DELIVERING COST-EFFECTIVE PASSIVHAUS PROJECTS AT SCALE IN RESIDENTIAL & DOMESTIC SECTORS 43
INDUSTRY RECOMMENDATIONS We asked our delegates to give their key recommendations
• Mike Roe, WARM: Incentivise rather than mandate, as it’s more practical.
• Daniel Levey, Serenity Projects: People need proper education on the benefi ts.
• Hannah Dixon, Progress In Practice Architects: There needs to be a long-term plan people can have access to, so they can prepare.
• Aaron McCarthy, Hive Group: I would like to see the Government incentivise Passivhaus so the community can grow organically.
GETTING ENGAGED
Evette Prout of Passivhaus builders Kind & Co said early engagement with a social housing client had enabled the fi rm to idenfi ty and avoid ‘overengineered’ Passivhaus
rising temperatures and protect residents, particularly resonant in this heatwave summer, with heat a “silent killer” in the words of Joel Callow, versus the much more visible deaths at Grenfell Tower. He said there was “no natural ventilation solution to high-density housing.” In terms of MVHR delivery, Cundey said that ‘design-only’ software layouts for MVHR are often wrong;, but site surveys and close supplier–installer collaboration can avoid oversizing and over-engineering. Hugh Franklin of Aeroseal UK also homed in on perceptions of construction risk in Passivhaus, in his question. He asked: “Of the fi ve core Passivhaus design principles: insulation, windows, ventilation, airtightness, and thermal bridge-free construction, do you consider airtightness to be the largest risk to delivering at scale?” He gave a forthright set of comments around the fear factor for clients on the ‘extreme’ levels of airtightness, versus the reality of practice. He said “many site teams view achieving the high levels of airtightness required in Passivhaus as the biggest “risk,” but this was because it’s new, not because it’s inherently more diffi cult to achieve. Hugh Franklin of Aeroseal UK (who specialise in air-tightiness solutions), said that air testing day was “like a school sports day,” in terms of the levels of excitement and expectation from this new discipline. Lorna Taverner said that Willmott Dixon had managed to get
air-tightness “down to 0.25,” and that now the fi rm’s “bigger risk” was building “thermal bridge-free.” She admitted that in London, in a “non-combustible situation,” the company “will not build a timber frame building that has no thermal bridges,” and they “are spending a lot of money getting those modelled, because [for insurers] it just doesn’t exist.” Michael Brett said that the onsite culture shift towards a painstaking focus on details was huge compared to previously. “From where they were three years ago, the level of care and attention and detail that they put into a project now is out of this world.” Lastly, Craig Simms from Technal focused on commercial viability, suggesting that currently Passivhaus wasn’t viable at scale in mainstream housebuilding. “What needs to change in the way projects are designed, specifi ed and procured to make Passivhaus commercially viable at scale in mainstream residential development?’ The delegates used this to springboard a conversation around the dangers of ‘Passivhaus principles’ being used for projects rather than actual certifi cation; Simms saying this can result in “two different prices” for
• Craig Simms, TECHNAL: Remove the association with Passivhaus automatically being about pound signs.
• Evette Prout, Kind & Co: Reach out to consumers. • Attzaz Rashid, Barratt London: Outcome-based performance targets on heating demand, overheating, air tightness, ventilation and in-use performance. Allow policy fl exibility where evidence shows you have better outcomes than the default position.
• Jean Dib, SRE: Enhance the passive measures at the start of projects, to make things easier.
• Ann-Marie Fallon, Architype: Incentivise through outcome-based metrics, so a carrot not a stick, and mandate post-occupancy evaluation. Leverage the Building Safety Act to bring quality control, and see healthy buildings as a public right, not an asset.
• Craig Cundey, Ubbink: Increase training standards; what is offered currently isn’t good enough.
• Sarah Mohamed: Focus on building performance, and academia and industry should collaborate to educate future generations.
• Hugh Franklin, Aeroseal UK: An outcome-based solution that isn’t very confusing would be grasped with both hands by the industry.
• Michael Brett: Building Regs should be scrapped and rewritten, and it’s all about what the guys onsite do.
• Lorna Taverner, Willmott Dixon: “We have a massive skills shortage; we need to bring the conversation to where new industry recruits are.”
• Mark Slater, WWA Studios: Amalgamate Building Control with Clerk Of Works into a ‘super inspector’ role.
different specifi cation levels in tenders. Lorna Taverner gave the fascinating but worrying insight that
Willmott Dixon has found they are “always undercut because other people will be saying we’re Passivhaus principles, not Passivhaus certifi ed.” She said the risk factor here from ambiguity in tenders was “very challenging.”
The group agreed that designing to ‘Passivhaus principles’ rather than going the whole hog, and therefore possibly ending up with ’Passivhaus-lite’ schemes, was not advisable. It was seen that compromise of this sort would also potentially lead to “perverse outcomes,” as Passivhaus is implicitly designed as a package solution with inter-related compliance components, not as a “pick and mix.”
Many thanks to our sponsors, Aeroseal UK, TECHNAL and Ubbink.
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