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
TIMBER IN BUILDING Balancing ecology and construction
RIBA Climate Challenge 3 projects assessed against 2030 targets
Onwards & upwards
Deep retrofit & extension, inspired by Victorian villas
Decarbonising heating Why fabric efficiency is essential
Issue 39 £5.95 UK EDITION
SLUMBERJACK Oak frame passive B&B opens its doors
EDITOR’S LETTER
PASSIVE HOUSE+
SAME HOUSE, DIFFERENT HOME.
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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
Pat Barry Irish Green Building Council Toby Cambray Greengauge Building Energy Consultants Guy Fowler Advanced Housing Systems Peter Nickels architect Marc Ó Riain doctor of architecture Peter Rickaby energy & sustainability consultant Andy Simmonds AECB David W Smith journalist Jason Walsh journalist
editor’s letter ISSUE 39
W
ith COP26 looming large, a thought about climate change occurred to me recently: this is an issue that is never going to go away. Climate change has already moved from the margins to become a permanent feature of the news media, and the sad truth is that, as the climate emergency continues to worsen, it is bound to become an increasingly prominent aspect in all of our lives, whether we like it or not, for the rest of our lives, for the rest of our children’s lives, and on and on. The prospect is exhausting, but if we accept this truth, it can spark an epiphany in us. We will never escape this issue, but if we face it head on, and with urgency, we still have a chance to determine the extent to which it dominates our future. Delaying and accepting compromises that achieve some progress at a rate that balances inconvenience against ambition is frankly not good enough. There is a need for urgent, radical action, from government policy to the business world, right down to the decisions we take as individuals. I understand and accept the arguments that the vast majority of emissions are caused by a small number of extraordinarily polluting companies, and that the attempt to focus on individual responsibility has been a clever yet extremely cynical distraction tactic. But our actions as individuals can force the change we need – be it in terms of demanding our politicians regulate pollution far more seriously and punitively than has been the case up until now, or in terms of making profound changes in how we make a living, and how we live our lives. Ultimately, this will also mean taking
decisions which go against all conventional wisdom, in that they will cause declines in economic activity. Curiously, this seemingly intractable problem may not present itself in the short term. This is because we must invest heavily – albeit wisely, and in a way that minimise upfront emissions – in measures that will realign our civilisation on the lowest carbon trajectory possible. A perfect example is building a passive house, if we have first identified that we must build, rather than retrofit, and ensured that we build it to the size we need, in the right location, and using the lowest carbon materials possible. In so doing, we are investing in creating a climate action asset that will, with any luck, prevent emissions from occurring for multiple generations. This is infinitely preferable to approaches which rely on the decarbonisation of heat, for the simple reason that even decarbonised heat has to be paid for, and that earning money to pay for this heat will likely involve emitting carbon too. The deeply ingrained habits, dependencies, conventions and behaviour patterns that we have historically been unwilling or unable to detach from need to stop. The issue is never going to go away. Face up to the problem fully now, and we avoid consigning ourselves to a future plagued by constant reminders that we did not do enough, or that we did not set examples for others to follow. The future of the planet may not be clear, but our conscience can be. Regards, The editor
GPS Colour Graphics www.gpscolour.co.uk | +44 (0) 28 9070 2020
Cover
Malvern Oak Frame B&B Photo by Mark Bolton
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
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INTERNATIONAL This issue features a passive house hostel situated in the town of Zegama, on the route of the Camino de Santiago.
NEWS Architects call for urgent climate action ahead of COP26, Passive House Plus to launch Building Performance Annual, and a new study confirms “systematic inequalities” in indoor air pollution.
COMMENT Dr Marc Ó Riain looks back at the Saskatchewan House from 1977, which established the principle of prioritising energy demand reduction; Dr Peter Rickaby investigates what options are available to decarbonise heating; Pat Barry of the Irish Green Building Council on why we urgently need smart and circular design that allows us to build with fewer raw materials; and Guy Fowler asks if, after 30 years, the passive house standard has been a success or not.
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CASE STUDIES Heart of oak
A striking new oak-framed passive house in an area of outstanding natural beauty in the English countryside has just opened its doors to the public, and already there has been a flood of guests seeking to experience life in a passive house.
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Onwards and upwards
This Enerphit project in the suburbs of South Dublin has dramatically transformed and extended a dated 1970s dwelling by adding an extra storey, radically reducing its energy consumption and creating a smartly-designed, light filled family home and office.
Seeing the wood for the trees:
Placing ecology at the heart of construction In recent years, as energy efficiency targets for new buildings have tightened, attention has turned to cutting the embodied carbon of buildings. But if we are serious about solving the ecological emergency as well as stabilising the climate, we must look even further than embodied carbon, and think more deeply about the core values we apply to materials and buildings.
Witness the phitness
Hampshire house hits 70% energy saving via Enerphit The deep retrofit of this 1930s dwelling on the Hampshire coast provides a pitch perfect example of how to transform old dwellings while preserving their original structure and minimising embodied carbon, utterly transforming the living space without the need for an extension, and creating a cosy home that uses two-thirds less energy than before.
INSIGHT
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MARKETPLACE Keep up with the latest developments from some of the leading companies in sustainable building, including new product innovations, project updates and more. How do breather membranes work? How do underlays manage to let water vapour through while keeping the rain out? Toby Cambray delves into the physics…
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IN BRIEF Building: 95 m2 hostel Location: Zegama, Basque Country Building method: CLT with wood fibre insulation Standard: Passive House Classic
INTERNATIONAL PASSI VE & ECO BUIL D S F R O M A R O U N D TH E WO R LD
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I N T E R N AT I O N A L
BASQUE COUNTRY
Photos by Jorge Allende
PILGRIM’S HOUSE, BASQUE COUNTRY
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uilt on the route of the Camino de Santiago in the interior of the Basque Country, this simple and elegant hostel in the town of Zegama was built to accommodate 12 pilgrims. It was commissioned by the local town council, which had two key stipulations: that the finished building had to meet the passive house standard, and that because it was going to sit beside the town’s timber museum, it had to be constructed from wood. The town of Zegama sits among the forested hills of the Basque Country, and the hostel itself sits right at the entrance to Aizkorri-Aratz Natural Park, which is known for its endless beech woods. Designed by architects Natxo Ibarretxe and Iñaki del Prim, the finished hostel is a lesson in spare-but-smart design. The careful orientation of the building, the modestly sized glazing, and the deep-set windows meant no additional shading was needed externally on the south-west façade. The size of the north-east elevation, meanwhile, was minimised to prevent heat loss to cold winds in the autumn
and winter. Inside, the internal layer of OSB board was left exposed, creating a simple-yet-warm detail that eliminated the need for extra wall finishes. The finished hostel features two communal bedrooms, with six bunks each, plus a simple living and dining space, an adjoining kitchen, and two bathrooms. It was primarily constructed with a cross-laminated timber system that was sourced and manufactured locally, while wood fibre was used as the main insulation material, and the hostel is externally clad with timber too. Meanwhile, the building’s heat pump and underfloor pipework can provide active cooling, should it be needed in summer when the building is fully occupied (the building’s peak cooling load of 10 W/m2 is almost equal to its heating load of 11 W/m2). All-in-all the simple palette of materials, beautiful detailing and guarantee of passive house comfort at the Casa Del Peregrino makes us want to visit almost as much as the forests and hills outside do.
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BASQUE COUNTRY
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
8 | passivehouseplus.co.uk | issue 39
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NEWS
PASSIVE HOUSE+
NEWS
(above) A selection of the 14 winners from this year's Passive House Awards. For the full list see www.passivehouse-international.org.
Passive house celebrates 30th birthday at international conference
T
he Passive House Institute celebrated the low energy standard’s 30th birthday at the 25th International Passive House Conference in September. Around seven hundred participants registered for the conference, which mostly took place online due to Covid. Addressing the conference, Diana Ürge-Vorsatz of the UN's Intergovernmental Panel on Climate Change (IPCC) warned that more frequent extreme weather events could be expected as a result of climate change, and that CO2 emissions must be reduced to net zero. She also called for the transformation of every building, using solar PV systems, into a mini power plant. "We cannot wait any longer. The next two decades will be decisive for seeing how the climate affects humans in the next two hundred years," she said. Meanwhile in his speech, the director of Germany’s Federal Environmental Agency, Dirk Messner, emphasised the social benefits of building to the passive house standard — namely, that energy efficient construction and renovation offers a high level of living comfort for building occupants. "Let us build houses and districts which are good for the people," he said.
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Uwe Schneidewind, lord mayor of the German city Wuppertal, told the conference that the city wished to become “climate neutral” by 2035, and that the passive house standard represented a critical way of achieving this goal. During the four days of the conference, more than one hundred speakers presented diverse ways in which energy efficient construction and refurbishment have been applied to buildings across the globe. Ecological building materials, social housing, summer comfort and ventilation concepts were also discussed in detail in separate lecture sessions. During the conference, the Passive House Institute also launched the German language version of PHPP 10, and announced that the English version will be released next spring. New features to the software include a stress test for summer comfort, and the ability to compare calculated energy use with measured consumption data. Award winners revealed Two UK projects that have featured in Passive House Plus were among the winners at this year’s global Passive House Awards, which were presented at the conference. Lark Rise passive house in Buckingham-
shire, designed by bere:architects, won in the single-family home category. The house was previously featured in issue 36 of this magazine. It is certified to the passive house plus standard, and is designed to have extremely low energy consumption and to meet the majority of its own energy needs via a large solar photovoltaic array and battery. Meanwhile the retrofit of two semi-detached Victorian dwellings in Manchester to the Enerphit Plus standard, by passive house consultancy Ecospheric, won in the special “living comfort” category. The project was featured in issue 28 of Passive House Plus. Twelve other award winners were announced at the event (see photo panel), and the full list of recipients is available at www.passivehouse-international.org. "Buildings constructed to the passive house standard require much less energy and significantly lower emissions are produced over their life-cycle,” said Jan Steiger of the Passive House Institute on presenting the awards. “All winners are a perfect example of how an extremely sustainable building standard can be implemented with a high architectural quality and in completely diverse ways.” •
PASSIVE HOUSE+
NEWS
Architects call for urgent climate action ahead of COP 26 A
head of the Built Environment Summit (28-29 October) and COP26 (1-12 November), the Royal Institute of British Architects (RIBA) and Architects Declare have published a report demonstrating the critical role the sector must play in reducing greenhouse gas emissions. ‘Built for the Environment’ brings together research and evidence from industry experts to prompt the built environment sector to scale-up its capabilities, and sets out bold recommendations to governments ahead of COP26. These range from reporting emissions on a consumption basis to adapting building codes that support the decarbonisation of buildings. RIBA and Architects Declare are encouraging organisations from across the global built environment sector to endorse the report and its recommendations, which calls for:
where we require change, particularly within challenging political landscapes and inadequate policies. Industry and governments need to work together to accelerate the global decarbonisation of buildings. I encourage the entire sector to endorse and amplify the report’s recommendations – we must speak with one voice to deliver a clear and urgent message.” Maria Smith, director of sustainability at Buro Happold and editor of the report, said: “This report is a call for governments across the world to include built environment actions in their net zero plans. The built environment sector can be a transformative force in meeting the challenges of the climate and biodiversity emergency. The knowledge, tools, and skills exist, but support and infrastructure is needed to mainstream best practice and bring about the transition to a fair and sustainable built environment for all.” The report can be downloaded from www.architecture.com. •
• G overnments to ensure environmental targets are science-based and fair – this means reporting greenhouse gas emissions on a consumption-basis, and including built environment actions and all sources of emissions within net zero plans (including nationally determined contributions). • G overnments to shift focus onto reducing absolute emissions, as opposed to reductions per square metre of building area, or per person. Greenwashing or reliance on large offsets will not help us meet our collective goals. • G overnments must both mitigate and adapt to the climate and biodiversity emergencies. Nature-based solutions and traditional ecological knowledge, wisdom and technologies are central to both. • Th ose operating within the built environment to actively adapt practice. From breaking down silos between disciplines and competencies, to communicating and sharing information, to shifting cultural ideas of beauty and design, the entire sector must adapt. • I nformation to be openly and widely shared to enable collaboration and transparent decision-making. This includes information around land, buildings, ecosystems, and infrastructure, as well as knowledge and skills. • S ocial justice to remain at the heart of all action. This means involving those impacted by change in decision-making, and together designing social policies to facilitate a transition to a fair and sustainable built environment, taking steps to ensure unintended negative consequences are addressed quickly and fairly.
Built for the environment Addressing the climate and biodiversity emergency with a fair and sustainable built environment
The report comes ahead of Architects Declare and RIBA’s Built Environment Summit – a two-day virtual conference on 28 and 29 October – that will provide an opportunity for the sector to unite ahead of COP26. RIBA President, Simon Allford, said: “As we approach COP26 and the critical juncture to limit global warming to below 2 C, we must unite as a sector to drive change. “This timely report emphasises the critical role our professions can and must play to tackle the climate emergency, and clearly states
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NEWS
PASSIVE HOUSE+
COP26 house to showcase fabric first, low carbon build methods
The COP26 House wall build up features 1) 22 mm timber boarding internally; 2) on battens with 40 mm Steicoflex insulation; 3) on 12 mm Medite Propassiv boards; 4) on timber studs with 140 mm Steicoflex insulation; 5) on 80 mm Steico Special Dry boards; 6) on Steico UDB breather membrane; 7) on 30 mm battens 8) and 30 mm counter battens; 9) on timber cladding.
A
new demonstration house currently being erected in Glasgow in advance of this year’s COP26 climate conference will showcase build systems and methods for achieving zero carbon housing to the world. The timber frame house is being constructed by Beyond Zero Homes, a coalition of organisations aiming to demonstrate how “beautiful, affordable, healthy and comfortable homes can be developed with minimal impact on the environment, throughout their lifecycle”. The group is led by architect Peter Smith of Roderick James Architects, and includes leading manufacturers and suppliers in the sustainable building sector such as Ecomerchant, Medite SmartPly, NorDan, Steico, Fakro, and Paul Heat Recovery Scotland, as well as Home Grown Homes, the forestry company BSW, and contractor Robertson. After COP26, the house will be dismantled into its original 1.2 metre-wide panels and be transported in its entirety to its new home near Aviemore, where it will form one of a scheme of 12 affordable houses. The 65 square metre house has been designed to minimise embodied carbon, using local timber and natural, sustainable materials. According to a provisional life cycle analysis carried out by Circular Ecology, the house has an embodied carbon of 374.4 kg of carbon dioxide equivalent per square metre (kgCO2e/m2) during building life cycle stages A1 to A5 (raw material supply through to construction), but sequesters more than double that amount (815.2 kgCO2e/m2)
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in wood-based products during the same period. This carbon will be kept out of the atmosphere so long as these wood products remain used in this or any other structure into future. For life cycle stages A1 to A5, B4 (refurbishment) and C1 to C4 (end of life), the total embodied carbon is 515 kg/m2/yr, well inside the RIBA 2030 Challenge target of 625 kg/m2/yr (though the RIBA challenge also includes other B stages). For a small, detached house, especially with a double height space, achieving the RIBA operational energy target of 35 kWh/m2/year has been more of a challenge. “Whilst the RIBA target is extremely difficult to achieve for this particular house design, we like a challenge and are investigating a variety of different ways of heating the building to ensure we meet the target,” said architect Peter Smith. “For larger houses using this same build system, the target is significantly easier to achieve.” The house, which was largely built off-site, was specifically designed to use homegrown C16 spruce to avoid the need for imported timber. The timber frame walls also feature SmartPly Propassiv, an airtight OSB certified by the Passive House Institute, as well as Steico wood fibre insulation both externally and between the studs. “We have made conscious, informed choices about every material in the house to minimise embodied carbon,” said architect Peter Smith. “In particular, responsibly sourced timber and natural materials are used as much as possible in the structure, with
reduced reliance on concrete and steel.” He added: “All timber elements, which make up the vast majority of the structure, can be re-used or recycled at end of life, as the house has been designed to be easily dismantled.” All fittings, external cladding, and windows have been screwed in place rather than nailed or glued so that everything can be easily removed, repaired or replaced. While not aiming to achieve the passive house standard, passive house design principles have been applied, including an airtightness target of 0.6 air changes per hour, minimisation of thermal bridging, and heat recovery ventilation. Walls, roof, and floor are designed to U-values of 0.13 to 0.14. The house has a space heating demand of approximately 25 kWh/m2 per year, with this demand provided by an infrared heating system. Meanwhile all windows are triple glazed, and while there is plentiful glazing, the use of large roof overhangs and eaves were designed to avoid overheating. In addition, the wood fibre provides protection from temperature peaks due to the combination of low thermal conductivity, high specific heat capacity and high density. “Here is one example of a building that exceeds our 2030 targets for embodied carbon and dramatically reduces operating energy compared to current benchmarks, using existing products, existing suppliers and existing skills. It shows just what we can achieve with new build right now,” said Will Kirkman of project sponsor Ecomerchant. •
Specify responsibly
PASSIVE HOUSE+
NEWS
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NEWS
PASSIVE HOUSE+
Study confirms “systematic inequalities” in indoor air pollution By Kate de Selincourt
A
new analysis of the exposure of London households to indoor pollutants highlights “systematic inequalities” in exposure, overwhelmingly driven by factors beyond the control of those people worst affected.i The researchers from UCL in London, and Public Health England, investigated the socio-economic distribution of a wide range of factors that worsen the risk of poor air quality at home. Analysis of the available literature and datasets demonstrated that the great majority of these risk factors were worse for people in worse socioeconomic positions. In contrast to the suggestions that people need more information or education to address poor indoor air quality (IAQ), the study found the inequalities were “structural,” i.e., built into the geography of the neighbourhoods and the construction of the homes that people occupy. The low-income households worst affected are least likely to be able to make changes that would improve the situation, the study found. They usually cannot afford to move, often cannot afford to repair or replace appliances, and are more likely to be tenants and therefore dependent on landlord co-operation for remediation and repairs. The team explored five factors that are known to affect exposure to indoor pollution: location and ambient outdoor levels of pollution; housing characteristics, including ventilation properties and internal sources of pollution; occupant behaviours; time spent indoors; and underlying health conditions. The team focused on three pollutants known to have serious impacts on health and life expectancy: PM2.5, nitrogen oxides (NOx) and carbon monoxide (CO). Modelling was carried out to investigate the likely impact of combined factors such as airtightness, and indoor and outdoor air pollution. For almost all the variables examined, factors that would increase exposure to, or harm from, indoor pollution were more common or more severe for populations with lower socioeconomic status. While a few factors (such as combustion of solid fuels and gas within the home) trended the other way, overall, the gradients of risk overwhelmingly advantaged more privileged households and neighbourhoods over those with lower incomes. Thus, low-income households tend to have
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more people living in a smaller space. This is strongly linked to poorer indoor air quality, the researchers say. “Given an indoor source emitting air pollutants at a certain rate, a smaller volume will reach higher concentrations faster than the equivalent source for a larger volume,” the research says. This is compounded by the higher risk that the ventilation is broken. “The EHS indicates that action is required to repair extractor fans in the lowest... income group in 57.5 per cent of houses versus only 7.7 per cent in the highest,” the paper concludes. Low-income households typically occupy more airtight buildings, and homes with more adjoining dwellings. While this may reduce the amount of outdoor pollution entering, modelling by the team showed this is outweighed by the increased build-up of pollution from indoor activities such as cooking, laundry drying, etc. On top of that, in homes with more adjoining dwellings, there is much higher risk of ingress of pollution from neighbours, either directly through poorly sealed walls or floors/ceilings, from communal circulation, or from neighbouring windows. One of the commonest and most concerning “shared” pollutants is tobacco smoke. The more people you share a wall with, the higher the risk that at least one of them will be a smoker. And if you are in a low socioeconomic status neighbourhood, your neighbours are much more likely to smoke. “In 2018, 25.5 per cent of those in routine and manual occupations smoked compared with... 10.2 per cent of those in managerial and professional occupations,” the researchers found. This concern is backed by research by Dr Jenny Brierly at the University of Sheffield, who found neighbours’ smoke – including, often, cannabis smoke — is a concern for many social tenants.ii Even when ventilation is available, people may not always be comfortable using it. Fuel poverty, outdoor pollution (e.g., roads, or people smoking on the doorstep), security concerns and noise all make it less pleasant to open vents and windows. The researchers cite a study showing that window-opening behaviours between households of different socioeconomic status may drive inequalities in carbon monoxide poisoning. Outdoor air quality The study also added to the growing body
of research showing how severely unequal outdoor air quality is. Analysis combining data on socioeconomic status and air quality records showed that PM2.5 levels are higher in lower-income neighbourhoods. Even more striking is the gradient in proximity to HGV routes: diesel combustion is the largest source of oxides of nitrogen (NOx), which are known asthma triggers. The study also found that the lower your income, the less able you are to make changes that would improve air quality at home. Low-income households in the UK are more likely to be tenants, and thus depend on a landlord for repairs that would improve IAQ, for example to boilers or ventilation. They are also less likely to be able to afford to move to a quieter, safer neighbourhood farther from major roads and with fewer very close neighbours, as these will generally be financially out of reach (especially once travel costs are considered). To reduce IAQ-driven health inequalities, it is essential to cut outdoor air pollution and improve the outdoor environment, the authors say. But buildings must be improved too. “Policies aimed at ensuring all housing has sufficient ventilation, and that mechanical ventilation is maintained and operational, would significantly reduce indoor air pollution exposures. Increased compartmentalisation between flats would help to reduce air pollution entering from adjoining dwellings.” The government should put pressure on landlords to fix the problems the tenants have no control over, the authors say. “National housing policies that require the improvement of social and privately rented properties will benefit low-income individuals who are more likely to occupy these tenures.” • i S ystemic inequalities in indoor air pollution exposure in London, Ferguson et al, Buildings and Cities 2021 ii D r Jenny Brierly, University of Sheffield, Doctoral Thesis
“Ensuring sufficient ventilation, and that mechanical ventilation is maintained and operational, would significantly reduce indoor air pollution exposures.”
