life carbon assessment for the built environment’, and Table 11 in Level(s) User manual 2 (Publication version 1.1). Readers would be advised to compare both documents, both of which include the whole building and external works, albeit with some elements described differently. One major difference: RICS includes demolition and facilitation works – including specialist groundworks, which can contribute quite considerably to embodied carbon in some cases, such as excavating and transporting muck. As it stands Level(s) does not include these elements, but member states are free to include elements outside of the scope of Level(s) – and report on them separately, or to include totals with and without these elements. The RIAI targets follow the full Level(s) scope, but the RIBA and LETI targets exclude demolition and external works from the RICS scope. The RIAI, RIBA and LETI all state that analysis should include a minimum of 95 per cent of cost, including substructure, superstructure, finishes, fixed FF&E, building services and associated refrigerant leakage. Meanwhile LETI exclude the embodied carbon of renewable electricity generation, with the exception of building integrated systems. RIBA and the RIAI’s 2030 Climate Challenge targets set embodied carbon targets for buildings, including a target by 2030 of 750 kg CO₂e/m2 (gross internal area) for offices, 540 for schools and 625 for domestic buildings. The RIAI sets a higher target of 450 for dwellings above 133m2 or for low density homes of up to two storeys. RIBA and the RIAI require building LCAs to include A1-A5, B1-B5 and C1-C4, and do not include module D. LETI also includes a module A target, to focus attention on the upfront emissions. In general, the embodied carbon calculations published in Passive House Plus endeavour to align with the requirements set out by RIBA or the RIAI, depending on whether the project is UK or Ireland-based, though typically external works are omitted. Where some (typically minor) elements have been omitted, we try to ensure this is stated in the description. •

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Marketplace News EPDs key to reducing Partel launches new Acraline Roll adhesive embodied carbon – P Munster Joinery

eading Irish window manufacturer Munster Joinery has emphasised the importance of environmental product declarations (EPDs) for reducing embodied carbon in buildings. The company sees reducing embodied carbon as the next major step for the industry after tackling operational energy. “We have known for some time that buildings and construction are responsible for a huge chunk of carbon emissions, around 39 per cent of the world’s annual CO2 emissions,” said Marlene O’Mahony, quality manager at Munster Joinery. “We have become very good at limiting the amount of energy required to heat, light and cool buildings. But the industry is only now getting to grips with another large chunk of these emissions, the embodied carbon generated during the manufacturing and extraction processes of building products.” She said the transparent information provided by EPDs is now critical to cutting the embodied carbon of construction materials. “The availability of an EPD has a twofold impact. For the construction industry professional it offers a transparent source allowing the comparison of different products under a common set of environmental performance indicators. For the manufacturer it makes the environmental impact of products easily visible, enabling them to identify ways of reducing this impact. “For this reason, Munster Joinery have developed EPDs across a wide range of our products and we currently have five EPDs published and readily available on the Irish Green Building Council website. This makes accurate, unbiased, independently-verified sustainability data available to potential customers and specifiers, all of whom are becoming increasingly aware of the need for sustainable products. It has also allowed Munster Joinery to measure performance and set goals in regard to sustainability and carbon reduction. As we aim to design low carbon products to decarbonise building and infrastructure projects, EPDs are set to become a powerful resource.” All of Munster Joinery’s product ranges meet NZEB requirements as a minimum and eight product lines are certified by the Passive House Institute in Germany. “Our operations are tailored to minimise the use of energy and water, use materials that are environmentally friendly, use recycled materials wherever possible, minimise waste and continually reduce emissions,” O’Mahony said. “Much of our energy needs are met by two wind turbines with an electrical output of 4.2 megawatts. A biomass combined heat and power (CHP) plant with a capability of 12 MW thermal and 3 MW electrical also contributes significant amounts of green energy to the plant.” • (above) Munster Joinery has invested in a range of measures to minimise the company’s environmental impact, including wind turbines with an output of 4.2 MW.

