Passive House Plus (Sustainable building) issue 45 UK

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

FROM SMALL SCREEN TO DEEP GREEN Charlie Luxton’s visionary River Clyde Homes cracks the safe on decarbonising social housing

United ambitions

UN pushes for radical sustainable building action

Seal of office

Ireland’s first passive certified office building

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Bonny in Clyde

Issue 45 £5.95 UK EDITION

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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 e info@passivehouseplus.ie www.passivehouseplus.co.uk

Editor

Jeff Colley jeff@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

Lenny Antonelli journalist Toby Cambray Greengauge Building Energy Consultants Talina Edwards Envirotecture Sally Godber Warm Marc Ó Riain doctor of architecture Matthew Tulley Solid Carbon Storage Jason Walsh journalist

Print

editor’s letter W

hat is there to say? As I write these words the news has been confirmed that July was the world’s hottest month on record. And there is a palpable sense of change all around us. While much of southern Europe was burning, in Ireland it doesn’t really feel like we’ve had a summer. While the fires were raging in Italy and Greece, in Ireland it was a washout – July was the wettest month on record.

While of course we shouldn’t conflate climate with weather – a favourite trope of the morally bankrupt, immorally wealthy fossil fuel schills that have corrupted the discourse on climate over the years – this kind of disconnect may be a harbinger of what is to come. The question that occurs: does a warming world necessarily mean a warmer UK and Ireland?

The answer may well be yes, but there is uncertainty here. The reason? The Gulf Stream system – or more accurately, the Atlantic Meridional Overturning Circulation (Amoc) – may be on the verge of collapse, due to impacts such as the increasing melt of Greenland’s glaciers into the Atlantic. In a worst case scenario this may potentially occur by as early as 2025.

If that were to come to pass, what would the consequences be in this corner of the world?

Here the science isn’t settled, but the options on offer range from more rainfall and stronger storms, to much colder winters and much hotter summers. Ireland and the UK have the same latitude as Labrador in Canada – which Benjamin Franklin, who first charted the Gulf Stream, described as the “Land of the Eskimauxs.” Do we have to therefore consider the possibility of a markedly different climate, including potentially prolonged deep freezes and hot summers? One architect friend mused to me about using Newfoundland weather files to

ISSUE 45 stress-test their building designs.

While I say all of this, it’s important not to lose sight of our – at least for now – relatively privileged position in the kinds of disruption we face. I was consoling a Washington DC-based friend earlier, while he dealt with a flooded basement and storm-downed trees, and he gave some useful perspective. “I, like everyone who isn’t poor in the developed world live a charmed life,” he said, “so little to really complain about over a few hours mopping.”

Nevertheless, while we mustn’t ignore the issue of climate justice, we must build or retrofit now without due consideration for the climate and extreme weather variables our buildings may face – be it cold snaps, heat waves, oscillation between droughts and torrential rain pour, or just the insidious impact of increased horizontal rain and the impact of storms.

If I stop to reflect on the UN Environment Programme’s Buildings Breakthrough target, which says that “near zero-emission and resilient buildings are the new normal by 2030” I find them profoundly useful: they encapsulate the two heads of the monster that we must slay. We must mitigate, by cutting emissions to as close to zero as possible. But we must also adapt, and make our buildings – even our entire built environment, our ways of life – as resilient as possible in the face of such menacing uncertainty.

I must apologize for such a downbeat opening to this issue, which, as it turns out, is filled with stories to inspire hope: real buildings and initiatives that are the kind of medicine an increasingly climate-sick world needs. As luck would have it, that medicine tastes good.

Regards, The editor

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

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.

Official partner magazine of: • The Association of Environment Conscious Building

• The International Passive House Association

• The Passivhaus Trust

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CONTENTS

PASSIVE HOUSE+

CONTENTS COVER STORY

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BIG PICTURE Talina Edwards of Envirotecture describes an extraordinary off-grid passive house which uses straw and a range of low embodied carbon building materials to blitz regulatory requirements on fire, while delivering year-round comfort levels that the neighbours can scarcely believe.

NEWS UN pushes for radical sustainable building action; design and performance centre stage at UK Passivhaus Awards; and AECB 2023 Conference to focus on providing solutions for building in an age of climate chaos and biodiversity collapse.

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COMMENT Dr. Marc O Riain writes about an extraordinary Dublin project from 1994; Sally Godber writes about a new organisation offering passive house training at scale; and Matthew Tulley reports on a recent trip to Ireland, where a delegation of UK retrofit stakeholders visited to see what lessons could be learned.

CASE STUDIES From small screen to deep green

Charlie Luxton’s visionary new sustainable office The new Oxfordshire studio of Charlie Luxton Design, the practice of the well-known TV presenter and architectural designer, is deeply impressive for its exhaustive attention to sustainability across every facet of the project, from energy use and embodied carbon to the reuse of materials and the ecological restoration of the three-and-a-half-acre site. It’s a gorgeous building, too.

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Bonny in Clyde

Scottish housing association cracks the safe on decarbonising social housing How do you solve a problem like decarbonising social housing, and do so rapidly, en masse, in a manner that lifts vulnerable people out of fuel poverty while delivering warm, healthy homes?

River Clyde Homes may be about to pull off the seemingly impossible.

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High end passive house scheme lands in Killiney What happens when one of Ireland’s most seasoned passive house builders and a renowned design-led architecture practice collaborate? They create a head turning, high density passive house scheme that showcases the aesthetic possibilities of external insulation.

Seal of office

Ireland’s first passive certified office building While the passive house standard has had a lasting impact on the design and construction of new homes in Ireland, progress has been slower in commercial property. With the business world under increasing pressure to take meaningful climate action while providing better working conditions for staff, one new office building in the southeast may be a sign of things to come – and a beacon for a UNaffiliated project.

INSIGHT Banking on sustainability

Why a pillar bank is financing verified green homes Last year Irish banking behemoth AIB launched discounted development finance for homes certified to the Irish Green Building Council’s rating system, the Home Performance Index.

But what was behind the move, how is it being received and does this indicate the finance industry is getting serious about green homes?

Hope springs external

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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.

Flash floods and porous materials

While the most dramatic impacts of climateinduced flash flooding abounding on social media this year are all too obvious, other more insidious effects also pose risk to everything from agriculture to porous materials, as Toby Cambray explains.

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HUFF’N’PUFF

BIG PICTURE

BIG PICTURE PASSI VE & ECO BUIL D S F R O M A R O U N D TH E WO R LD If you were choosing how to build in a bushfire-prone region of Australia, you could be forgiven for skirting over the possibility of packing your walls with straw.

Talina Edwards of Envirotecture describes an extraordinary off-grid passive house which uses straw and a range of low embodied carbon building materials to blitz regulatory requirements on fire, while delivering year-round comfort levels that the neighbours can scarcely believe.

1. Huff’n’Puff Haus – a strawbale Passive House The Huff’n’Puff Haus is a new off-grid, energy efficient, natural and healthy passive house for retirement that is designed to be adaptable, bushfire and climate resilient. It is a contemporary strawbale house that is off-grid with completely self-sufficient power, water and waste.

Located in the southern part of Australia, it is a few hours’ drive inland from Melbourne in ‘high country’ in the Strathbogie Ranges, Tangurung country. The temperate climate means winter temperatures drop to freezing overnight, but summer highs can reach 40+ C. It was designed to settle unobtrusively into the natural landscape.

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2. The brief

We have owned the land (55 acres) since 2000 and dreamed about this for years.

When our clients initially approached us back in 2015, we’d just started learning more about the passive house standard and the importance of understanding building science for keeping a home comfortable and healthy – and energy efficient, which is a consideration for living off-grid.

What started as a conversation about a resilient and sustainable strawbale home in a rural location, soon offered us all a

new exciting challenge - was it possible to achieve certified passive house (with a low operational carbon footprint) whilst using materials with low embodied carbon too (with more bio-based materials like straw and timber)?

The whole team was eager to explore this possibility and make it a reality. Thankfully, there’s now a growing awareness about the importance of upfront carbon.

3. Bricks, timber or straw – which is best?

The strawbale walls we used were prefabricated “situp” panels made by John Glassford and team at Huff ’n’Puff. No big bad wolf or three little pigs here – this house will be strong and resilient for many years to come. The wall panel frames are crammed full of straw and sealed up for delivery – and it was observed they looked like a stack of coffins.

Being 350 mm – whereas a typical Australian wall frame is 90 mm thick – they are strong. The timber used for the framing is plywood, and this was very fortunate during the Covid materials shortages when typical timber studs were in very short supply.

Straw has excellent insulation values, is a waste-product from the farming industry, and as it’s a natural bio-based material it’s low in embodied carbon.

Once erected on site, the panels were temporarily wrapped up again to protect them from weather and from any curious rodents.

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HUFF’N’PUFF

BIG PICTURE

4. The wrong orientation?

An interesting siting challenge was that this regional location has lovely 360-degree outlooks, however the best views to the distant horizon are to the south.

In the southern hemisphere, we want to maximise solar gain from the north during our winters, while ensuring the building is appropriately shaded from the harsh summer sun.

Traditional principles of “solar passive

design” limit south-facing glazing as they lose too much heat from the home in winter. However, by looking at the building holistically and using PHPP as a design tool, we were able to test the performance impacts of adding (or removing) these southern windows and optimising the design to ensure every room in the house gets to enjoy the views – while not negatively impacting the internal comfort.

From an architectural design perspective, this was exciting news to realise that with passive house there aren’t necessarily “rules of thumb” that apply in every scenario – so our creativity as designers is not limited. In this case our clients desire to embrace those views, meaning we could have large windows to both the north and the south as we’d checked that it would still perform as intended.

5. Biophilic design Internally, the straw panels were finished with lime render which formed the internal airtight layer. The exception to this was the two bathrooms, as these were wet areas. They had internal Intello membrane installed so they could be lined with cement sheeting, waterproofing and tiles.

The lime render really contributes to the biophilic design of the home – the texture and natural colour is lovely. Sustainable timbers were also chosen to complement the render, creating a simple, calm colour palette.

Deep sills are another benefit of the lime-rendered straw, framing the triple glazed windows, and creating shelves in some locations – or enough space to sit in the window and enjoy the views in all directions to the countryside.

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6. Bushfire-prone area and external materials The intention was for this home to be safe, healthy, natural and non-toxic, with low embodied energy, durable and fireresistant materials. Due to the remote rural location, the threat of bushfire is real in hot dry summers, and due to a changing climate.

At the time we were also learning more about the Living Building Challenge and more ethical and responsible material choices – and we wondered if it was possible to have a certified passive house with no plastic. We realised this was potentially possible with rendered strawbale walls but could’ve been trickier to detail for the

ceiling airtight layer. We opted for Intello for the underside of the roof trusses, with a suspended ceiling to run the MVHR ducting through.

Our clients wanted to ensure their home was built to a higher ‘bushfire-prone’ standard than the building code required.

While the rendered-strawbale may have been suitable, the roof design would have needed to change with larger eaves if we’d wanted to protect external rendered walls. As this wasn’t aligning with the design concept of a long house reminiscent of an old woodshed in the paddock, and the additional bushfire protection we

were aiming for externally, we tried to source non-combustible magnesium oxide boards for cladding. However, thanks to the pandemic and supply issues, this unfortunately wasn’t to be, and we had to choose a non-combustible cement-sheet cladding instead.

Its neutral colour with clean lines does look lovely. This meant the external face of the strawbale was wrapped with a vapour-permeable membrane, with a ventilated cavity behind the cladding in a way more like typical lightweight walls would be constructed.

7. Views for days This home sits quietly in its place. It’s modest in size, selfsufficient in use, and a healthy home to live in harmony with the landscape.

While it is relatively small (TFA 171 m 2) in comparison to typical new Australian homes (240 m 2), inside it feels incredibly spacious and with connection to the distant horizon in every direction, and bright with lots of natural daylight.

It is a real retreat from the harsh elements all year round.

Our clients have shared how they love watching the sky change colours, and how this paints the landscape in varying beautiful ways – depending on the time of the day, the time of year, where they are in the house and the direction they’re facing.

This was a conscious design decision: to create space for contemplation and enjoy the views, to be able to chase the sun when desired, or to be able to seek shade and shelter from the winds when required too.

Photos: Marnie Hewson

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HUFF’N’PUFF

BIG PICTURE

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BIG PICTURE

HUFF’N’PUFF

8. That’s something a bit different.

Who will build a straw passive house in a rural location?

The site is reasonably remote, with not a lot of local builders servicing the area – particularly not ones who were familiar with straw bale construction or passive house performance.

This led us to working with Huff’n’Puff straw “Sit-up” panels (a prefabricated strawbale company) who could make the wall panels off-site and deliver them all boxed up ready to be erected.

Then with the expertise of a great team of builders, Hedger Constructions, who care about quality and were very open to learning something new, we had a successful outcome.

9. Flexibility and adaptability The house design balances the integration of passive solar design principles with the site constraints and local climatic conditions – view, orientation, site slope, sun, wind and rain. It has also been designed with a zoning of spaces unlike a typical family home, creating a flexibility of use with one wing of the house occupied by its permanent residents while the second wing can adapt to fulfil the needs of visiting family and friends when required. The ‘guest’ wing is within the same thermal envelope but separated by an external timber-lined covered entry/hallway space.

This creates a sheltered transition between outside and inside, whilst also creating privacy between the homeowners and their guests. Our clients have shared how well this is working for them and their visitors – making the home feel a lot larger than it is by utilising these outdoor spaces as extra rooms.

10. Thermal envelope and airtightness The floor plan for this house is relatively long and thin (37 m long by 6.7 m wide), with the roof trusses spanning the full width in the north-south direction. This meant the house could be constructed with the floor, external walls and roof structure all up, insulated and airtight before any internal walls were built. This simplified things for the builders internally with installing the MVHR and dealing with other services.

You don’t often see a whole house’s thermal envelope volume in one space like this, without the visible interference of internal partitions. It did create a distorted sense of size during the construction process but was clever to construct it in this way.

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HUFF’N’PUFF

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HUFF’N’PUFF

11. Why the odd roof pitch?

This home is off-grid, which means it’s completely self-sufficient for power, water and disposing of waste on site. There is no gas connection (or bottled LPG gas), so it is an all-electric home with enough solar PV and batteries to run the home and charge electric vehicles too.

The roof of the house was designed with an asymmetrical gable, so the north-facing pitch was steeper – a more appropriate angle to harvest that renewable energy from the sun, maximising the solar collection. The carport is at the western end of the house, which creates an asymmetrical double gable profile and adds a little fun and a modern twist to the roof line.

12. Beauty is in the eye of the beholder One of the design intentions was to keep the house size more modest, but create great functional use of all the space, while maximising the views, and creating a warm and welcoming space to be in.

There are appropriately sized eaves to the north to shade the house from the harsh summer sun while ensuring the occupants can enjoy natural daylight and views to the landscape all year round.

Our clients’ neighbours commented on this as they live in a typical ‘wooden tent’

with little insulation, single glazing, and no external shading. In an attempt to keep cool in summer they close all the curtains and keep the house dark. It was a stark contrast for them to visit a home that was perfectly comfortable inside despite the sweltering heat – and still light and bright and a joy to be in!

Our clients also told us how their home was the ‘talk of the town’ while under construction, as everyone was curious about this “big, long shed with small windows”.

Yet when the neighbours visited, they all commented on how deceptive appearances could be from afar, and how truly beautiful this home feels to be in. (We know that a passive house’s beauty is more than skin-deep.)

The last word should go to our clients: “We are delighted to be in the house,” they said. “It really is wonderful. Thank you for your skill and thoughtfulness in designing our lovely home.”

SELECTED PROJECT DETAILS Architect and interior designer: Envirotecture Builder: Hedger Constructions Prefabricated SIP supplier: Huff-n-Puff Strawbale Constructions Passive house consultant: Alex Slater Passive house certifier: Detail Green Stylist: Belle Bright Windows: Logikhaus Ventilation: Fantech Cladding: Cemintel Barestone Airtight membranes: Pro Clima

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NEWS

PASSIVE HOUSE+

NEWS UN pushes for radical sustainable building action The United Nations is pushing for a rapid drive to make the world’s buildings sustainable – aided by an international coalition centred in the Wexford town of Enniscorthy.

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he Enniscorthy Forum has signed a memorandum of understanding (MoU) with the UN Environment Programme (UNEP) on a broad collaboration to accelerate the global transition to decarbonised, high performance buildings – including the UN’s Buildings Breakthrough target of making “near zero-emission and resilient buildings the new normal by 2030.”

Founded to support the UN sustainable development agenda, the forum has launched a global network, the Buildings Action Coalition (BAC), with a membership comprising community-centric organisations, global industry players, and academia – and set to include Zero Ambitions Partners, a new sustainability communications and strategy consultancy co-founded by Passive House Plus editor Jeff Colley.

The MoU between the Enniscorthy Forum and UNEP was announced at a major ministerial summit hosted by the forum on 27-29 June in Enniscorthy. The MoU includes a collaboration with UNEP’s Global Alliance for Buildings and Construction (GlobalABC) on the Buildings Breakthrough target. Led by the French and Moroccan governments, 16 countries have signed up to date.

Mark Radka, chief of the energy and climate branch of UNEP, said: “We are delighted with our newly formalised relationship with the Enniscorthy Forum and look forward to a strong and enduring partnership that helps raise the performance of buildings and the built environment on a global scale. Experts from Ireland helped initiate the UN’s High Performance Buildings Initiative and this prompted creation of the Enniscorthy Forum. UNEP values and appreciates the Irish government's support for the Enniscorthy Forum and the activities of its Buildings Action Coalition.”

The Enniscorthy Forum is supported by the Irish government and the summit was attended by senior industry figures, government officials, community-based organisations, and leading academics from around the world. Participants called on the Irish government to endorse the Buildings Breakthrough target, and the initiative has been placed on the government’s agenda for review and consideration.