PASSIVE HOUSE+
NEWS
Oil heating sector pivots to biofuels, but green groups raise concern By Lenny Antonelli
T
he UK and Ireland’s oil heating industry says it has taken a “major step forward” in the use of biofuels in domestic oil boilers, with early tests concluding that hydrotreated vegetable oil (HVO) works in virtually all existing oil boilers. A statement from industry bodies OFTEC and UKIFDA said a switch from kerosene to HVO could reduce carbon emissions from oil boilers by almost 90 per cent, but green groups raised concern about the true carbon footprint of common HVO fuels. “Nineteen sites… are now running hydrotreated vegetable oil (HVO) in a range of heating and cooking appliances in both domestic and commercial settings,” read the statement from OFTEC & UKIFDA. “Each HVO installation is monitored regularly, and, to date, the systems have performed well with no significant issues reported.” OFTEC CEO Paul Rose said that the “initial trial results are highly encouraging and add further evidence to our belief that HVO offers oil heated households an attractive, low cost, low disruption solution to decarbonisation.” The group said that oil boilers can be converted to run HVO for a cost of around £500. HVO is a liquid biofuel that can be produced from a variety of bio-based feedstocks, so the sustainability and carbon footprint of each must be assessed individually. Crown Oil, which supplied the HVO for the boiler trialsi, said the fuel it imports is “100 per cent used cooking oil based”. It is also certified by the International Sustainability & Carbon Certification. OFTEC told Passive House Plus that its carbon savings figure was produced by the BRE, which calculated a carbon emissions factor of 36 g of CO2 equivalent per kilowatt hour for waste-derived HVO, compared to 298 g for kerosene. Globally, HVO feedstocks can include virgin vegetable oils such as palm, soy, and rapeseed oil, but proponents say that a move to “advanced” waste feedstocks now make the fuel more sustainable. Virgin oils have been heavily linked with deforestation in the tropics, and rising food prices. “Waste and residue” feedstocks can include used cooking oil, by-products of vegetable oil processing, and fatty wastes from animal industries, but environmental NGOs question whether there is enough supply of genuine waste feedstocks to meet demand. “The challenge with advanced feedstocks is that either there are not enough of them, or they are not genuinely advanced. The aviation,
road transport and chemical sectors are all competing for advanced feedstocks, of which there are a limited and potentially decreasing supply,” said Andrew Murphy of the Brusselsbased NGO Transport & Environment (T&E). Advanced or not? The Finnish oil refining company Neste, the world’s largest producer of HVO, says its fuel is based on 92 per cent “waste and residues”, and that it is aiming for 100 per cent by 2025 (the French company Total Oil, another major manufacturer of HVO, says it typically achieves 30 to 40 per cent waste and residues at its La Mède biorefinery in France, with the rest coming from vegetable oils like sunflower, palm and rapeseed). Neste also says that in the “medium to longer term” it is aiming to develop advanced feedstocks from plastic waste, forestry and farm residues, municipal solid waste, and from the cultivation of algae. But environmental NGOs question whether some of the key waste feedstocks typically used for HVO warrant that definition. One such feedstock is palm fatty acid distillate (PFAD), a by-product of palm oil refining. While proponents say it is a legitimate waste product, critics say that demand for PFAD can also drive deforestation. A 2017 studyii funded by the International Council for Clean Transportation concluded that, “PFAD based biofuels are likely to have a higher net climate impact than the fossil diesel they would replace”, due to indirect land use change — that is, demand for PFAD diverting the material from other sectors and stimulating demand for virgin palm oil, leading to deforestation. Meanwhile, recent research commissioned by T&E concluded that demand for used cooking oil (UCO) across the EU could double within a decade to meet renewable energy targets. It warned this would increase UCO imports from palm-producing countries like Indonesia and Malaysia. “Countries that would use UCO for animal feed and other products may end up exporting theirs while using cheap oil, like palm, at home,” said Cristina Mestre, biofuels manager at T&E. It also warned that this increase in demand could incentivise fraud (the mixing of virgin oils into used cooking oils). The European Waste-to-Advanced Biofuels Association says that used cooking oil is “one of the most highly regulated commodities in the
world” and that it is covered by “[c]omplete traceability” through its value chainiii. Green groups, however, say existing biofuel auditing and verification mechanisms are not effective. “We are deeply concerned that HVO is being used and promoted in ever more sectors, from aviation fuels to cars and now as a heating fuel, too,” said Almuth Ernsting of the NGO Biofuelwatch. “While a limited amount of HVO can be made from genuine waste products such as used cooking oil, such waste products are in very short supply and come nowhere near meeting current HVO demand… EU and UK biofuel sustainability and greenhouse gas standards still permit biofuels from palm oil and soy to count towards renewable energy targets, and they are based on a flawed greenhouse gas methodology which ignores the greatest source of emissions – indirect land use change.” The EU is aiming to phase out the use of virgin palm oil by 2030, but this will not include palm by-products like PFAD. Easier than retrofit The oil heating industry sees HVO as a way of meeting decarbonisation targets faster, and without the complex logistical and financial challenge of deep retrofit. OFTEC is calling for the British and Irish governments to remove duty on HVO to stimulate uptake, to include HVO-fuelled heating systems in home energy grants, and to remove trade barriers to the import of these fuels if they meet sustainability requirements. “There is a clear and robust system of checks to ensure that all HVO imported into the UK is renewable and sustainable,” an OFTEC spokesperson wrote to Passive House Plus. He said that this was via a 'proof of sustainability' (POS) statement that is instigated at raw material collection point and which transfers through the supply chain. •
i Crown asked us to clarify that the fuel was supplied at a higher rate as Road Transport Fuel Certificates cannot be claimed for applications such as heat generation. ii 'Waste not want not: Understanding the greenhouse gas implications of diverting waste and residual materials to biofuel production', Dr Chris Malians, Cerulogy, 2017 iii Used Cooking Oil biodiesel: best in class to decarbonise road transport', Euractiv.com, 29 Oct 2019
ph+ | news | 17
DR MARC Ó RIAIN
COLUMN
The Saskatchewan House, 1977 In his latest column on the history of low energy building during the 20th century, Dr Marc Ó Riain looks back at the Saskatchewan House, which was built in Canada in 1977, and established the principle of prioritising energy demand reduction over active systems.
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e have all probably heard the saying that a dollar spent on energy conservation is equivalent to ten dollars spent on energy generation, in terms of real energy saved. It is the basis for the principle of ‘passive first’, supplemented by active technologies. As low energy building technology developed in the late 1970s and early 1980s, this was a finding that was starting to dawn on many researchers, and nowhere more so than at Saskatchewan House in Canada in 1977. The Philips House (Aachen 1974), the
It acted as an exemplar, with thousands of people visiting monthly. first Zero Energy House (Copenhagen 1975) and Lo-Cal House (Illinois 1975) were all driven initially by interest in active systems like heat pumps or seasonal thermal storage tanks. The insulation of these buildings would have been to improve the efficiency and performance of the active equipment within a test building. Designers attempted to reduce fabric heat loss by passive means to make the heat pumps and other technologies viable. Harold Orr and a team of researchers, which included William Shurcliff, Dave Eyre, Bob Besant and Rob Dumont, were interested in heat exchange technology and solar thermal collectors in their 1977 Saskatchewan project. By focusing on energy conservation or passive aspects first, Orr and the team realised that “conservation is much less expensive than solar. For every dollar we spent on reducing heat loss from the house, with a better air barrier and more insulation, we saved at least $10 on the size of solar collectors and equipment needed to achieve the same thing” (Orr 2013). Using this principle, they super insulated
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their house against winter night temperatures of -24 C. The climate of Saskatchewan had very small solar gains in the winter months and the researchers decided to optimise the angle of the 17.9 m2 array of solar collectors on the facade, creating a skewed and unique form. This form and building typology developed from first principles rather than aesthetics, a low energy house from the ground up, form following function! It was a low energy solar-heated residential structure, which acted as an exemplar, with thousands of people visiting it monthly. It was designed with wall insulation specified at six times the concurrent standard, triple glazed windows, no basement and a very tight air envelope supported by an active heat exchanger. Unlike the Copenhagen House, the researchers rejected seasonal heat storage tanks due to the potential for heat loss. By removing the basement and suspending the ground floor above the soil they could effectively mitigate 80 per cent of downwards heat loss. Orr believed that greater demand-side space heating savings could be made by "reducing air leakage by 80%; we would have a 64% reduction in heat loss without touching the windows and doors, walls, and ceiling. If we use 6 times as much insulation in the walls and ceiling and use much better windows and doors, we would be down to a total heat loss that is about 20% of the heat loss of a conventional house”, and the remaining demand could be met with renewable solar and heat exchangers. He also found that building a double wall was cheaper than cross-battening the interior of the external wall, and that blown mineral fibre was much cheaper than rigid insulation, having identified the potential to locate the vapour barrier on the outside of the internal wall, and thus avoid potential services clashes. The construction achieved 0.8 air changes per hour at 50 Pascals. The house layout, with the living accommodations and most windows facing south, and utility accom-
modations to the north, plus shading devices, heat exchanger and super-insulation, would influence Wolfgang Feist’s principles of passive house in 1988. Feist said: “At the time we knew about other similar buildings —buildings made by William Shurcliff and Harold Orr —and we relied on these ideas” (Holladay 2015). Although these early documented exemplars of low energy housing and retrofit were all residential applications, they established energy conservation and demand reduction as the first principles of low energy design. n
Photo: © Harold Orr
Sketch: © Marc Ó Riain 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
COLUMN
How will we decarbonise heating? Insulating our homes is critical and must be our first priority, but how do we get the rest of the way to zero carbon? Dr Peter Rickaby investigates the options…
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e are committed to ‘net zero carbon’ by 2050. The use of fossil fuels for space and water heating, and for cooking, will not be permissible. There has been much promotion of decarbonisation options, but it is important to distinguish opportunities from myths. It is also important that we are not distracted by questions to which reliable answers will not be known for some time. Instead, we should be making progress in a ‘no regrets’ direction, while keeping options open. Questions to which the answers are not yet known include: • W hat will the emissions factor for electricity be in 2050? • H ow would local electricity networks cope with the electrification of heat? • What will the penetration of heat networks be? • To what extent will hydrogen be available via the gas network? • What will be the characteristics and costs of battery packs? • H ow might ‘smart homes’ technology help match supply and demand? We do know that demand reduction is an essential feature of all options. The no regrets
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strategy is therefore: 1 I mprove the building fabric to reduce heat demand. 2 Improve the building services to satisfy the remaining demand efficiently, and remove fossil fuel appliances. 3 Top-up performance to zero carbon when more is known about the residual emissions from electricity, and about other options. This approach gives us a little time to deliver stage one, while working out the answers to the questions above so we can decarbonise heat at stage two. If grid electricity is not completely decarbonised, stage three may involve local renewable energy systems and storage. However, Lowe and Oreszczyn (2020) point out that a convex trajectory to zero carbon may involve twice the emissions between now and 2050 than are associated with a concave trajectory in which early progress is made, so there is a case for prioritising decarbonisation as well as reducing demand (see diagram below). In the average UK dwelling, 87 per cent of energy use is for space heating, hot water and
cooking. Homes use nearly four times as much energy in the form of heat as in the form of power. The most frequently discussed option for decarbonising heat is to ‘electrify’ it, i.e., change to appliances such as heat pumps. This does not at present deliver decarbonisation: the emissions factor for electricity is similar to that for gas. However, progress is being made towards the decarbonisation of electricity by replacing fossil-fuelled generation with renewable systems such as wind power. Currently, the cheapest source of electricity supplied to the grid is offshore wind. If we convert all heat demand to electricity demand, we will need the equivalent of nearly thirty times as much wind power supplying the grid as we have now. If we use heat pumps with an average CoP of 2.5 we will still need the equivalent of twelve times as much wind power. If we adopt the ‘fabric first’ approach described above and reduce demand by 60 per cent, we should be able to reduce the factor from twelve to four. This emphasises how important demand-reduction via retrofit is to decarbonisation. Another problem is that local electricity distribution networks do not have sufficient capacity to cope with a four-fold increase in demand. This is exacerbated by the transition to electric vehicles, which may increase demand by a further factor of three. This emphasises
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(above) Sketch of concave and convex carbon dioxide emissions reduction trajectories (source: Lowe and Oreszczyn 2020).
the importance of ‘smart’ demand management and the potentially transformative effect of local energy storage smoothing out the supply-demand mismatch. Electrifying heat is not a decarbonisation panacea, but it has a contribution to make, enabled by retrofit. Where we do it, there are technical considerations. Heat pumps supply heat at a relatively low temperature: typically, between 40 C and 50 C, therefore, for heat
Using hydrogen for heating makes little sense.
distribution within a home a larger radiator area is needed, or underfloor heating. An air source heat pump will struggle to cope with the demand of a poorly insulated house, especially during a prolonged cold snap; it is therefore essential to reduce demand to a level that the heat pump can satisfy, by improving insulation. Electricity currently costs more than gas, so unless homes are well insulated householders will see their costs rise, and fuel poor households will be disadvantaged. Tariff reform would help to address this: currently in the UK public subsidies are applied to gas, but energy efficiency levies are applied to electricity. This is the reverse of the arrangement we need to promote decarbonisation. Another frequently discussed option is connecting homes to local heat networks. Developing heat networks in urban areas (they are not viable in rural areas) is expensive and disruptive, and the supply has to be matched to demand. Small scale networks for blocks, estates or mixed-use developments have a part to play. If we can establish heat networks, the challenge is to secure zero carbon heat for them to supply. Sources include waste, biomass and hydrogen, but supplies are limited. The potential extent of heat networks is not clear, but networks have a contribution to make by reducing demand on the electric-
ity grid. Where networks are developed, the connection of new developments and retrofit schemes may become mandatory. Much has been claimed about replacing the natural gas that we distribute to our homes with hydrogen. When hydrogen is burned the only combustion product is water, so this is an attractive option. The problem is how to make the hydrogen; there are three methods:
DR PETER RICKABY
other system must also be in place. For cooking, replacing gas-fired hobs with electric hobs is straightforward. However, electric hobs are not as controllable as gas hobs, and electricity is more expensive than gas, so this change may be resisted. Electric induction hobs are more controllable, but they are expensive; prices may fall as demand increases. What can we conclude? Decarbonising heat is not easy, but it is urgent. There are several options, none of which is yet viable as a generic solution, but some of which will have a role to play. For urban areas with zero carbon heat networks, connection is probably the best option. Elsewhere, using electric heat pumps seems a good option, provided we can decarbonise the supply and increase local distribution capacity. Hydrogen heating makes little sense and seems unlikely to become widespread. While these options are being developed, the ‘no regrets’ approach is to focus on insulating our buildings, in order to reduce the demand for heat as much as possible. n Reference Lowe, R. and Oreszczyn, T. (2020) Building decarbonisation transition pathways: initial reflections. CREDS Policy brief 013. Oxford, UK: Centre for Research into Energy Demand Solutions.
• ‘Grey’ hydrogen is manufactured from fossil fuels, with substantial emissions. • ‘Blue’ hydrogen is manufactured the same way but with carbon capture and storage, a technology that has so far proven elusive and expensive. • ‘Green’ hydrogen is made by electrolysing water, so green hydrogen can be zero carbon if the electricity is zero carbon. Essentially this means wind power. The question raised by the green hydrogen option is why would we use electricity from wind to make hydrogen, then send the hydrogen to homes to be burned in 90 per cent efficient boilers, when we could send the electricity to the homes instead and use it in heat pumps at 250 per cent efficiency? Delivering 1.0 joules (J) of heating requires approximately 1.2 J of natural gas, or 1.6 J of electricity to make 1.2 J of green hydrogen; but only 0.4 J of electricity is needed to deliver 1.0 J of heat via a heat pump. Thus, using hydrogen for heating makes little sense, and the emerging role of hydrogen is as an industrial fuel, for large vehicles and for energy storage. Hydrogen heating seems unlikely to become common. Local solar systems have a role to play. Electricity from solar PV can be stored in batteries or used for water heating, or solar thermal systems can be used to make hot water. In both cases the solar systems can raise the tank temperature and reduce the load on the heat pump. In the UK, a solar thermal system can typically supply half of a dwelling’s annual hot water demand with no emissions. However, the solar input is insufficient in winter, so an-
Graph: Centre for Research into Energy Demand Solutions, 2020
(above) Insulating homes, heat pumps, and solar PV can all be part of the mix of solutions towards decarbonising our heating systems.