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artel has upgraded the performance and functionality of its Acraline Roll adhesive with new technical features. The company said that Acraline offers a “unique sealing solution for membranes” in the construction of passive house and low energy buildings. Partel described Acraline Roll as an innovative response to increased demands for adhesive solutions, and as an alternative to conventional air sealing technologies such as liquid adhesive. “It is a unique compound, because it combines the advantages of liquid adhesives and adhesive tapes, resulting in a smart bonding approach with outstanding immediate adhesion properties,” said Hugh Whiriskey, technical director of Partel, who was involved in the R&D process. The roll adhesive — for sealing of internal and external membranes — forms a complete, tested system in accordance with Part L and DIN 4108-11. Partel said that Acraline Roll is set apart by its functionality: “It’s quick and easy to apply directly from the roll, with the simple handling of a pressure-sensitive adhesive, ensuring permanent elastic airtight connections, without any drying time needed.” Ideal for a very wide range of substrates, the roll sealing tape adheres to surfaces with residual moisture and can be processed even at temperatures as low as -20 C. Both during processing and after application, Acraline Roll offers maximum adhesion accuracy thanks to its high-performance translucent acrylic adhesive, engineered to achieve optimum peel, tack and longterm strength. Partel said that the product is a 100 per cent solvent-free adhesive, with outstanding water and temperature resistance. That makes it a reliable solution for durable airtight connections. The Acraline Roll adhesive was introduced to Ireland in March and is now available in the UK, US, and mainland Europe. For further information, see www.partel.ie. • (below) The new Acraline Roll adhesive, from Partel.

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Steico offering free wood fibre insulation samples L eading German wood fibre manufacturer Steico is now offering free samples of its Steicoflex wood fibre insulation to anyone in the UK or Ireland who requests it. Steicoflex comes in flexible wood fibre batts and offers a lambda value of 0.036 W/ mK, which Steico said is the lowest of any natural wood fibre-based material. The product is also certified by the prestigious Institute for Biologically Sound Construction (IBR) in Rosenheim as being harmless to human health. Steicoflex is also certified by the Forest Stewardship Council — as is Steico’s entire range of softboard products — and stores 85 kg of biogenic carbon (CO2e) per cubic metre of the product, according to the company. “Being a wood fibre product that is manufactured in Europe, close to the forests from which the wood is sourced, Steico is also less prone to supply issues than other comparable insulation materials at the moment,” said Will Kirkman of leading Steico distributor Ecomerchant. Kirkman also emphasised that when comparing Steico to other insulation products, it is critical to look at density

and thermal performance alongside the price. “Steico wood fibre insulation is much denser than comparable materials; mineral wool is typically 18 to 20 kg per cubic metre, but Steicoflex is 60 kg, a feature that ensures that your insulation also works during the summer months by reducing the risks of overheating. When comparing prices of alternative materials, you get real bang for your buck when buying a material that works all year round,” he said. To order a free sample of Steicoflex, go to tinyurl.com/SteicoFlex. Meanwhile, Ecomerchant is also reporting a positive early response to its new Faay HV84 Indoor Climate Wall. This is a strong, rapid-install partition wall system made from 100 per cent natural materials (flax, wood fibre and timber). The product consists of a dense flax core with a factory-bonded wood fibre surface, onto which a natural, breathing finishing layer such as lime or clay plaster is applied. Faay HV84 is a “breathing wall” which Kirkman said can help to improve indoor air quality, as well as thermal and acoustic performance. Passive House Plus wrote about the product last year, and Kirkman said this

has generated strong early interest, even though the company has yet to formally advertise the product. The Faay HV84 Climate Wall stores 170 kg of carbon per m2 of the product, according to Faay. • (below) A free sample of Steico insulation is available to order at tinyurl.com/ SteicoFlex.