Speaking at the event, Yves-Laurent Sapoval, senior advisor to the director general of planning, housing and nature at the French ministry

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(above l-r) Pictured are signatories including (top row) Passive House Massachusetts president Hank Keating; A2M founder Sebastian Moreno-Vacca; AECB CEO Andy Simmonds; River Clyde Homes director Richard Orr; Passive House Pennsylvania director Dave Parker (representing Passive House Network); Building Energy Exchange executive director Richard Yancey; (bottom row) passivhausMaine executive director Naomi Beal; Enniscorthy Forum CEO Barbara-Anne Murphy; Passive House for Everyone! co-founder In Cho; and Passive House Institute head of training Susanne Winkel.

of ecological transition, affirmed support for the initiative: “We consider improving the performance of buildings and the built environment to be imperative if we are to achieve the objectives set forth in the Paris Climate Agreement, and we look forward to working with the Enniscorthy Forum to accelerate achievement of tangible progress through the GlobalABC towards the Buildings Breakthrough target.”

The Passive House Institute was among a number of organisations from either side of the Atlantic which formally joined the coalition to coincide with the summit, alongside Building Energy Exchange, Building Innovation Hub, Built Environment - Smarter Transformation, Onion Flats, Passive House Canada, passivhausMaine, Passive House Network, River Clyde Homes, and South West College. Meanwhile, the Association for Environment Conscious Building (AECB), The Energy Coalition, Passive House for Everyone, Passive House Massachusetts, A2M, and Zero Ambitions Partners signed letters of intent to join the BAC. The BAC aims to advance the cause of high-performance building and a more sustainable built environment, and accelerate tangible action on decarbonisation and improving quality of life everywhere, by developing a pan-continental forum to share the experience and expertise from some of the world’s foremost experts in the field.

The BAC’s knowledge-sharing and anti-gatekeeping ethos is being driven by its coalition partners. By promoting and demonstrating the transformative benefits of high-performance buildings it is pushing for a quicker adoption of

best practice methods in planning, design and construction across the world.

Zero Ambitions Partners co-founder Jeff Colley and Enniscorthy Forum CEO Barbara-Anne Murphy signed the letter of intent in a ceremony at Enniscorthy Castle on the occasion of the summit.

“We recognise the potential for the Buildings Action Coalition to make a major contribution to raising the performance of the world’s buildings and the built environment,” said Colley.

“There is real substance in the coalition’s approach. Strong engagement with the UN sends out a significant positive signal, but the focus on engagement with grass-roots organisations will make a real difference.

“We’re excited to join the coalition to offer our help in raising awareness, recruiting, setting priorities for strategic communications, and assembling the required resources.”

Enniscorthy Forum CEO Barbara-Anne Murphy said: “We look forward to welcoming Zero Ambitions Partners to the coalition. They are extremely effective at outreach and information sharing, which is precisely the kind of support this initiative needs now.

“We have a significant programme underway to mobilise resources and disseminate knowledge, experience and best practices to transition towards high performance building. Given their competence in strategic communications, Zero Ambitions Partners will have an important role to play.”

Scott Foster, an adviser to the Enniscorthy Forum and former director of the Sustainable Energy Division of the UN in Geneva, said: “Improving the performance of buildings and the built environment is the one action that can deliver integrated solutions at scale in a timely fashion to produce tangible outcomes on economic, social, and environmental resilience, quality of life, and climate, among other desirable outcomes, and in the process advance employment, innovation, and investment.

“This launch is an exciting development for the Enniscorthy Forum and is proof that small local organisations can achieve big things with the right support, the right partners and the right vision. The Buildings Action Coalition has far-reaching ambitions to help transform the built environment worldwide.”

For further information visit www.enniscorthyforum.org •

PASSIVE HOUSE+

NEWS

AECB conference: building, climate chaos and biodiversity collapse

(above) Broadcaster and ecological architectural designer Charlie Luxton will be delivering a plenary talk; (below) Todmorden, West Yorkshire.

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he AECB 2023 Conference will focus on providing solutions required for building in an age of climate chaos and biodiversity collapse.

Headline speakers for the two day event on 29-30 September will include broadcaster and ecological architectural designer Charlie Luxton, natural resource, climate change and climate finance consultant Prof Steven M Newman, building physicist Prof Robert Lowe, and energy and climate research fellow Dr Lai Fong Chiu.

On the first day of the event, which will be hosted at the School of Natural Building at Tod College in Todmorden, West Yorkshire, the AECB will update delegates on a whirlwind of activity by the association in recent months including developments with the AECB’s CarbonLite suite of standards for new build and retrofit, on how the new standards can complement the passive house standards to create a practical, evidence-based route to decarbonisation for all buildings.

AECB CEO Andy Simmonds will update delegates on the association’s new collaboration with the UN-affiliated Buildings Action Coalition, and describe how this may afford the chance to accelerate the en masse decarbonisation and greening of buildings in the UK and internationally.

Prof Newman will give a plenary talk on the first day on urban forestry, drawing from his work on climate change, diet and sustainable livelihoods.

Charlie Luxton – whose deep green retrofit for his architectural practice is profiled in this issue of Passive House Plus - will give a plenary on the second day giving his thoughts on low energy buildings, embodied energy and the circular economy.

Luxton’s talk will be followed by a joint plenary by Prof Lowe and Dr Chiu on systems shocks and peak oil.

As with all AECB events, knowledge transfer will be at the forefront with thought-provoking talks and case studies from fantastic speakers, AECB experts and carefully-selected suppliers together with hands-on technical workshops, an exhibition area and plenty of time for questions and discussion.

A number of interactive, hands-on and technical workshops will enable delegate to get to grips with selected topics in more depth such as the AECB standards and schemes, biodiversity and food, building climate resilient buildings in the Global South, software and the use of ‘natural’ materials in theory and practice.

The full programme is available at https:// aecb.net/aecb-conference-2023/ with discounts on registration offered until 1 September. •

Coalition forms to develop net zero carbon standard A

cross-industry steering group has joined together to develop a standard for verifying UK buildings as net zero carbon.

Buildings are directly responsible for around a quarter of carbon emitted by the UK, according to the UKGBC’s Whole Life Carbon Roadmap. There is therefore no credible pathway to net zero for the UK economy without tackling emissions associated with the construction and operation of the UK’s building stock.

Photo: Tim Green

While significant progress has been made in defining what ‘net zero’ means for buildings in the UK, a process of market analysis showed a clear demand for a single, agreed methodology. The UK Net Zero Carbon Buildings Standard is intended to enable industry to robustly prove their built assets are net zero carbon and in line with the UK’s national climate targets. Leading industry organisations BBP, BRE, the Carbon Trust, CIBSE, IStructE,

LETI, RIBA, RICS, and UKGBC have joined forces to champion this initiative.

The standard will cover both new and existing buildings and will set out performance targets addressing operational energy and embodied carbon emissions to align with the UK’s 2035 and 2050 emissions targets. It will also cover the procurement of renewable energy and the treatment of residual emissions, including carbon offsetting. •

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NEWS

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Design and performance centre stage at UK Passivhaus Awards A

pioneering co-housing scheme, a cubeshaped self build, a cork and polyester-insulated retrofit to a 1970s house, a glulam timber school, and a curved college building were the winners at the 2023 UK Passivhaus Awards.

While awards for buildings tend to focus on newly completed projects in spite of the absence of post occupancy data, the Passivhaus Awards instead require entrants to demonstrate proven performance over time – and eagle-eyed readers may recognise some of the winners from previous issues of Passive House Plus.

Over 200 people attended the awards on 5 July, which were sponsored by Ecology Building Society, Knauf Insulation and Munster Joinery.

The competition was fierce, with an inspiring array of exemplary projects on display.

For the first time there was a tie in the residential new build category, with two markedly different joint winners: Ostro Passivhaus and Cannock Mill Cohousing.

Designed by Anne Thorne Architects, the groundbreaking Cannock Mill Cohousing is a wonderful example of what can happen when communities manage to forge an alternative to speculative housing development: a 23-unit cellulose-filled timber frame scheme in Colchester, Essex which simultaneously combats loneliness and climate change, and featured in issue 40 of Passive House Plus.

Paper Igloo Architects’ Ostro Passivhaus in Stirlingshire, which featured in issue 37, is a striking example of how great design can overcome even the most onerous self-imposed

18 | passivehouseplus.co.uk | issue 45

restrictions: the woodfibre-insulated, cubeshaped building could barely have had a better form factor, but the fenestration and beautifully-detailed diagonal Siberian larch cladding and reveals give this project a real visual flourish.

With polyester clothes and Cork interior décor conjuring images of the 70s, it seems fitting that both materials should find a home in a retrofit to a house built in that decade: Bowman’s Lea. The Harry Paticas-designed retrofit to a London townhouse, which won the retrofit award, uses recycled polyester to insulate the loft, and cork internal wall insulation.

The winner in the non-domestic category was passive house stalwarts Architype’s Hackbridge Primary School, a beautiful, passive house plus-certified school near the pioneering experimental green housing scheme BedZed. The building, which is achieving net zero operational carbon, includes a cellulose-insulated panelised structural timber frame with glued laminated timber (glulam) columns and beams and a Larsen truss – a system which uses timber boarding to frame out the external insulation zone while minimising the use of timber.

Meanwhile Hamilton Architects’ Erne Campus won the people’s choice award. The curved new home for South West College, Enniskillen, generates four times more energy on-site than it uses. The world’s first educational building - and currently the largest building – to be certified to the passive house premium standard, Erne Campus is also BREEAM Outstanding certified.

The shortlisted projects included a number of other exemplary projects, such as:

• Tooley Foster’s Foleshill Health Centre, Coventry – the first NHS certified passive building; • Roger Burton’s Chester Road Passivhaus, Stockport – a timber frame home with a large PV array and only electric convective heaters. The project was commended; • Michal Rudnicki and Huff & Puff Construction’s Parc y Rhodyn, Wales – a straw-filled structural insulated panel (SIPs) house in Wales, that also meets the One Planet Development policy and is entirely off-grid; • A D Practice’s Harpenden Enerphit Plus, Herts – a PV-roofed deep retrofit published in issue 43 of Passive House Plus • RDA Architects’ Modernist Enerphit Plus, London – a sensitive retrofit to a 1960s modernist house published in issue 44 of Passive House Plus • Mark Siddall’s Shepherd’s Barn. Durham – an Enerphit Plus retrofit using the box within a box approach – with a cellulose-insulated timber frame built within original and rebuilt stone walls.

To view all winners and finalists, visit https://tinyurl.com/UKPHA23 • (above) Bowman’s Lea and Hackbridge Primary School, two of the winners at the 2023 UK Passivhaus Awards.

Bowman’s Lea photo: Harry Paticas/Agnese Sanvito Hackbridge photo: Architype/Jack Hobhouse

COLUMN

SALLY GODBER

Cynicism and inspiration It’s common for people who’ve taken passive house designer or tradespeople courses to say it has transformed how they think about buildings – that once you’ve seen it, you can’t unsee it, and that it fundamentally affects your approach on any projects. Sally Godber, director of leading passive house certifier Warm explains how one new community interest company, Coaction Training CIC, hopes to mobilise the industry.

C

urrently, energy literacy within our industry is so low that to enact the level of change we need, legislation alone – when it comes – is not going to be enough.

Within every project, irrespective of the client’s sustainability aspirations, there are a multitude of opportunities to make improvements. I’m not just talking about the big-ticket items like triple glazing, but rather tweaking a construction so it can be built without thermal bypass occurring, or reducing hot water pipe lengths that would otherwise contribute to overheating. Many of these low or no-cost opportunities are missed because no one is aware of the issues. We need a workforce who have the technical understanding to spot and address such issues.

Many construction professionals that I talk to feel frustrated that they can’t do more to enact change, but they’re wrong.

All of us, no matter what our role, have the ability to improve the performance of the buildings in which we’re involved.

I’ve found two key ways of using the knowledge I’ve gained from working in passive house which don’t rely on a strong sustainability brief from the client: 1. Stealth: With the right knowledge there are all kinds of modifications that can be applied to design or construction that might seem small but will make a tangible difference that you can do now. For example, our trainer Rupert Daly says: “in timber frame projects I specify the insulation width to be the same as the void between studs, so it’ll fit well without needing to be cut”.

This means the construction team is set up to do a good job, and the risk of air gaps which severely reduce the performance of the insulation is minimised. It’s a small but signifi-

cant change, and you can read more about how insulation fails through thermal bypass from another of our trainers Mark Siddall in his recent paper, ‘Thermal bypass risks’.

2. Informing the client and team of the impact of their decisions. I was recently told by a supplier of structural insulated panels (SIPs) that their thermal bridging was “such a tiny number we didn’t think it needed worrying about”.

I was able to put them right and gave them the opportunity to improve. Clients don’t always want to go for improvements, but you might just be surprised.

Hopefully, these examples make it clear that you don’t need to wait for the right client or project to come around, although we want that to happen too. All you need is the right knowledge and that’s exactly what we’ve developed. Our Coaction (formerly CarbonLite) training courses are a direct response to this situation. We know passive house gives you the key to really understand building performance. After all, it was developed specifically to address the ‘performance gap’ between design aspirations and real building energy performance.

So, who needs this training? Well, everyone. Energy performance doesn’t fall into the lap of any single role; pipe fitters, architects, clerk of works, are all undertaking activities that have an impact, so they all need some understanding of the issues. For the record, I’ve seen firsthand great solutions come out of multi-disciplinary teams tackling a problem that would usually be pigeonholed in one person’s court, and I guarantee it’s much more fun. We offer a range of courses at different levels; there’s something for everyone.

Passive house training at scale is the leg

All of us, no matter what our role, have the ability to improve the performance of the buildings in which we’re involved.

up that the industry needs, irrespective of what our building regulations are up to.

This is of course challenging, as we’ve got twenty-five trainers and there are a lot of people to train, but it’s also the exciting bit. We’ve assembled a collective of experts across a spectrum of disciplines, to give a variety of opinions with a common drive for change in our industry.

The opportunities to make real change, and in particular, to work more collaboratively are all waiting, we just need you to join in! n

ph+ | sally godber column | 19

DR MARC Ó RIAIN

COLUMN

An early green building in a changing Ireland It’s fair to say that green building wasn’t a thing in early 90s Ireland, which makes one extraordinary Dublin project from 1994 all the more remarkable, as Dr. Marc O Riain writes.

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lmost 30 years ago, designers and researchers set out to create a modern ‘green’ building on a vacant lot in the centre of Temple bar at the outset of its regeneration. I, at the time, was street-painting across from Trinity and had a good view of the queue that formed a day before the apartments went for sale. Word on the street was one could get paid for holding a spot in the queue for potential buyers of the eight apartments. So, what made the Green Building an instant hit?

Supported by €3m in European funding in 1994, Tim Cooper with Murray O'Laoire Architects developed a design for the Green Building. It was described in a 2007 feature in Construct Ireland, the progenitor magazine of Passive House Plus, as “an innovative mixed-use development of offices, apartments and shop units laid out around a six-storey central courtyard designed as a semi-external atrium space with a glazed operable roof. The atrium's roof is oriented southwards and designed to naturally ventilate and light the building”.

The building was designed with a low glazing factor and high interior radiant panel surfaces supplied by low temperature solar water heating. It was cooled in the summer by drawing cold air up through the atrium at night using canyon and stack effect ventilation. The building benefitted from its compact apartment units’ mid terrace location, thus reducing surface heat loss. The envelope uses a mineral wool external insulation sys-

20 | passivehouseplus.co.uk | issue 45

tem coupled with south-facing double glazed windows and triple glazing on the north face.

Although the roof initially featured wind turbines combined with solar electric panels (PV), the turbines would be later decommissioned because they were not successful. “The problems have been two-fold: firstly, their vibrations were heard in the penthouse apartments causing some discomfort for residents and, secondly, they failed to reliably produce power due to turbulence,” Walsh wrote.

The PV panels were another matter. The PV energy production (3,000 kWh/a) met 75 per cent of associated heat pump electrical demand (4,000 kWh/a) when built.

Although grid connected, surplus electrical energy was fed back to the grid for free, as there was no associated purchase tariff at the time. “When we first put them in (PV panels) we couldn't grid connect,” Cooper told Walsh in 2007. “So, we had to put in the massive accumulator and a stack of inverters. That is now all redundant. The grid-connected photovoltaic alone is much more efficient than the photovoltaic and turbines were together, before".

Space heating and domestic hot water was driven by a ground source heat pump and evacuated solar tubes on the roof. The vertical ground source heat pump runs at a very efficient 5:1 co-efficiency of performance, which is impressive even by today’s standards. Interestingly Cooper reports that bedrock temperatures in Dublin have risen 2.5 C in the past 28 years since the bore-

hole was first measured, either a reflection of global warming or urban heat island effect.

Whatever the reason, it must be improving the heat pump efficiency.

This early Irish example of low energy building design had a blend of passive and active solutions. Of the active solutions the PV and ground source heat pump would appear to function well with the internal thermal mass of the building fabric. It was definitely a signpost for things to come, as building standards in Ireland had just been introduced in 1992 and energy efficiency standards under Part L of the Building Regulations, didn’t differ too much from the 1974 elective standards. It would be the Kyoto protocol in 1998 which would drive the European Union to introduce the Energy Performance of Buildings directive in 2002 which would have a direct impact on the design of our buildings going forward. It is perhaps only today, almost 30 years later, that we have caught up with the Green Building in Dublin. It is a testament to the visionaries who brought this new ground in a very conservative country which itself was on the brink of change. n 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.

Photos: David Ruffles

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M AT T H E W T U L L E Y

COLUMN

UK retrofit meets Irish retrofit With the UK’s nearest neighbour setting ambitious targets to deep retrofit a quarter of its housing stock by 2030, a delegation of UK retrofit stakeholders visited Ireland to see what lessons could be learned, as Matthew Tulley writes.