Dr Peter Rickaby helps to run the UK Centre for Moisture in Buildings and the Building Envelope Research Network at University College London. He is also Technical Director of the Retrofit Academy and chairs the BSI Retrofit Standards Task Group.
ph+ | dr peter rickaby column | 21
PAT B A R R Y
COLUMN
Cutting embodied carbon: doing more with less We won’t be able to reduce the embodied carbon of construction fast enough just by switching to lower carbon materials, says Pat Barry of the Irish Green Building Council, so we urgently need smart design that allows us to build with less, and to create a genuine circular economy for building materials. [Editor’s note: This article was written for our Irish edition. We reprint it here because we think it will prove applicable and beneficial to readers in the UK too.]
I
f everyone on the planet lived like the Irish, we would need 3.1 planets, ahead of the UK who only need 2.6 planets. The recent interest in embodied carbon in construction and climate action is hence welcome. Yet, there is a danger in focusing exclusively on carbon intensity per square metre. The Irish Green Building Council (IGBC), in its submission to the government’s consultation for its revised climate action, pointed out that Ireland will increase levels of home construction from
as possible. Car sharing schemes like GoCar and Yuko demonstrate that a product as a service can also result in major carbon savings for the built environment. According to Berkley university research carried out in North American cities, one shared car could in some cases replace the need for up to 11 other vehicles.i This could allow local authorities to relax minimum car parking rules for new developments, and thus reduce the need for carbon-intensive underground car parks. Not many incremental
In a climate emergency, provision of dedicated parking for a new home is now as daft as providing a chimney. 21,000 to 30,000 a year. Economist Ronan Lyons suggests the figure is closer to 50,000 a year. This will lead to a massive increase in carbon emissions and resource consumption from the construction sector, when the country is supposed to be cutting its emissions by 51 per cent in eight years. In simple terms, embodied carbon equals the carbon intensity of a material multiplied by the quantity of that material. Reductions in the carbon intensity of materials won’t happen fast enough to reach our target, so we also need to focus on quantity. That means housing more people with the least quantity of resources and material use possible. Circular thinking Circularity in construction is one key strategy. The goal is to retain value for as long as possible, through reuse, restoring, regenerating, recycling, circulating and re-manufacturing — and most importantly through co-operation. This encompasses urban planning, buildings, infrastructure and materials. It means breaking the linear make-break-waste model and replacing it with one where we can extract the maximum value from every product for as long
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changes to building regulations can beat the carbon savings of both eliminating the cars and the basement! In a climate emergency, provision of dedicated parking for a new home is now as daft as providing a chimney. Circularity at the urban scale Well-designed villages, towns and neighbourhoods offer the advantages of the circular economy, allowing efficient use of shared space, infrastructure, materials and energy. Densifying existing towns means reusing the same infrastructure more efficiently. A building properly designed and located should last 200 years and the infrastructure even longer. Dublin’s Phoenix Park tunnel was built in 1877 with manual labour, and is now proposed to be repurposed as part of a new metro, saving tens of millions of euros. We lost sight of this over the past 50 years and abandoned living space in our villages and towns often in favour of remote oversized homes, usually built when a household is starting a family. These often have maximum occupancy for only 18 to 20 years and are then largely underutilised. Enabling first-time buyers to refurbish a derelict building in a local town or village
instead would save substantial emissions from embodied carbon and transport, bring towns and villages back to life, and free up scarce construction material and labour. This requires a reversal of traditional financial and government policy, which prioritises the purchase or construction of new homes, to instead incentivise the renovation of underused space. Building in flexibility To extend the life of our buildings, they must be designed to adapt to other uses. This means thinking through floor-to-ceiling heights, location of sanitary services, stairwells, circulation, and floorplate depth, to test whether adaptation to other uses is possible. This can even mean trade-offs in increasing initial carbon emissions to extend the useful life of the building. Design of simple structural grids without obstructions allows better use of space and maximises furniture layouts. Within the Irish Green Building Council’s Home Performance Index certification, indicators for universal design ensure that homes can continue to be used throughout a person’s lifetime even if they are subject to a temporary mobility impairment. Innovation to integrate a range of shared social spaces or shared guest bedrooms and workspaces within housing are also needed. This would allow families to temporarily expand their space as needed, rather than building redundant space into each home. This may mean a move away from standard models of ownership or rental toward hybrid models that guarantee tenure and security. As your family grows you occupy more space and you pay into the pot, then when your family contracts as children leave you receive an income when you give up this additional space. No space is wasted. Designing for disassembly & product as a service Where a building inevitably will have a short life span, it is essential that every component is designed for disassembly. The concept of buildings as material banks
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PAT B A R R Y
(above) The Palais de Tokyo, a building renovated by Lacaton & Vassal, who won the 2021 Pritzker Prize. Lacaton & Vassal's philosophy is to reuse existing buildings, and sometimes to do nothing to the building; (left) the flat pack build system by Irish offsite specialist Glavloc, which lends itself towards disassembly.
imagines them as temporary material warehouses, where a product should come out of the building at end of its life with at least the same value it had when it went in. But this requires knowing what is in the product, and having digital material passports for each component. It also requires thinking through how each component is assembled and conceiving the different layers of the building as having different lifespans, from the core structure to the cladding to the internal finishes.
say a hotel or school. London is the first city to require circularity statements for developments over 5,000 square metres at planning stage. This requires the design team to think through the implication of their design to minimise resource use looking at all the indicators outlined above, including design optimisations, adaptability, and disassembly. The city has developed a series of useful primers on circularity, which are available at tinyurl.com/CircularLondon.
Making circularity measurable & regulated To transition to circularity, we need definitive quantitative and qualitive indicators. Level(s), the EU frameworks for sustainable construction, sets out several indicators including design for adaptability, design for deconstruction and disassembly, and measurement of waste and overall resource efficiency. Simple indicators such as the ratio of usable area to gross area tell us how efficiently a building is designed, but more complex evidence may require demonstrating alternative plans of the building converted to other uses, eg, an office block to
Practical implementation of circularity As part of the CircularLife EPA-funded project, IGBC will be testing the use of circularity indicators and is inviting design teams to participate in workshops, including one with Dutch architects and “urban miners” Superuse Studios, to develop circularity strategies for their live projects. Regenerate is one cloud-based tool developed by the University of Sheffield’s Urban Flows Observatory that the IGBC intends to trial. It takes a design team through a series of steps from early strategic design onwards through a series of questions and prompts, covering every concept outlined above,
scoring the circularity of the building, and measuring the degree to which strategies have been integrated. IGBC’s review of circularity indicators is intended to feed back into guidance on the integration of circularity in development plans and public procurement. IGBC will also pilot an online materials exchange platform with a Dutch partner, creating material passports for materials coming out of demolition, and finding potential users using blockchain. We are also rolling out a series of webinars on circularity across the autumn. These are available on our online learning hub at www.igbc.ie. None of this is easy! The solutions are not quite there yet but by switching to ‘think circular’ mode in our construction brains, hopefully rapid innovation will follow. This may yield faster results than just incremental reductions in per-square-metre embodied carbon. n
Impacts of car2go on Vehicle Ownership, Modal Shift, Vehicle Miles Traveled, and Greenhouse Gas Emissions', Elliot Martin & Susan Shaheen, Transportation Sustainability Research Center, UC Berkeley.
i
ph+ | pat barry column | 23
GUY FOWLER
COLUMN
Passive house 30 years on:
qualified success or brilliant failure? As the stringent fabric-first, low energy standard enters its fourth decade, Guy Fowler asks what sort of impact it has made on the world, and where it should go from here.
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y question is whether passive house has been, or can become, the success it promised all those years ago. My personal view is what follows. It has been influenced, mitigated and corrected by conversations with four of the leading lights in building physics and architecture. • Rob McLeod is professor of sustainable building engineering at Graz University of Technology in Austria. He co-authored the ‘Passivhaus Designer’s Manual: A technical guide to low and zero energy buildings.’ • Toby Cambray is co-founder of Greengauge, the building physics and engineering consultancy specialising in sustainable, low energy design. He is also a columnist for Passive House Plus. • Richard Hawkes is a passive house architect and is perhaps best known as the designer of the Crossway passive house. He
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specialises in projects designed under Paragraph 80, which allows for architecturally exceptional dwellings in locations where planning would otherwise be difficult to achieve. • Nicholas Browne is my favourite architect. It’s a safe bet that Nicholas would be fairly immune to the Teutonic seductions of physics and leans more towards Philip Johnson’s stance on architecture: “The job of the architect today is to create beautiful buildings. That’s all.” I work for a small and quite specialist ‘modern methods of construction’ (MMC) company that recently made its passive house certified details freely downloadable — superstructure, substructure and basement. And when I say I, I mean we the team, which includes my co-pilot Neil Bricknell. The intention in making these details available is to give confidence to architects and, to a lesser
degree, their clients, in making the decision to build to the passive house standard. And to drum up some business along the way. One obvious metric of success is numbers. How many passive house certified builds are there? Around Frankfurt, publicly funded buildings require passive house certification (as is the case in around forty other districts across Europe). But most of the developed world has failed to build many passive developments as a proportion of new builds. The UK apparently needs a couple of hundred thousand new homes a year, although it doesn’t usually manage this number, and precious few are passive. My particular interest is in building palaces, or at least a Castle Drogo or two, with well shod clients who want a thing of beauty that might eventually get listed building status, hopefully well after they’ve sold up or shuffled off their mortal coil. You would expect passive house to be an easy sell to these
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clients. After all, the psychology around purchasing top end cars is complex but presumably involves wanting ‘the best.’ So why can’t I sell passive house to these people? In my world, we tend to sell half the time directly to a client who finds us sympatico – I don’t know why, let’s say the unassailable logic of the brilliance of our stuff. Otherwise, we are selling to an architect. The relationship sometimes becomes a triangle. It must be roughly the same way for any of our competitors in this market. So, let’s get inside the mind of the affluent client who is, say, a self-builder who might limit the ‘self ’ part of the build to their choice of construction system. Then we’ll penetrate the mind of the architect. Inside the mind of my imaginary client, they do want the best. It’s just that the definition of best evolves with the project. When we introduced a client to Richard Hawkes, before he entered his palace-building phase, their first criterion was for a certified passive house, their second was size (it needed to be rented out in the summer), and their third was budget (there was a real upper limit). Passive house was impossible for that size and budget, simple as that. But what about a client without an initial budgetary concern? They have a plot they’ve fallen in love with. Most of our projects are like this. It has a sea view over the dunes, peers down a wooded valley or perches perilously atop a cliff. That then determines the orientation and if it’s north facing, so
With passive house, you can’t trust your gut unless you set out from the start to run a rigorous process with the intention of completing certification. be it. If there is a pre-existing building that is being demolished, often the original orientation will be maintained as a planning condition. The same with over-shading, and the protected trees must stay in place – as they should. The brief is flexible – but must include five miles of bifold windows, an orangery, and be single storey. None of this calculates well in the monster spreadsheet that is the Passive house Planning Package (PHPP). Suddenly, certification, already a slightly dubious unknown, falls down or out of the priority list. After all, the building is based on passive house ‘methodology’ and PHPP is used. Isn’t that good enough? And it’s all top of the range: 85 per cent efficiency MVHR; U-values for the opaque elements of around 0.1; windows were going to be passive certified but they were ugly and so dropped in favour of some prettier ones but still triple glazed; and
GUY FOWLER
airtightness that exceeds building regulations by a lot. What’s not to like? Unfortunately, PHPP says it’s still far further from the mark than everyone hoped. Toby Cambray worked with us on a project in Iceland that was a bit like this, with great clients. There is a volcano. There would be, and it isn’t extinct by any means. Obviously, the view of the volcano determines the north facing aspect. There is a ‘greenhouse’ along the same face. But what really killed the numbers was the fact it was a bungalow. On the upside, the Icelandic climate is more benign than we expected, the place and people are lovely and the cost/time construction equation locally means that the MMC/offsite route makes lots of sense. The architect’s mind Now locate your nearest safe space and let’s enter the mind of our imaginary architect. How much passive house is in there, and where is it located? While passive house has not achieved much market penetration, it has started the conversation and informed the ensuing debate. By 2021, It has almost certainly permeated the consciousness, perhaps conscience, of most architects. If passive house interest and knowledge is a spectrum, at one end (we’ll arbitrarily assign it the left end) there is something akin to a fanatical ideologue who has nailed his colours irrevocably to the mast of the Passive House Institute’s Darmstadt HQ. At the other end, either there’s the insouciant who has identified
The Crossway passive house, designed by Richard Hawkes
ph+ | guy fowler column | 25
GUY FOWLER
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COLUMN
energy efficiency as a single item to be right sized within the myriad concerns of architecture; or there’s the downright anti-PHer. I have some sympathy with the entire spectrum. To sell passive house, you need an argument for everyone. Unless, that is, you are a system supplier like me, in which case the extreme left will generally have a tried and trusted ecosystem of suppliers. That’s fair enough. Building anything with as many bits as a house can be a risky business, and adding in passive house certification does not make it simpler. If you have found a good team, stick with it. Richard Hawkes has that good supplier
The brief is flexible — but must include five miles of bifold windows and an orangery.
ecosystem but operates, I think, in an interesting spectral position. The Crossway passive house has both form and function, and the passive house juices from that project were soaked up and imbue all his subsequent designs. Richard’s extraordinary success with Paragraph 80 projects suggests you can marry aesthetics with building physics. Except, perhaps you can’t. My colleague Neil has been building for 40 years, winning Daily Telegraph Home of the Year as well as having a project on Grand Designs. For 30 years he has used MVHR with excellent airtightness and U-values and, since 2011, we have been using PHPP regularly to inform the design for self-builders who come to us with their architect’s planning consents. These clients typically have a sustainability criterion, but not necessarily a passive house certification one. Unfortunately, the results are often distressingly far off the mark, even when our team’s gut informally predicted we would be at or near the passive benchmarks. With passive house, it seems you can’t trust your gut unless you set out from the start to run a rigorous process with the intention of completing certification. Continuing our journey through the labyrinthine mind of the architect, we might come across some more mundane resistance to passive house. Things like cost, time, complexity, fear of the unknown and fees. It will cost more, although the grander the house, the costs associated with passive house become de minimis. In a social housing scheme, the reported 8 or 12 per cent increase in cost might be the contractor’s profit. And there’s an ethical conflict in a housing scheme designed to help the homeless if 12 per cent less homes are built. Time? It will
make more time, although those things that are sent to try us, such as a good party wall dispute, will make passive certification look like a walk in the park timewise. Complexity and fear of the unknown can be taken together. The discipline alone of building to the passive house standard can simplify a project, and once you have done one, both complexity and anxiety should largely evaporate. Downloading CAD details might help with the anxiety, but there seems to be precious few details available that are actually buildable. Then we come to fees. Unless there is passive expertise in the architectural practice, it will have to be bought into the team. Integrating external teams can be difficult, although commonplace. The architect partner might have gone to a certified passive house (CEPH) designer course to stay informed, but might not have stayed for the exam. On my course, I vaguely remember there were about fifty people in the classroom and less than 10 in the exam room. Alternatively, the partner might have sent a keen junior to the course to report back. Either way, I learnt a lot of building physics at the BRE, but not so much on the practicalities of certification. Therefore, the fees will increase and include costs external to the practice. If an MMC or system route is favoured, and it should be, you can argue that the details become irrelevant as the offsite construction company will design and engineer the building. That might be considered as eating the architect’s lunch, but most details are easily implemented by third parties or can be built onsite in the traditional manner. The last port of call in the mind of the imaginary architect who occupies the middle or towards the right end of our spectrum, is the issue of design freedom. I think this is where Nicolas Browne sits. Just as the palatial project has been bagged, with the potential to leave a laudable mark on the landscape — and earn the respect you deserve from RIBA, English Heritage and the Financial Times weekend arts section — you hamstring yourself with another design constraint in the form of passive house. Putting aside the assertion that constraints can be the lifeblood of creativity, it’s not a tempting burden, especially if the standard is unfamiliar. Should the aesthetic trump the energy demand of your dream home? I found this scurrilous take on this subject on the web: ‘While the built environment currently accounts for almost half global carbon emissions, we don’t think you should worry about it. That burden rightly belongs with the larger developers who can make a difference. ‘Unfashionably, we are more interested in the beauty of the environment and think that physics should inform design, not the other way around. So, we provide you with world leading, proven physics models and the knowledge of how to practically build them. But you decide how much sustainability to build in.
GUY FOWLER
‘Do not doubt our commitment to sustainability: we have built houses out of recycled materials. And we have our own English woods where you can select your own timber for us to mill. But it should be your choice. The author lives in a 200-year-old stone cottage in South Devon and will never insulate the walls. Because they look nice.’ Ok, I wrote it, and it’s meant to be a bit contentious, but it probably more or less reflects the view of a reasonable number of architects, whether they admit it or not. The “design informed by physics” view aims to answer the question of which is your worse dystopian future: a landscape of polystyrene spheres encapsulating people popping Soma, or hedgerows of sprightly volk sporting warm coats? There must be a middle way. So, there we have it. Apart from an initial flirtation with passive house it’s undisputable that selling the concept to architects and the grander end of self-builders is hard work and often unsuccessful. Those people who are better at it than me, I shall accuse of selection bias. How do we judge passive house 30 years on? There’s no doubt it’s caused a bit of a stir. If it becomes part of building regulations, it will cause a bigger one, with a panoply of unintended consequences. I would like it to remain a voluntary standard for the time being. If mandatory, and I would understand mandating it while the seas rise and the skies burn, perhaps a draft dodging Section 106 type contribution to benefit the local community would unfetter design for those few special cases. A bit like Paragraph 80. Either way, the standard is mature and needs to evolve beyond measuring a single target of energy demand and tinkering with classic, plus and premium fizzy varieties. The first step in a holistic expansion of passive house might include a far more sophisticated look at carbon. Beyond that, and this one is a giant step, taking into account well-being and the uplift of the human spirit is, well, vital. The likes of Rob McLeod should be repurposed to distil this quintessence from ecopsychology and inject it, along with other relevant parameters of complexity, into some genetic algorithm that will optimise building design beyond passive house. My flight of fancy aside, we surely need to seek a better understanding of the role the built environment plays in the inverse relationship between wealth and well-being in the developed world. Meanwhile, passive house is the best we have. Be careful how you use it and don’t let beauty become physics’ ugly sister. n
Dr Guy Fowler (MB BS) is co-founder of Advanced Housing Systems, and winner of two SMART Awards for R&D innovation as well as the Jersey Construction Council Sustainability Award.
ph+ | guy fowler column | 27
OAK FRAME HOUSE
CASE STUDY
HEA RT OF OA K A striking new oak-framed passive house in an area of outstanding natural beauty in the English countryside has just opened its doors to the public, and already there has been a flood of guests seeking to experience life in a passive house. By David W Smith
28 | passivehouseplus.co.uk | issue 39
CASE STUDY
OAK FRAME HOUSE
IN BRIEF Building: 182 m2 detached B&B Method: Oak frame Location: Malvern, Worcestershire, England Standard: Passive house classic certified Energy bills: £25 per month for heating, hot water & cooling (see ‘In detail’ for more)
£25 per month
ph+ | oak frame house case study | 29
OAK FRAME HOUSE
CASE STUDY
It seemed so fantastic, we thought the house was not really ours.
