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Last Tuesday PDP London attended the annual UK Passivhaus Conference, which focused on health, wellbeing and embodied carbon, as well as providing a forum for discussing the future of the standard in the UK in light of the recently released UK Government’s Clean Growth Strategy.

The visitors were treated to an inspiring introduction from Emma Osmundsen of Exeter City Council, who compared her team’s experience with Passivhaus to space exploration, as well as proudly announcing the council’s ambition to deliver St Sidwell's Point, a £25m state-of-the-art Passivhaus leisure centre, by 2020.

Tomás O'Leary, a distinguished international Passivhaus pioneer, provided a candid overview of the standard’s adoption around the world, noting that the officials in Vancouver have recognised Passivhaus as the “easiest, cheapest and most proven” way to achieve the city-wide sustainability goals and are making extraordinary progress.

David Moorcroft, Director of Regeneration & Development at Norwich City Council, explained that the reasons behind the council’s recent large-scale roll-out of Passivhaus projects were threefold: social, economic and environmental. Not only did he note the expected decrease in energy bills and rent arrears, but also explained that a 5% premium was anticipated on private sales.

Nigel Marsh of Baker Ruff and Hannon reported that although Passivhaus projects in the UK tend to cost 10-20% more than those built to Building Regulations, the actual uplift due to the standard is difficult to quantify. Not only do these buildings tend to additionally feature building biology measures (e.g. non-toxic materials; limited exposure to human-made radiation), they also currently represent a “low volume product” and attract “risk premiums” due to their procurement methods, making any comparison to mass-building difficult. At the International Passivhaus Conference in Vienna earlier this year a typical increase of 6.7% was reported for Austrian-based projects, which evidences the greater uptake of the standard in the region.

During the session chaired by PDP London partner Marion Baeli, Thomas Gartner of Gale & Snowden made a very pertinent reference to the 2004 MacLeamy curve, noting that design effort should be front-loaded to minimise the cost of design changes. This approach is inherent to the Passivhaus process, which relies on detailed building performance simulation right from the start. As a member of the Passivhaus Trust, we believe this is key to achieving exceptional comfort and user satisfaction in buildings.

Marion Baeli of PDP London, who led  the first Passivhaus retrofit project in the UK, comments: “Passivhaus projects can be very expensive if designed by people who are not technically experienced and only see the standard as a marketing tool. We should resist this expensive and unproductive approach and rather spend longer on optimising the design (junctions, building form efficiency etc.) to better respond to the local context, local skills and the client’s budget”.

Lynne Sullivan provided an excellent overview of the retrofit standards framework, reiterating that a whole-house approach and an understanding of moisture transfer is crucial in avoiding unintended consequences. Alain Speed, the Technical Coordinator at PDP London, who shared his experience of undertaking the WUFI hygrothermal modelling course last year, comments:  ”The retained moisture can compromise occupants’ health and undermine the integrity of the building fabric. WUFI scan help mitigate these risks by predicting hygrothermal performance long into the future.”

In our recent article we discussed progress in the implementation of the Each Home Counts recommendations, a government report sparked by the failures of a “single measures” approach and the lack of investor confidence in retrofit. In her talk Sullivan also referred to the Investor Confidence (ICP) Project and its Investor Ready Energy Efficiency (IREE) certification, which may provide a model for adoption in the UK as well.

Michelle Sánchez of PDP London, who recently completed a PhD in Sustainable Life Cycle Assessment of the Vertical Opaque Envelope, marked out the presentation by Simon Sturgis as a highlight. She adds: “...it is very important for designers to start thinking about embodied energy and carbon, because we focus too much on the operational use and lose control of the real impact that our buildings are having. As Sturgis pointed out, if we analyse the impact over the whole life cycle of a window and compare double and triple glazing, double glazing would have less impact due to the lower embodied carbon (despite the increased operational energy) — which is contrary to popular belief! As designers we need to make an informed judgement on the choice of material based on energy, embodied carbon but also comfort.”

At the conference we also heard numerous first-hand accounts of outstanding air quality, improved night’s sleep and tangible thermal comfort in Passivhaus buildings. Although some try to monetise these benefits, we believe any such attempts will fail to value them highly enough. With the advantages of Passivhaus so clear and undisputable, as O’Leary put it, #whatsyourexcuse?