Andy Mitchell appointed CEO of Green Building Store

reen Building Store has announced the appointment of Andy Mitchell as its new managing director, helping to build on the company’s established position at the forefront of the low energy and passive house building market. Andy previously worked for 12 years at Natural Building Technologies, in a variety

of roles including managing director and previously both technical and sales director. He has also held directorship roles within a number of other companies and organisations working within the field of sustainable construction. Andy’s knowledge and experience ranges from modular construction to the thermal performance of buildings and construction product innovation. Andy Mitchell commented: “I’m delighted to join Green Building Store and help build on its nationwide reputation for technical expertise and outstanding customer service. I feel very privileged to begin working alongside an exceptional team of colleagues in what is the next exciting chapter of Green Building Store, as it widens its leadership in the marketplace to support the uptake of sustainable building in the UK.” Bill Butcher and Chris Herring, founding directors of Green Building Store, commented: “It is fantastic to have somebody of Andy’s experience and knowledge join the business and to know that the

company has a safe pair of hands to take it forward as part of the next steps of its journey as part of the Efficient Building Solutions group. Andy’s comprehensive understanding of sustainable construction and innovative building materials will be an enormous asset for the company. We look forward to working alongside Andy and, over time, passing on the baton to him.” Philip Fellowes-Prynne, CEO of Efficient Building Solutions, the parent company of Green Building Store, added: “Finding the right candidate to be managing director of Green Building Store has been challenging. I am delighted that we have found Andy Mitchell, who combines extensive experience within sustainable construction and a commitment to Green Building Store’s core vision and values, with strong commercial experience.”• (above left) New Green Building Store CEO Andy Mitchell.

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Ecological disappointed at ‘unambitious’ Part L E

cological Building Systems has expressed its disappointment with the latest updates to Part L of the building regulations in England. The update is designed to provide an interim framework prior to the proposed Future Homes standard, which is to be issued in 2025. The aim of the 2022 interim standard is to achieve a 31 per cent reduction in energy use for new dwellings. The air permeability backstop has been tightened from 10 m3/hr/m2 to 8 m3 hr/m2 – this is 3 m3/hr/m2 higher than the original draft proposal of 5 m3/hr/m2. “Whilst there are some positives to glean in the new Part L document, such as the elimination of sample testing [every building now needs to be tested], this essentially still means that England has the worst regulative backstop airtightness in Europe,” said Ecological’s UK technical manager, Neil Turner. “Setting a target of 8 m3/hr/m2 is barely better than previous legal limit of 10 m3/ hr/m2 which was set in 2002. Surely the industry has moved on since then? In fact, a figure of 8 m3/hr/m2 is still behind the now

obsolete equivalent standard for Ireland in 2011, which was set at 7 m3/hr/m2! In reality, since the Irish TGD Part L introduced its latest NZEB standard, airtightness levels are now averaging 2.55 m3/hr/m2 in new dwellings. “Setting such an unambitious backstop gives a clear signal to industry to carry on as usual. As airtightness is one of the most cost-effective means of reducing fabric heat loss, and can be cost effectively carried out at the building stage, it makes this meagre improvement even more baffling.” “The benefits of attaining an airtight building envelope are widely known ranging from reduced heat losses, reduced risk of interstitial condensation, improved acoustic performance and improvements in thermal comfort to name a few.” Turner said that a reduction in uncontrolled air infiltration into the building also allows for a more constant ambient temperature. This, in turn, improves the efficiency of air source heat pumps, which are going to be the main source of heating in the future. “Some people believe that an airtight

building will result in poor indoor air quality. This is not the case, as airtightness should also be combined with adequate controlled ventilation such as MVHR. The guiding principle is to ‘build tight and ventilate right’,” he said. “There is a perception that airtightness is expensive. However, tested and certified airtightness tapes, membranes, and penetration seals are a tiny fraction of the overall cost of construction and result in a very short payback for the homeowner. Substituting fit for purpose airtightness products with items such as basic silicone caulk and basic tapes merely results in a building not being airtight within a reltively short timeframe after occupation. “Airtightness technology has evolved over the last two decades. Solutions such as Pro Clima airtightness grommets, Aerosana Visconn airtightness paints and other solutions have led to a simplification of executing airtightness effectively on site. This makes attaining much higher levels of airtightness on site even more possible.” •