A
ndrew and Linda Burnett have been on quite a journey. When they began looking for a retirement home near Malvern, in Worcestershire, back in 2013, their aim was simply to purchase a house in the area that they could convert into a bed and breakfast. But they ended up opting to self-build the first oak-framed passive house B&B in the UK. An eight-acre field with 700 pear trees, 75 plum trees and seven beehives was not part of the original plan either. “When we set out we’d not thought about building an environmentally friendly house and we hadn’t even heard of passive houses,” says Andrew. “But we’ve shifted the whole idea of our bed and breakfast now. All but two of the guests staying since we opened at the beginning of July have done so to experience staying in a passive house, and to ask us about our experiences of self-build.” As for the land attached to their house, it has brought about a complete change in
30 | passivehouseplus.co.uk | issue 39
lifestyle. “Our old house in Kent had a third of an acre with one plum tree and I said to Linda, ‘this grass cutting is getting a bit much at weekends, let’s look for something smaller’. And we ended up buying part of a former fruit farm with two orchards, which we’re now restoring,” says Andrew. “We’re also turning a four-acre field into a wildflower meadow and we’ve planted new hedges. I’ve learned to use a chainsaw, and I own a compact tractor and gigantic lawnmower. A beekeeper comes to look after the bees, and we get annual rent of two jars per hive. We’re making plum and damson jams and more things with pears than you can throw a stick at.” When their search began for a new home, the couple were living in a village in Kent. To make it easier, they relocated to a rented bungalow near the spa town of Malvern, in Worcestershire, where Linda grew up. The couple visited a few barn conversions and liked the idea of a house with exposed
CASE STUDY
wooden beams. But no suitable property was available and the idea of a self-build became more attractive. In 2015, Andrew and Linda visited a self-build exhibition at the NEC in Birmingham, where they came across Oakwrights, a Herefordshire-based oak frame design-and-build practice. There were three specialist providers of oak-framed houses available, but Oakwrights was the only one offering their own insulation and encapsulation system as well. Oakwrights’ founder Tim Crump brought up the idea of passive house construction. Andrew and Linda liked the idea and began to do some research. Initially the appeal was the promise of exceptionally low heating bills during their retirement. The next step was to visit and stay in Oakwrights’ show home in Herefordshire. “After we stayed in The Woodhouse, we both said, ‘that’s it, that’s what we want!’” says Linda. The show-house gave the couple a clear
Photos: Mark Bolton
direction forward. They liked its oak framed gable ends and traditional tiled roof. They decided they wanted a brick finish on the ground floor and timber cladding above, which would fit in with the barn conversions in the local area. But they still needed to find a plot within a ten-mile radius of Malvern, and that did not prove easy. Andrew was working outside the area as a public health consultant, so Linda took charge of finding a site. It was practically a full-time job. She spent a year trawling through websites for hours every day. Finally, after a couple of near misses, she spotted a large plot in an area of outstanding natural beauty (AONB) between the Malvern and Suckley hills. The picturesque site with its panoramic views and tranquility won them over and their offer was accepted in October 2016. The site had existing planning permission for a smaller two-storey dwelling and the pre-
OAK FRAME HOUSE
vious owner had begun excavating part of the valley in preparation for that build. But the design for the new oak frame passive house was substantially different, and a new application had to be submitted. Based on Andrew and Linda’s wishes, Oakwrights’ in-house architectural team designed the house with the living space upstairs to offer panoramic views. Their en-suite master bedroom is also upstairs and has a walk-in dressing room. Meanwhile, the two en-suite guest bedrooms are downstairs, along with a home office and the large hallway. There is space to install a lift one day too, if necessary. The Burnetts originally wanted to build a four-bedroom home, but later opted to reduce it to three, which allowed Oakwrights to design larger bedrooms and left space for a double-height hallway with a “bit of a wow factor”. Oakwrights also included two south-facing gables and a rustic tiled roof, which helps the
ph+ | oak frame house case study | 31
OAK FRAME HOUSE
CASE STUDY
AirMaster: the first duct free MVHR solution for Passivhaus schools
Visit www.sav-systems.com/smart or call: +44 (0)1483 771910 32 | passivehouseplus.co.uk | issue 39
CASE STUDY
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1-4 The ground floor consists of an Isoquick insulated foundation system and reinforced concrete slab; 5 the slab is completely encased by the insulation to prevent thermal bridging; 6-8 construction of the oak frame underway; 9 fitted to the frame is Oakwrights’ encapsulation system, which features I-joists insulated with cellulose.
OAK FRAME HOUSE
home to blend into its setting. “There are also an east-facing and a west-facing gable ends, the four gables creating an intriguing roof externally and substantially adding to the attractiveness of the high ceilings in the upstairs rooms,” Andrew says. The south elevation has four large, tripled-glazed lift and slide doors alongside a triple-glazed front door and two roof lights. The emphasis was on positioning windows, doors and balconies to take advantage of the views of the hills and garden. “There’s an Oakwrights vernacular running through all our designs. It uses areas of oak outside, as well as large and well-proportioned windows,” says Oakwrights architect Craig Alexander. While the dwelling that was originally intended for the site had a north-south axis, with large east and west facing facades, this would have presented an overheating risk from low-angle morning or evening sun. So Oakwrights’ design flipped the main axis to east-west, giving the house a large south-facing façade (within 30 degrees of due south is considered ideal for a passive house). “We balanced potential summer heat grains through the south-facing windows with the introduction of shading from the balcony structures, with integrated blinds above,” Craig says. Planning permission for the build was achieved without any issues even though the use of cellulose insulation to achieve onerous U-values meant having thick wall and roof build-ups, and consequently, increasing the overall size of the house so as not lose internal floor space. Legal complexities held the project up and it was not until April 2018 that the first spade went into the ground. Andrew and Linda chose a young and enthusiastic firm of builders called Furber Young, which turned out to be one of the best decisions they made. “While Andrew was away I came to sit in the field and watched the build almost every day. It was wonderful to see the oak frame being pulled into place by the crane. You could see the markings on the beams showing where they needed to go. It’s a shame Andrew couldn’t watch, but I filmed it for him,” Linda says. “When I came down I would bring cake and everyone was friendly and welcoming. The builders had all been at school and college together. They were great friends and there were a few stag-dos during the build. They even came across at weekends specially to show Andrew what they’d done.” Andrew and Linda had planned the build meticulously together with Furber Young, Oakwrights and Green Building Store, who provided the mechanical ventilation with heat recovery system (MVHR) and the triple-glazed doors and windows. As a result, everything went smoothly and the house was completed a week early in just 11 months. The work also came in on budget. Project costs were £699,000, added to the land costs
ph+ | oak frame house case study | 33
OAK FRAME HOUSE
CASE STUDY
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CASE STUDY
OAK FRAME HOUSE
SELECTED PROJECT DETAILS
Clients: Andrew & Linda Burnett Architecture & passive house design: Oakwrights Civil & structural engineer: J Turner & Associates Main contractor: Furber Young Developments Airtightness testing: db Air Tightness Testing Build system supplier: Oakwrights Airtightness tapes, membranes & wood fibre insulation: Ecological Building Systems Airtight OSB: Medite Smartply Additional airtightness tapes: Siga Wall & roof insulation (cellulose): Isofloc LM, via Oakwrights Insulated foundations: Isoquick Windows, doors & MVHR: Green Building Store Roof lights: Velux Shading: Solihull Blinds Ltd Ground source heat pump, DHW tank, underfloor heating: Energy Zone Lighting: Mr Resistor Wastewater treatment: Conder sewage treatment unit, via Furber Young Developments Mortgage: Ecology Building Society Self-build site insurance and structural warrantee: Protek
of £413,00, so around £1.1 million in total. Andrew and Linda moved in on 5 March 2018. At first, they could barely believe they owned such a property. “For weeks it felt like we were on holiday. It seemed so fantastic, we thought the house was not really ours and any minute we’d have to pack up and leave,” says Linda. The MVHR system keeps the house feeling fresh. Meanwhile, a ground source heat pump takes heat from the field to warm up the hot water and the underfloor heating in the hallway and bathrooms. Oakwrights also designed an enhanced version of their WrightWall Natural and WrightRoof Natural encapsulation system to seamlessly wrap around their frame, which is prefabricated in their Herefordshire workshops and includes recycled paper cellulose insulation. While working at home during the second Covid-19 lockdown, Andrew enjoyed walking barefoot on the warm tiles. The house was certified to the passive house classic standard in September 2019. According to Andrew, the house is performing better than predicted in PHPP, the passive house design software, for both electricity consumption and overheating. “PHPP stipulates that overheating must not exceed 25C for more than 10 per cent of the time. Our estimation was for 1.9 per cent, but we’ve had data loggers measuring internal
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1 & 2 Smartply Propassiv airtight OSB3 board on the inner side of the wall build up, with all joints taped; 3 continuity of insulation between the upstand of the Isoquick insulation foundation system and the insulated wall panels; 4 external leaf ready for erection of brick rainscreen to the outside of the Oakwrights encapsulation system; 5 construction of the insulated encapsulation system at first floor level; 6 installation of the insulated roof panels; 7 false eaves and verge fixed to the outside of the encapsulation system to give the appearance of traditional construction without creating a thermal bridge; 8 airtightness taping around door frame; 9 additional Xtratherm rigid insulation to the inside of the frame for the Velux roof light.
ph+ | oak frame house case study | 35
OAK FRAME HOUSE
CASE STUDY
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36 | passivehouseplus.co.uk | issue 39
Director Architype
CASE STUDY
and external temperatures every 30 minutes and our overheating over 12 months was 0.57 per cent, which is absolutely brilliant,” he says. “And also, for electricity the PHPP predicted 98 kWh per square metre for everything, whereas our level was 61.65 kWh.” The Burnett’s current ‘green’ electricity supplier predicts their annual electricity bill will be £1,560, which covers all their energy costs. Any other energy required to heat the house comes from the sun, people in the house, the heat output from household devices, and recovery of heat from air removed in winter. Back in 2014, in the couple’s Kent house, which was about 140 square metres rather than the current 200 square metre house, they paid more than £3,500 for energy. But their oak-framed house is as much an aesthetic experience as it is thermally efficient. Andrew and Linda particularly enjoy having two balconies at the front. “They provide shading from the summer sun, but they make the house look more interesting. We frequently eat on one balcony and we’ve put comfortable chairs on the other one. It’s idyllic sitting there with a single malt enjoying the views across the fields,” says Andrew. “The wildlife is also incredible. There are birds of prey and swallows in the sky and we see deer coming out of the woods. A family of badgers arrives every night and we have visits from a little fox. All of that is easy to see from the house, especially in the living room with the windows that go right down to the floor. But the views are incredible everywhere.”
OAK FRAME HOUSE
EMBODIED CARBON
O
akwrights commissioned John Butler Sustainable Building Consultancy to analyse the embodied carbon of the house, using PHribbon. The analysis included the substructure, the superstructure (excluding stairs), internal walls and intermediate floor, wall and ceiling finishes (but not floor finishes) and building services. The services included the ground source heat pump, heating and hot water pipes, underfloor heating system, but not the external collectors, or the associated excavation. The MVHR system is included, along with the stainless-steel ductwork. Electrics were not included. Internal doors, baths, and sinks were also included, but the kitchen fit out wasn’t included. The building’s timber windows and MVHR system were assumed to need one replacement each within the 60-year time period for the LCA, though it was assumed that the ductwork would last for 60 years. The heat pump was assumed to need two replacements. All other components were assumed to last for 60 years or more. Based on these assumptions, the building achieved a cradle to grave score of 71.1 kg of CO2e, or 339 kg CO2e/m2
GIA, comfortably beating the revised RIBA 2030 Climate Challenge target of 625 kg CO2e/m2. The figure for module A alone – which deals with emissions up to the point of practical completion of the building – is 274 kg CO2e/m2 GIA, with a further 270 kg CO2e/m2 GIA sequestered in the building’s timber, meaning that if it was permitted to engage in carbon accountancy sleight of hand and net sequestered emissions off against upfront emissions, the two figures would almost cancel each other out. Instead, it is considered that the sequestered CO2 is released into the atmosphere at the building’s end of life. Even if the CO2 sequestering products were assumed to be reused or recycled, the amounts sequestered would pass on to that future use, meaning that in the context of this building’s LCA, it’s effectively no different to the products being incinerated at their end of life. The A1-A3 emissions (the materials, from cradle to factory gate) for the as built external walls comes out at 10.8 tonnes of embodied CO2e – compared to 21.7 t for a rendered cavity wall alternative of the same walls.
Homeowners Andrew and Linda Burnett
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
ph+ | oak frame house case study | 37
OAK FRAME HOUSE
CASE STUDY
H E A T I N G I S S O Y E S T E R D A Y. . . T H E F U T U R E I S H E AT P U M P V E N T I L AT I O N Ÿ MVHR Ÿ heating Ÿ cooling Ÿ hot water Ÿ COP: 3-12 Ÿ for super-
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38 | passivehouseplus.co.uk | issue 39
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hpv series
THE STREET
CASE STUDY
OAK FRAME HOUSE
IN DETAIL Building type: 182 m2 (treated floor area) detached, oak-frame, certified passive house Location: Storridge, Malvern (Malvern Hills Area of Outstanding Natural Beauty) Completion date: March 2019 Cost: £1.106m (£699,000 for the build, £413,000 for the site) Passive house certification: Certified Space heating demand (PHPP): 13 kWh/m2/yr Heat load (PHPP): 10 W/m2 Primary energy demand (PHPP): 108 kWh/m2/yr Heat loss form factor (PHPP): 3.06 Overheating: 1.9 per cent of the year >25C (projected in PHPP); 0.57 per cent (measured) Number of occupants: 2 + B&B guests (PHPP completed based on 4 occupants) Airtightness (at 50 Pascals): 0.57 m3/hr/m2 Energy performance certificate (EPC): B (89) Total electricity consumption: 8,366 KWh per year for all energy (29 Oct 2019 - 30 Sept 2020), equates to 45.93 kWh per m2 treated floor area. Energy bills (measured or estimated): From Oct 2019 to Sept 2020 Andrew and Linda paid £1,289 for the above quantity of energy (£107 per month), including all charges. The ground source heat pump consumed 1.489 kWh over 12 months up to 7 August 2021, so on the same tariff it would cost £300 (or £25 per month) to run the heat pump for space heating and cooling, and domestic hot water. Tariff rate of 19.943p per kWh inc VAT used. Thermal bridging: Use of low thermal conductivity cavity wall ties, thermally broken window frames, insulated reveals. Thermal bridge
Y-values (figures in W/mK): eaves: - 0.009; verge: - 0.043; valley: 0.034; base to wall: - 0.028; normal corner: - 0.049; wall to flat: - 0.029; pitch to flat: - 0.003; reverse verge 0.027; reverse pitch to flat: - 0.80 Ground floor: Isoquick insulated foundation system incorporating 250 mm BASF Peripor EPS insulation completely encasing 300 mm reinforced concrete slab (with 50 per cent GGBS). U-value: 0.127 W/m2K Walls: 12.5 mm plasterboard internally, followed outside by 46 mm service void battens with mineral fibre insulation (0.039 W/mK), 12.5 mm Smartply Propassiv airtight OSB3 board, all joints taped, 300 mm JJI I-beam frame factory filled with Isofloc cellulose insulation (0.038 W/mK) to 72 kg/m3, 60 mm Gutex moisture resistant insulation board (0.039 W/mK), Solitex Fronta Humida breather membrane, ventilated cavity, rainscreen of either: 102.5 mm brickwork (ground floor) or horizontal timber boarding (first floor). U-value: 0.10 W/m2K. Sloping ceiling: 12.5 mm plasterboard internally, followed outside by 46 mm service void battens/ mineral fibre insulation (0.039 W/mK), Novia airtightness membrane, 9 mm OSB, 300 mm JJI I-beam frame factory filled with Isofloc cellulose insulation (0.038 W/mK) to 72 kg/m3, 60 mm Gutex moisture resistant insulation board (0.042 W/mK), Solitex breather membrane, vented pitched roof with battens, counter battens and clay tiles. U-value: 0.10 W/m2K Flat capped ceiling: 12.5 mm plasterboard internally, followed outside by 100 mm service void battens, 12.5 mm Smartply Propassiv airtight OSB/3 board, all joints taped,2 x 300 mm JJI I-beam frame factory filled with Isofloc cellulose insulation (0.038 W/mK) to 72 kg/m3, 60 mm
Gutex moisture resistant insulation board (0.042 W/mK), Solitex breather membrane, vented pitched roof with battens, counter battens and clay tiles. U-value: 0.07 W/m2K. Windows & external doors: Triple-glazed, argon-filled, wood-framed windows and doors from Green Building Store Ultra range. U-value: 0.75 W/m2K (based on whole window U-value for standard window 1,230 mm x 1,480 mm for this range). The windows and doors have insulated frames, with Swisspacer Ultimate edge spacers; 52 mm thick triple glazed units. Roof windows: Four Velux GGU passive house certified roof windows. U-value (whole window): 0.51 W/m2K (EN ISO 12567-2) Space heating & cooling: Ground source heat pump 3-8kW Mastertherm modulating unit with desuperheater (COP 4.5) for domestic hot water and underfloor heating in the three en-suite bathrooms, hall and boot room. There are also electric towel rails in the three bathrooms. The heat pump also has a cooler battery that can drop incoming air temperature 5 to 7 C during hot weather. Domestic hot water: Ground source heat pump as above heating 400 litre unvented Tempest cylinder from Telford Stainless Steel Ltd with two probes and a switch to enable heating of upper 200 L or whole tank. Tank also fitted with an electric immersion heater controlled by a timer to ensure once-weekly Legionella pasteurisation heating to just above 60C. Ventilation: Zehnder Comfoair Q MVHR; Passive House Institute certified efficiency 90 per cent. Water: Low flow fittings used.
ph+ | oak frame house case study | 39
OAK FRAME HOUSE
CASE STUDY
Leading designer, supplier and installer
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40 | passivehouseplus.co.uk | issue 39
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Unit 11 Bushell Estate, Lester Way, Wallingford, OX10 9DD
CASE STUDY
Brink Heat Recovery
Stiebel Eltron
Ventilation Systems
Air Source Heat Pumps
The Brink Flair range of MVHR systems is far ahead of its time when it comes to performance, ease of installation and connectivity. The appliance offers more possibilities for both homeowners and installer alike. It is more efficient and quieter and it uses considerably less energy than any other comparable product.
OAK FRAME HOUSE
The Stiebel Eltron WPL-A 05 Premium air source heat pumps are not only suitable for heating and DHW operation but also provide cooling in the summer months. Since the inverter unit achieves high flow temperatures even at very low outside temperatures of down to –25 °C, they are equally suitable for use in new build and modernisation projects.
High Efficiency Heat Exchanger >90% efficiency (Holmak TST35)
Air source heat pump installed outdoors for heating and cooling
Constant Flow Fans (EBM) for accurate flow measurement with integral anemometer.
75 °C flow temperature enables high DHW temperatures
Electrical pre-heater with high efficient heat transfer, intelligently controlled
Low operating noise thanks to infinitely adjustable fan speed and
Bypass with servo-motor, 100% airtight due to 2K-technology
encapsulated refrigerant circuit. Sound Power level (EN 12102)48 dB(A)
4 adjustable speeds (even activated by touch screen)
Futureproof and eco-friendly refrigerant with high efficiency (R454 C)
Ultra-low energy consumption (SFP ~0.15 Wh/m³!)