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s we all know, removing a lot of fossil fuel use from our homes will need a lot of them to be retrofitted. Ten of us came over from the UK to see how Ireland have been getting on with the job. Retrofit is complicated, there are a lot of options to consider and for many homeowners it’s a journey into uncharted and dangerous waters. This is why the 17 Irish one-stop-shops have put the customer at the centre of their approach.

The visit started off with talks and a meal with one-stop-shop directors and project designers. Caroline Ashe from Kore Retrofit Ltd said how they help homeowners select which measures are right for them and then specify the retrofit. They then de-risk by selecting and monitoring the contractors, and carry out quality control checks throughout and at the end of the retrofit.

The following day we visited a ‘work in progress’ in Thurles, Co. Tipperary, where we saw a terrace house retrofit nearing completion. This had a typical set of challenges, with mostly external insulation, but also internal insulation on one side where the neighbour-

ing property had an extension that didn’t match up on height and depth. Because the whole house was also being refurbished at the same time, the new bathroom and kitchen could accommodate the change in inside wall thickness of the internal insulation. There were comments about the air source heat pump in the small rear yard, but as in many properties there is little choice on where to install – and behind the new triple glazed patio door you couldn’t hear it at all. The retrofit is transforming a cold and draughty home into a lovely new, comfortable place to live.

We also visited a much larger detached renovation a bit outside of town – we were asking about the metal strip at the base of the external wall insulation and whether it would be a thermal bridge. The tradesmen reminded us about mice and rats in the country – and the importance of the design being vermin proof! Again, this retrofit was part of a major re-design of the home so it was a full building site – definitely not something that could be lived in through the retrofit. On other jobs where it was just external insulation and air-

(Above) The UK delegation during a tour of an Electric Ireland SuperHomes deep retrofit in Thurles, Co. Tipperary.

22 | passivehouseplus.co.uk | issue 45

tightness, windows, ventilation and a heat pump, then it was all done around the homeowner living there – just one day away while plumbing was connected up.

The Templemore Arms Hotel had a lovely private room for soup and sandwiches and a ‘question time’ format with estate agents from Sherry FitzGerald Gleeson, and a local project manager. We heard that there is now a significant premium on both rental income and property values from homes with A or B Building Energy Ratings (BERs, the Irish equivalent of EPCs) – and a home that is retrofitted will not remain empty for long. The high cost of retrofit is more than recovered in property values in Ireland.

We finished off at TUS (Technological University of Shannon) hearing about heat pump performance, since all of the retrofits done by one of the leading one-stop-shops, Electric Ireland SuperHomes, are free of fossil fuels. We also learned about the quality assurance processes used by the contractors, and the site visits by the project managers of the one-stop-shops. There is independent quality assurance also done on a sample of retrofits

by KSN Energy on behalf of the state agency responsible for retrofit grants, the Sustainable Energy Authority of Ireland (SEAI). We had heard from SEAI via a video link after breakfast. SEAI provide significant grant funding for retrofit but also have adopted SR 54, Ireland’s code of practice for retrofit, and commission KSN to ensure the standards are maintained.

It was a busy day and a half, but we mixed pleasure with business. We were well looked after at Abbey Court Hotel who were pleased that ‘in person’ events have returned after Covid. Most also joined the optional excursion to the music session in Paddy Rohan’s (every Wednesday evening) – a very traditional Irish pub including a grocers shop in the front part. As one of our visitors said: ‘Thank you so much for sharing your time and knowledge with such energy and openness. The visit was inspiring and informative in equal measure, and has greatly increased our collective understanding of the possibilities for retrofitting the UK’s aging housing stock.”

For more information contact m.tulley@ solidcstore.org n

LUXTON

CASE STUDY

IN BRIEF

Building type: Steel barn converted into 204 m2 office and recording studio Method: Flat pack I-beam timber frame, wood fibre insulation, material reuse and biodiversity focus Location: Oxfordshire Standard: Uncertified passive house Energy use: Beyond net zero. Net export of 1,400 kWh from Jan to mid July 2023, excluding EV charging.

Embodied carbon: Meets LETI 2030 target and RIBA 2025 target See ‘In detail’ panel for more information.

24 | passivehouseplus.co.uk | issue 45

CASE STUDY

LUXTON

FROM SMALL SCREEN TO DEEP GREEN CHARLIE LUXTON’S VISIONARY NEW SUSTAINABLE OFFICE The new Oxfordshire studio of Charlie Luxton Design, the practice of the well-known TV presenter and architectural designer, is deeply impressive for its exhaustive attention to sustainability across every facet of the project, from energy use and embodied carbon to the reuse of materials and the ecological restoration of the three-and-a-half-acre site. It’s a gorgeous building, too.

By Lenny Antonelli

ph+ | luxton case study | 25

LUXTON

CASE STUDY

country’s old growth forests made a lasting impression on him. He moved to a farm in England at the age of nine and says playing in streams and climbing trees helped to foster his love of nature.

Charlie and his wife Kate, who is CLD’s studio manager, were finishing their own house next door when this three-and-a-halfacre plot came up for sale. It had been used to keep horses and had a steel-framed barn surrounded by heavily grazed paddock. The CLD team had been working in Charlie and Kate’s old thatch cottage down the road, but this site offered the perfect opportunity to create a purpose-built studio.

20 kW PV array 1. 1.

20 kW PV array 2. Corrugated metal skin 2. 3.Corrugated metal Reclaimed walkaway usedskin as solar shading Existing and adapted steel frame 3. 4.Reclaimed walkaway as solar shading 5. Steico timber inner frame 4. 6.Existing and adapted steel frame Internorm triple glazed windows 5. 7.Steico inner frame Existing timber concrete slab Insulation above slab glazed windows 6. 8.Internorm triple Void for services and ease of construction 7. 9.Existing concrete slab 8. Insulation above slab 9. Void for services & ease of construction

I

f you’re a fan of architectural TV shows, you will know Charlie Luxton from programmes such as Building the Dream, Homes by the Sea, and Building a New Life in the Country. What you may be less aware of is the sheer depth and breadth of his knowledge of — and commitment to — sustainable building.

Charlie heads his own small practice, Charlie Luxton Design (CLD). When the firm decided to build a new studio just outside the village of Hook Norton in Oxfordshire, it was a chance to push the envelope across a swathe of sustainability metrics in a way that is often difficult when working for a client. “If I’m going to do a project for me, I have to make it a massive education piece,” he says.

His commitment to environmental protection stretches back to his childhood in Australia, when protests to save some of the

26 | passivehouseplus.co.uk | issue 45

Building-within-a-building From the outset, Charlie was keen to make use of the existing barn. “We stripped it back very carefully and engineered it so we could work with the existing concrete slab,” he says. “We took down the walls, took all the wood out of the stables for reuse, and basically tried to design a [new] building that could use as much of the existing structure as possible.”

Building on the existing slab required extra thick walls to spread the load of the new studio. But with a goal to get close to the passive house standard and a preference for natural insulation, the walls were always likely to be quite thick.

Charlie served as principal contractor and recruited as many local trades as he could. The team laid a thin layer of levelling screed and then set out to build a new timber-framed studio within the structure of the old barn.

“The idea was very much to build a building within the building,” he says, “so that we didn’t put any additional load on the frame, because the frames of those buildings are really only designed to take themselves, and the wind.”

But the barn did provide a sheltered space within which to build the studio. The CLD team chose a timber I-beam system from German wood product specialist Steico.

Each of the beams was digitally modelled and precut before being delivered to site.

It’s a low-waste system Charlie had grown to like on previous projects.

“The thing about going with these precut systems is you can get an entire building on one lorry,” he says, and this was one of many ways he sought to reduce the carbon footprint of the build.

Steico laminated veneer lumber (LVL) — a mass timber product that takes dozens of thin layers of wood and glues them together to create a structural timber panel — was used for posts and beams, and around the building’s Internorm timber aluclad triple glazed windows. Durelis VapourBlock, a structural chipboard that also provides airtightness and vapour control, frames the

walls and roof internally, and serves as the main airtightness layer too. The walls and roof were pumped with blown cellulose insulation (Charlie brought his local labourers down to PYC Systems in Welshpool for training in how to install it), and then lined internally with Fermacell board, which is made from recycled gypsum and paper.

The team clad the structure in dark, powder-coated standing seam steel and British-grown larch and fitted a cap of EPS insulation — salvaged from another project — above the LVL ridge beam to stop thermal bridging down through the steel joist hangers. “We were really careful about that level of detailing,” Charlie says. The roof is finished with a 20 kW solar PV array.

Design for reuse Inside, the team fitted 250 mm of EPS insulation over the existing slab. This was laid without any glue so that it could be easily reused in future. “We planned it all out on a computer so that we could do it with as few cuts as possible,” Charlie says.

The team also used a hot wire cutter to cut the insulation as cleanly as possible, to stop microplastics from breaking off. The floors are finished with boards made from English elm.

An obsession with minimising the environmental impact of materials permeated the whole project. “We really tried to reuse as much as we can,” Charlie says. Timber reclaimed from the horse stables was reused for internal finishes. An oak-framed sliding door was salvaged from another project and re-purposed as an internal screen. Old walkways from the site were reused as solar shading. Recycled furniture and second-hand appliances were specified throughout. Outside, rather than completely dig up the concrete yard, the team simply broke up some areas of concrete and planted within it.

Charlie says that thinking about how to reuse materials at scale was one of the big takeaways from the project. “How do you use the things you’ve got to make the buildings you need?” he asks. “And how do you do that at scale? How do you find the materials, log the materials, test the materials, certify the materials?” These are some of the next big environmental questions for the building sector to get to grips with.

The CLD team also thought about how the building, and its components, might be used long into the future. “We sort of tried to imagine how you might minimise disruption for other phases of the life of the building,” he says. The building has been plumbed for future conversion to a house, and it’s been framed so that more doors can easily be installed in future.

Cladding and roofing were also fixed to be easy to remove.

CASE STUDY

LUXTON

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In the seven years since the Luxtons bought the site, it has gradually become richer in wildlife, and noticeably louder with the sounds of nature.

Minimalist heating The finished studio achieved an airtightness score of 0.3 air changes per hour and is within the parameters for passive house certification. The building is both heated and cooled, when needed, by an air source heat pump that warms or cools supply air being drawn into the building through a Passive House Institute-certified heat recovery ventilation system from Airflow, the specialist ventilation supplier who suggested this project to Passive House Plus for this article. The system, along with the lighting system, is managed by a building automation system from Wiise.

It’s a fairly minimal approach to heating, and Charlie says it keeps the building sufficiently warm on all but the three or four coldest days of the year. But while the building was wired for infrared radiators to top up the heating, he decided against putting them in. “Given how little we would use it, I suspect the embodied energy would make no sense whatsoever,” he says.

So instead, on freezing winter mornings, an old electric radiator, covered in paint, is wheeled to provide some extra heat, and Charlie says this works well.

And what about comfort on hot days?

The heat pump provides cooling too, and on the hottest day of 2022, when temperatures in Oxfordshire exceeded 38 C, the temperature in the studio was a warm-but-acceptable 26 C. An external shade limits solar gain from the high summer sun to the south-facing studio space.

The 20 kW solar PV array provides electricity to the studio, to two electric cars, and to Charlie and Kate’s own house next door. So far this year, as of 12 June, the three buildings have used 11 mW of electricity in total, but only 2.4 mW of this was imported from the grid, with the rest — almost 80 per cent — coming from solar power. Charlie is planning to install a battery next year.

Finished photos: Ed RS Aves | Other photos: Charlie Luxton Design

Studio space And what about the spaces inside? What kind of studio did a group of architects and designers want to create for themselves to work in? Kate says that while the old thatched cottage was a pleasant space, it wasn’t really suitable for an office. “For clients coming, it was slightly weird,” she says.

For the new studio, the team wanted to have an open plan working area that fostered collaboration, but also separate rooms for calls, meetings, or quiet working. And with its light filled spaces and warm timber finishes, the new studio is certainly a beautiful space to work in.

“I know the team love coming here,” Kate says, “post-Covid there has been a culture of working from home, but we didn’t suffer from that. The guys wanted to get back into the office and be all together, and I think having this building is a huge part of that.”

She adds: “It’s a place that we want our clients to come to, we want to have meetings here, we want to share it with people.”

CLD does not use the whole building — about one third of the footprint is a music studio for writing and rehearsal, rented by a friend of Charlie’s, and some work was needed during the build to ensure this would be acoustically separated. “You can hear a little bit of drumming, but nothing bothersome, actually it’s really quite nice,”

ph+ | luxton case study | 27

LUXTON

CASE STUDY

www.ecomerchant.co.uk info@ecomerchant.co.uk +44 (0) 1793 847 444

SUSTAINABLE BUILDING MATERIALS FROM FOUNDATION TO RIDGE

WINNER OF THE SUSTAINABILITY PRIZE

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

Charlie Luxton Principal, Charlie Luxton Design Black Barn Studios by Charlie Luxton Design Winner of Architects' Journal Sustainability Prize 2023 28 | passivehouseplus.co.uk | issue 45

CASE STUDY

LUXTON

he says.

The needs of this space were factored into the design of the building management systems by Wiise. When musicians press record in the studio, the ventilation system – which is inaudible to the occupants but may be detectable in recordings – is temporarily turned off.

1

6

2

7

3

8

4

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5

10

1 Charlie Luxton in the old building. The slab and steel frame were retained, and some blocks were reused; 2 levelling screed to existing slab; 3&4 Steico I-beam frame going up; 5 Caberfloor chipboard on 100 mm Platinum EPS, including channels cut for 75 mm semirigid Airflow ducting, with a further 150 mm EPS beneath; 6 25 mm battens on Durelix Vapourblock airtight vapour control board and Pro Clima airtight tapes, after the Steico Zell woodfibre insulation was blown in; 7 Fermacell boards; 8 Luxton and the Airflow Flexi DV1600 MVHR system; 9 Panelvent under Solitex Fronta vapour permeable breather membrane; 10 battened and counterbattened wall awaiting the powder coated corrugated iron cladding and roofing.

Rewilding the site Outside, the team’s attention to detail extended well beyond the boundaries of the building. The site was heavily cropped and packed with hardcore and rubber crumb, and as soon as they got the site, Charlie wanted to start restoring biodiversity.

This included planting over seven hundred native trees — particularly elm, alder and black poplar — plus new areas of wildflower flower meadow, and native scrub with crab apple, dog rose, hazel and rowan.

Charlie estimates that it will take about twenty years for the surrounding site to sequester, in the soil and new vegetation, the building’s carbon footprint (excluding the PV array – see embodied carbon section below) of sixty-seven tonnes. He says this is based on back-of-the-envelope sums, but he’s having more detailed calculations performed soon, and developing a longer-term biodiversity management plan.

He says that in the seven years since they bought the site, it has gradually become richer in wildlife, and noticeably louder with the sounds of nature. “Last year waking up at certain times of day and in certain weather was extraordinary,” he says.

“That’s just been joyous to be honest with you… the sense of wellbeing it gives you to bring a land back to biodiversity health. It just feels amazing.”

The project was a winner of the sustainability prize at the 2023 Architects’ Journal Small Projects Awards. “That was a real vindication of what we’ve done and what we’ve worked towards,” Kate says. “To get that industry recognition was so exciting and we feel incredibly proud of it.”

I asked Charlie what the biggest challenge on the building was, but he says it all went pretty smoothly. “It went really well if I’m honest,” he says. “Do you know why? Because it was incredibly rational. And that’s the biggest lesson I think is, we just need to make things a lot simpler, to make all of our buildings a lot simpler.” He says that simpler buildings mean quicker and cheaper builds, less travel to site, lower embodied energy, and more flexible and longer-lasting buildings. It makes it easier to deliver airtightness and eliminate thermal bridges, too.

“And I think it’s actually really liberating to say I can make a really simple building, and if I concentrate and work really hard on that, it can be beautiful.”

ph+ | luxton case study | 29

LUXTON

CASE STUDY

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Launching a new product is never easy, but in the space of only two months we’ve received over 150 enquiries through two issues of the magazine and all have been very fruitful. We have been quoting straight after the magazine is out. A lot of the customers enquiring have genuine current projects and this is reflected in how many respond to our follow ups.

It is no doubt in my mind that this team are one of the best I have dealt with out of the many publications we use. They deliver and they deliver quality!

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To enquire about advertising, contact Jeff Colley on +353 (0)1 2107513, or email jeff@passivehouseplus.ie

www.passivehouseplus.co.uk 30 | passivehouseplus.co.uk | issue 45

THE STREET

L in Re Or d a rig pr o h Sur pert v ey project

The Stables Tunnel Farm Swerford Road Hook Norton OX15 5QB

W0 Fire Call Point Wall

W01

Quiet work room

LED in joinery LED under shelves

LUXTON

DW01

Work Space

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Meeting Room

Wall

CASE STUDY

Single pipe Wall

E Wall

E Single pipe

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LED in joinery

WIDER SITE PLAN B

E Wall E Wall

E Wall

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E

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B

Kitchen

LED under shelves

South Facing Terrace

D02

Atrium

A

Pre-app 23.09.19 P1

P2 24.12.19 01608 730086

10 M 5 0

Do not scale off this drawing. This drawing is to be read with all other contract documents. Any discrepancies are to be reported to the Architect. At construction status, this drawing remains design intent only. All information to be checked by contractor for site accuracy and fit. Drawings are subject to statutory approvals and site surveys.

info@charlieluxton.com

Planning

A-

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Beanacre Cottage, Ropeway, Hook Norton, Oxon, OX15 5QB

EFire Call Point Wall

W03

W04

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Wall E

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Store

Flexible Work Space

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E

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Fire Panel

Embodied carbon calculations were conducted by passive house consultant Richard Bendy of The Healthy Home, using the AECB’s PHPP-based embodied carbon calculation tool, PHribbon. I amended these calculations to consider the effect of different product specifications in a couple of high impact areas. The project was then compared against the embodied carbon targets for offices in the RIBA 2030 Climate Challenge, and the LETI 2030 design targets.