Mitsubishi heat pumps 6-7 times lower CO2 than condensing gas boilers

eading sustainable heating, ventilation and air conditioning systems manufacturer Mitsubishi Electric has produced analysis showing the whole life carbon calculations of its heat pumps may be six to seven times lower than comparable condensing gas boilers. Mitsubishi Electric UK – which manufactures heat pumps in its Livingston-based factory – assessed the embodied carbon of eight heat pumps including six domestic units, and two commercial units against CIBSE’s TM65 methodology for calculating the embodied carbon of building services, which was published last year. The assessment included Mitsubishi’s residential monobloc air-to-water heat pump range, including the QUHZ W40VA – a 4 kW air-towater heat pump which uses R744 refrigerant, and is becoming popular with passive house designers. R744 is the name for refrigeration-grade CO2, which combines two properties of note for sustainable buildings. R744 can achieve hot water at a higher co-efficiency of performance (COP) than more traditional refrigerants – which may make it ideally suited to passive houses, where in some cases the hot water load may be higher than the space heating load. R744

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also boasts an ultra-low global warming potential (GWP). One of the largest environmental impacts of a heat pump can exist in its refrigerant circuit. R410 – which is still commonly used in many heat pumps – has a GWP of 2088, meaning that each kilo of refrigerant in the machine is equivalent to 2,088 kg of CO2. R744, by comparison, has a GWP of 1 – because a kilo of R744 is simply a kilo of CO2. The machine posted an impressive total of just 618 kg CO2e. The analysis also included five heat pumps in Mitsubishi’s PUZ range – respectively including 5, 6, 8.5, 11.2 and 14 kW outputs, which posted relatively low embodied carbon scores ranging from 1,294 to 1,798 kg. The PUZ range uses R32, a refrigerant which has a GWP of 675 – a marked improvement on R744 and R410a, which remain commonly used in heat pump applications with requirements for low temperature heat. The analysis, which used CIBSE’s midlevel TM65 calculation approach, focused on the outdoor units, meaning separate analysis would be required to quantify the embodied carbon of indoor units, including a hot water tank. The analysis included the embodied carbon and estimated operational carbon of each heat

pump over an assumed 15-year design life, and compared the combined totals against equivalently sized gas boilers with a nominal embodied carbon score of 300 kg CO2e, and assumed efficiencies of 93 per cent. In each case, the combined whole life carbon score for the six heat pumps was six to seven times lower. Laurent Widloecher, residential heating product manager at Mitsubishi Electric said: “Mitsubishi Electric is serious about sustainability. Heat pumps are a key part of the climate fight because of their ability to deliver massive carbon savings compared to gas – reductions that will become even greater as the electricity grid continues to decarbonise. But we can’t afford to ignore the emissions released in manufacturing, maintenance and ultimately the end of life of heating systems. Mitsubishi can help to ensure that operational carbon savings don’t come at the cost of a needless embodied carbon penalty.” Widloecher added that as monobloc technology contains its refrigerant within the unit, no refrigerant charge or refill would be required on site or over the product lifetime in normal use. •

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D R TO B Y C A M B R AY

COLUMN

When will energy efficiency have its day? In spite of the ongoing global energy crisis, Toby Cambray wonders why energy efficiency seems likely, once again, to be the bridesmaid rather than the bride. ‘May you live in interesting times’ is apparently a western, faux-Chinese expression but to my mind that only makes it more apposite, in an ironic sort of way; for the times they are certainly interesting. Events over the last few months have thrown the energy trilemma — climate change, energy security, and fuel poverty — into a relief sharper than ever. This hattrick of inter-related issues has of course been growing in severity for a long time, but the invasion of Ukraine seems to have upped the ante very rapidly.

the surface of the myriad, interconnected issues influencing our energy supply, none the less we must ask ourselves what should we do about it? How can we meaningfully address the energy trilemma? The right wing in the UK would have us frack our way out of the problem, which certainly wouldn’t mitigate climate change, and may or may not reduce prices. I would be surprised if the price of petrol and diesel reduces to pre-invasion levels in the future, after the public have adapted to the increased price, and the

Or is it that a nice big infrastructure project is just a lot simpler both to sell and to deliver than 25 million retrofits, and actually taking on Big Housing over new build standards? n

Why has energy efficiency consistently failed to capture the public and political imagination?