Can be integrated into a home network and controlled via smartphone
Ultra-low sound level
Highest efficiency all year round for low operating costs thanks to optimally matched components
Plus PCB available as a post-mounted option Connects to smart devices and Amazon Alexa
For a high recognition factor and a consistent appearance of the visual identity of the Brink brand it is important that the corporate identity of Brink is used correctly. To guarantee this we have made the Design Guideline. In this derived version for the Brink partner is determined how partners can make usage of our logo and means. In cases where the Guideline is not clear or does not provide responsable Marketing specialist of Brink may be contacted.
Proud To Be A Brink Partner
A Member of Passivhaus Trust
Brink Climate Systems are based in the Netherlands and are one of Europe’s leading manufacturers of ventilation units. Brink Climate Systems use their knowledge and years of experience to develop top-quality climate solutions. With a constant focus on innovation and sustainability. Brink knows how important a pleasant and healthy climate is. With their systems for ventilation, hot water preparation, heating and cooling, they want to contribute to this.
The Passivhaus Trust is the UK affiliate of the International Passivhaus Association. The Trust is an independent organisation that provides leadership in the UK for the adoption of the Passivhaus standard and methodology. Its aim is to promote the principles of Passivhaus as a highly effective way of reducing energy use and carbon emissions from buildings in the UK, as well as providing high standards of comfort and building health.
CVC Ltd is the official UK supplier of Brink products and are certified as a Brink export partner.
For details on the Passivhaus Trust see: https://passivhaustrust.org.uk/ ph+ | oak frame house case study | 41
NEW FOREST ENERPHIT
CASE STUDY
IN BRIEF Building: Deep retrofit to 144 m2 detached home Method: External insulation on cavity brick wall Location: Barton-on-Sea, Hampshire Standard: Enerphit (certified) Space heating cost: £36 per month (see ‘In detail’ for more)
£36 per month
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CASE STUDY
NEW FOREST ENERPHIT
W I T NE SS T H E
P H I T N E SS HAMPSHIRE HOUSE HITS 70% ENERGY SAVING VIA ENERPHIT The deep retrofit of this 1930s dwelling on the Hampshire coast provides a pitch-perfect example of how to transform old dwellings while preserving their original structure and minimising embodied carbon, utterly transforming the living space without the need for an extension, and creating a cosy home that uses two-thirds less energy than before. Words by David W Smith
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NEW FOREST ENERPHIT
CASE STUDY
Homeowners Julie Botham and David Dacombe
D
avid Dacombe and Julie Botham spent the best part of three decades living in a cold and damp four-bedroom 1930s detached house, in Hampshire. Passionate environmentalists, they set out to insulate the 144 square metre brick property a few years ago. But somewhere along the way, their ambitions soared and a new goal emerged to achieve the Enerphit (passive house) standard for retrofits. The project ended up costing 50 per cent more than they initially envisaged, but their “new” home achieved Enerphit and has transformed their living experience. “We spent a scary amount of money in the end, but we’re very pleased with the house and definitely glad we did it. We’ve ended up with almost a brand-new home,” says David, a retired engineer (the project was not fully costed until the contracting stage, and bids from builders came back higher than anticipated). “We get lovely comments from visitors and passers-by about the outside. The tiles have been replaced with slates which together with white and grey render gives a contemporary appearance outside. Inside, the main advantage is the comfort all-year round as it used to be cold, draughty and damp in winter.” Before consulting an architect in 2016, the couple spent a long time thinking through their options. One ambitious plan
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was to knock down their existing house and build three townhouses in its place, then sell them and use the profit to build a passive house. “But we couldn’t find a suitable plot anywhere in the local area, and we felt it wasn’t a green thing to do because of all the embodied energy,” says David. Neither did they want to tear themselves away from the local area, where they have lived since 1994. The house is 500 metres from a beautiful stretch of coastline, near Bournemouth, and close to the border of the New Forest National Park. Another option was to attempt a DIY approach to insulation. David read up on how to do this and started by stripping off the plaster in two rooms. But the reality proved more complex than the manuals had suggested. “Cold bridges were a big issue. If you don’t get rid of them, you end up introducing even bigger ones,” David says [editor’s note: when you insulate internally, any remaining cold bridges — uninsulated paths that cut through the insulation layer — are exacerbated and potential points for condensation]. At this stage, they opted to seek the help of a professional architect. RIBA recommended three local architects and the couple were impressed with Ruth Butler, who also lives in Hampshire. She had previously built four passive houses, including her own home, previously featured
Ground Floor
First Floor 1 2 3 4 5 6 7 8 9 10 11 12 13
entrance hall kitchen dining room living room utility / plant room WC & shower garage landing bathroom bedroom bedroom (master) bedroom bedroom
CASE STUDY
in Passive House Plus issue 33. When David and Julie met her in 2016, their intention was simply to improve the insulation. But it was obvious that significant internal changes would in any event be essential to upgrade the airtightness. The couple had become familiar with the Enerphit standard and decided to go for it. Ruth worked with the couple to develop options in 2017 and showed them three reconfigurations using 3D models. David and Julie wanted an open-plan design and agreed to get rid of a conservatory. Ruth convinced them to give up plans for an extension in favour of spending more money on the existing structure. The original roof structure was kept too, and all-in-all the house provides a first-class example of how to undertake a deep retrofit while preserving as much of the existing building as possible, in order to reduce the embodied carbon of the build. An analysis in PHribbon calculated the embodied carbon of the retrofit at 111.7 kgCO2e per square metre, for building life cycle stages A (product stage) through to C (end of life). For comparison, this smashes even the older, more stringent RIBA 2030 target for new build homes of 300 kgCO2e, emphasising the importance of preserving existing structures. There was no opposition from New Forest District Council to the application for plan-
Photos: Peter Langdown Photography
ning. But finding the right builder proved far more challenging. When David and Julie’s initial choice pulled out just as the project was about to get underway in mid 2018, they nearly gave up. “It was very frustrating and we were on the verge of quitting,” David says. “There were a few builders with passive house experience in other parts of the south, but no one was prepared to travel for a small job.” Ruth persuaded them to change their strategy and give it another shot. Instead of looking for a specialist, they put out a tender for skilled local builders and hoped to train them up in passive house methods. There were two bids and Ruth advised them to go with Tuakana Construction, who are based nearby. “I thought they’d be a good fit for an Enerphit project as they’d worked on a lot of historic buildings,” Ruth says. “I think there’s a synergy with the attention to detail you need for passive house projects.” The builders began work in February 2019 while the couple rented a property for eight months. Tuakana’s operations manager Neil Woodley says the company likes to be stretched by new challenges, but admits to a few nerves at the outset. “We were a bit daunted at first because we weren’t sure what would happen if we didn’t meet the Enerphit criteria. We even joked that if we don’t get passive house accreditation, do we not
NEW FOREST ENERPHIT
The experience of living in the house is radically different now.
get paid? But when you break it down, if you follow all the necessary details, you reap the rewards,” he says. The key to success was to get the experienced team of builders thinking a little bit differently. “The foreman in charge had been doing things in a certain way for 30 years,” Neil says. “Suddenly he was asked to do things differently, the standard methods and processes he had been adopting for years were suddenly not permitted, basic things like the running of electrical and plumbing services were carried out in a completely different way. The few times we slipped up were where we did things out of habit that we have always considered good practice in a standard build, but you have to think differently in passive house. It comes down to understanding the reason behind the different ways of doing things. If you realise why all the little details are important, it becomes a much much more logical process.”
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NEW FOREST ENERPHIT
CASE STUDY
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1 The cold and damp 1930s detached house prior to renovation; 2 the old conservatory on the south-facing side was removed, allowing direct access to the garden; 3 as much of the existing roof timbers as possible were retained; 4 Bill Butcher (left) of Green Building Store providing on-site airtightness training; 5 airtightness taping at joist ends; 6 mineral wool between rafters with 50 mm PIR insulation fixed to underside of rafters; 7 Intello vapour control and airtightness membrane to ceiling; 8 airtightness taping around the Lacuna bi-fold door; 9 airtightness taping around ventilation ductwork penetrations; 10 the house’s only fixed heating source, a 1.5 kW Zehnder electric radiator, waiting to be installed; 11 using a smoke pencil to identify air leaks; 12 a blower door test underway — the project achieved an airtightness result of 0.48 air changes per hour.
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CASE STUDY
NEW FOREST ENERPHIT
SELECTED PROJECT DETAILS
Clients: David Dacombe & Julie Botham Architect: Ruth Butler Architects Main contractor: Tuakana Construction M&E engineer: Cundall Civil & structural engineer: Andrew Waring Associates Energy consultant: Cundall Passive house consultant: Green Building Store Passive house certifier: Mead Consulting Electrical contractor: LSB Electrical, Plumbing & Heating Airtightness tester: BRE External wall insulation system: Permarock, via Specialist Rendering Services Airtightness products: pro clima, via Green Building Store Windows & doors: Green Building Store Electric radiator: Zehnder Ventilation: Brink MVHR, via CVC Direct Passive fire safe door: James Latham
To challenge their pre-existing habits, all the builders in the team received half a day’s hands-on airtightness training from Bill Butcher, director of Green Building Store. That proved invaluable: the project went on to achieve an airtightness of 0.48 air changes per hour, beating not just the Enerphit standard of 1.0 but also the passive house new build standard of 0.6. “The success was in many ways down to the training. The building team really related to Bill as a fellow builder. It meant that they all started off on the project with the same language and understanding,” says Ruth. Naturally, one of the main difficulties of achieving Enerphit was working around the original structure. “You’re stuck with all the thermal bridges, and it can be complicated to get the airtightness line around the existing pieces of construction,” Ruth says. “It’s a nice challenge to have and you have to get your brain working in how to resolve issues in the simplest, most practical way possible. We chose to use plaster parge on the walls [as the airtightness line] and put membranes over the existing floor and ceiling.” To create an open-plan space the team removed a number of walls. The builders knocked through the old entrance lobby and pulled down the wall between the kitchen and dining room. The kitchen was re-modelled entirely. “Opening up the living and dining areas and having the stairs as part of the house makes it feel like a much bigger house. We’ve taken away a rather ratty old conservatory on the south-facing side which was preventing direct access to the garden. They’re keen gardeners so that was import-
ant for them,” she says. Ruth’s plans for the retrofit included a new thermal jacket for the house. This involved installing a rendered external insulation system on the outside of the cavity brick walls, raising the timber flooring to add insulation and installing a Brink mechanical ventilation with heat recovery unit (MVHR). All the old heating pipework was stripped out, leaving just one 1.5 kW fitted electric radiator, and one portable 1.5 kW radiator that is now used in the lounge (separate to the open-plan area). This ultra-minimal heating setup is testament to David, Julie and Ruth’s confidence that the house will perform as it is designed to (of course, the mild climate on the south coast of England also made it easier to achieve the Enerphit standard). The house had recently had most of its old windows replaced with triple glazed units from Green Building Store. But during the retrofit these had to be re-positioned to accommodate the external wall insulation, and some windows were moved too. Thankfully, this this was reasonably easy to accomplish
as straps had been used to fit the windows. They were moved 200 mm out into the insulation zone, and deeper extension sills were fitted. There were not as many structural changes to the four bedrooms upstairs. But the design enlarged the bathroom, allowing both a shower and bath to be fitted. The builders also reconfigured the roof slopes and removed a dormer with two windows, so the bedrooms became less constrained. To be awarded an Enerphit certificate, retrofitted homes must achieve a maximum space heating demand of 25 kWh/m2/yr. PHPP, the passive house design software, showed that the remodeled house’s space heating demand was 19 kWh/m2/yr, and it was certified in 2020. It was a finalist in the 2021 UK Passivhaus Awards in the small projects category. David and Julie have monitored the house’s energy consumption over the past two years and they are using approximately one third of what they were pre-retrofit, although this has only resulted in marginally lower energy
ph+ | new forest enerphit case study | 47
THEPASSIVHAUS
NEW FOREST ENERPHIT
CASE STUDY
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CASE STUDY
bills – likely due to comfort-taking and the switch from comparatively inexpensive gas to direct electric for heating and hot water. (see ‘In detail’ for more). In summer, they generate a small amount of electricity from their 12 m2 solar PV array and never switch the heating on. David says the lounge can sometimes get too warm, but that they manage this with an internal blind and by opening the bi-fold doors. In winter, the fitted electric radiator in the open place space provides whole house heating; the portable radiator in the lounge is only used on very cold winter days. The experience of living in the house, David says, is radically different now. For Ruth Butler, the New Forest Enerphit project proved equally as life-changing. Although passionate about passive house new build, she points out that retrofitting old houses is more critical to the climate crisis. “When they said they were interested in a deep retrofit I jumped at the chance. It turned out to be a landmark project in my career as an architect. It helped me to realise that deep retrofitting was my primary concern as an architect.” The New Forest Enerphit turned out to be her final design for her own company, Ruth Butler Architects. In February 2020, she took a new job with Pritchard Architecture, in Portsmouth. The company carries out a lot of conservation and conversion work and Ruth’s role is to work on low energy refits. Her current projects include retrofitting a home in Prinsted, near Chichester and converting a barn into offices for Seven Sisters Country Park.
NEW FOREST ENERPHIT
EMBODIED CARBON
A
n embodied carbon analysis by PHribbon author Tim Martel and sustainable building consultant John Butler revealed high and low estimates for cradle to grave totals, with the difference in results depending on the assumptions made about component lifespans and consequent replacement. The high estimate was based on using the default values on expected lifespans from the RICS document, ‘Whole life carbon assessment for the built environment’. This assumed a lifespan of 30 years for windows, external doors and renders, and a 20 year lifespan for the ventilation system and ductwork. The low estimate – which was informed by the results of a destructive monitoring study on the first passive house 25 years after it was completed, assumed a 60 year lifespan for the windows, doors and renders and ventilation ductwork, with one replacement of the ventilation system. In both cases, it was assumed the PV array would last for 30 years.
The high estimate resulted in a total of 20.9 tonnes, 136.1 kg CO2e/m2 – less than a quarter of the 625 kg total set for dwellings in the RIBA 2030 Climate Challenge. The low estimate total was 16.9 tonnes of CO2e, or 110.1 kg CO2e/ m2 – less than a fifth of the RIBA 2030 target. In either case, the result confirms the importance of focusing on retrofit over new build in terms of reducing embodied CO2. The analysis included the external envelope, including new roof, along with the ventilation system and ductwork. The ventilation system calculations were based on a draft Product Environmental Passport for the Brink Flair unit, which hasn’t yet been independently verified, and calculations for the ductworks provided by ventilation supplier CVC systems, in accordance with CIBSE’s TM65 methodology. Any changes to the internal layout and finishes were not included, nor was the building’s single electric panel heater.
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
(above) Comparison of imported and solar-generated electricity for the retrofitted house, versus David & Julie’s old energy consumption figures.
ph+ | new forest enerphit case study | 49
NEW FOREST ENERPHIT
CASE STUDY
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50 | passivehouseplus.co.uk | issue 39
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CASE STUDY
NEW FOREST ENERPHIT
IN DETAIL Building type: Deep retrofit to 144.4 m2 (treated floor area) detached 1930s house Location and site: Village site, Barton-on-Sea, New Forest Completion date: September 2020 (practical completion & handover September 2019) Space heating demand (PHPP): 19 kWh/m /yr Heat load (PHPP): 13 W/m2 Heat loss form factor (PHPP): 2.86 Overheating (PHPP): 0 per cent of year above 25C Number of occupants (PHPP): 2.9 Primary energy renewable (PHPP): 72 kWh/m2/yr 2
MEASURED ENERGY CONSUMPTION: Before: 147 kWh/m2/yr (20,061 kWh total, 17,730 kWh of gas & 2,331 kWh electric, for 2018) After: 45.74 kWh/m2 (or 6,605 kWh total, 12 months from Sept 2020 to Sept 2021) Energy bills (estimated): Based on measured energy use (electricity + gas) prior to retrofit, and based on Energy Saving Trust figures from June 2021 on average tariffs, the calculated pre-retrofit combined electricity and gas bill for this property of £1,302 per year, including VAT and standing charges. Based on post-retrofit metered electricity consumption, the cost drops slightly to £1,168. This is due to the higher price of electricity (based on an average tariff of 16.36p per kWh versus 4.17p per kWh of gas) in spite of the house’s energy use dropping by two-thirds. This is an indicative figure and we give it for illustrative purpose only. In reality the homeowners say their total annual bill has reduced from approximately £1,490 per year to £1,040, as estimated on their latest bill, including all charges. Given that the gas bill pre-retrofit may have included hot water use
and cooking, we haven’t attempted to estimate heating costs pre retrofit. Based on PHPP figures for space heating, and the EST electricity tariffs, the post retrofit heating use is estimated at £437 per year, or £36.42 per month. Airtightness (at 50 Pascals): 0.48 air changes per hour GROUND FLOOR Before: Mix of uninsulated concrete floor and uninsulated suspended timber floor After: Concrete slab insulated with 50 mm PUR insulation. U-value: 0.257 W/m2K. Suspended timber floor with air tightness membrane (Contega Solido) and 80 mm PUR insulation beneath. U-value: 0.166 W/m2K WALLS Before: Render, brick cavity walls After: Permarock external insulation render system comprising render on 100 mm graphite EPS, on existing 100 mm brick cavity walls, 100 mm blown bead insulation into existing cavity, brick inner leaf, plaster parge as airtightness layer. U-value: 0.27 W/m2K ROOF Before: Concrete roof tiles followed beneath by felt, sarking boards, plasterboard ceiling internally. Loft mineral wool insulation. After: Fibre cement slates externally, followed inside by battens/county-battens, existing roof structure and sarking board, 400 mm loft mineral wool insulation between and over ceiling joists and continuous with cavity wall insulation, highly vapour permeable membrane to underside of mineral wool (pro clima Solitex Plus), plasterboard
ceiling with skim finish. U-value: 0.09 W/m2K WINDOW AND DOORS Ultra triple glazed timber windows by Green Building Store. Overall reference U-value of 0.75 W/m2K (the existing GBS windows were repositioned and some new ones installed). Two Lacuna bi-folding doors installed (each including three glazed sections 2.52 m high x 2.2 m wide). Heat treated beech frames, with breathable off-white paint. Ug value: 0.72 W/m2K, Uw 0.90 W/m2K. New Moralt Ferror Passiv Fire Safe door added between utility room and garage (By James Latham). HEATING SYSTEM Before: Gas boiler & radiators throughout entire building After: 1.5 kW Zehnder Road electric panel radiator to open plan living area; one plug-in 1.5 kW radiator in lounge VENTILATION Before: No ventilation system. Reliant on infiltration, chimney and opening of windows for air changes After: Brink Flair 325 heat recovery ventilation system, Passive House Institute certified to have heat recovery rate of 91 per cent. Green materials & features: FSC certified timber, re-use of existing kitchen units in utility room, re-use of some existing sanitaryware, cork flooring in bedrooms, low flow water fixtures, rainwater butts to garden. Electricity: 12.7 m2 solar photovoltaic array.