The scope included the whole building, with the exception of reused/recycled items such as the retained concrete slab, steel frame and blocks for a first course of blockwork, along with brise soleil made from a recycled walkway. Groundworks were not included.

Fixed furniture and equipment – including reused appliances – were also omitted, as were external works, along with ductwork, pipes, electrical fittings, and the Mixergy hot water cylinder, but the vast bulk of the building was included.

In the absence of quantified data on construction process-related emissions, the calculations rely on the default assumption in the RICS methodology, where construction process emissions are derived based on the value of the project. In this case, the construction process-related emissions, which are taken to represent 23 tonnes of CO2e, are likely an over-estimate, given the care taken by the project team to minimise emissions throughout the build.

400

Wider Site Plan

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LED on top of ducts

Fire Call Point

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LED under shelves

Embodied carbon

By Jeff Colley

25

7

6 7

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50 M

1.2. Writer’s Black Retreat Barn Studio 3. Site entrance 2.4. Parking Writer’s Retreat Existing concrete yard adapted for 3.5.planting Site entrance Native woodland 4.6.7. Wild Parking flower meadow & grassland 5. Existing concrete yard adapted for planting 6. Native woodland 7. Wild flower meadow & grassland 1. Black Barn Studio

In several cases, where the specified product didn’t have source data – such as an Environmental Product Declaration, default data, or CIBSE TM65 calculations in the case of building services – data was taken from EPDs or Product Eco Passports on similar products, to produce an indicative result. Most notably, this was the case with regard to the PV array, EPS insulation, air-to-air heat pump and heat recovery ventilation system.

Based on the precautionary principle, in the case of the building’s large PV array, where the specified product didn’t have an EPD, a similar product a with high embodied CO2 score was included in the calculations.

Charlie Luxton Design

On this basis, the building scored a cradleto-grave total of 814 kg CO2e, meaning it meets the RIBA 2025 target for offices.

As Passive House Plus has shown previously, this total was dominated by the large PV array, which contributes a whopping 59.3 per cent of the total – albeit based on a panel with an EPD showing a high embodied carbon score, given the absence of an EPD for the actual panels used. If the roof mounted array is omitted, the total is just 332 kg CO2e/m2. This ignores the energy generated by the array, and is based on the conservative requirement set by RICS that any replacement materials/technologies within

ph+ | luxton case study | 31

LUXTON

CASE STUDY

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CASE STUDY

Detail Study

LUXTON

D E TD AE I LT AS ITLU S D TY U D Y

Roof Construction: Roof Construction:

Roof Construction: - Photo voltaic panel voltaic panel - Photo - 0.7mm corrugated sheet metal sheet - 0.7mmmetal corrugated • Photo voltaic panel - Existing steel frame steel frame - Existing • 0.7mm corrugated metal sheet - Ventilated void - Ventilated void - Solitex Fronta Quattro breather membrane - Solitex Fronta Quattro breather membrane • Existing steel frame - 12.5mm Panelvent - 12.5mm Panelvent - 300mm Steico I-BeamSteico & blown woodfibre insulation - 300mm I-Beam & blown woodfibre insulation • Ventilated void - Duralis Vapourblock board, taped board, for airtightness - Duralis Vapourblock taped for airtightness - 25mm service void service void - 25mm • Solitex Fronta Quattro breather membrane - 12.5mm Fermacell board, finished & painted - 12.5mm Fermacell board, finished & painted • 12.5mm Panelvent • 300mm Steico I-Beam & blown woodfibre insulation • Duralis Vapourblock board, taped for airtightness • 25mm service void • 12.5mm Fermacell board, finished & painted Wall Construction: Wall Construction:

Wall Construction: - UK grown larch cladding - UK vertical grown larch vertical cladding treated softwood counter batten - 50 x50mm treated softwood counter batten • UK grown larch vertical cladding -- 5050 x50mm x50mm treated softwood batten - 50 x50mm treated softwood batten - Solitex Fronta Quattro breather membrane - Solitex Fronta Quattro breather membrane • 50 x 50mm treated softwood counter batten - 12.5mm Panelvent - 12.5mm Panelvent - 300mm Steico I-beamSteico & blown woodfibre insulation - 300mm I-beam & blown woodfibre insulation • 50 x 50mm treated softwood batten - Duralis Vapourblock board, taped board, for airtightness - Duralis Vapourblock taped for airtightness • Solitex Fronta Quattro breather membrane - 25mm service void service void - 25mm - 12.5mm Fermacell board, finished & painted - 12.5mm Fermacell board, finished & painted • 12.5mm Panelvent • 300mm Steico I-beam & blown woodfibre insulation • Duralis Vapourblock board, taped for airtightness • 25mm service void Floor Construction: • 20mm English Elm wood floorboards Floor Construction: Floor Construction: • 22mm Glued Caberdeck - 20mm English Elm wood floorboards - 20mm English Elm wood floorboards - 22mm Glued- 22mm Caberdeck Glued Caberdeck • 100mm HP EPS 100 (laid for re-use) - 100mm HP -EPS 100 (laid for re-use) 100mm HP EPS 100 (laid for re-use) - 150mm EPS-PREMIUM (laid for re-use) 150mm EPS 100 PREMIUM 100 (laid for re-use) • 150mm EPS PREMIUM 100 (laid for re-use) - Fully taped -radon Fully membrane taped radon membrane • Fully taped radon membrane - 20mm levelling screed - 20mm levelling screed - Existing concrete slab - Existing concrete slab • 20mm levelling screed • Existing concrete slab

SELECTED PROJECT DETAILS

Client, architect, main contractor: Charlie Luxton Design Passive house consultant: The Healthy Home Structural engineer: Varndell Engineering Quantity surveyor: Andrew Bird Associates Electric contractor: AMR Electrical Contractor Airtightness tester: Aldas Life cycle assessment: The Healthy Home Building system supplier: Steico Wood fibre insulation: Steico Floor insulation (EPS): Kay-Metzeler Windows & doors: Internorm, via At-Eco Liquid airtight membrane: Blowerproof, via Ecomerchant Airtight tapes & membranes: Pro Clima, via Ecomerchant Corrugated metal roofing: Sandford Roofing Fit out: Hook Norton Construction British elm floorboards: Sutton Timber Heat pump: Panasonic, via Airflow MVHR: Airflow Solar PV: Aspey Energy Building management system: oxone, via Wiise Landscaping: Katie Guillebaud Garden Design Breathable sheathing board: Panelvent, via Ecomerchant Insurance: The Build Store Hot water cylinder: Mixergy Lighting: Darklight design Sanitaryware: Duravit Insulating blowing machine and training: PYC

the 60-year study period for the building must be assumed to have the same embodied carbon emissions as the initial one – a highly questionable assertion given the rate of decarbonisation in industry. Based on the projected lifespan of 25 years in the EPD for the default PV array chosen, this meant two replacement arrays were included.

It is worth adding, however, that if the value for what is currently the lowest emissions PV array on the market was used – the Sunpower Maxeon 3 – the totals for the PV array would have dropped by 73 per cent – or a cradle-to-grave total of over 26 tonnes, versus almost 98.5 tonnes. While this massive reduction owes mainly to the panel’s low carbon manufacturing – notably including the wafer and ingot being manufactured in Norway, using hydroelectric power – it’s also due to the panel’s higher output. For this calculation, 103 m2 of Maxeon 3 array had the same output as 120 m2 of the high carbon array that was assumed.

While thinking in terms of cradle-to-grave impacts is key, there is an argument that greater emphasis should be placed on reducing emissions now, provided it doesn’t lock in avoidable emissions over the lifespan of the building via operational energy use and avoidable repair or replacement of components.

For this reason, LETI has set upfront embodied carbon emissions targets, alongside cradleto-grave and operational energy targets.

On this basis, the building fares very well, registering a total of 217 kg CO2e/m2, comfortably beating LETI’s 2030 target for upfront embodied carbon target for office buildings of 350 kg CO2e/m2.

It’s also worth noting that because both RIBA and LETI – quite reasonably – have separate embodied carbon and operational energy performance target, the extra carbon

0

0

2M

2M

Charlie Luxton Design

invested in reducing emissions over time is counted, but the carbon saved through energy efficiency and generation of renewable energy isn’t. It may be the case that the upfront carbon pays back very quickly, which is precisely why it makes sense to have embodied carbon and operational energy targets, rather than trading one off against the other.

One factor which substantially helps: LETI’s targets don’t count roof-mounted PV arrays, instead regarding them as part of the grid, which drops the upfront total by 157 kg CO2e/m2.

Based on LETI’s definitions of upfront emissions alone – excluding the PV array – the biggest embodied carbon total comes from the standing seam galvanised steel cladding at over eight tonnes – an estimate which would have increased if the impact of the vertical steel ribs on surface area of materials was considered.

While LETI’s targets don’t permit CO2 sequestered in materials to be offset against the emissions released upfront, the reliance on timber and wood fibre insulation means that at the point of practical completion, the building’s materials had absorbed and stored 176 kg CO2e/m2 – over 80 per cent of the upfront total.

Another factor significantly affecting the cradle to grave totals is the life cycle assessment requirement to consider the sequestered CO2 in the building’s timber and timber-based materials as effectively being released into the atmosphere at the building’s assumed end of life. 35.9 tonnes of CO2 stored in the building become 40.8 tonnes at the end of life, through a combination of the emissions being assumed to be released, and the extra carbon spent in transporting and processing the materials at that stage.

ph+ | luxton case study | 33

LUXTON

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CASE STUDY

LUXTON

IN DETAIL Building type: 204 m2 (gross internal floor area) timber frame building comprising architectural studio and music studio.

Treated floor area: 195 m2 Site type & location: Village edge site, Hook Norton, Oxfordshire.

Budget: £340,500 (£1,669 per square metre).

Inclusive of landscaping but exclusive of VAT, fees and loose furniture.

Completion date: January 2022 Passive house certification: Not certified Space heating demand (PHPP): 12 kWh/m2/yr Heat load (PHPP): 10 W/m2 Primary energy non-renewable (PHPP): 15 kWh/m2/yr Primary energy renewable (PHPP): 13 kWh/m2/yr Renewable energy generation (PHPP): 65 kWh/m2/yr Heat loss form factor (PHPP): 3.6 Overheating (PHPP): 4 per cent of year above 25 C Number of occupants (PHPP): 12 Embodied carbon: When assessed in line with requirements of the RIBA 2030 Climate Challenge, the whole-life cycle carbon footprint (A1 to C4, excluding emissions from operational energy and water use) calculated as 76.4 tonnes CO2e or 814 kg CO2e/m2 gross internal area in PHRibbon. 59.3 per cent of this total is based on the PV array alone, albeit based on conservative default data), meeting the RIBA

2025 target for office buildings.

Measured energy usage: 39.8kwh/m2/yr Airtightness (at 50 Pascals): 0.3 air changes per hour Ground floor: 22 mm elm floorboards, followed underneath by Caberfloor Chipboard flooring, 100 mm timbers at 600 mm centres with 100 mm platinum EPS, on 150 mm timbers at 1200 mm centres with 150 mm white EPS, on radon-proof DPM, on levelling screed, on existing concrete slab. U-value: 0.13 W/m2K. Walls: Polyester powder coated corrugated iron cladding to existing steel frame, followed inside by ventilated cavity, breather membrane, Panelvent breathable sheathing board, Steico I-beam system with 300 mm Steico Zell wood fibre insulation, Durelos Vapourblock airtight vapour control board, 25 mm services zone, Fermacell board. U-value: 0.132 W/m2K Roof: Polyester powder coated corrugated iron sheet on steel frame, followed underneath by wind-tight membrane, Panvelvent breathable sheathing board, Steico I-beam system with 300 mm Steico Zell wood fibre insulation, Durelis Vapourblock airtight vapour control board, 25 mm services zone, 12.5 mm plasterboard to ceiling. U-value: 0.132 W/m2K Windows & doors: Internorm HF410 triple glazed timber-aluclad windows throughout.

Plus, Internorm HS330 timber/aluminium lift and slide door. Installed U-value range: 0.70 to 0.82 W/m2K. Heating & ventilation system: Airflow Flexi DV1600 MVHR system. Passive House Institute

certified heat recovery rate of 86 per cent.

Extracts up to 1,600 m3/h (0.44 m3/s) at 200 Pa. A Panasonic PACi Elite single phase inverter air conditioner/heat pump (with R32 refrigerant) provides heating or cooling to MVHR supply air via a DX coil.

Electricity: 20 kW solar photovoltaic array on the south-facing roof. Provides electricity to this building, three electric car chargers and to the house next door. Between 1 January and 12 June 2023, the PV system had supplied 8.6 mW out of 11 mW consumed on the site, with 2.4 mW imported from the grid.

Biodiversity and landscape: 2,100 m2 of land stripped of hard standing, rubber crumb and returned to wildflower and scrub. 180 tonnes of hardcore taken from land for local recycling. 25 m3 of rubber crumb reclaimed from menage for reuse locally. 1,800 m2 native scrub, 2,500 m2 of wildflower and over 700 native trees planted.

The next step is to analyse the biodiversity net gain and develop a long-term management strategy with local wildlife trust.

Sustainable materials: Steico PEFC certified timber building system, steel barn and concrete slab retained, salvaged oak door reused as internal screen, salvaged timber from horse stables used for internal finish, walkways recycled as solar shading, rubber crumb reused locally, concrete blockwork and site hardcore reused. Floor insulation, cladding and roofing are designed to be easy to remove and reuse in future. English larch cladding, English elm floorboards. Recycled furniture and secondhand appliances throughout.

ph+ | luxton case study | 35

RIVER CLYDE

CASE STUDY

BONNY IN CLYDE SCOTTISH HOUSING ASSOCIATION CRACKS THE SAFE ON DECARBONISING SOCIAL HOUSING How do you solve a problem like decarbonising social housing, and do so rapidly, en masse, in a manner that lifts vulnerable people out of fuel poverty while delivering warm, healthy homes?

River Clyde Homes may be about to pull off the seemingly impossible.

By Lenny Antonelli

R

apidly decarbonising our built environment is an urgent task, but it poses a vicious puzzle: how to do it fast, but do it well? And how to pay for it? Deep retrofit is complex, and poorly executed upgrades have a history of causing damp and mould.

The UK and Ireland both plan to become zero carbon societies by 2050. Both countries will need to upgrade a large majority of their homes — two million dwellings in Ireland, twenty-seven million in the UK— by 2050. This will require an unprecedented scaling up of retrofit, and an unprecedented level of investment.

The UK government sees heat pumps as

36 | passivehouseplus.co.uk | issue 45

one answer to this challenge — it wants to install 600,000 every year from 2028 onwards to deliver low carbon heat to homes, with less emphasis on fabric upgrades.

But heat pumps require careful design and installation, and if electricity prices are high, they can run up frightful bills in poorly insulated homes. Deep fabric upgrades are better at cutting fuel poverty and making homes comfortable, but they can be complex and expensive.

One housing association in Scotland has come up with a different answer to this puzzle. River Clyde Homes, which manages 6,000 dwellings in Inverclyde, west of Glasgow, wants to decarbonise its housing

stock through a mix of whole-house retrofit, low carbon heat networks, and by generating its own renewable energy.

Passive house advocates might shudder at the idea, but the association thinks that the way to decarbonise and eliminate fuel poverty is to perform more modest whole-house retrofits, and then meet heat demand via low carbon heat networks, powered by heat pumps and other renewables.

Duncan Smith, head of energy and sustainability at River Clyde Homes, is honest about the challenges of performing very deep retrofits over large numbers of dwellings.

“The fabric measures that we would like to do are probably challenging both practically

CASE STUDY

and financially for all of our homes,” he says.

The association is currently deep retrofitting a block of 90 homes to the AECB’s CarbonLite Retrofit L2 building standard, an energy standard based on passive house principles, but with a space heating and cooling demand of 50 kWh/m2/yr rather than the target of 25 kWh/m2/yr for the Passive House Institute’s retrofit standard, Enerphit, and an airtightness q50 requirement of 2.0 rather than the Enerphit n50 target of 1.0. In fact Smith says the project is on course to exceed the energy targets of the CarbonLite New Build L3 standard, which strictly speaking isn’t applicable to retrofits, and has tighter targets of 40 kWh/m2/yr and an airtightness q50 score of 1.5 or better.

But as Smith thinks ahead to how River Clyde Homes will retrofit most of its 6,000 dwellings, he says it will need to adopt a more pragmatic approach and get the balance right between fabric and heating.

“I think the reality is about eighty per cent of the time we’ll be between 50-80 kWh for space heating demand, with four air changes per hour of airtightness,” he says. The emphasis will still be on careful whole-house retrofit, with cheap and publicly-owned renewables supplying the remaining heat demand. “We can address fuel poverty, we can eradicate dampness and mould, and we can do it in a practical way,” he says.

River Clyde Homes currently has about eight hundred dwellings on three district heating networks, mostly run on biomass, but envisages a major of expansion of this, with future networks running on heat pumps.

Where next for district heat?

District heating is hardly new. The oldest known example comes from France, where hot spring water was first piped to thirty homes in the spa town of Chaudes-Aigues during the 14th century.

In Europe, district heating provides over sixty per cent of residential heating in Denmark, and fifty per cent or more in each of Sweden, Estonia and Lithuania. By contrast, heat networks currently meet just two per cent of the UK’s heat demand, but the government envisages a major expansion in the coming decades.

Of course, district heating is only as green as the fuels it uses. Globally, nearly ninety per cent of district heat was produced by fossil fuels in 2021, especially in China and Russia. Renewables represent about five per cent of global supply, and most of this comes from burning biomass or waste.

