22nd January 2012
There is a lot of building underway here in Cambridgeshire and no doubt many of these new houses will aspire to the Passivehaus design, even if not all meet its exacting standards. However, the thousands of new houses in this region will only represent a small proportion of the UK’s housing stock. Much of the rest will need a retrofit to give them anywhere near the thermal efficiency of a modern, new-build, family house. This level of retrofitting is both expensive and complicated and much of the low hanging fruit has now been picked. Homes not amenable to cavity wall insulation will be harder to bring up to anything approaching the Passivehaus standard: given that the cost of doing so would be high compared to the market value of the house itself. It is also the case that many of the people living in fuel poverty are in houses that leak energy and are difficult to insulate from both a technical and economic point of view.
Perhaps it would help if we started thinking about the ‘Activehaus’ as well as the Passivehaus. Most structures, with some modification, are capable of capturing and retaining heat. Also southwest facing walls are potential solar energy collectors. These facts are sometimes missed because householders spend summer months getting rid of as much solar derived heat energy as possible. However, for most of the year, passive solar energy has the potential to radically cut fuel bills and for a few months of can actually eliminate the need for any other form of heating.
Thanks to the feed in tariff and subsidies for PV panel installations a significant number of homes in the UK are now energy Activehaus’s and produce electricity. Passive solar has the potential to take this concept one step further and enable the householder to generate heat energy directly. What is more the householder will be able to do this with technology available from local builders rather than specialist engineers.