“But how much will it cost?”. Anyone involved with Passive Houses hears that question a lot. Ross Brown of eHaus reckons an extra 20%, according to this article. I’ve also heard clients say their house cost the same as their neighbour’s. My favourite answer is, ‘It depends’. Then I go on to say, 5-15% more. Why the huge range?
Well, there are a LOT of factors that come into play. The biggest is how much the design is a retrofit from a performance point of view. If you had already built your house and then asked me to upgrade it to a Passive House, you would expect it to cost more than if we built it right from the start.
Similarly, if the design is highly articulated with lots of bits and pieces sticking out and a tonne of glass, it will cost much more to retrofit for performance at that stage in the design. Even architects who are trained in Passive House don’t necessarily focus on performance as much as they could to reduce cost. This can be good or bad depending on the brief but it certainly contributes to this large range of added cost.
The most affordable custom certified Passive House will be one commissioned by an educated client who specifies that level of performance at the outset and works with a PH-trained designer or architect. The client and designer can work out the compromises to reach certifiable energy efficiency within budget. The no-brainer is to reduce the size of the house a little and reduce the glazing area. There’s always money to save in kitchens and bathrooms too.