But in Sweden, Denmark, Austria, Estonia and Lithuania, more than fifty per cent of district heat comes from renewables. Sixty per cent of all renewable energy in Europe now comes from biomass though, and this has not been without controversy.

Last year, environmental NGOs fought, but ultimately lost, an effort to remove woody biomass from Europe’s Renewable Energy Directive because of concerns over its climate and environmental impact. In 2021, a group of five hundred scientists and economists wrote a letter to world leaders asking them to stop burning trees for bioenergy because of its impact on climate and biodiversity.

The letter said there has been a shift in

RIVER CLYDE

1

2 1 Duncan Smith, head of energy and sustainability at River Clyde Homes; 2 a rendering of the new façade of Prospecthill Court, a tower block being retrofitted to the AECB CarbonLite Retrofit Level 2 standard by River Clyde Homes

ph+ | river clyde case study | 37

RIVER CLYDE

CASE STUDY

1 A wind turbine at Whitelees Wind Farm, the UK’s largest onshore wind farm, which is located near Glasgow; 2&3 Queens Quay regeneration project features the UK’s largest heat pump powered district heating system, featuring two 2.6 megawatt water source heat pumps built by Star Refrigeration; 4 the housing stock features a diverse range of housing typologies including tower blocks and tenements; 5 an Enerphit project from Duncan Smith’s time at Renfrewshire Council; 6 & 7 renderings and an elevation of Huntley Drive, an RCH deep retrofit project.

recent years from burning forestry wastes for bioenergy towards burning whole trees or large portions of stem wood, releasing carbon that could otherwise remain stored in forests.

“Regrowing trees and displacement of fossil fuels may eventually pay off this carbon debt, but regrowth takes time the world does not have to solve climate change,” the letter read. “As numerous studies have shown, this burning of wood will increase warming for decades to centuries.”

Expansion of heat pumps, wind and solar will be critical to replace biomass and fossil fuel powered heat networks. Duncan Smith says that River Clyde Homes want to exploit the huge potential for renewable energy that exists in the Clyde itself, and along the west coast of Scotland. “Water based heat pumps are absolutely the way to go,” he said. “We have access to huge amounts of freshwater, and lots of wind too.”

Queens Quay An exciting template exists just down the estuary in Clydebank. There, the Queens Quay regeneration project features the UK’s largest heat pump powered district heating system. Two 2.6 megawatt water source heat pumps capture heat from the Clyde and deliver it to a heat network that extends for three kilometres from east to west, and 750

2

38 | passivehouseplus.co.uk | issue 45

1 metres from south to north. The heat pumps use ammonia, which has a global warming potential of zero, as their refrigerant, and deliver about three units of heat for every unit of electricity.

3

Queens Quay will eventually feature over 1,000 homes, a health centre, care home, leisure centre, offices, shops and civic spaces.

“In terms of what the network could be expanded to, it could be five or six times the

CASE STUDY

4

RIVER CLYDE

5

Shared Boundary

Solar PV panels x12 Proposed extended verge for EWI Proposed replacement windows - Nordan triple glazed timber/ aluminium installed to existing walls

Proposed recycled composite tiles Proposed replacement windows - Nordan triple glazed installed to EWI layer

Proposed 150 mm External wall insulation - EPS with silicon render finish

Proposed aluminium rainwater goods Proposed 150 mm external wall insulation - Phenolic with silicon render finish Proposed Air Source Heat Pumps

6

Shared Boundary

7

ph+ | river clyde case study | 39

RIVER CLYDE

CASE STUDY

40 | passivehouseplus.co.uk | issue 45

CASE STUDY

RIVER CLYDE

1 Albertslund heating plant, which heats the whole Albertslund suburb in Copenhagen including; 2 these non-profit social housing apartments from Bo-Vest.

size, it’s just a matter of putting the pipes in the ground,” says Dave Pearson, group sustainable development director of Star Refrigeration in Glasgow, which built the heat pumps. “The Clyde itself could supply well over 1,000 times what we’re doing at the moment.”

Pearson points out that with its abundance of wind energy, the carbon footprint of electricity in the south of Scotland is particularly low. The region also has nuclear power.

Between January 2020 and October 2023, the south of Scotland had the smallest average carbon footprint for electricity of any UK region at 47.28 gCO2e/kWh (the worst performing region was the south of Wales, at 316.94 gCO2e/kwh).

“The only things holding back subsequent projects are a coordinated effort to push buildings away from gas towards district heating, but more importantly a radical rethink on electricity pricing,” he says. Heat pump operators are currently paying over 30p per kilowatt for electricity, even though wind farms are selling it to the grid from just 4p per kilowatt. This is down to a “slew of outdated policy levers”, Pearson says.

Across the Irish Sea, the recently opened Tallaght District Heating Scheme in Dublin takes waste heat from Amazon’s Tallaght data centre and uses it to heat 32,800 square metres of public buildings, including Technological University Dublin’s local campus, plus the county hall and county library. The heat network is operated by Ireland’s first publicly owned, not-for-profit energy company.

Notwithstanding the question of whether building new data centres is a good idea — they are projected to account for twenty-eight per cent of Ireland’s electricity demand by 2031 — there remains huge potential to capture waste heat and distribute it via heat networks. Dublin’s energy agency Codema says there is enough waste heat and deep geothermal energy in the city to heat one million homes via district heating, with most of the waste heat coming from power stations, data centres, wastewater treatment plants and industry.

In the UK, the energy consultancy Fairheat estimates that waste heat from the industrial sector, wastewater treatment plants and incineration plants could supply fourteen per cent of the country’s space heating and hot water demand.

Locally owned heat & power But if heat networks are to help eliminate

1

2 fuel poverty, we may need to embrace new models of generating and selling energy.

Last year, district heating made headlines in both the UK and Ireland, with residents of apartments running on gas-fired heating reporting eye-watering energy bills. The sector suffers from a lack of regulation in both countries.

In the UK, residents in council homes and private flats serviced by district heating have faced bill increases of up to seven hundred per cent, the Social Market Foundation has warned. Tenants have not benefitted from the government’s recent energy price cap be-

cause heat networks are treated as businesses rather than homes.

“The problems in heat networks disproportionately affect the worst-off families,” said Will Damazer, author of a report for the foundation on how to make heat networks fairer. “They have to put up with higher prices, worse regulation and less control over their heating and energy use.”

Residents serviced by district heating often have no option to change supplier, creating monopolies that can exacerbate the risk of price gouging. Duncan Smith believes the only way to protect tenants, and to shield

ph+ | river clyde case study | 41

RIVER CLYDE

CASE STUDY

Putting Puttingpeople peopleand and Putting Putting people people and the theplanet planetfirst first and the theplanet planetfirst first

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42 | passivehouseplus.co.uk | issue 45

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CASE STUDY

them from high energy prices, is for housing associations to start producing their own renewable energy.

“One of my concerns with energy security is that unless you tackle it head on, you’re always going to be dependent on the market, which quite frankly is broken,” he says.

“So, are we going to let the market provide energy, or do we look for models that are more equitable, more sustainable?”

Smith envisages River Clyde Homes building out heat networks, powered by water source heat pumps along the Clyde.

And he foresees the association developing its own wind and solar farms to power those heat pumps with cheap, clean electricity.

“If we want to look at big industrial heat pumps to produce low temperature heat, we need to think about how we feed those units. If we buy from the gird, we’re exposed to the same prices that you and I are exposed to,” he says. “If we put a turbine on the hills and produce energy, we think we can provide electricity for 4p per kilowatt.”

The association could then sell heat to its tenants for between 4p and 8p per kilowatt, he says. “For any income level, that’s solving fuel poverty.”

Energy service companies Public or co-operative energy utilities are

rare in the UK and Ireland, but far more common in mainland Europe. Of Denmark’s 350 district heating companies, approximately eighty per cent are owned co-operatively by their members, and most of the rest are owned by municipal authorities. There are few private companies in the sector, and a legal requirement to sell networked heat as cheaply as possible helps to keep prices down.

Germany, meanwhile, has around nine hundred stadtwerke, or municipal utilities, which are owned by local authorities, and which supply water, energy and other essential services. Today, stadtwerke account for sixty-five per cent of heat distribution in Germany, and they enjoy strong public trust.

Smith is excited about the possible knock-on benefits of locally owned, renewable heat networks. For example: there are about 40,000 homes in Inverclyde, and the average annual UK energy bill is about £2,500, which means £100 million leaves the area each year and goes to large energy companies. The same calculation could be performed for almost any region of the UK or Ireland. How would it benefit communities to have that money circulating in the local economy instead?

Smith envisages publicly-owned energy service companies using waste heat from

RIVER CLYDE

district heating networks to provide cheap energy to new enterprise parks, or to heat indoor, vertical farms that might otherwise rely on high carbon fuels. But more than that, he says providing cheap renewable heat is about improving people’s lives and health.

He points to recent research showing that British children who grew up during austerity were, on average, five centimetres shorter than their Danish counterparts, with diet, healthcare, living conditions, illness and poverty to blame. Meanwhile, almost one quarter of homes in Scotland experience fuel poverty , while twenty-four per cent of Scottish children live in poverty.

“This energy crisis we’ve got right now is much bigger than affordability,” he says, “it’s a health crisis.”

It doesn’t look like energy prices will become less volatile in the near future. So, is it time for housing providers and communities to start taking the generation of cheap, renewable heat and power into their own hands?

1 A large heat pump powering a district heating system at Frederiksberg Forsyning, Copenhagen; 2 Logstor insulated pipework for district heating in Albertslund.

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

1

Heat pump photo: Linda Bergholt Bertelsen

2

ph+ | river clyde case study | 43

CHURCH ROAD

CASE STUDY

IN BRIEF Development type: 47 unit housing scheme, comprising apartments, duplexes and houses Method: Externally insulated hollow block walls with brick slips Location: Killiney, Co. Dublin Standard: Passive house classic Heating costs: €74 to €265 per year *Prices based on the smallest (77 m2) and largest (220 m2) homes in the scheme.

See In detail panel for more information.

44 | passivehouseplus.co.uk | issue 45

CHURCH ROAD

CASE STUDY

HOPE SPRINGS EXTERNAL Section A-A

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Living room Ensuite Stairs Bed 3 Bed 1 Storage Utility

HIGH END PASSIVE HOUSE SCHEME LANDS IN KILLINEY What happens when one of Ireland’s most seasoned passive house builders and a renowned design-led architecture practice collaborate?

They create a head turning, high density passive house scheme that showcases the aesthetic possibilities of external insulation.

By Jason Walsh

ph+ | church road case study | 45

CHURCH ROAD

CASE STUDY

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uilding new homes in the middle of a housing crisis would seem uncontroversial. There are always pitfalls, however, from planning objections to the temptation to scrimp on quality simply in order to get numbers up. In light of this, any significant development will face an uphill battle getting planning permission, not to mention the danger that buyers will be nonplussed by the attention to technical detail.

And yet this is precisely what has been delivered in Egremont: 47 dwellings on a one-hectare site, designed to a high standard with extreme care taken to meet sustainability goals, including the passive house standard.

And all of this done in a district not known for approving planning for new housing of any sort, let alone a high-density mix of terraced houses, apartments and duplexes.

Located on Church Road in Killiney, County Dublin, the homes in Egremont are A2-rated and all electric, heated by an integrated air-based heating and ventilation system in the smaller units, and air-to-water heat pumps in the larger ones. Developed by Durkan Residential and designed by Ruth O’Herlihy of architects McCullough Mulvin, the development also saw consulting input from Irish passive house pioneer Tomas O’Leary of MosArt. When it comes to low energy building and retrofit, Durkan Residential has form. The firm set up an external insulation arm, Ecofix, in 2009, with pioneering green architect and sustainability consultant Jay Stuart. The

46 | passivehouseplus.co.uk | issue 45

firm built what remains Ireland’s largest passive house scheme, the 59-unit phase three of Silken Park in City West, and a sheltered housing scheme that became one of Ireland’s largest Enerphit schemes, St Bricin’s in Arbour Hill, Dublin city. Durkan Residential’s Barry Durkan said that, with this development, the twin goal was to meet the energy efficiency and sustainability standards that the company has put at the centre of its work, but to do so without making any compromises on design.

“Church Road is quite architecturally unique. It was always going to stand out. We did go down the road of passive house four or

five years ago, and I wanted to continue to do so,” Durkan said.

This proved a point, he says: the passive house standard could be adapted to all manner of architectural forms, including quite adventurous ones.

“The design called for lots of cantilevers, lots of balconies. That’s what I like about passive house: it’s a scientific model, so you eliminate all of the cold bridging, and you can prove you have done it. There’s no guesswork,” he said.

This is especially important as Durkan wanted the buildings to have design elements not typically associated with passive

CASE STUDY

CHURCH ROAD

It proves the point that a passive house doesn’t have to be a rectilinear box.

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house developments.

“Airtightness is a real challenge with cantilevers,” he said.

In addition, sedum roofing added additional natural insulation to the main insulation layer beneath, but its primary focus was to consider the environment in a broader sense than energy use. Egremont was built on the grounds of two demolished houses in a

Photos: Terry McDonagh

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leafy suburb. As a result, adding 47 dwellings required deep consideration of landscaping.

“The whole idea of the development is, because it’s an infill site with lots of houses around it, we had to help it blend into the landscape,” Durkan said.

The result has been transformative. Durkan Residential committed to the passive house standard some years ago, but until now, and

particularly with the ongoing housing crisis, energy issues have been secondary for buyers who are often happy to get any home. With Egremont, however, buyers have taken note of the buildings’ performance.

“It’s the first time we’ve had buyers with an interest in passive house. Up to now it has been location and price. It’s only until you live in one that you really understand it. People hate change,” he said.

Arguably, rising energy costs have played a role in this, alongside growing concern about climate change. Nonetheless, there can be little doubt that developing architecturally interesting houses that spark imagination helps.

However, one choice made at Egremont also represents a deviation from convention: the walls are externally insulated single leaf 9 inch hollow block, sitting on an insulated foundation system.

A combination which he had used successfully on Silken Park, Durkan says this choice made sense, but that he has often had to argue the point.

ph+ | church road case study | 47

CHURCH ROAD

CASE STUDY

“I’ve had a lot of push back from architects, engineers, building control [and so on] on single leaf, but if you externally insulate and use a single leaf block the results are excellent.

Condensation does not occur, and it releases heat [back] into the home. They’ve been using this kind of system in Germany for the last 30 or 40 years,” he said.

In the end, Durkan Residential worked with sympathetic architects and engineers and, as a result, Egremont is another step in the journey it has been taking to sustainability.

“I guess sustainability was always part of what we did. We have worked with really good architects in the UK and Ireland. We met passive architect Jay Stuart, and that’s how we went down that road,” Durkan said.

The project was passive house certified by MosArt, led by Tomas O’Leary, who built the first passive house in the English-speaking world and will be well known to readers of Passive House Plus. O’Leary says he likes to think of the role of certifier as being a quality gatekeeper. Part of this, he says, is helping the team rise to challenges.

“In a project like this, for a lot of people in the design team it was new, so the learning curve was pretty steep. The architecture on this project, at face value, doesn’t lend itself to passive house: recessed balconies, cantilever rooms, roof lights, but it proves the point that a passive house doesn’t have to be a rectilinear box,” he said.

“Thermal bridging was a challenge, but we worked with the engineers and architects in

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

48 | passivehouseplus.co.uk | issue 45

the detailing. It’s a real self-learning process and it’s very gratifying,” he said.

The project is now due to be submitted for the Irish Green Building Council’s Home Performance Index (HPI) certification, which includes consideration of embodied carbon and a broad range of quantifiable sustainability indicators. This is a reflection, O’Leary says, of Durkan Residential, and Barry Durkan in particular, having a sharp eye for sustainability.

“Barry really gets passive house. Very few developers have that. It’s so refreshing working with him. He has replicated a building system that he developed in Silken Park,” he said.

For his part, Durkan downplays his own

role in the project’s success, praising the role of Durkan Residential’s commercial manager Terry Maguire, who is procuring and project managing the whole project, and the funders, NAMA. “They backed our green agenda from the word go,” he said.

Architect Ruth O’Herlihy – who provides an architect’s statement below – was away on holiday when Passive House Plus approached her for additional comment, but her practice colleague and co-director Corán O’Connor spoke to us.

“As a practice, McCullough Mulvin has been interested in energy efficient building for some years. It all started with a lecture,” O’Connor said.

“Personally, I went to a lecture by Tomas

CASE STUDY

[O’Leary] in Dublin Castle about ten years ago and I got wind of the passive house concept that way,” he said.

“Church Road, nevertheless, represented something of a departure for McCullough Mulvin as the majority of the practice’s work is in public buildings. But some of the knowhow the practice picked up on sustainability in other projects was transferable,” says O’Connor.

“A lot of our work is not one-off houses, and this project was developer-led. Barry has been doing this for quite a while in the threebed semi world. In the commercial world, BREEAM and NZEB have been coming in for some time,” he said.

The attraction of the techniques that have grown up in the wake of passive house is that McCullough Mulvin, as a practice, puts significant focus on building fabric.

CHURCH ROAD

“We’ve always had an interest in doing things simply, trying to hold on to simple things […] before we add in the tech,” O’Connor said.

McCullough Mulvin’s design for Egremont added one additional complexity to the build: each dwelling is unique. Indeed, despite being a development, the contemporary design is more akin to high-end one-off houses than giant schemes.

