The Passivhaus standard can be used on many types of buildings; offices, schools, gyms, so it is by no means limited to housing. On a similar note, Passivhaus is not prescriptive of the construction method; one could build a timber frame house, a masonry school, or a reinforced concrete frame 10 storey office block, all of which can achieve Passivhaus performance.
Passivhaus sets out a means to achieve the ever improving energy performance standards required of the construction industry. It is a tried, tested and successful approach to designing and constructing very low energy buildings, with thousands of examples built over the last 20 years all over Europe and beyond. In adopting Passivhaus, the sector can be confident in providing buildings that really deliver the cost effective, long term energy performance targets clients are asking for.
There is a learning curve to overcome in designing and building to the Passivhaus standard in the UK. Energy performance must be considered from the very outset of the design process which doesn’t often happen here. Good workmanship and very stringent quality control on site is required. In terms of public perception there may be myths to overcome for example concerning the opening of windows: You can open the windows in a Passivhaus whenever you want!
Sustainbility standards like BREEAM and the Code for Sustainable Homes are environmental assessment methodologies; they are tools to assess and improve the environmental performance of buildings on a more holistic level than Passivhaus, they include for example consideration of the materials used in construction, water consumption of the building, provision of recycling bins etc. Passivhaus is concerned with energy efficiency, which of course is a very important part of creating sustainable buildings, along with the comfort of occupants. Passivhaus and BREEAM or the Code are complimentary, a Passivhaus that also addresses the wider sustainability issues in BREEAM or the Code may also achieve a rating under these schemes. Likewise, Passivhaus is a very good place to start when setting out to attain the higher level ratings.
Yes, the design principles that are central to new Passivhaus buildings can be applied to refurbishment projects. To achieve the standard it is essential to address air tightness and thermal bridging. Passivhaus certification requires a maximum of 0.6 air changes an hour during pressure testing and virtual elimination of thermal bridging; these are likely to be challenging on refurbishment projects. Even if a refurbished building is not a certified Passivhaus, it is still possible that it could reach achieve the EnerPHit Standard which is specifically designed for refurbishing housing, the certification criteria has ben relaxed slightly to allow the cost of applying the Passivhaus standard to be less onerous. A refurbished EnerPHit building may have a space heating energy requirement of 25 kWh/m2.yr, rather than the 15 needed for full Passivhaus certification with an airtightness level of 1 air change an hour, EnerPHit exceeds the performance of a new building built to most current national standards.
Passivhaus has a positive future, an increasing number of projects are being designed and built to the standard, with input both from BRE and a number of other consultancies. A pre-requisite of wider adoption is a sufficient skill base amongst designers; for this reason BRE provides Certified Passivhaus Designer training, a worldwide professional qualification for those who want to design to the Passivhaus standard.
A potential driver for wider uptake of Passivhaus is the May 2010 re-cast of the Energy Performance of Buildings Directive which calls for EU member states to require all new buildings to be ‘nearly zero energy’ by 2020. It also requires an indication of primary energy use in kWh/m2 per year, the metric in which the Passivhaus standard is expressed. Passivhaus is the most tried, tested and successful way to achieve ‘nearly zero energy’ buildings, in mastering it now, we will be well placed for the future.
Wide adoption of Passivhaus as a energy performance standard has obvious benefits in reduced fuel consumption; as the UK recently became a net energy importer this can only be a good thing for the UK economy.
Passivhaus is very much a ‘fabric first’ philosophy because energy efficiency is the most cost effective way of reducing CO2 emissions, much more so than building mounted renewable technologies. In the current economic climate we need to reduce emissions in the most cost effective way possible.
Passivhaus also provides the opportunity, given sufficient demand, for manufactures and suppliers to provide the high quality components Passivhaus buildings require. Currently these are generally imported from the continent. A success story in this regard is the Vale Passive Window, developed by a consortium of Welsh business, it has now become, with the assistance of BRE Wales, the first Passivhaus Institute certified component to be designed and manufactured UK.
Passivhaus adoption, particularly in the social sector also has significant potential to reduce fuel poverty and the health and therefore the significant economic costs to individuals and the economy as a whole that stem from people living in substandard housing which is cold, damp or expensive to heat.