Author: Rachel Mitchell -
The 2017 international Passive House conference was set against a backdrop of reducing carbon emissions in Europe and the need to divest from fossil fuels to meet both national and local targets. Energy efficiency is key to this and passive house standards for both new build and existing buildings were proposed as the benchmark for domestic and non-domestic dwellings
The conference theme was ‘passive house for all’, and ‘all’ had many strands and meanings, some of which were less apparent, but may in the end have the greatest impact on the passive house movement.
‘Passive house for all’ meant many climates, and examples were given from the very cold to warm and humid climates. Each had their own the challenges, in cold climates PHPP is sensitive to very small changes to insulation and thermal bridges, in warm and humid countries delivering cooling and moisture extract are the priorities. The presentations showed that the passive house standard is applicable and achievable in all these situations and that solutions and products are developing to meet these challenges such as a theoretical MVHR unit that will extract heat and moisture from warm humid dwellings and use this heat to create hot water.
‘Passive house for all’ also means delivery at scale, moving from a niche market to district wide developments. The EU funded project Sinfonia supports Germany’s targets of reducing fossil fuel reliance. (interestingly Germany’s priority is to remove nuclear power from the grid before coal and gas). This can only be achieved though wide scale deep retrofit projects to existing dwellings. Deep retrofit was the only solution as undertaking moderate refurbishment risked ‘locking in’ less energy efficient components and interventions which may require further upgrading later, or worse not be improved upon for cost reasons.
Delivering at scale also means building bigger, and several examples of high rise multi-family dwellings were given, both new build and retrofit. Here the challenges are very different.
How do you test the air tightness of a whole building containing 352 new apartments when the plasterboard is being installed on the ground floors before the airtightness work has been completed on the upper floors? The answer was to create zones to test sections, this gave confidence to the air tightness strategy and allowed for modifications to be implemented through the build.
Building at scale will also impact on the choice of services, 352 MVHR units means 704 punctuations in the building envelope, so centralised systems make better sense for air tightness, and release precious floor area in individual apartments, which in cities like New York is critical. However, in existing buildings the layouts may mean that individual heating and ventilation systems may be needed, especially in buildings were there is mixed tenure, i.e. tenants and leaseholders. An example was given of in-wall MVHR units which are suitable for small homes and apartments.
In Austria where many apartment blocks have external render this could be used as an external air tight layer, which avoids complex detailing at intermediate floors. A new product which was yet to go into production was demonstrated, which could test the air tightness of external render before any insulation is added to ensure that it is sound and suitable for creating the air barrier.
The main positive from the conference was how much more widespread passive house is becoming and how a standard, that was designed for the German climate, is being adapted and developed so that is it applicable in a wide range of climates, countries and building types.
The negative, many of the buildings are still being developed as prototypes, with people learning on the job, many presenters said they would not do now, what they did in the examples they were giving. The challenge to try and overcome this so that knowledge and training includes practical solutions to common problems to prevent each building being a ‘first’.
'Passive House for all' presents a challenge to the Passive House Institute who manage the standard and the brand. If ‘all’ means global adoption, it is likely that different countries may have different approaches. The US already talk in BTUs and R values rather than kWh and U values and China may create its own relevant standards. Worldwide adoption has many advantages, look at the PV industry where prices have fallen, access to cost effective components would remove many of the barriers to passive house, however maintaining quality is key and ensuring that the rigor which means that a certified passive house will deliver on its design intent, is maintained
Image from passivhastagung.de
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