ph+ | new forest enerphit case study | 51
INSPIRED BY VICTORIAN VILLAS
CASE STUDY
ON WA R D S AND U P WA R D S DEEP RETROFIT AND EXTENSION INSPIRED BY DARTRY’S VICTORIAN VILLAS This Enerphit project in the suburbs of South Dublin has dramatically transformed and extended a dated 1970s dwelling by adding an extra storey, radically reducing its energy consumption and creating a smartly-designed, light filled family home and office. By Jason Walsh
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
IN BRIEF Building: 251 m2 detached home & office Method: External insulation on blockwork Location: Dartry, Dublin Standard: Enerphit (passive house retrofit, certification pending) BER: A3 Heating & hot water bill: €47 per month (to run the compact heat pump for space heating, hot water & ventilation, for a family of six and two home offices. See ‘In detail’ for more)
€47 per month
Aerial photos: Sam Neely
Areas of contrast render colour at ground floor level
EAST ELEVATION
AS BUILT peter nickels architects client: Peter Nickels & Edelle O'Doherty project: The Willows, Sunbury Gardens, Dartry, Dublin 6 wi-s-2c
drawing: Proposed Elevations drawing no: 1312/AB/007
revision:
scale: 1:100 @ A3
SOUTH ELEVATION
The Willows, Sunbury Gardens, Dartry, Dublin 6 e: mail@peternickelsarchitects.ie m: +353 (0) 86 315 8902
date: May 2019 © peter nickels architects
EAST ELEVATION
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
W
hen architect Peter Nickels took on the The Willows project, he was working for the most demanding of clients: himself. This deep retrofit involved partially demolishing a dated 1970s dwelling and replacing it with a modern, energy efficient, and taller building. The Willows was not Nickels’ first refurbishment, but it was an opportunity to put his interest in passive design into practice. “I had refurbished my own home before and I sort of realised fairly soon afterward, within five or six years, that I could have done things differently. In the last ten to 15 years things have changed tremendously in terms of what we’re trying to achieve,” he says. In 2013 Nickels and his wife Edelle O’Doherty bought the house — a two-storey flat-roofed structure in Dartry, Dublin 6 — with the aim of undertaking an extensive renovation. When finished, it would have to serve not only as a home to their family of six, but also as an office for both (Edelle works as a nutritional therapist and functional medicine practitioner). “I thought ‘this is an opportunity to do things properly,” Nickels says. The couple, both widowed and each with two teenage children, had decided to
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bring their two families together. Buying a house to raise the blended family was a huge stepping stone, Nickels says. They had been renting nearby and had seen the house come up for sale, although at first sight it did not appear to be an obvious choice. “It was one of a pair of identical infill houses which had been built in the side garden of a large Victorian redbrick villa. These houses were completely out of scale and character with their surrounding context – to one side was Sunbury Gardens, a Victorian architectural set piece, comprising three-storey redbrick villas, all protected structures, arranged around a formal landscaped garden. To the other side was a 1990s development of three-storey townhouses.” The positive thing about this was the existing house had neither aesthetic nor historical value. “I felt pretty free in the design, because of the age of the building,” Nickels says. “There was nothing precious about it, even though we were right next to these protected structures. Whatever we did was going to make it perform better, function better, and look better.” Nickels received planning permission for the refurb in 2016, but at first the aim wasn’t to go passive. It was only after this
CASE STUDY
that he became an avid reader of Passive House Plus, and subsequently decided to undertake training to become a certified passive house designer. “I designed the scheme and obtained planning permission before undergoing passive house training – so although originally it did embody many of the principles of passive house, the scheme needed to be reviewed and the details re-visited before tendering.” He says this magazine was a big help in finding the right materials and suppliers. “I was looking for passive house performance window systems and external insulation systems, and originally was considering timber frame on the top floor as a lightweight way to extend over the existing structure.”
Nickels was working for the most demanding of clients: himself.
Main photos: Andrew Campion
Technical challenges Angelo Babos, owner of main contractor Leopardstown Construction, says that working for an architect building his own house only had a positive effect on the project. “The only thing I could see different from other jobs in terms of the client being an architect was that he was able to make changes in the layout, finish and location of [things like] electricals,” he says. This does not mean the job was easy, though. In fact, soon into the build major problems requiring remedial work made themselves apparent. “We had to dig out some of the old lobby and found the middle wall and back were not strong enough to put another floor on.” At this point, total demolition was considered. But Nickels says that by now, the importance of limiting the embodied carbon of the build was high on his mind. This guided a lot of the big decisions, such as preserving as much of the existing structure as possible, in spite of the technical challenges. Some of the original walls had have to be rebuilt for structural purposes, and while Nickels originally wanted to specify timber for the second floor, he ended up using
INSPIRED BY VICTORIAN VILLAS
lightweight thermal blocks from Mannok due to concerns over the compatibility of different render systems applied over timber frame and block, and the associated detailing issues. Thankfully, Angelo Babos and his team were not entirely new to passive house construction. “I have done other passive house standard building, a lot of upgrading, especially heat recovery ventilation and Part L compliance,” Babos says. “Because of the changes in regulations over the last few years, architects are keeping an eye on airtightness and upgrading the U-values of walls.” Although retrofitting is increasingly seen as the only way Ireland can, at least in terms of its housing stock, meet its climate targets, Babos says the sheer amount of skilled labour required should not be underestimated. “When you have a retrofit it’s much harder than building from scratch,” he says. “It was very hard to go around and make it airtight, you have weak spots to deal with. That made my life and my lads’ life very hard; we had to put a lot of work in to make it right.” The main airtightness layer was formed by internal plaster on the new walls and exist-
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
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
56 | passivehouseplus.co.uk | issue 39
CASE STUDY
ing plaster on old walls, which needed to be re-done in places. Airtightness tapes from Partel were used to seal junctions, while Blowerproof liquid airtight membrane was applied along door thresholds and where the external walls met the concrete slab (below where plaster could be applied). Babos says that while the job was challenging, the positive side of this is that it was a learning experience, and a better one than you can get in the classroom or workshop. “Next time will be easier as we learned a lot. When I did a course, back in 2013, we brought techniques from the workshop, but that was a workshop not reality. And when you go outside into the world you have to do a lot of research,” he says. Nickels says part of his reasoning in choosing Leopardstown Construction was the need for confidence. “We tendered to builders who had passive house experience and passive house training. Angelo came at it with a very rigorous approach, he was thinking things through, methodologies and so on.” Design for life Clues as to how to extend the dwelling lay in the original design: the house had a central staircase and hall, running east-west, dividing the plan into two equal halves, and the roof was flat. Nickels says: “The obvious design solution was to go up – forming a new stair
over the existing straight stair flight, a new second floor comprising a master bedroom to the north, and a spacious home office on the southern side with views out to the trees and the Dublin mountains. This solution provided the space required, without extending the footprint any closer to surrounding boundaries – and brought the house into scale with the three-storey Victorian houses and the 1990s townhouses.” The decision to build up rather than out also provided another embodied carbon win: it improved the building’s form factor, the surface area from which heat can escape, to such an extent that the house could meet Enerphit, the passive retrofit standard, even without digging up the floor slab. This is despite the fact that there was only 50 mm of insulation underneath. “This is where the use of the PHPP software really came into its own,” Nickels says, “to analyse and inform important and costly decisions like this.” (Some of the slab did ultimately have to be replaced to allow for underpinning of walls.) At first floor level, the simple arrangement of the original house meant that the layout could be re-configured to provide four equally sized bedrooms, which were large enough for double beds and work desks, something that will have proved its value in recent months. “This was the perfect democratic solution for four teenagers studying from home and meant that none of the children had to set-
INSPIRED BY VICTORIAN VILLAS
He became an avid reader of Passive House Plus.
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
THERMAL COMFORT AT THE WILLOWS
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emperature and humidity monitors were fitted in several rooms in the house, as the project was part of the SEAI Deep Energy Retrofit scheme. In the first year post-retrofit, the overall indoor air temperature (as measured by the return air on the Nilan unit) did not rise above the 25 C threshold for overheating specified by PHPP, the passive house design software. The top floor office was prone to localised higher temperatures, as it has a large south-facing window (with shading) and two rooflights (without shading). In practice, this was not a particular problem, as it is a large house and temperature differentials can be eased by leaving internal doors open. In addition, the rooflights can be opened to allow cross ventilation on the top floor. Conversely, the den at ground floor, which is located to the north of the house and has three external walls and a flat roof, does not benefit from solar gain during the day, and has intermittent occupancy. It is therefore regularly cooler than other rooms. This was anticipated at the design stage, and an electrical point was provided here so that an electric convector heater could be added later.
Peter Nickels, architect & homeowner
A HUGE CHANGE IN AIR QUALITY
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1 The southern side of the house prior to renovation; 2-5 much of the external wall on the south elevation at ground floor level was removed and replaced with full height glazing, and the relocated kitchen now feels like part of the garden; 6-8 the masonry walls were insulated externally with graphite enhanced EPS with silicon render finish.
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uring construction, extensive mould growth inside the stud partitions in the kitchen was discovered as a result of water leakage. One family member, who suffers with rhinitis and has a sensitivity to mould, had difficulty with the air quality in this room. But it had not been known that that the issue was within the fabric of the building. The clean filtered air supplied by the Nilan ventilation unit has now resulted in a huge change in indoor air quality for him and for the whole family. In addition to the improvement in air quality, Edelle was particularly keen to avoid the introduction of toxins into the interior of the house. Specifications therefore included Keim mineral paints – which are solvent and chemical free, non-allergenic, odourless and breathable — and Keracoll Cementoflex cement-based resin floor topping, a seamless thin finish with very low volatile organic compound (VOC) emissions that was applied over the floor slabs.
Peter Nickels, architect & homeowner
CASE STUDY
INSPIRED BY VICTORIAN VILLAS
SELECTED PROJECT DETAILS
Clients: Peter Nickels & Edelle O’Doherty Architect: Peter Nickels Architects Main contractor: Leopardstown Construction Structural engineer: Niamh O’Reilly Structural Engineering Heating & ventilation: Nilan Ireland Passive house consultant: Earth Cycle Technologies Quantity surveyors: FMMP Electrical contractor: John Bombu Electrical Airtightness tester: Building Envelope Technologies External wall insulation system: Atlas Aval EPS insulation: Thermotech Thermal breaks: Partel Thermal blocks: Mannok Low thermal conductivity structural fixings: Schoeck, via Contech Accessories Roof insulation: Saint-Gobain Additional roof insulation: Gutex, via Ecological Building Systems Floor insulation: Xtratherm Airtightness tapes: Partel Liquid airtight membrane: Blowerproof Ireland Windows & doors: Viking, via Prestige Aluclad Roof lights: Fakro Cement fibre cladding: Cembrit Ireland Resign floor topping: Keracoll Cementoflex, via Stone Seal Roof slates: Tegral Warm roof system: Moy Materials Solar PV: Sunpower Ventilation installation: Allied Air Conditioning Eco paints: Keim, via McConnell Coatings
tle for a tiny ‘box room’ – which is a typical issue in many existing house types,” Nickels says. At ground floor, the existing plan again made it very simple to swap the kitchen and living room, with the kitchen relocated to the southern side of the house where it has views out to the garden, whilst the living room was moved to the north side, with a large west-facing window, where it is bright in the evening. Much of the external wall on the south elevation at ground floor level was removed and replaced with full height glazing, so the kitchen feels like part of the garden, and the movement of the sun around the house throughout the day can be fully experienced. With the addition of the extra floor and steeply pitched roof, the house is now much
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Airtightness works included 1 use of blowerproof liquid airtight paint, seen here at the wall-to-floor junction; 2 & 3 use of airtightness membrane behind joist ends and partition walls; 4 Partel Izoperm membrane behind service cavity battens to the roof; and 5 Partel Conexo tape around window frames; meanwhile thermal bridging measures included 6 Schoeck Isokorb thermal breaks; 7 & 8 and Partel Alma Vert structural insulation (seen here in green).
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
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CASE STUDY
INSPIRED BY VICTORIAN VILLAS
EMBODIED CARBON
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he building’s embodied CO2e emissions were calculated by John Butler using PHribbon, resulting in a cradle to grave figure of 79.1t CO2e, or 282 kg CO2e /m2 GIA when calculated in accordance with the RIBA 2030 Climate Challenge. The biggest element of this total was the external walls – including new and retrofitted walls (22.6t CO2e), followed by the solar PV array (15.4t), a new roof system (8.6t), building services (6.1t), windows, doors and roof windows (6.1t), the steel frame (6t), and demolition (5.8t). Sixty-year lifespans were assumed for all building fabric, excluding the flat roof system, where 30 years was assumed, and 40 years for the render system, based on the Atlas Aval NSAI Agrément certif-
icate. The PV array and compact heat pump were assumed to have 30-year and 20-year lifespans respectively, with the ductwork assumed to last for 60 years. Where Environmental Product Declarations (EPD) were not available for the exact product, data from equivalent products was used (e.g., from the closest matched Product Environmental Passports for a heat pump and EPD for a different EWI system), or emissions are based on emissions for the component materials (e.g., window frames and ventilation ducting). In all 69 per cent of materials mass and 82 per cent of lifecycle stage A-C material emissions are accounted for by EPD data and 18 per cent by reference values (mainly from the ICE database).
3 1 The roof features three Fakro quadruple glazed timber aluclad roof lights, while the new roof finishes include 2 fibre cement slates to the pitched sections; and 3 bituminous membrane on the flat.
more visible from the street. But the increased scale and massing fits much better alongside the Victorian villas that inspired the house’s design. Their influence is reflected in features such as the prominent street-facing gable and the grouping of windows at first and second floor level (with brise soleil for shading). An existing mature pear tree was also retained to provide summer shading to the south elevation. The merging of passive principles, aesthetics and meeting the needs of a modern family — all things missing from many mass-produced houses — should be the logical outcome of the reality of construction, Nickels says: it should all be right. “There’s so much money invested in construction that you have to succeed on all fronts. Reducing embodied and operational energy is obviously critical to all building projects now, but as an architect the challenge is not just to incorporate these requirements but to use them to inform and help generate a contemporary design aesthetic.” Though it seems unlikely that he would settle for a standard house, Nickels said the pressure created by the surrounding context helped. “There was a real challenge, being surrounded by historic red brick houses, to make a low energy, contemporary design work.” Additional words by Peter Nickels
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INSPIRED BY VICTORIAN VILLAS
CASE STUDY
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CASE STUDY
INSPIRED BY VICTORIAN VILLAS
IN DETAIL Building type: Detached 251 m2 (TFA) home, created from the retrofit of 179 m2 1970s dwelling. Site & location: Urban site, Dartry, Dublin 6 Budget: Not disclosed Completion date: September 2020 Passive house certification: Pre-submission for Enerphit certification Number of occupants: 6 BER Before: D2 (295.2 kWh/m2/yr) After: A3 BER (54.16 kWh/m2/yr) PHPP Space heating demand: 24.6 kWh/m2/yr Heat load: 13 W/m2 Primary energy demand: 94 kWh/m2/yr Heat loss form factor: 1.16 Overheating: 2 per cent of hours above 25C Energy performance coefficient (EPC): 0.431 Carbon performance coefficient (CPC): 0.401 MEASURED ENERGY CONSUMPTION Before: 132 kWh/m2/yr (January to December 2018 inclusive, all energy use, gas & electricity) After: 33.76 kWh/m2/yr (September 2020 to August 2021 inclusive, all energy use, all electricity) ENERGY BILLS Before: €2,500 on gas and electricity for all of 2018. After: €1,294 on electricity (September 2020 to August 2021 inclusive). Includes all energy use. This period included lockdowns when the house was fully occupied with six people working/ studying from home. The measured energy consumption for the Nilan Compact P heating & ventilation unit between September 2020 and January 2021 inclusive (1,811 kWh total), which we have estimated (and likely overestimated) to increase to a total of 3,644 kWh over 12 months. Bonkers.ie suggests a cheapest available bill of €567/year or €47 per month to run the heat pump for space heating, hot water and ventilation – for a family of six and two home offices, and with higher-than-normal occupancy due to the pandemic. The heat pump energy use figures include VAT but exclude standing charges & PSO levy, as these charges apply for any dwelling with an electricity connection. This also assumes no contribution from the PV array to power the heat pump. Summer heat pump data was not available due to IT issues. AIRTIGHTNESS (AT 50 PASCALS) Before: 11.32 (m3/hr)/m2
After: 0.98 (m3/hr)/m2 GROUND FLOOR Original floor (before): Generally, 150 mm concrete floor slab on 50 mm PIR insulation. U-value: 0.488 W/m2K. Original extension floor: 150 mm concrete floor slab on 25 mm EPS insulation. U-value: 1.078 W/m2K Original floor (after): Existing floor build up retained generally. Approx 25 per cent of slab replaced where required by underpinning works. Upgraded floor build up: 150 mm concrete slab on 100 mm PIR insulation U-value: 0.261 W/m2K New extension ground floor: 150 mm concrete slab on 150 mm PIR insulation. U-value: 0.141 W/m2K WALLS Original walls (before): 103 mm brick outer leaf followed inside by 100 mm cavity filled with EPS blown bead, 100 mm concrete block inner leaf, 13 mm plaster. U-value: 0.335 W/m2K Original walls (after): 120 mm or 140 mm graphite enhanced EPS insulation with silicon render finish externally, over existing cavity wall build up as above. U-value: 0.146 W/m2K or 0.133 W/m2K New extension walls: 200 mm or 220 mm (depending on location) graphite enhanced EPS insulation with silicon render finish, over 200 mm Quinn Lite (Mannok) standard blocks laid on flat, 13 mm plaster internal finish to form airtightness layer. U-value: 0.138 W/m2K or 0.128 W/m2K ROOF Original roof (before): Flat roof, bituminous roofing felt on 18 mm plywood, followed underneath by timber firring pieces, and timber joists with approx 175 mm mineral wool insulation between joists, 13 mm plasterboard internal ceiling finish. U-value: 0.190 W/m2K New flat roof over den (retaining original roof structure): Bituminous roof membrane on 200 mm Xtratherm PIR insulation, on 18 mm OSB3 deck laid to falls, over timber firring pieces and 175 mm deep existing timber joists; Isover Metac mineral fibre insulation between joists (average depth 325 mm), on Partel Izoperm airtightness/ VCL membrane below joists, 50 mm battens to form service cavity below joists, 13 mm plasterboard internal ceiling finish. U-value: 0.071 W/m2K Extension pitched roof: Fibre cement roof slates, on 50 mm counter battens, 50 mm battens to form ventilated air space and breather membrane; on 35 mm Gutex Multiplex Top wood fibre board insulation laid over 200 mm deep timber rafters; Isover Metac mineral fibre insulation between rafters, on Partel Izoperm airtightness/VCL membrane below rafters, on 50 mm battens to form service cavity below rafter with 50 mm mineral fibre insulation within cavity, on 13 mm plasterboard internal
ceiling finish. U-value: 0.145 W/m2K Extension flat roof (over utility room): Bituminous roof membrane on 200 mm Xtratherm PIR insulation, on 18 mm OSB3 deck laid to falls, Partel Izoperm airtightness/ VCL membrane above joists, over timber firring pieces and 175 mm deep timber joists, 13 mm plasterboard internal ceiling finish. U-value: 0.113 W/m2K WINDOWS & DOORS Before: Mixture of double glazed PVC, aluminium and timber windows, solid timber front door. Overall approximate U-value: 3.50 W/m2K New windows: Viking DK88 triple glazed windows. Timber frames at first & second floor, timber aluclad at ground floor. Argon-filled, with two low-E glasses (Planitherm One) and SGG Swisspacer Ultimate warm edge solution. Average whole house U-value 0.80 W/m2K New pitched roof windows: Fakro FTT U8 Thermo quadruple glazed timber aluclad roof light. Overall window U-value 0.58 W/m2K New flat roof windows: Fakro DXF DU6 non-opening triple glazed roof light with multi chamber PVC kerb profile. Overall window U-value 0.70 W/m2K HEATING & VENTILATION Before: Gas fired back boiler with low temperature hot water radiators and 2 x gas fires. Natural ventilation through hit & miss wall vents. No mechanical ventilation to kitchen or bathrooms. After: Warm air distribution from the Nilan Compact P XL combined heating & ventilation unit. Passive House Institute certified to have heat recovery efficiency rate of 80 per cent. The Compact P unit uses the return air heat exchanger to pre-heat supply air being distributed to the house, and for hot water with its integral DHW tank. Space heating supplemented by three Dimplex Girona electric panel convector heaters, located in circulation areas. The electric heaters are controlled by the Nilan unit and only switched on when the return air temperature for the whole house falls below the temperature designated by the user on the Nilan unit. In addition, a supplementary buffer hot water tank is pre-heated (when excess solar PV production allows) and raises the water temperature to the Nilan unit to reduce energy consumption. Green materials & measures: Keim EcoSil mineral paint (solvent free, non-allergenic, odourless and breathable); Partel Alma Vert thermal break (made from recycled PET material); Keracoll Cementoflex cement-based resin floor topping. Electricity: 10 square metre Sunpower solar photovoltaic array with average annual output of 2.34kWh. Surplus electricity generated is diverted to the hot water buffer tank. Point provided for future electric vehicle charger.
