We are responsible for the technical design and construction on the UK’s first two officially certified Passivhaus retrofits, projects that were exciting and which presented huge challenges to solve the energy efficiency problems each property presented. We’re extremely proud of what we achieved so it may come as a surprise to find that we wouldn’t necessarily recommend attempting to achieve Passivhaus standard in a retrofit. Why is this?
The main reason is cost: Passivhaus is an extremely rigorous standard (for example total air leakage at Princedale Road had to be reduced to an area no larger than the size of a £2 coin) and so for the average retrofit, the cost savings to be made by going Passivhaus just don’t stack up. A building must be in need of complete and total renovation for it to make financial sense.
However, there are still plenty of innovative and cost effective ways to reduce the energy burden on a house and make it as low energy as possible, from triple glazed windows and solar thermal systems – we even make insulated furniture to maximise heat retention whilst retaining as much internal floor space as possible which, in a typical Victorian property for example and as properties start to move to the European model of sale per m2, is an important consideration!