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1 Several courses of Mannok blocks to start external walls; 2 floor Insulation EWI to foundation; 3 slab poured. see insulation again to front; 4 steel beams for cantilevered sections of townhouses; 5 Mannok block courses to wall plate level; 6 Tektherm plate thermal breaks to thermally isolate structural fixings; 7 windows sitting in external insulation layer; 8 Roben brick slips being fitted to external insulation; 9 bituminous cap sheet layer of IKO green roof system; 10 Siga membrane to roof structure and Skylux iWindow3 triple glazed roof windows; 11 Blowerproof paint-on airtight membrane used here at a concrete ceiling to blockwork junction; 12 fire collars for ductwork penetrating the ceiling.

ph+ | church road case study | 49

CHURCH ROAD

CASE STUDY

SELECTED PROJECT DETAILS

Client: Durkan Residential / NAMA Architect: McCullough Mulvin Architects Mechanical/electrical engineer: Metec Civil/structural engineer: CS Consulting BER assessor: Buildcert Passive house certifier: MosArt Main contractor/project management: Durkan Residential External insulation and airtightness contractors: Ecofix Mechanical contractor: MCD Plumbing Electrical contractor: Armour Electrical Airtightness tester/consultant: Building Envelope Technologies Fifty percent GGBS mortar: Kilcarrig Quarries Green cements: Milford Quarries Quantity surveyors: Conway McBeth External insulation: Baumit, via Chadwicks Thermal blocks: Mannok Green roof system: IKO Airtightness membrane: Siga Paint-on airtightness seals: Blowerproof Ireland Windows and doors: Carlson Roof lights: D&R Daylight Services Ltd. Compact heat pumps and ventilation systems: Nilan Ireland Air-to-water heat pumps: Unitherm Fit-out, furniture, flooring and carpets: Minima Sanitaryware: Rocca, via Bathhouse Attenuation tank: Resolute Engineering Group Ltd. Landscaping: Buggle Landscaping Insurance: Le Cheile

O’Connor praised his colleague’s work, saying McCullough Mulvin had achieved the feat of creating a high-density scheme that felt anything but.

“From our point of view, it was about making the green agenda important, also the fact that we kept as much of that green land. 47 units on one hectare, this is high density – but it doesn’t feel like an urban scheme: it’s like a landscape scheme”.

Indeed, O’Herlihy’s design not only resulted in unique houses, it also avoided a simple grid. Instead, homes are laid out in four terraces that have been ‘cranked’ or bent to shift perception of scale as well as situate them better in the landscape.

This runs counter to general expectations of passive houses, O’Connor said.

“We didn’t just drop in a grid of terrace houses; we bent them to make them feel quite natural and organic”.

In addition, the wider landscape of south County Dublin and Wicklow also figured.

50 | passivehouseplus.co.uk | issue 45

CASE STUDY

It’s the first time we’ve had buyers with an interest in passive house.

Up to now it has been location and price.

“You want it to have a dialogue with Killiney hill, and it looks out toward the Sugar Loaf [mountain]. It’s a site-specific response,” he said.

“There are dozens of neighbours here, to the back of the scheme alone here are half a dozen houses and we wanted to preserve their views of the Wicklow mountains, so we put the short gable ends against their side”.

O’Connor says that he hopes the development will spark conversation about the future of high-density housing in Ireland, as it offers an alternative to uniformity and considers the environment in the widest possible sense.

“There’s so much talk at the moment about low-rise, high-density. We should be asking: how can good design be used to make these the best possible places to live,” he said.

surrounded by and shot through with mature trees – for the insertion of four canted blocks comprising 47 passive units.

The blocks are oriented east / west to maximise the light penetration and their cranked forms create a series of generous external public spaces including a children’s playground.

Their juxtaposition allows for parking to be dispersed, fractured by landscaping and access roads which twist up the site, their impact mediated by the geometries.

Two blocks of three-storey family houses take up each side of the site with two blocks containing apartments (duplex over ground floor) defining the centre of the site.

The sinuous geometry of the scheme is accentuated by the unity of materials – buff brick with green roofs and a series of carefully scaled inset balconies in all blocks that capitalise on views of the Wicklow mountains.

Living spaces are dual aspect and designed to be flexible, shot through with light that is brought deep into the houses & duplexes via roof lights and voids that allow it to penetrate. Generous landings below these give unique opportunities for the owners to make

CHURCH ROAD

them their own – maybe a library, maybe a home office, maybe a playroom.

The houses are a collection of flexible spaces designed for both living and working and for all stages of life.

Generous gardens to the rear of each have a stunning elevated backdrop of mature hedgerows and trees. The project has been carefully landscaped to draw together the existing context and enhance this with new levels and planting. Stone from the site has been used to create level changes using gabion baskets and sliced-in paths culminating in a public terrace elevated at the rear of the site looking towards the Leadmines chimney.

A simple palette of natural materials seeks to draw out the colours of the landscape making the buildings of the place. The varied views, available from the units resulting from their differing orientations, seeks to start a new conversation about how we live as a community: oblique connections are established between the blocks and perspective views change as you move, released by the way the light falls on the building planes.

Architect’s statement: Ruth O’Herlihy, McCullough Mulvin The site, on the side of a hill in South County Dublin, along with a progressive client inspired an idea that we would try to make a green housing project together.

Four individual sites were combined on a south facing slope – a beautiful backdrop

ph+ | church road case study | 51

CHURCH ROAD

CASE STUDY

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52 | passivehouseplus.co.uk | issue 45

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CASE STUDY

CHURCH ROAD

IN DETAIL Development type: Speculative housing scheme of forty-seven passive houses, including apartments, duplexes and terraced houses of various sizes, indicatively including 73-97 m2 two-bed apartments, 125-175 m2 duplexes and 165-220 m2 three-bed houses.

Site type and location: Suburban infill site, Church Road, Killiney, Co. Dublin Completion date: Construction in progress Budget: €17m Energy standard: NZEB and passive house classic (pending) Energy costs: Smallest (73 m2) apartment: €74-88 per year.

Largest (220 m2) house: €223-265 per year.

These prices assume occupants opt for smart meters, with tariffs based on Electric Ireland’s Home Electric+ Night Boost offer, 03 August 2023. The prices are for space heating only, and assume 20 per cent of usage at day rate, 30 per cent at night rate, and 50 per cent at night boost rate (between 2-4am). The prices assume a seasonal COP of 3.

Space heating demand (PHPP): 16 kWh/m2/yr (Blocks A and C), 17 kWh/m2/yr (Block D) and 19 kWh/m2/yr (Block B) Heat load (PHPP): 9 W/m2 (Block A) and 10 W/ m2 (Blocks B, C and D) Primary energy non-renewable (PHPP): 90 kWh/m2/yr (Block A), 109 kWh/m2/yr (Block B), 91 kWh/m2/yr (Block C) and 106 kWh/m2/yr (Block D).

Primary energy renewable (PHPP): 44 kWh/m2/ yr (Blocks A and C), 52 kWh/m2/Yr (Block B) and 51 kWh/m2/yr (Block D) Heat loss form factor (PHPP): 2.08 (Block A), 2.18 (Block B) and 2.05 (Block C and D) Overheating (PHPP, expressed as percentage of year above 25C): 1 per cent (Blocks A and D), 0 per cent (Block B), 5 per cent (Block C) Number of occupants (assumed in PHPP

calculations): 24 (Block A, 34 (Block B), 32 (Block C) and 34 (Block D) Green building certification: The project will be submitted for certification to the IGBC’s Home Performance Index Embodied carbon: Not yet calculated (subject to HPI certification) Airtightness: All homes will meet 0.6 ACH @ 50 Pa (final tests pending). Airtight strategy includes sand / cement plaster layer to inner face of blockwork, Siga membrane to roof, with taping and Blowerproof paint-on membrane used around services and floor junctions and hard to reach areas.

Thermal bridging: The use of external insulation – also brought below ground level – largely minimised thermal bridging. Several courses of Mannok Aircrete blocks were used at the base and top of external walls. Windows and doors with thermally broken frames sit proud of wall on structural insulation within insulation layer. Tektherm plate thermal breaks used at external stairs and canopy connections.

Ground floor: 150 mm in-situ reinforced concrete slab (airtight layer) on 100 mm EPS insulation on gas barrier DPM on 200 mm EPS insulation. U-value = 0.10W/m2K Walls: Single leaf masonry with Baumit external insulation system, comprising 15 mm clay facing brickslip by RobeN, 5 mm adhesive mortar & basecoat render, 160 mm EPS Platinum EPS70 (thermal conductivity 0.031 W/mK), 5 mm adhesive mortar & basecoat, 215 mm hollow concrete blockwork, 12 mm sand and cement render (airtightness line), 20 mm service cavity, 15 mm plasterboard & skimcoat finish.

U-value: 0.17W/m2K Roof: Iko green roof including sedum mix blanket, 80 mm growing substrate, 20 mm drainage layer, 7 mm bituminous cap sheet and underlay, 220 mm Xtratherm FR/BGM insulation bonded to deck (thermal conductivity 0.025

w/mK), VCL, 18 mm ply decking, firring pieces to falls, 276 mm (minimum) Posi-joists, 15 mm plasterboard & skimcoat finish.

U-value: 0.11W/m2K Windows and external doors: Carlson triple glazed timber aluclad windows.

U-value (typical) = 0.79 W/m2K Roof windows: Skylux iWindow3 triple glazed roof windows. Uw-value: 0.5 W/m2K Heating system (Apartments & Duplexes): Nilan Compact P Passive House Institute-certified compact heat pump (air-based heating integrated with heat recovery ventilation, post heater, and domestic hot water) with 180 litre buffer tank. Hot water and the majority of heating is provided by the Nilan Compact P. Heat is extracted from the exhaust air after the heat exchanger via a heat pump and then used to heat a hot water tank.

The hot water tank stores the heat and when required provides hot water. The energy stored in the hot water tank can be extracted for use by the post heater when heating is required. There are electric radiators installed to provide top-up heating as and when required.

(Houses): LG Therma V R32 monobloc air-to-water heat pumps, with a SCOP of 4.45 and Energy label rating of A+++, supplying radiators and 180 litre buffer tank. The heat pumps feature a corrosion resistant heat exchanger designed for humid conditions and coastal regions, and produce 100 per cent power output down to -7 C ambient temperature, with an operation range of 25-65 C without an electric backup heater.

Ventilation: Nilan Compact P — Passive House Institute certified to have heat recovery rate of 80 per cent Potable water use: Not yet calculated (subject to HPI certification) Change in ecological value: Not yet calculated (subject to HPI certification)

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SENAN HOUSE

CASE STUDY

SEAL OF OFFICE IRELAND’S FIRST PASSIVE CERTIFIED OFFICE BUILDING

While the passive house standard has had a lasting impact on the design and construction of new homes in Ireland, progress has been slower in commercial property. With the business world under increasing pressure to take meaningful climate action while providing better working conditions for staff, one new office building in the southeast may be a sign of things to come – and a beacon for a UN-affiliated project.

By John Hearne

54 | passivehouseplus.co.uk | issue 45

SENAN HOUSE

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Building type: Four-storey, 4,710 m2 office building Method: Steel frame with celluloseinsulated timber panels Location: Enniscorthy, Co. Wexford Standard: Passive house classic

Embodied carbon: Meets RIAI 2030 Climate Challenge target See In detail panel for more information.

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landmark development on a prominent site just outside Enniscorthy in Co. Wexford has become Ireland’s first passive house certified office building.

Built by longstanding passive house contractor Michael Bennett Group under a design and build contract, Senan House was designed by passive house architects MosArt. With that combination of expertise behind it, this building was always going to be exceptionally high performing. It also represents an early benchmark in respect of embodied carbon for Irish office buildings.

“Ever climbed Croagh Patrick?”, architectural technologist Stephen Donoghue asks in response to a query about the challenges posed by the site. Enniscorthy is a hilly town.

Its new technology park – of which Senan House is the lead building – is cut into the side of a steep hill that runs down to the Wexford road and the river Slaney, which run parallel to each other for about five kilometers outside the town. During the early stages of the project, preparing a sloping site and getting levels right was very challenging, not least because of the unstable wet marl that comprises so much of the land in this part of the country. The payoff comes in a striking building with fantastic views. Senan House runs on a slightly cranked north-south axis, with views of the river valley to the west. You can see the town with its spires against the backdrop of the Blackstairs Mountains to the north while St. Senan’s Hospital – a distinctive Victorian building now converted into

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apartments – can be seen through the southern windows.

Art McCormack of MosArt explains that the reference building for this project was a successful tech incubation space called The Hatch Lab down the road in Gorey. Once brought on board by Michael Bennett, MosArt created a masterplan for the site, which included the construction of a sister building alongside Senan House. Wexford County Council, who plan a pedestrian and cycle bridge linking the town centre and the technology park, owned the site and supported the development through all its phases.

A variety of design options – including the possibility of creating a construction training centre – were explored before the team settled on a rational, flexible office building. The first plan ended at the third storey, but following input from Wexford County Council, it was decided to add a fourth, recessed, penthouse-style storey facing west to the river.

Further proof of the support of the local authority comes in the fact that it took just five weeks to get through planning.

“The steep site was one of the main design problems,” says Art McCormack. “So, we used the higher ground to the east to create a bridge and enter the building at the firstfloor level.”

In the original plan, the central bay which projects towards the river housed a multiheight atrium. The site was subsequently sold to a private company however, and, as McCormack puts it “they added insight into

The HVAC units have yet to operate. So far, things are really comfortable.

how the offices might be optimised.” Rentable floor space was expanded, and the atrium took on more modest dimensions.

McCormack explains the north-south alignment follows the contours of the site and makes sense in terms of road layout and how the building would be accessed via that aforementioned bridge linking the car park with the first floor.

The detailed design stage coincided with the pandemic and everything that went with it. A subcontractor was commissioned to provide the timber wall panels that the design team had settled on. Covid-related issues forced that contractor out of the project in mid 2020 however, and finding a replacement proved challenging. During this period, the design team almost decided on a cross laminated timber (CLT) construction. This is the process of using bonded layers of solid wood panels for floor, roof and wall elements, thereby achieving carbon savings that are vastly superior to concrete and steel. In the

CASE STUDY

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5 ROOF PLAN

1 GROUND FLOOR PLAN

1. Ground floor plan

2 FIRST FLOOR PLAN

2. First floor plan

5. Roof plan

end however, the financials didn’t add up, and PYC Construction stepped into the breach with their I-beam system. They built and supplied the factory-fabricated timber panel I-joist system that was used on the build – a low embodied carbon system designed to be airtight, breathable and windtight. The 240 mm wide panels comprise Propassiv boards on the inside taped at edges, I-beams fully filled with close to roughly 67 kg/m3 of Warmcel cellulose, Meditevent board and Pro Clima Fronta Wa, taped for wind tightness.

While the panels came pre-taped, they were taped together for airtightness, and taped to the concrete slab and roof.

Stephen Donoghue lists the advantages of this build approach. “There’s less mess, it’s cleaner and safer, and the panels go up faster, plus you get better quality. And you don’t need scaffolding. There was no scaffolding erected on this building.”

In order to avoid thermal bridging where the external walls meet the structure, the panels were hung from the steel beams. This was one of several strategies deployed to ensure an unbroken thermal envelope. Though the bridge at the main entrance looks as though it’s connected to the building, it is structurally separate, and actually ends 5 mm from the wall. On the top floor, a 10 mm load-bearing insulation was used to separate the steel base plate which supports the roof canopy from the insulation below, and rainwater downpipes were wrapped with foil-backed insulation from roof to ground floor.

Windows, curtain walling and external doors are Passive House Institute certified.

The windows have thermally broken aluminium frames, which were manufactured locally by Reynaers Aluminium. Unusually in an office space, all units are triple glazed, and glazing covers 23 per cent of the structure. At 1.34, the building has an excellent heat loss form factor.

According to the PHPP, there is zero risk

Photos: Paul Tierney

ph+ | senan house case study | 57

SENAN HOUSE

CASE STUDY

that the air temperature will exceed 25 degrees over the course of the year. In the absence of brise soleil, overheating risks are mitigated by glass with three separate G values, ranging from 42.7 per cent down to 27.8 per cent.

Art McCormack notes that there was a particular overheating risk in an office high in the central bay, which projects east but also has exposure to the southern sun. Again, that risk was dealt with using glazing with a very low G value.

Doubts about the airtightness strategy planned for the raised mono-pitch steel panel roof prompted the build team to construct a mock-up onsite, and test its airtightness, just to see if it would work. It didn’t. The dovetailed system failed, so all the panel joints and roof-to-wall junctions were taped by airtightness contractor Aerzeal Ltd, with input from Joe Fitzgerald from Ecological Building Systems and Roman Sypura from Clioma House. The subsequent test confirmed an excellent score of 0.15 ACH at 50 Pa. There is no oil or gas onsite – the office is fully electric. Integrated units from Nilan – two per floor – look after heating, cooling and ventilation. These units are connected to the Nilan Cloud system, a cloud-based management system which allows the facilities manager to remotely control the system as they wish, rather than going to individual control panels, and which enables remote servicing and maintenance. A large PV array supplements the power load. At one point, the plan was to mount the panels on the pitched roof, but the change to the roof spec

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58 | passivehouseplus.co.uk | issue 45

as a result of airtightness issues prompted a rethink, and the panels – 119 in all – were relocated to the flat roofs.

The system was actually installed by the building’s first tenant – Pinergy Solar Electric.

CEO Ronan Power explains the system generates an annual average power of just over 44,000 kWh, with peak power of just over 48,000 kWh. “The install here was quite similar to those we’ve done with other corporate customers.

Because this was a building still under construction rather than a retrofit, however, it was quite a complex lift and build, with a number of health and safety issues. So far, the generation appears to be excellent.”

He expects the system to offset in the order of 20 per cent of the building’s total power demand. There is also an export connection under ESB Networks’ mini-generation connection process which effectively compensates users for any unused electricity that is exported to the grid.

Power says that he and his colleagues moved in last February. “We’ve our feet under the table at this point, and it’s great, we love it here.

Senan is very aligned to our core values, in terms of sustainability, and it’s nice knowing we’re in a passive building.”

Though the company has not yet seen a full heating and cooling season, first impressions are very good.