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INSIGHT
SEEING THE WOOD FOR THE TRE E S
PLACING ECOLOGY AT THE HEART OF CONSTRUCTION In recent years, as energy efficiency targets for new buildings have tightened, attention has turned to cutting the embodied carbon of buildings by switching from materials like concrete and steel to lower carbon alternatives like timber. But if we are serious about solving the ecological emergency as well as stabilising the climate, we must look even further than embodied carbon, and think more deeply about the core values we apply to materials and buildings, and the manner in which we use them. By Lenny Antonelli & AECB CEO Andy Simmonds
O
n 30 May 2019, British architects Steve Tompkins and Michael Pawlyn launched the Architects Declare pledge, now widely shared in the industry, which states that, “the twin crises of climate breakdown and biodiversity loss are the most serious issues of our time.” It continues: “For everyone working in the construction industry, meeting the needs of our society without breaching the earth’s ecological boundaries will demand a paradigm shift in our behaviour. Together with our clients, we will need to commission and design buildings, cities and infrastructures as indivisible components of a larger, constantly regenerating and self-sustaining system.” Since spreading to become the wider
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#ConstructionDeclares and #BuiltEnvironmentDeclares pledges, it has been signed by almost 7,000 companies across the global building industry. The first issue addressed in the pledge, climate breakdown, is an ever-growing focus for the construction sector — as evidenced by tightening energy efficiency regulations for new buildings, the growth of standards like passive house, and the more recent push to measure and limit embodied carbon. But the second issue, the biodiversity emergency, still remains largely unaddressed by the industry. What is the biodiversity emergency? The ecological crisis is just as immediate as the climate crisis. Global populations of
vertebrate animals have declined by an average of 60 per cent since 1970. Just three per cent of global land ecosystems remain intact, while the world’s total mass of insects is falling by a rate of about 2.5 per cent annually, threatening a collapse of nature, scientists say. Destruction of primary rainforest is also accelerating, and the Amazon rainforest is nearing a point of irrevocably switching from canopy rainforest to open grassland (see passivehouseplus.ie & passivehouseplus.co.uk for a referenced version of this article). If climate change has been a rather nebulous concept, ecological collapse is arguably more so. It is happening all around us, yet is easy to miss because we are so disconnected from nature. It also challenges the idea that
INSIGHT
CHART 1.C: CARBON REDUCTION CURVE
(above) Hierarchy of ways to reduce the carbon footprint of construction. Source: HM Treasury (2013) and Green Construction Board (2013).
we can ‘fix’ environmental crises through technological solutions, instead requiring a complete reinvention of our relationship with food, materials, and the rest of the living world. Knowing how to respond effectively to ecological collapse is difficult from within a technological and growth-based mindset. But just like reducing our consumption of meat and dairy, which generally require more land than plant-based foods and thus put greater pressure on natural habitats, we can also seek to limit the area of land, and the quantity of raw natural resources, required to produce and maintain our buildings. We can also explore specifying materials that are, or could be, produced as integrated by-products of healthy ecosystems. Half Earth The importance of simply setting aside more land for nature, free of extractive human use, should not be underestimated. It is perhaps best exemplified by the ‘Half Earth’ idea devised by EO Wilson, the great evolutionary biologist, which proposes setting aside half the planet for nature. Wilson was one of the developers of island biogeography theory, one of the most important ideas in twentieth century ecology. This states that the smaller an island of habitat is — think a natural forest surrounded by monocultures of wheat — and the further it is from other habitat islands, the fewer species it will support. “When 90 per cent of habitat is removed, the number of species that can persist sustainably will descend to about a half,” Wilson’s project website, half-earthproject.org, states. “If on the other hand, we protect half the global surface, the fraction of species
protected will be 85 per cent, or more. At one-half and above, life on earth enters the safe zone.” Wilson’s Half Earth idea has captured the imagination of many, but also been criticised by those questioning whether, if deployed, it could lead to the displacement of poorer people in the majority world. One study concluded that one billion people live in areas that the project has earmarked for protection and restoration. How they would be affected depends on the type of management envisioned for these areas. Whatever its flaws, the Half Earth idea does at least make clear the scale of action needed to restore the earth’s living systems. Half Earth also has an important principle at its heart: that we share the planet with other species, and that we might seek to limit our own footprint to make space for them. Ecological restoration must now be at the heart of everything we do, including construction. And it cannot just focus on the world’s last remaining biodiversity hotspots in the tropics. If we expect developing nations to save their last wild habitats in the interests of a stable biosphere, we must lead by example and restore our own depleted ecosystems here in western Europe. Embodied carbon: just the beginning As the building industry seeks to lower its carbon footprint, it has increasingly looked to timber as an alternative to materials like plastics, fired clay, concrete and steel. As well as causing less pollution in manufacture, timber-based products can be sourced from well-managed forests and woodlands, which draw down carbon as they grow. This atmospheric carbon is sequestered in the tissues of trees’ roots, trunks, branches, and
ECOLOGY IN CONSTRUCTION
leaves. The current thinking in our industry is that where timber extraction from a forest is managed in a sustainable manner, under the various certification schemes, that growing trees for long-term uses such as construction can ‘be good for the climate’. Construction timber is of particular interest in climate conversations because of its longevity: carbon in shorter-lifespan products, such as pulp, paper, pallets, woodchip and fencing, is generally returned to the atmosphere much sooner. Venerable research bodies, including the Intergovernmental Panel on Climate Change (IPCC), the Royal Society, the Potsdam Institute, and the Committee on Climate Change (CCC) have endorsed strategies of using more timber in the built environment. However, switching from energy and carbon intensive materials to timber and other natural fibres must be just the starting point, rather than the end point, of our journey to explore ever more ecological ways of creating and refurbishing buildings. Beyond the concepts of ‘up front’ and ‘embodied’ carbon, we must develop our understanding of the land-footprint of the resources we use, and their wider impact on the living world. While Environmental Product Declarations (EPDs) now thankfully provide us with a lot more information about the environmental impact of construction products — including climate warming, acidification, eutrophication and resource depletion — they do not yet include any specific metric for biodiversity loss, a difficult parameter to measure and present meaningfully. (An impending update to how EPDs are calculated, however, will introduce a requirement to include carbon emissions resulting from direct land use change in a product’s life cycle. It will also remove the ability to claim carbon sequestration if wood is sourced from a native forest not otherwise managed for timber extraction). Restoring flourishing ecosystems while transitioning from a growth-driven economy to an equitable circular and sustainable society — one that works within the planet’s ecological limits — is an urgent task, yet it is also a job that will take decades. For a safe climate, and the restoration of nature, we will need many years of social, natural and economic rehabilitation — along,
Use natural resources extracted from our shared biosphere respectfully and efficiently.
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mostly likely, with periods of fossil fuel “cold turkey”. This presents humanity with our greatest creative challenge. Rising to it is not a chore but potentially our best opportunity in half a century for a renewed sense of meaning and purpose. Our industry’s immediate tasks include radically reducing the operational and embodied energy of all construction. In addition, we are likely to have to fully decommission some of our most polluting infrastructure, salvaging what we can from the dismantling. The fossil fuel valves must be turned down each year, and will have to be almost completely closed within a decade to avoid the nightmare of a world with more than 1.5 C of warming. The reality is that we also need to minimise the area of land and the quantity of raw natural resources required to produce our buildings. And while material substitution — replacing high embodied carbon materials with lower embodied carbon ones — is important, it will never be sufficient within a growth-driven system. And it is not more important than fundamental measures such as building less and building more modestly, prioritising the retrofit of existing infrastructure, developing a genuine circular economy for building materials, and creating low land-use, zero-carbon construction materials. This is the essence of the challenge facing us: we need to use human ingenuity and our inherent ability to cooperate to do more with less, in order to live safely within the ecological limits of the Earth. We suggest the following framework of principles to guide building design, and selection of materials. 1. Sufficiency Before building something, we should start by asking if it is really needed, and if there any strategic alternatives to the brief. Discuss this early, once you have your client’s trust. Prepare and signal your ‘sophisticated sufficiency’ arguments in advance and market them cleverly. Can existing structures be reused first or retrofitted first before creating something new? We encourage everyone to critically examine claims about the need for new buildings, particularly when a project seems to be designed simply to provide a return on capital, rather than benefitting people or nature. Even if we replace polluting materials with “greener” ones, we will not solve the ecological crisis if growth, profit and inequality remain the dominant values in our society and economy. In its 2019 report on tackling the UK housing crisis, the UK Collaborative Centre for Housing Evidence concluded that the goal of building 300,000 new homes annually in the UK would not lead to a significant drop in prices, but would lead to more
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(above) The Doughnut Economics framework, which aims to ensure the basic needs of all people are met while not exceeding the earth’s environmental capacity, can be used to help guide decisions on when new construction is needed.
empty homes. A report from the think tank Green House reached similar conclusions. This is not to say that new construction is never required, sometimes even on a significant scale, but such claims must be critically scrutinised. We suggest employing the Doughnut Economics framework of ensuring the basic needs of all people are met, while not exceeding the earth’s environmental carrying capacity, to ensure all development remains within the ‘safe and just space’ for humanity. This framework will become increasingly important as we seek to meets the material needs of all people, and improve living standards for those in the majority world, while restoring the biosphere. 2. Simplicity Designing and building as simply as possible — true value engineering or “integrated design”. Asking: can this building be made simpler and more modest? Can the building be smaller or use less materials through innovative engineering approaches? 3. Circular economy Explore circular design approaches. Design realistically for reuse and disassembly, be open about your assumptions for the endof-life stage of buildings and products, in order to facilitate wider discussion and development. Design buildings to last a long
time, or at the very least, to be easily disassembled and their parts easily reused. For example, can insulation and other materials be easily separated, with significant value retained, and be reused or repurposed at the end of the building’s life? At the very least design and build to facilitate easy recycling — incineration for energy should be the very last resort. 4. Efficiency – only take what you need Use natural resources extracted from our shared biosphere respectfully and efficiently to substitute for higher embodied carbon materials. Use as few materials as possible to achieve the design. Using a “renewable” material inefficiently, whether to ‘develop the market’ or ‘store carbon’ is wrongheaded – efficient use of the same quantity of material, substituting for higher carbon options across many projects, makes far more sense. The latest State of Europe’s Forests report, by the pan-European body Forest Europe, says that European forests are expanding, storing carbon, and supplying wood on a “sustainable basis”. The area of forest in Europe has increased by 9 per cent over the last 30 years and the amount of carbon it stores has grown by half in that time. The forest area protected for biodiversity stands at 24 per cent and growing. But the report warns that threats associated with global heating — droughts, heat-waves, bark-beetle out-
INSIGHT
ECOLOGY IN CONSTRUCTION
The new systems view of life should form the conceptual framework for how we view materials derived from the natural world
(above) Recent analysis, though the subject of much debate, suggests that the size of forest clear-cuts in Europe increased by approximately 30 per cent from the period 2011-2015 to 2016-2018.
breaks, and forest fires — are now a major risk. It says there is a limit to the capacity of forests to respond to increased demand for wood products, carbon sequestration, and other functions. Demand for biomass for energy and materials has grown in Europe since 2000, and over 70 per cent of this comes from forestry (growth of bioenergy has been particularly rapid, to meet renewable energy targets), According to a recent report from the consultancy Material Economics, by 2050 demand for biomass in the EU 27 and UK will exceed available supply by 40 to 70 per cent. Recent analysis, though the subject of intense debate, suggests that the size of forest clear-cuts in Europe increased by approximately 30 per cent from the period 2011-2015 to 2016-2018. The rate of afforestation is also slowing, and the European Commission’s latest State of Nature report, published last year, says that: “the increased extraction of forest products and intensified forestry practices have diverse impacts on the various habitats and species protected under the nature directives.” It also says: “Over the last few centuries, forests managed to varying degrees of intensity have replaced almost all of Europe’s natural forests. Currently, less than one third of Europe’s forests are uneven-aged, 30 per cent have only one tree species (mainly conifers), 51 per cent have only two to three tree species, and only 5 per cent of forests have six or more tree species.” One major 2018 study of forests across northern Europe concluded that, in general, the more efficiently a forest produces wood, the less effective it as at conserving biodiversity. In Sweden, natural forests are being systematically clear-cut and replaced with even-aged plantations, according to five environmental NGOs. Recent logging of protected forests has also been reported in Estonia, Lithuania, and Romania. And with
(above) The UK and Ireland are among the least forested countries in Europe, meaning there is potential for new forests of all types, from ecologically-minded timber production to those purely set aside for nature. See the ‘Home Grown Homes’ programme delivered Wood Knowledge Wales for an example of a project that has aimed to develop a market for locally grown construction timber.
Image source: European Environment Agency
extractive demand on land increasing, nature is more at risk of being squeezed out. So, while supporting a move from concrete and steel to timber and other natural fibres, our primary goal should be to dramatically reduce the quantity of raw materials needed in the first place. When specifying timber or other natural materials, how efficiently they are used can minimise the pressure on landscapes. As well as prioritising reclaimed or recycled materials where possible, smart choice of build system matters too.
For example, when comparing types of timber construction, one recent review concluded: “For buildings up to about six storeys, CLT uses substantially more timber to achieve the same function as a light timber frame building. For buildings over six stories, the use of CLT together with light timber frame may use less timber than CLT alone, and for buildings taller than ten stories, the only proven system to date is the external glulam frame supporting internal CLT units.” Exploring the use of DLT (dowel laminated timber) as a glue-free
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alternative to CLT also offers potential for improving on ‘mass timber’ practice. Reducing our use of biomass-based fuels (in favour of energy efficiency and cleaner renewables) and of shorter-lived forest products (through efficiency, recycling and making do with less, rather than by replacing them with plastic) might allow us to use a greater proportion of our forests for long-lasting construction timber. In the UK and Ireland, which have some of the lowest tree cover in Europe, there is no doubt room for more forests of all types, both for ecologically-minded timber production, and to be set aside for nature. There may also be potential for designers, foresters, and ecologists to explore together the potential for under-utilised forestry products that could be harvested sustainably, such as forestry wastes, lower grade timber, small diameter trees removed during thinning, coppiced poles, and bamboo, reeds, and grasses. (We would like to see much closer collaboration between the building industry and ecologists in general).
phors of western civilisation — one that has now ultimately expressed itself in all manner of ecological destruction. “The approach to the natural world encouraged by reductionist thinking—conquering nature and nature as machine — has created imbalances that are becoming increasingly unstable. As we peer into the future, the threat of uncontrolled climate change looms, in addition to other impending global crises such as deforestation, freshwater scarcity, and an accelerated extinction of species.” It would be a mistake to view whole land-
scapes, crops, trees, forests, or natural materials purely as a machine for human utility — whether the function of that machine to be provide food, building materials, or carbon sequestration. Lent calls for a new worldview, “based on the emerging systems view of life—recognizing the intrinsic interconnectedness between all forms of life on earth and seeing humanity as embedded integrally within the natural world.” This new systems view should form the conceptual framework for how we view materials derived from the natural world.
5. Upskill, measure the carbon, be honest Measure embodied carbon as transparently and accurately as possible, along with embodied energy. Be open and transparent. Quantify carbon emissions and stored carbon clearly and separately rather than combining them into one figure. 6. Become a systems thinker In his profound and influential book, The Patterning Instinct, the systems thinker Jeremy Lent outlines in painstaking detail how the metaphor of nature as a machine to be engineered, rather than something living and animate, became one of the root meta-
(above) The density of structural timber used to achieve a given height of building for various structural systems.
Source: ‘The wood from the trees: the use of timber in construction’, Renewable and Sustainable Energy Reviews, Volume 68, Part 1, February 2017, Pages 333-359.
Spruce forest affected by bark beetle outbreak in the Harz, Germany.
Source: Fährtenleser (CC BY-SA 4.0) 68 | passivehouseplus.co.uk | issue 39
INSIGHT
ECOLOGY IN CONSTRUCTION
“All construction is likely to warm the climate”
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Source: Lilly M (CC BY-SA 3.0) (above) Białowieza, one of Europe’s last large remaining tracts of old growth forest; (top) the Glengarriff Valley in County Cork harbours some of the most extensive woodland in Ireland, with a core of ancient oak forest surrounded by naturally regenerating native woodland and areas of conifer plantation.
7. Connect with the forest Of course, make sure your wood is properly certified. But if any of it is locally grown, can you visit and build a connection with the forest where it grew, and with the people who grew and processed it? What can you learn about environmental issues and forest management in the regions it is sourced from? Can you specify wood from forests where managers are actively practicing ‘close to nature’ forestry or engaging in ecological restoration? (see for example www. prosilva.org). The future of building materials Ultimately, we should not view timber as the end-game for ecological construction materials either. Natural materials such as
straw, mud and hemp — long overlooked — are worthy of much further research and market development. And in the future, innovative factory-based biotechnologies using bacteria and fungi could allow us to produce buildings using far less land and resources. Scientists have already used E.coli to produce both limestone and styrene, the chemical used to make polystyrene, one of the most common insulation materials. Cyanobacteria have also been used to grow a bio-based structural building material. Building materials based on fungi also have the potential to create safe, low carbon materials that sequester carbon using agricultural and industrial wastes, though there is still a long way to go for these technologies.
n insightful paper published earlier this year that uses dynamic life cycle assessment to compare the climate impact of concrete, steel and timber buildings, concludes with a warning that “any form of construction is likely to warm the climate”. The authors, all experts in the fields of sustainable engineering and energy, state that the primary aim of the construction sector should now be to “avoid new construction unless the societal benefits are clearly justified”. The paper says widespread adoption of timber over steel and concrete in buildings can substantially reduce — but not eliminate — climate impacts, provided the timber is from sustainably managed forests. It also adds: “This raises the question of resource availability: what are the wider potential impacts of increased timber demand? Planting new forest may be appropriate in some locations, but competing land demands for food production, urban space and biodiversity should not be overlooked.” It notes that many developing countries, where most new construction is anticipated, are those where sustainable timber supplies are under most pressure. It calls for researchers and designers to work more closely with forest managers to develop timber buildings and supply chains that are responsive to the sustainable management of local forests. The paper also says: “The climate benefits of timber components improve the longer that their stored biogenic carbon is prevented from re-entering the atmosphere. Structural engineers should therefore exert whatever influence they can to maximise longevity of building structures and create opportunities for reuse, whilst also reusing existing buildings wherever possible.” The paper, ‘Embodied carbon assessment using a dynamic climate model: Case-study comparison of a concrete, steel and timber building structure’ is published in Volume 33 of the journal Structures.