What the situation has really reminded us of is the importance of energy security and the financial costs. I was surprised to learn that onethird of the UK’s diesel comes – or rather came – from Russia. We’ve also seen UK petrol and diesel prices shoot up 40 or 50 per cent since the invasion; this comes on top of the increase in retail electricity and gas thanks to the raising of the tariff caps coming into effect on the 1 April (but announced back in February and presumably planned even further back). The bulk of this increase is due to increased wholesale costs. While this has been linked to a lag in supply increase as economies recover from the pandemic, this seems to be a simplistic analysis. The conflict has also reinvigorated tensions over Nord Stream 2, the gas pipeline from Russia to Germany, and thence to the rest of western Europe. One of the motivations for the line was Germany’s decision to close down its nuclear power stations in the aftermath of Fukushima. Despite what you might infer from the lack of coverage, thousands of activists continue to undertake actions under the banners of Extinction Rebellion, Insulate Britain and others, to draw attention to the climate emergency. This short pen portrait doesn’t even scratch

72 | passivehouseplus.co.uk | issue 41

same applies to gas. Why would producers sell the resource they know full well to be finite at less than we have shown we will pay? Boris Johnson has announced plans for up to eight new “home-grown” nuclear power stations, which might be relatively low carbon but come with a host of other issues, least of all that it will take 30 years to bring them online. And the “homegrown” slogan is laughable even by his standards – we have no uranium for one thing, and for another Hinkley C that is funded by China and being built by France. There is of course another way, and given the publication you’ve probably been wondering when I’ll get around to the punchline – simply using a lot less energy can of course address all of these matters in one fell swoop, with a raft of co-benefits to boot. What I can’t understand is why energy efficiency is always the bridesmaid and never the bride. It’s not the only thing we need to do of course, but why is it that this issue has consistently failed to capture the public and political imagination? Is it obscure but powerful vested interests opposing any ideas about less consumption of anything? Or a banal vanity that means we crave the shiny new high-tech silver bullet?

Toby Cambray is a founding director at Greengauge and leads the building physics team. He is an engineer intrigued by how buildings work and how they fail, and uses a variety of methods to understand these processes.

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EMBODIED CARBON CALCULATIONS DATA SHEETS ecodan.me.uk/tm65

DATA

QUHZ-W40VA CIBSE TM65 Embodied Carbon Mid-level Calculation Including Operational Carbon Benchmark Estimate Assessment date:

29th of September 2021

Assessor:

Residential Product Marketing

Organisation:

Mitsubishi Electric

Contact:

embodied.carbon@meuk.mee.com

Embodied Carbon Result with 'Mid-level TM65 Calculation' Method:

618 (kg CO e) 2

Operational Carbon Result:

3,756 (kg CO e) 2

Total = 4,374 (kg CO e) 2

TM65 Embodied Carbon Results with Refrigerant Leakage (kg CO₂e)

Operational Carbon Estimate (kg CO₂e)

Potential carbon savings vs a gas boiler

5,000

10,000

15,000

20,000

25,000

30,000

35,000

Operational carbon data for heating requirements, according to heat pump ErP ﬁche at medium temperature (55ºC), average climate conditions and equivalent boiler heat output. (Does not include thermal store data). Gas boiler assumptions: embodied carbon of 300kg CO2e, efﬁciency of 93%, service life of 15 years. Carbon factors sources: Electrical grid according to Greenbook forecast for residential use. (source: gov.uk, IAG spreadsheet toolkit for valuing changes in greenhouse gas emissions, sheet conversion CO₂). Gas network according to SAP 10.1 carbon emissions factor (source: BRE Group, SAP-10.1-01-10-2019, Page 171).

QUHZ-W40VA - Product Information Type of product

A2W Heat pump

Capacity of equipment (kW)

Product weight (kg)

55.85

Material breakdown for at least 95% of the product weight? (Y/N)

Service life of the product (years)

Type of refrigerant

R744

Refrigerant GWP

Refrigerant charge (kg)

1.15

Energy consumption of the factory per unit of product (kWh)

14.08

Location of manufacture

Asia

Product Complexity

Category 3: High

ecodan.co.uk

Passive House Plus (Sustainable building) issue 41 UK

Articles inside

The world energy crisis