“The building seems to be performing very well. Bear in mind, mine is a corner office, with two external windows. We’re monitoring humidity and CO2, and everything is staying within normal levels. There’s just our-

selves – twenty-four people – and one other tenant so far. That’s not a huge load, and the HVAC units have yet to operate. So far however, things are really comfortable.”

And there’s no comparison with the company’s last office, he says, which was old, with all an old building’s flaws. It’s currently being retrofitted.

“Ours is a growing business, so this is ideal for us. We’ve got space to expand, and we signed a ten-year lease because we want to continue to stimulate employment here.”

CASE STUDY

SENAN HOUSE

Embodied carbon A cradle-to-grave embodied carbon calculation was done by Ciaran Flanagan of MosArt using One Click LCA. The scope included all the big ticket items within the building itself - the foundations, superstructure, thermal envelope, PV array and heat pump and ventilation system – but did not include the external works, including the car parking area, which would likely have

added a significant amount. The building fit out was excluded, as were the ducts, pipes and cables for buildings services.

In many cases punitive default data from One Click was used, in the absence of Environmental Product Declarations, most notably in the case of the three largest sources of the building’s embodied carbon: the structural steel frame, concrete, and PV array,

1

2

4

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which respectively contributed 1,200 tonnes, 371 tonnes and 180 tonnes of CO2e to the building’s cradle-to-grave total of 2,357 tonnes – or 484 kg CO2e/m2 of gross internal area, comfortably inside the RIAI 2030 Climate Challenge target for offices of 750 kg CO2e/m2, albeit with omissions from the scope including a potentially large total for external works.

3

6

1 The steel frame structure; the thermal envelope takes shape with 2 PYC Construction’s cellulose insulated, airtight panels and 3 windows and steel battens and counter battens; 4 airtightness tests were conducted on a mock-up of the roof system to catch and address leakage issues; 5 & 6 to obviate thermal bridging where the external walls meet the primary steel structure, the wall panels were hung by steel lugs from the steel beams; 7 the windows have thermally broken aluminium frames, which were manufactured locally by Reynaers Aluminium; 8 a 10mm thick Farrat TBK structural load-bearing insulation was used to separate the steel base plate from the insulation within the structure; 9 precaution was taken to wrap rainwater down pipes with foil-backed insulation from roof to ground floor; 10 heating comprises air-based heat distribution via two Nilan VPM 360 MVHR units per floor.

ph+ | senan house case study | 59

SENAN HOUSE

CASE STUDY

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60 | passivehouseplus.co.uk | issue 45

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CASE STUDY

SENAN HOUSE

UN Connection One thing the project team could not have anticipated is the building becoming emblematic of a UN-backed high performance building initiative, but that is what has happened.

Early in the project, builder Michael Bennett organized a visit to the site by a delegation that included Scott Foster, then director of sustainable energy at the United Nations in Geneva. During his decade-long tenure at the UN, Foster worked with experts to develop the UN’s Framework Guidelines for Energy Efficiency Standards in Buildings that were at the heart çof the high performance buildings initiative. The guidelines were endorsed by the Committee on Sustainable Energy in 2017 and then by the UN Economic and Social Council in 2018.

Foster credits Tomas O’Leary as a catalyst for the discussions that led to the creation of the guidelines.

Foster and Washington DC-based consultant Robert Cavey supported establishment of an entity in Enniscorthy, the Enniscorthy Forum, to support the UN’s sustainable development agenda. The remit for the forum includes not only buildings and the built environment, but also energy, diplomacy, health and education. In the process of the forum’s institution they worked with Michael Bennett, who championed Enniscorthy for the new organization and sits on the forum’s board.

Under the stewardship of CEO Barbara-Anne Murphy, the forum now has launched the Buildings Action Coalition, a global collaboration comprising partners from industry, communities, academia, NGOs, governments – all stakeholders in the built environment. “Our partners are dedicated to making real and rapid differences in the built environment around the world to enhance quality of life globally

while meeting the climate challenge,” said Foster.

The coalition convened an international summit in Enniscorthy in June to celebrate the recent signing of a memorandum of understanding with the UN Environment Programme. The memorandum of understanding sets out a broad collaboration between the Enniscorthy Forum and the UN to advance the buildings breakthrough target proposed under the Glasgow Breakthrough Agenda. The target calls for near-zero emission and resilient buildings to be the new normal by 2030. Foster notes how helpful it is to have a landmark building in Enniscorthy that demonstrates how high performance can be achieved, “The forum’s logo represents the castle of yesterday, the building of tomorrow, and the bridge of transformation”.

SELECTED PROJECT DETAILS

Client: Moyne Point Ltd Main contractor: Michael Bennett & Sons Architects/passive house designers/ landscape architects: MosArt Ltd Mechanical engineers: Arkman Mechanical designers: Colman Reynolds Associates Civil/structural engineer: John Quigley & Associates Energy consultant: JOT Energy / IES Quantity surveyors: Nolan Construction Consultants Mechanical contractor: Ollie McPhilips Ltd Ventilation contractor: AirCon Mech Electrical contractor: Bunclody Engineering Fire alarm & access control: Bluerock Networks Airtightness tester/consultant: Greenbuild Structural steel: Wall Steel Structural thermal breaks: Farrat Insulated wall panels: PYC Construction Thermal building blocks: Mannok Roof insulation: New Century Roofing Floor insulation and screeds: Niall Barry and Co. Ltd Airtightness contractor: AerZeal Ltd Windows, doors and curtain walling: Reynaers, via Curran Aluminium Cladding supplier: Cembrit, via New Century Roofing Flooring and carpets: Matt Kilroy Heating, cooling and ventilation: Nilan Ireland Primary hot water system: Ollie McPhilips Ltd Photovoltaic supplier: Pinergy Solar Electric

ph+ | senan house case study | 61

SENAN HOUSE

CASE STUDY

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CASE STUDY

SENAN HOUSE

IN DETAIL This building, Senan House, is the first in a series of buildings in the Enniscorthy Technology Park (ETP) that are intended to stimulate economic growth and development in Enniscorthy Town and its surrounds, as well as augmenting a sense of purpose and pride. The site, positioned on a slope that overlooks the river Slaney and its gentle flood plain, is highly visible from the town.

A new pedestrian and cyclist bridge is planned to cross the river Slaney, linking the town centre and the ETP, thus ensuring greater sustainability. It has been commented that this building makes a 21st century contribution to the form and profile of the town that is noteworthy for landmark structures from bygone years, including the Anglo-Norman Castle and two elegant Victorian church spires.

Building type: Senan House comprises a four-storey detached office building of 4,710 m2 with the top-most floor set back as a gallery balcony to provide penthouse offices.

Construction comprises factory-produced timber wall panels with Warmcel cellulose insulation that hangs on a steel primary structure.

Site type & location: The building is the first in the Enniscorthy Technology Park on a site owned by Wexford County Council and zoned for Business and Technology Park. It is a peri-urban site northeast of Enniscorthy Town, Co. Wexford looking onto the N11 linking to Wexford Town and over the river Slaney and its flood plain.

Completion date: February 2023 Budget: €6.5 million for construction and €8 million including site development and external works, but not including site purchase and professional fees.

Passive house certification: Passive House Classic (certification in process) Space heating demand: 18 kWh/ m2/yr Space cooling demand: 1 kWh/ m2/yr Heat load: 10 W/m2 Space cooling load: 6 W/m2 Primary energy: 149 kWh/m2/yr Heat loss form factor: 1.34 (Total thermal envelope of 5,708.32 m2 / TFA of 4,238 m2) Overheating: PHPP): 0 per cent of year above 25 C. Number of occupants: 377 Energy performance coefficient (EPC): 0.52.

Carbon performance coefficient (CPC): 0.53.

BER (SBEM/NEAP): A2 (52 kWh/m2/yr)

Embodied carbon: 484 kg CO2e/m2 TFA, calculated using One Click LCA (cradle-to-grave, excluding operational energy and water). See article for detailed description.

Measured energy consumption: N/A – would require a minimum year’s occupation and use.

Airtightness: 0.15 ACH at 50 Pa or 0.540 m3/m2/ hr at 50 Pa. Thermal bridging: Point thermal bridge where steel posts supporting projecting roof canopy at top floor meet the gallery. A 10 mm thick Farrat TBK structural load-bearing insulation (0.187 W/ mK thermal conductivity) was used to separate the steel base plate from the insulation within the structure.

Thermal modelling was carried out at the plinth, particularly regarding the penetration of floor insulation by steel stanchions. Likewise, the plinth was modelled to see whether the thermal block used as a thermal break could be reduced. It was, thus, established that a reduction was feasible.

Precaution was taken to wrap rainwater down pipes with foil-backed insulation from roof to ground floor, and ventilation ducts were isolated with insulation from the external walls.

Main access via a steel and concrete bridge that remained structurally independent of the building.

To obviate thermal bridging where the external walls meet the primary steel structure, the wall panels were hung by steel lugs from the steel beams.

Ground floor: 150 mm reinforced concrete slab reinforced with fiberglass thread on 125 mm PIR insulation (thermal conductivity 0.022 W/mK), on Visqueen EcoMembrane loose-laid polyethylene DPM, U-Value: 0.169W/m2K. Walls: 8 mm Cembrit fibre cement rainscreen board, on treated and planed timber battens and counter battens faced with EPDM and profile ribs, on factory-fabricated s.w. wall panels from PYC Construction comprising Pro Clima Solitex Fronta WA membrane, on 12 mm Smartply Medite Vent Board (vapour-open), 240 mm deep I-sections @ 600 mm centres filled with blown Warmcel cellulose 0.15 W/mK thermal conductivity), on 12.5 mm Smartply ProPassiv airtight board on 12.5 mm plasterboard. U-value: 0.152 W/m2K Roof: Single-ply membrane with standing seam on pitched roofs on RK Roofliner with 10 mm insulation. U-value: 0.12 W/m2K This insulation abuts directly to the perimeter parapet balustrade and to high-density Rockwool

insulation beneath the recessed glazing forming part of the wall for the top floor in order to minimise thermal bridging.

Fenestration: Passive House Institute certified windows, curtain walling and external doors.

Aluminium thermally broken frames with argon-filled triple glazing. Whole-window and curtain walling U-value installed: 0.63-0.90 W/ m2K, depending on orientation. Average U-value installed: 0.71 W/m2K. North-facing glazing: U-value of 0.6 W/m2K and a g-value of 42.7 per cent.

East, south and west-facing glazing: U-value of 0.5 W/m2K and a g-value of 36.7 per cent.

Modelling with SBEM established that a single office located above the main entrance and with east and south exposure could suffer from more critical over-heating and, thus, comprises a U-value of 0.5 W/m2K and a g-value of 27.8 per cent.

Doors: Installed U-values of 0.93-1.3 W/m2K, depending on orientation.

Typical Psi-values for fitted windows are 0.060 W/mK at heads, 0.047W/mK at cills and 0.058 W/ mK at jambs.

Heating, cooling and ventilation system: Air-based heat and cooling distribution via the 2 x Nilan VPM 360 heat recovery ventilation units per floor. Each unit has a 3,600 m3/h capacity, combining passive and active heat recovery as well as heating and cooling to all office spaces.

The building is completed to a shell and core standard with fit-out by future tenants.

Individual split units to meet localized heating and cooling needs if necessary for each office area are, therefore, to be selected as tenants assume occupancy.

Electricity generation: Vertex S solar photovoltaic array with an average annual output of 44,386 kWh and 48,196 kW peak power. The majority of the electricity thus produced is used on site, with the excess exported to the grid.

Four car parking EV chargers fitted and there is a provision in 20 per cent of car parking spaces for future EV charging.

Sustainable materials: Timber frame panels using FSC certified timber; cellulose insulation, glass fibre reinforcement in (above ground floor) concrete floor slabs instead of more conventional steel reinforcement bars, locally produced high performance windows and curtain walls.

ph+ | senan house case study | 63

AIB HPI

INSIGHT

BANKING ON

SUSTAINABILITY WHY A PILLAR BANK IS FINANCING VERIFIED GREEN HOMES Last year Irish banking behemoth AIB launched discounted development finance for homes certified to the Irish Green Building Council’s rating system, the Home Performance Index. But what was behind the move, how is it being received and does this indicate the finance industry is getting serious about green homes?

By John Cradden and Jeff Colley

T

hese days sustainability is a core part of business for banks like AIB, particularly when you hear numbers like €600 million. That’s the amount of green finance that the pillar bank has already lent over the last 12 months to developers here in return for submitting their schemes to an international green building standard known as HPI (Home Performance Index) which is spreading like wildfire – with over 20,000 homes built or in development to the standard to date.

The motivation for developers is twofold.

Firstly, AIB is offering discounted finance to developers in return for certifying schemes to the HPI. Secondly, the bigger developers know that the writing is on the wall: the investment community is increasingly moving towards demanding verifiable sustainability claims on real estate projects as ESG (environmental, social and governance) reporting requirements become the norm in the investment community.

Given that AIB’s offer is tied to the HPI, it’s worth understanding just how rigorous this flourishing new national certification scheme for new homes is.

Developed and managed in Ireland by the Irish Green Building Council (IGBC), the HPI is the residential equivalent of wellknown green building certification systems for non-domestic property like LEED or BREEAM, and takes a holistic approach to evaluating the sustainability of new housing with 35 measures including calculated energy efficiency, embodied carbon, monitored indoor environmental quality, biodiversity, land use, water use, universal design and accessibility to public transport, schools and amenities.

“I think the reason the uptake is very successful in AIB is because they lend to developers with large developments which may include investors from pension funds,” said IGBC programme manager Johanna Varghese. “Often, long term investors are looking for certified properties as it provides a cer-

64 | passivehouseplus.co.uk | issue 45

tain amount of assurance that the buildings are built well, are durable, energy efficient and sustainable with many ESG requirements fulfilled. In addition, the value often appreciates over time.”

So how did the bank come across the HPI standard and why did it appeal? AIB has been prioritising its sustainability agenda for some time. Under the leadership of chief executive officer Colin Hunt, it had pledged some time ago that 70 per cent of all its new lending would be “green’’ or “transition’’ by 2030, and that it would be net zero in all its own lending activities by 2040 (excluding agriculture).

With those two key targets in mind, Paul Kelly, head of sustainability at AIB’s real estate finance division, told Passive House Plus that, as a leading player in the development finance space, the bank felt it had a duty to more than just encourage developers to tick the sustainability box.

“With that leadership position comes responsibility and so we’re conscious that we have to bring customers with us…and to leave no one behind,” he said.

As a platinum member of the IGBC, all the roads were clearly leading to the adoption of HPI as its standard, not least once it emerged

that several of its developer clients were also members too. “If I look at our customer base, it’s almost an overlay of the IGBC,” he said.

“What we wanted to do was come up with something that, I suppose, resonated with our own values in terms of trying to do more.” International recognition was important, said Kelly, but also that it was “independently verifiable”. In developing the HPI, the IGBC aligned it with the EU’s Level(s) sustainable buildings framework, taxonomy on sustainable finance and European Committee for Standardization (CEN) standards, along with Irish building regulations and the international Well certification for communities. The certification was awarded 5 out 5 for best practice and transparency by the European Construction Sector Observatory.

Kelly said that in addition to the HPI’s international credentials, AIB was attracted to the fact that the HPI goes far beyond energy performance calculations. “BERs are an important tool in that they align to the taxonomy and all of that,” he said. “But, equally, they have their restrictions and limitations.”

“What we liked about HPI was that it took into account the location, it took into account water usage, daylight, the overall emis-

INSIGHT

sions. It took in biodiversity, acoustic performance … a huge amount more than just the BERs. And so we looked at that and we said, yeah, you know, that’s a good basis. But then we engaged with the IGBC and we had some really good conversations with Pat (Barry) and his team and they understood what we were trying to do, and that we were trying to put a process in place from our perspective that could be robust.”

Kelly’s own route to spearheading the AIB’s sustainability drive in real estate finance was a circuitous but interesting one that started with a project in social housing. In the course of working with smaller developers all around the country to build a national profile, he was encouraged to help them get a foothold in ‘turnkey’ social housing. “I realised that there were disparate strands, but I then said, let’s pull together a fund here….and so we actually kind of almost created a sausage machine that would allow the bank consider these kinds of social housing deals a lot quicker, a lot more smoothly, a lot more efficiently.”

This involvement in the social housing space segued naturally into sustainability, with Kelly later joining the board of the Oakfield Trust, where he focused on kicking off funds to help social enterprises. That led to getting invited to discussions and proposals around green bonds, and later green loans and ESG and before long he gained a name as AIB real estate finance’s “green guy”.

“So it started off small in effect,” he said.

“In a bank you have your day job, and then you have your after-hours stuff.” He agreed with his bosses that this was unsustainable (“no pun intended”, he jokes) so, to no-one’s surprise, sustainability became the day job.

The over €600-odd million worth of loans generated by AIB’s current green development finance offering is currently having the most resonance with developers building private rental sector (PRS) developments. “The reason being that the purchasers of PRS are particularly concerned about ESG credentials said Kelly.

But how much of a cost premium is HPI

adding? Remarkably little, it turns out. “We modelled it, and we found with the PRS schemes that there’s a cost of approximately €350 per unit on HPI, when you take into account the extra design features, going through the processes, the extra paperwork”.

So what the bank tries to do is ensure any margin reduction will enables the HPI costs to be covered “and some”.

“We offer this to every customer that walks in the door. Every time they get a term sheet from us it will say ‘your margin is X, if you go with HPI it’s Y.’ And it’s always a reduction.

It’s 0.1% which sounds small, but we modelled it and realised that we are covering the

AIB HPI

cost double.”

Given that these PRS schemes tend to be large projects, even relatively small cost savings can add up. “Let’s say the customer’s cost is €100,000 for doing HPI,” says Kelly.

“The average margin reduction was meaning to them about €200,000. So they’re getting all the costs covered. They’re getting a better product for their purchaser, they’re helping the environment, and they’re quids in. We as a bank are taking a hit on that margin income, but we are happy to do that because we’re trying to prompt customers to move in the right direction.”