This article was funded by the Association for Environment Conscious Building. A fully referenced version can be found online at passivehouseplus.ie & passivehouseplus.co.uk.
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MARKETPLACE
PASSIVE HOUSE+
Marketplace News New Brink Flair 225 MVHR unit launched
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he new Brink Flair 225 heat recovery ventilation unit from Brink Climate Systems has officially been released. According to Brink it comes with some “exciting” technologies including highly efficient EC constant flow fans, fitted with rotating vane anemometers, TFT colour touchscreen for easy programming, 100 per cent bypass, guided vanes for equal airflow over the whole heat exchanger, condensate connection, with special ball syphon included and a pre-heater with a larger surface and new aerodynamic design. This passive house certified unit is available from CVC Systems (recently rebranded from CVC Direct), Brink’s official UK supplier. Brink Climate Systems has used constant flow fans in its MVHR units since 1990 and employs software that monitors changes to airflow in its systems. This adjusts the fan speeds accordingly, ensuring that the dwelling is ventilated at the correct rate, with the fans working at optimum efficiency and airflows equally balanced. The constant flow fans in the Brink Flair 225 MVHR unit have been manufactured to Brink’s specifications and provide an accurate
control of the airflow. This is achieved using an anemometer fitted to the discharge tube of each fan which enables a fast and very precise response to airflow requirements. The integrated digital programmer enables a system to be commissioned easily, with balanced airflows (as an unbalanced system can swiftly lose thermal efficiency, and cause pressure differences between the internal and external environments). The Brink Flair 225 includes the same proven heat exchanger used on the rest of the Flair family with vanes guiding the airflow over the whole surface area of the heat exchanger. This design feature provides a laminar airflow to the heat exchanger, giving an even distribution of air through the heat exchanger for higher thermal efficiency and lower pressure loss (Pa). The Brink Flair 225 is tested and listed on SAP Appendix Q and is certified by the Passive House Institute. CVC Systems is the sole UK supplier of Brink passive house-certified products. See their new website at www. cvcsystems.co.uk. • (left) The new Brink Flair 225.
Heat pumps still best way to cut heating emissions – Mitsubishi
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espite recent focus on the launch of the UK’s hydrogen strategy, heat pumps are still the most logical technology for cutting carbon emissions from home heating appliances, according to Mitsubishi Electric UK. “Heat pumps are here now, and they offer a viable solution to heating our homes in a low carbon way that will help tackle climate change,” said Max Haliwell, communications manager at Mitsubishi Electric. “The UK was the first major country to make it law that greenhouse gas emissions will be net-zero by 2050. When you consider 15 per cent of our total emissions comes from heating our homes, it’s easy to see why this is a major focus. “To help achieve this, the government has announced that it is banning gas and oil-fired boilers in all new build homes from 2025. And this is where heat pumps can really help. The gas and oil lobby are fighting to show that they can remain viable in a low carbon economy, and heat
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pumps are a real threat to their dominance in the heating industry. It’s also worth noting [that] those parties pushing hydrogen as part of the solution also seem to be running an ‘anti-heat pump’ message. “Yet there remain questions about the carbon intensive production needed for this hydrogen technology and, if it can work on the scale needed, it’s at least 10 years away – we simply don’t have the time to wait around.” Haliwell said that the Heat Pump Association has set up a new programme to help train up to 40,000 installers each year, and Mitsubishi Electric said it has also introduced online learning to make training “easier, cheaper and more accessible to everyone.” “Heat pumps are still more expensive than gas boilers, but gas has been the dominant method of heating our homes for over 70 years,” Haliwell said. “Heat pumps have been around just over a decade fitting in around 40,000 properties. The
sooner we grow the number of installers and produce ten times more heat pumps a year, then the costs will come down for installation. “Whilst it’s true that a heat pump will work most effectively in a highly insulated property, they can work well in even the most basic of homes. So, regardless of any plans the government may or may not have to help improve insulation in homes, heat pumps do offer a viable alternative.” For more information see www.ecodan. co.uk. •
PASSIVE HOUSE+
Building sector must take the lead on embodied carbon
MARKETPLACE
Efficient ventilation key to healthier indoor spaces – Partel
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espite disappointment in the green building sector at the government’s failure to address embodied carbon in the Future Buildings Standard, the industry possesses the knowledge, skills and supply chain to take matters into its own hands and start drastically cutting embodied carbon right now. That’s according to leading sustainable building supplier Ecomerchant and the Architects Climate Action Network (ACAN). “It’s tempting to think that there might be a council of despair and disappointment, but that most certainly isn’t the case within the industry itself…. There already exists a vast body of knowledge that has been built-up aimed at reducing industry’s reliance on fossil fuels,” write Ecomerchant and ACAN in a joint blog post published at www.ecomerchant.co.uk. “Each individual, whether they be a homeowner, specifier, investor or construction professional, has the agency to make decisions to decrease embodied carbon,” write the authors. “After all, while operational emissions can be reduced over time with building energy efficiency renovations and the use of renewable energy, embodied carbon emissions are locked in place as soon as a building is built or refurbished.” The authors then present a range of steps that those in the industry can take to cut embodied carbon on their own projects. These include: • U se materials that have low embodied carbon. Natural products, timber, wool, straw, hemp etc can act as a carbon store and are often manufactured using a low or renewable energy source. • Optimising the life cycle impacts for anything less than a 60-year span is not worthwhile. The management and control of moisture in buildings is critical to their longevity. The building fabric is prone to decay if the structure becomes damp. Natural materials are breathable and offer a good solution to dealing with moisture. • Build in flexibility. This may be addressed by creating a building that is either highly adaptable or with elements that can be reconfigured or reused. • Think about real costs. Cheap now can be expensive later as you need to replace or repair more frequently, adding to your operational costs. Every time you replace or refurbish a material, you add carbon emissions to your building account. Invest in durable materials. • Use multi-functional elements. For example, timber and straw modular systems can offer structure as well as excellent acoustic and thermal insulation, • Value life cycle assessments (LCAs) and environmental product declarations (EPDs) for measuring the carbon footprint and environmental impact of buildings and their constituent materials. To read the full article visit www.ecomerchant.co.uk.
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artel, specialist in developing sustainable building envelope materials, is aiming to raise awareness of the key role of efficient ventilation for safer and healthier indoor living spaces. The company recently ran a campaign titled ‘Breathe healthy with efficient Lunos ventilation.’ During the pandemic, the World Health Organisation has recommended a ventilation rate of ten litres per second per person in both residential and non-residential settings, or sixty litres (or six air changes) in healthcare facilities. “We’re gratified to have been able to play our part in educating and informing business owners and homeowners about the critical role of adequate ventilation,” said Hugh Whiriskey, founder and technical director at Partel. “Ventilation not only enhances human health and comfort by improving indoor air quality and reducing the impact of airborne viruses, but it also controls humidity and protects the structural integrity of buildings.” There has been particular focus on improving ventilation in schools to prevent the spread of Covid-19, with CO2 monitors being supplied to schools across the country so that teachers can monitor indoor air quality (IAQ). While welcoming this move, Partel technical consultant Dara McGowan said that it is only through efficient mechanical ventilation that schools can guarantee a supply of fresh air while keeping staff and students comfortable. “First, window-opening alone is too crude a measure to provide adequate ventilation for indoor air quality while minimising energy demand, and second, it will cause discomfort for students.” He continued: “A continuous mechanical extract (CMEV) system, or a mechanical ventilation system with heat recovery capabilities (MVHR) is a much more effective way of providing excellent IAQ while maintaining occupant comfort. “Decentralised MVHR is one of the most common ventilation strategies in central Europe and is what makes Partel’s Lunos system somewhat unique in the UK and Irish market. Decentralised ventilation negates the need for a large central ventilation unit, instead using smaller individual units which are installed in the wall of each room.” “Lunos Nexxt units are constantly supplying fresh air and extracting stale air, increasing the air change rate in the room. These units have been specifically designed for large spaces, such as classrooms, and are capable of up to thirty litres per unit, meaning three units would provide enough fresh air for approximately thirty students. And unlike common purge ventilation techniques, the Lunos system can maintain a comfortable temperature in classrooms.” Partel’s technical design specialists can calculate an appropriate ventilation rate for any type of project. This service is often available free of charge as part of the company’s technical support. McGowan said that perhaps the biggest advantage of decentralised MVHR in a school setting is the simplicity of retrofitting compared to a centralised system. For more information visit www.partel.co.uk and the Partel YouTube channel. The latest video in the company’s Tech Knowledge Series demonstrates how the Lunos ventilation system can be easily designed to meet all living spaces and building types. • (above) Schematic image showing Lunos decentralised controlled home ventilation systems.
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MARKETPLACE
PASSIVE HOUSE+
AirMaster’s flagship MVHR awarded passive house certification
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AV Systems has announced that the AirMaster AM 1000 has been awarded passive house component certification in conjunction with the company’s Danish partner, Airmaster A/S. The company’s flagship AM 1000 is the first decentralised, duct free, mechanical ventilation unit with heat recovery (MVHR) on the market to be awarded the certification. This enables the AirMaster AM 1000 to be used in passive school buildings. “Our time working with the City of Edinburgh Council inspired SAV Systems to undertake passive house certification,” said Jonathon Hunter Hill, product manager for AirMaster at SAV Systems. Edinburgh has set ambitious targets to achieve net zero by 2035, leading the council to apply passive design principles to all its new schools. SAV Systems had previous experience in the world of passive house standards, having supplied Danfoss heat interface units to the award-winning Agar Grove in Camden, the UK’s largest passive house heat network. Ventilation in school buildings is vital for creating comfortable learning environments, but schools looking to achieve passive house standards face a tough challenge. There are a range of approved MVHR solutions available under the passive house framework, but many of these are centralised systems, which normally have high specific fan powers. Besides increased energy consumption due to the ductwork, buildings with centralised systems must also be designed to accommodate such systems. “The AirMaster AM 1000 makes installation easier whist achieving ultra-low energy targets,” said Hunter Hill. “AirMasters are decentralised and air distribution is duct free, so fan power is kept to a minimum. A typical classroom installation requires one AirMaster AM 1000 with intake and exhaust connection to outside.” The AM 1000 can recover up to 90 per cent of the room’s heat using an aluminium heat exchanger, slashing the building’s heat load and heat loss. The result is a much lower carbon footprint, whilst maintaining all the benefits to the indoor environmental quality, according to SAV Systems. Decentralised units like AirMasters have also been shown to have as much as 48 per cent less embodied carbon than centralised systems due to the substantial reduction in equipment required, the company said. Jonathon Hunter Hill added that he is, “proud of the certification and excited that AM 1000 can offer passive house schools the opportunity to benefit from a decentralised MVHR strategy”. • (above) The AirMaster AM 1000, a decentralised MVHR system that has been awarded passive house certification.
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Ecological Building Systems launch Thermo Hemp Combi Jute insulation
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cological Building Systems have launched Thermo Hemp Combi Jute insulation in Ireland and the UK. Manufactured in Germany, this natural, flexible insulation material is made from a mixture of upcycled natural jute fibres and hemp. The natural jute fibres are sourced from discarded cocoa and coffee bean bags which have been processed using 100 per cent renewable energy, and then combined with hemp, which is renowned for its ecological credentials, and which sequesters considerably more CO2 when it is growing than is released in processing it. Thermo Hemp Combi Jute therefore combines the best properties of each material to create a unique high-performance insulation product. Ideal for both new builds and retrofit, Thermo Hemp Combi Jute is safe to handle and requires no special equipment or extra precautions to use. The insulation batts are available in a range of thicknesses from 40 mm to 100 mm, with widths of either 375 mm or 580 mm, and are ideal for installation into timber members at 400 mm or 600 mm centres. For areas which require a greater depth, the batts can be doubled up on top of each other for added insulation. Ecological Building Systems said the high heat storage capacity and low thermal conductivity of both jute and hemp assist in ensuring a building is warmer and more cost effective to heat during winter months, but also less likely to overheat in summer – a particularly beneficial feature for rooms within attics which are often characterised as being too cold or oppressively hot, depending on the season. Thermo Hemp Combi Jute also provides effective soundproofing and has attained a Class A sound absorption rating according to EN ISO 11654. Thermo Hemp Combi Jute also has full European Technical Approval (ETA), which verifies its performance characteristics. “Substituting building materials with a high embodied energy for more environmentally benign solutions such as Thermo Hemp Combi Jute is an effective way for homeowners and specifiers to reduce upfront carbon emissions from our buildings,” said Ecological Building Systems group technical manager Niall Crosson. Further information regarding Thermo Hemp Combi Jute can be found at www.ecologicalbuildingsystems.com. •
(above) Ecological Building Systems has launched Thermo Hemp Combi Jute natural insulation in the UK and Ireland.
PASSIVE HOUSE+
MARKETPLACE
The AECB CarbonLite Retrofit Course (CLR)
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Get zero carbon ready with this industry leading course Learn how to do advanced energy efficient retrofit. Deepen your understanding of building physics and the risks associated with retrofit measures to enable you to make informed decisions. “No other online course prepares built environment professionals as thoroughly for the technical challenges of retrofitting the UK’s existing buildings to an excellent standard.” Andy Simmonds, CEO AECB The number of students on the UK’s leading advanced level e-learning course for domestic retrofit quadrupled in 2020 • All year-round availability. 130 Learning Hours. Self-paced online learning 8 in-depth modules. Learning Outcomes - 72 lessons • Standard cost for AECB members £410 + VAT • Requires understanding of retrofit projects and construction knowledge • CPD – Recognised by the Passivhaus Institut – 35 PHI points towards PHI Certification Renewal • Equips candidates to achieve the AECB Retrofit Standard Certification for your retrofit projects • To book please go to https://aecb.net/the-aecb-carbonlite-retrofit-online-training-course/
CPD Cert. in Building Energy Modelling using PHPP in collaboration with TUDublin
Sign up for this new CPD e-learning course starting 3rd November 2021 “The training looks really impressive and is certainly a comprehensive PHPP knowledge source.” Passivhaus Institut (PHI) • Designed to enable building design professionals to develop and apply an understanding of the international Passive House Planning Package (PHPP) • Single self-contained e-learning module from TUDublin’s MSc in Building Performance (Energy Efficiency in Design) programme • 6 weeks part time - 100 online learning hours (ends Friday 17th December 2021) £870 + VAT • Acquire 50 credits towards Passivhaus Institut (PHI) certification renewal • Attain 10 UK Credits/ 5 EU ECTs (Master’s level) are eligible to progress to the blended online Postgraduate Certificate in gradu • Course graduates Building Performance (Energy Efficiency in Design) • For the detailed course timetable go to https://tinyurl.com/aecbPHPPtimetable • To apply go to https://aecb.net/aecb-training-building-energy-modelling-using-phpp/
JOIN AECB TODAY https://aecb.net/join-the-aecb/
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TO B Y C A M B R AY
COLUMN
How do breather membranes work? How do underlays manage to let water vapour through while keeping the rain out? Toby Cambray delves into the physics…
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while back someone asked me how breather membranes work, and I admit to being initially stumped. I’m writing this in the hope that I’m not the only one to whom the answer is not immediately obvious. To be clear, we’re talking about the sort of materials that are used as underlay in roofing, or on the outside of timber frames; they let vapour out so as to avoid moisture accumulation (or, if you insist, interstitial condensation) but by some witchcraft, they also keep the rain out. The H2O molecules are the same, so what gives? If you wanted to make a breather membrane, there are two possible approaches. Firstly, we could make some sort of plastic sheet that’s thin enough to allow vapour to diffuse through fast enough. The drawback is that with typical materials, it would have to be really very thin – for example, common or garden 500-gauge polythene (that’s about an eighth of a mm) has an Sd value of around 50 metres – about right for a vapour barrier (though plain polythene isn’t really robust enough). But a “low resistance underlay” is, according to BS 5250, anything with a vapour resistance less than 0.05 m, so we’d need our breather membrane to be 1,000 times thinner. The cling film in your kitchen cupboard is roughly a tenth the thickness of 500-gauge, and 100 times thinner than that is really quite thin, with the obvious difficulties that brings (making it, and protecting it).
The answer comes down to an important property of water we call surface tension.
Of course, if you can make a polymer that’s much more vapour open, you could produce it in more practical thicknesses. The second approach is how most practical breather membranes work. If you’ve ever taken a moment to peel a bit apart, you’ll find they are fluffy, and fray at a torn edge,
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with no hint of a continuous membrane. They are made by spinning plastic into fine fibres and squashing them together while hot to make a sheet. This effectively creates a sheet with lots of small holes. This means water vapour can pass through much more easily and we don’t have to manufacture insanely thin layers of plastic. But why doesn’t the liquid water come through? They are not working by osmosis, or behaving like some sort of molecular sieve. The answer comes down to an important property of water we call surface tension. Surface tension is caused by the fact that molecules in water ‘prefer’ to be below the surface than on it. This manifests itself in several ways; for example, in the absence of other forces, a drop will form itself into a sphere. Although it is harder to see (apart from in special cases like the Prince Rupert’s drop – google this and thank me later), solids have surface tension too. When a liquid interacts with a solid, the relationship between the surface tensions plus that of air, sets up a contact angle, which we can observe in the shape of the droplets. If they are relatively flat, the contact angle is high, and the material is said to by hydrophilic; if it is low, the water ‘beads up’ and the surface is said to be hydrophobic. As long as the contact angle is lower than 90 degrees, the water won’t be absorbed into the material, because the surface tension acts like a balloon, stopping the liquid ‘dropping into the gaps’. Incidentally, when you put a fresh coat of Nikwax on your breathable jacket, you’re doing the same thing. And so, if the surface of our breather membrane is hydrophobic, it can have some gaps to let vapour through easily, but also prevent liquid water penetrating. I wanted to focus on the physics of these materials in this column, but I should also mention another disadvantage of most breather membranes: they aren’t good for bats. Essentially, bats crawling up the membrane tend to pull those fibres out and can get tangled up and die. There’s an excellent AECB webinar on the subject – do have a listen if you haven’t already. Details that avoid fibrous breather membranes are possible, and indeed bat-friendly membranes are available. Presumably these don’t rely on spun plastic fibres. I wonder how they work… n
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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ph+ | editor’s letter | 75
The renewable heating alternative
Serious about sustainability The Ultra Quiet Ecodan range of air source heat pumps from Mitsubishi Electric are some of the most advanced heating systems available. Designed specifically for UK conditions, Ecodan provides renewable, low carbon alternatives to traditional fossil fuel-burning heating systems. With an A+++ ErP Rating label across the range, homes can be heated for less while cutting CO2 emissions.
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ecodan.me.uk/ph