While engagement has been positive so far among AIB clients serving the PRS sector, Kelly cautioned that uptake wasn’t as strong among traditional house builders – and the bank has plans to fix that, starting by engaging with the IGBC to work out how to tackle it.

“It’s not good enough from our perspective that we see that estate houses, the HPI offering isn’t really quite landing,” he says. “Is that something to do with our offering, or is it that the HPI isn’t quite covering it? We’re literally just at the foothills of having those conversations with the IGBC. Is it whole life carbon, is it net zero? How might we try to develop a proposition for our developer customers that takes into account some of those future pieces? The principle is trying to prompt behaviours to look to the next thing.”

ph+ | aib hpi insight | 65

AIB HPI

INSIGHT

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INSIGHT

As it stands AIB launched a green mortgage offering with rate reductions for homes with a B3 BER or higher in 2021 – developed by the mortgage lending team before and separately from the green development finance initiative.

As AIB seeks to expand the footprint of its green development finance beyond PRS and into the traditional house builder market, Kelly says he expects to be “a bit more involved” with the mortgage lending team to understand what their end user customers’ wants are.

European market movement There is precedent here, with many banks in Europe starting to combine discounted developer finance with offering their own preferential rate to buyers of certified green homes, according to Dr Monica Ardeleanu, project coordinator for the pan-European Smarter Finance for Families initiative. “Our bank partners do not have to implement a new process for a green development loan.

The process connecting a green certified residential project to a development loan or retail home mortgage is exactly the same. The reduction in financing risk for green homes versus standard homes also applies to both types of loans.”

In 2019 the IGBC partnered with 12 green building councils, The United Nation Environment Programme’s Copenhagen Centre on Energy Efficiency, Habitat for Humanity International, and 11 other expert green organisations (along with Passive House Plus magazine) in the EU Horizon 2020-funded Smarter Finance for Families initiative to implement best-in-class green mortgage and green loan programmes, including preferential financing for renovation loans that are certified to ambitious green standards.

The initiative was also designed to support improving finance options for green homes in regions where energy affordability and fuel poverty are issues.

By the middle of 2023 over €8.5 bn worth of green home projects were built or un-

der the process of certification within the Smarter initiative. A new phase co-funded by the EU’s Life programme called Smarter Finance for EU will create a European Centre of Excellence to ratchet up the programme’s ability to catalyse and foster the development of green finance linked to credible building certifications. Drawing from the hard-won experience and expertise that have led to successful green home certifications and related finance products, the centre will provide key capacity building for the financial services and investment industries, as well as support for ensuring the rebuilding of Ukraine assists the country in their urgent need to transition towards greener energy and fuels.

With recognition of the need to address a confluence of planetary emergencies – meaning interest in green homes has never been higher – there is an all too real risk of greenwashing, or a rush towards poorly conceived solutions. That’s why a key element of Smarter Finance for EU is to focus on the adoption of verified green home rating systems, underpinned by rigorous assessments, including quantification of a home’s sustainability under a number of indicators.

According to Kelly, the rigour required for accredited green ratings offers additional benefits. He takes some comfort in the huge amount of paperwork (albeit all online these days) and sign-offs that developers have to process and push through every month for drawdowns, adding that “everybody is signing in their own blood that everything is in line with regulations”.

“But equally, I think that underscores why we would like to see more and more people on the new build side trying to push beyond regulations and taking that on as a challenge, because I think then that the risk of non-compliance starts getting heavily mitigated if people are moving on beyond even what the [current] regulations are. So that’s the view we would take.”

Kelly also believes the need to address the ESG agenda has had a positive influence on developers in terms of understanding their

AIB HPI

role in the supply chain of construction, including looking after customers when the building is handed over. “I think we’re all much more conscious of the interconnectivity between all of us, and that’s why, when I speak about AIB’s role, we speak about us but we speak about us in society as well.”

Kelly acknowledges that the larger PLCs and large private developers are the ones that have sustainability teams and are ahead of the ESG game because “they’re large enough to have the corporate head space to do it” and “are operating in a different ecosystem, even internationally”.

“What I find encouraging is that those large developers are…pushing that envelope or asking those questions and they’re receptive to the answers. So it’s not being foisted upon them. They are actually making mindful decisions to do this, to try to push beyond what they’re actually required to do, and it’s extraordinary to see how far they’re going.”

He cites the example of real estate firm IPUT’s new four-unit, 550,000 sq ft industrial buildings in the Quantum Logistics Park at Kilshane Cross in Dublin, (near Dublin airport) perhaps the first time someone has built such massive buildings in Ireland entirely in timber frame.

He is already hearing how hard some developers go in pushing their customers on sustainability, although very much at a measured pace. He recalls a conversation with one such developer, where he asked how comfortable he would be with AIB managers talking about issues like meeting the United Nations Sustainable Development Goals in relation to eradicating child labour and modern slavery. The developer replied that they had a sustainable procurement policy in place and was already having those conversations with sub-contractors.

AIB is taking a similar approach with its other customers, says Kelly, in terms of pointing the direction things are going and “giving people the opportunity to come along”.

ph+ | aib hpi insight | 67

MARKETPLACE

PASSIVE HOUSE+

Marketplace News Avoid thermal bridging with Bosig Phonotherm 200 (RG550)

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hermal bridges will most likely occur where one building element meets another, for example a wall meeting a window. These key building junctions present a linear thermal bridge which run along the entire length of each element.

The consequences of not addressing a linear thermal bridge are a major cause for concern as warm internal air cools and allows water vapour to condense, potentially resulting in mould growth, building deterioration, and poorer indoor air quality which may have an adverse impact on occupant health.

New windows and doors usually have high thermal resistance and good U-values.

They are essentially filling up the holes in the building’s outer envelope, which represents a lot of missing insulation. Despite this, the connection between doors or windows to adjoining insulated building elements is all-toooften poor. As a result, heat can find a way out between the high-performance frames and the insulated building and these weak connections between the elements are often the cause of surface mould in the reveals of windows and doors.

What about at thresholds? Take a large sliding door, for example. The considerable weight of this element requires rigid sup-

port from beneath with a high compression resistance, such as a layer of concrete. Conventional insulation usually doesn’t have the compression resistance needed to support a heavy sliding door. This poses a risk of a significant thermal bridge where the high-performance door meets the cold concrete. To avoid a linear thermal bridge in this area, structural insulation is needed to separate the frame from the concrete, and that’s where Bosig Phonotherm 200 (RG550) provides the ideal solution.

When measuring heat loss at a linear junction we use the Psi value to describe how much energy in Watts is being lost per metre of a junction for every degree of temperature difference between inside and outside (W/ mK). By contrast, a metre long linear thermal bridge with a Psi value performance of 0.40 W/mK is equivalent to an extra 1 m2 section of wall with a U-value of 0.40 W/m2K. The use of structural insulation such as Bosig Phonotherm 200 (RG550) could result in Psi values improving to 0.04 W/mK or better, thereby reducing heat loss by up to 10 times.

Optimising junctions with load-bearing insulation such as Bosig Phonotherm 200 (RG550) can offset the risk of low temperatures and prevent unnecessary heat loss. Bosig

Phonotherm 200 (RG550) insulation board is made entirely from upcycled polyurethane, a material that would typically be disposed of in landfill and does not contain any formaldehyde, and has an independently certified Environmental Product Declaration and well as European Technical Assessment certification.

More information can be found at: https:// www.ecologicalbuildingsystems.com/ product/phonotherm-200. •

(above) Bosig Phonotherm 200 (RG550) loadbearing insulation, here shown in a door threshold detail.

Proctor opts for PV to cut emissions

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he A. Proctor Group factory in Blairgowrie has recently been upgraded with solar PV panels to provide a significant part of its energy from renewable sources and substantially reduce its carbon emissions. The high-performance 30kWp Solar PV system was installed to the roof at the manufacturing site by specialists Forster Energy.

Based on current electricity consumption, the company said the new system is expected to provide the equivalent of a reduction of 201,741kg of CO2 emissions over 20 years.

The investment is a reflection of the Scottish manufacturer’s increased focus on sustainability, with the company emphasizing it is working to ensure that its actions have a positive impact from a social and environmental perspective.

In 2022, the company set up a dedicated sustainability focus group, led by the group’s

68 | passivehouseplus.co.uk | issue 45

managing director, Keira Proctor. The group includes specialists from technical, operations, manufacturing, IT, marketing, sales, and accounts, and continues to review internal processes and materials and work closely with external supply chains and customers. The company is also driving improvements in the critical areas of reduced waste, and recycling.

Amongst the A. Proctor Group’s product portfolio is a wide selection of high-performance products and solutions aimed at helping the energy efficiency of new and existing buildings. The company said the change to a highly efficient renewable energy source at the manufacturer’s site is in line with this aim – and with the need to transition businesses to become more sustainable. • (left) The new 30 kWp PV array on the roof of A. Proctor Group’s factory in Blairgowrie.

PASSIVE HOUSE+

MARKETPLACE

Partel launches range of airtight grommets and accessories

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eading manufacturer of air and windtight systems Partel has announced the launch of the Kabseal line of airtight solutions for detail sealing, in addition to its new airtight electrical back box, Electriseal Box. One of the most complete ranges of solutions in its category, Kabseal features airtight pipe and cable grommets, along with radon grommets.

With a focus on exceptional performance, reliability and energy efficiency, Partel believe these innovative products are set to revolutionise the market.

Partel said the phA Class Passive House Institute-certified airtight cable grommets Kabseal Pro and Kabseal Pro 6 use cutting edge technology to offer reliable solutions for sealing cable penetrations. Available in various dimensions and suitable for internal and external use, these grommets have been designed to ensure a secure and permanent airtight seal,

effectively preventing air leakage and optimising energy efficiency. Specially designed for multi-cable use, Kabseal Pro 6 can accommodate multiple cables, making installations hassle-free. Partel said that their user-friendly installation and exceptional durability will ensure long-lasting performance in residential, commercial and industrial settings.

While Kabseal Pro can also be used for sealing pipes of different diameters, Partel has also launched Kabseal Heat, a remarkably heat-resistant grommet of up to 250 C for sealing exhaust pipes and other temperature-sensitive openings. Partel said the advanced safe design and superior sealing capabilities of these pipe grommets eliminate air leaks, providing unmatched protection against energy loss.

The company has designed Kabseal Gas and Kabseal Slab to address the unique challenges of radon mitigation systems. By creating an airtight seal around pipe, cable and supply line penetrations, these grommets prevent the entry of radon gas into living spaces, ensuring the health and safety of occupants.

Partel said these grommets are an essential component in radon mitigation strategies, offering peace of mind and compliance with regulatory standards.

Meanwhile, Kabseal Cap has been designed as an “extremely practical” airtight conduit seal to provide a fast, convenient solution for creating secure, durable seals around multiple cables within a conduit. With a versatile range

of sizes, Kabseal Cap offers a suitable option for various conduit dimensions, ensuring a perfect fit for project-specific requirements.

Engineered to facilitate smokeproof and airtight connections, this product has been designed to be equally adept at sealing empty conduits, to provide a comprehensive solution for any electrical installation needs.

Finally, Partel describe its new airtight electrical back box Electriseal Box as “a gamechanger in electrical installations”. Engineered to enhance safety and energy efficiency, Electriseal Box creates an airtight seal around electrical connections, preventing air leaks and the ingress of dust and moisture. With a robust construction and compatibility with standard electrical fixtures, Partel describe these back boxes as a “must-have” for residential and commercial electrical systems.

“Partel is proud to unveil our comprehensive range of airtight solutions, Kabseal,” Partel CEO Hugh Whiriskey. “These innovative products demonstrate our commitment to providing reliable, efficient, and sustainable solutions that meet the evolving needs of our customers.”

For detailed information and technical specifications visit partel.co.uk • (above left) Pictured are two of the main options in the Kabseal range, the Kabseal Pro 6 (left) multi cable grommet and Kabseal Heat, a heat resistant grommet.

Beattie Passive announces appointments

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assive house pioneer and modular construction specialist Beattie Passive has made a series of appointments to strengthen its project management, HR, and architectural design teams.

James Little, formerly of Elements Europe, Barratt London and Berkeley Group, has joined the firm as a project manager, and will be responsible for leading Beattie Passive’s net zero and passive house standard modular housing projects from pre-construction through to completion. Little spent over 16 years at Sir Robert McAlpine, where he worked on a series of major commercial developments, including the Emirates Stadium in London.

Beattie Passive has also appointed a new human resources manager, Natalie Higgs. Another experienced hire, Higgs will lead recruitment, employee engagement, health and wellbeing.

With production currently well underway on several modular projects, and with more in the pipeline, Beattie Passive has been focused on scaling its business to meet demand. In addition to recruiting almost 60 timber frame fabricators since

the start of the year, the firm has also increased its working factory space, with plenty of room in reserve for continued expansion in the future.

Beattie Passive has been appointed to three major offsite construction frameworks this year and has also expanded its roster of Flying Factory partners, who use the Beattie Passive Build System, under licence, across the UK. One of these partners, Ashcot Construction, recently delivered the first passive standard homes for social housing provider Stonewater, in Chard, Somerset. Another partner, Creating Enterprise, is building passive homes across North Wales. The most recent addition is Cubed Homes, who have completed their training course at the Beattie Passive Academy and will be delivering passive standard housing across the southeast of England.

To manage the increased workload, Beattie Passive has added another architectural technician to its in-house design team. Dan Sanders, an experienced REVIT user, joined the company in April and is assisting on modular projects.

In May, Beattie Passive hosted the bi-annual

BOPAS Forum, giving delegates a tour of its offsite factory in Norwich. In June, the company sponsored the inaugural Unlock Net Zero Live Awards and was ranked 171st in J.P. Morgan Private Bank’s annual list of the Top 200 women-powered businesses in the UK. •

(above) James Little, Beattie Passive’s new project manager.

ph+ | marketplace | 69

D R TO B Y C A M B R AY

COLUMN

Flash floods and porous materials While the most dramatic impacts of climate-induced flash flooding abounding on social media this year are all too obvious, other more insidious effects also pose risks to everything from agriculture to porous materials, as Toby Cambray explains.

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his year winter didn’t get the memo, and this summer we seem to proceed directly from non-stop rainstorms to glorious sunshine; perhaps a sign and a symptom of the changing climate.

Where I live, the ground went from a boggy mess to a cracked, hard-baked moonscape, with grass struggling to get going where the soil has been churned up.

Low river levels also indicate the ground water has quickly receded. Counterintuitively, these dry conditions can actually increase the risk of flash flooding. This got me thinking about how liquid water interacts with soil, and that it can tell us something about how our buildings work.

It turns out I’m far from the first person to have these thoughts – in fact, we have the advances made in agricultural science to thank for our current understanding of moisture storage and transport in building materials. It is of course really important to understand how water moves around in soil for plant health, and the research on this topic was transposed to building materials decades ago.

A large pressure is created, sucking liquid into the pores.

What has this got to do with flash flooding? The absorption of liquid into porous materials is governed by two counteracting effects: capillary suction and viscous friction. Capillary suction is the meniscus effect – the phenomenon where the surface of a molecular substance such as water curves up when it touches another material. But it's the meniscus effect writ large (or if you like, very, very small). Consider a cup of tea. A small force due to the interac-

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tion between the tea and cup exists around the circumference and lifts the edges of your tea up the sides of the cup, maybe a millimetre or two. Imagine the diameter of the cup shrinking until the curve of the meniscus meets in the middle; the surface area reduces faster than the circumference (and hence the total lifting force). Keep shrinking the tube and that force starts to overcome the weight of the water. Keep reducing that diameter to the sub-millimetre scale and the force on the tube of water becomes enormous compared to the area of the tube, so a large pressure is created, sucking liquid into the pores. This is capillary suction and it is the reason brick, stone and other porous building materials suck up water.

On the other hand, there is viscous friction slowing things down – it’s the reason your honey is runny (but less so than water), and is the subject of the world’s longest continuously running laboratory experiment, the pitch drop experiment.

It’s harder to drink lemonade through a narrower straw. At the sub-millimetre scale of the pores in building materials, the viscous friction of water is considerable, and increases as pore size reduces.

These effects are therefore in direct competition, both increasing in magnitude, but in different directions, as pore size reduces. They are both non-linear effects, and there is a sweet spot at around one micron, where the balance between the two effects results in the fastest transport. It just so happens that the pores of lime-rich mortars are mostly in of this size, hence their very useful moisture transport properties. Many stones and bricks have larger pores, which hold onto water less tightly, so it tends to move from the masonry unit into the mortar. Cement-based materials have mostly very small pores (and significantly fewer of them – they are denser) in which viscous friction dramatically slows transport, so moisture drying is much slower.

So, if a material is relatively dry, the liquid transport will be driven by the behaviour of the smaller pores – that is where the water prefers to hang out. The liquid transport in these pores is dominated by viscous friction and is therefore relatively slow.

There are other, more important reasons why dry soil doesn’t absorb water quickly – the plate-shaped particles of clay form a less porous matrix when dry, and damp surfaces are more hydrophilic. But all together these factors mean a heavy shower is more likely to overwhelm the short-term absorption capacity of dry soil because it can’t suck it up fast enough, potentially resulting in run-off. Somewhat moist soil will absorb more readily, but of course if the ground is saturated this will also cause run off. This raises questions about how our changing climate will influence runoff; severe storms after longer dry spells are bad news for the soil and the areas within its watershed.

The shift towards more extreme weather is very relevant in building materials, not least via the increasing risks of flooding. This is neatly captured by the Four Cs proposed by Chris Sanders and the late Neil May (visit tinyurl.com/4csPHP to read about the Four Cs - editor). All of us working with buildings, but particularly those including porous materials, should be aware of the likely changes in rainfall patterns, and what these might mean for our buildings, as well as our agriculture. n

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

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