I've been prompted to prepare this blog posting after Mark Elton highlighted a blog entry by Mel Starrs on a new group of housebuilders calling itself the 'Futures Group'. This group includes Taylor Wimpey, Barratt Homes, Bovis, Redrow, Miller and McCarthy & Stone and they have produced a report that tries to put a brake on the forthcoming improvements required in the UK Building Regulations.
One of the old myths that is being pedalled is the notion that well insulated homes overheat in summer. The report says:
"…concern is being expressed about summer overheating in well insulated new homes. Evidence is anecdotal in the main, with little published, verifiable information available, but studies to date suggest that SAP is inadequate in this area and an approach employing more complex dynamic modeling is required to more accurately assess and understand the mechanisms involved."
Well we have evidence from Technology Strategy Board funded research on several of our buildings, both new build and retrofit, that establishes very clearly that well insulated homes do NOT overheat in summer if it they are designed with either (a) conventional sized south facing windows or (b) large south facing windows with external blinds.
In fact, the graphs taken from our soon to be published report of our Hounslow Retrofit-for-the-Future refurbishment with 240mm of external insulation and other passivhaus features such as triple glazing show that indoor temperatures are in fact COOLER in summer than in winter, and the insulation helps keep the buildings cool.
Far from requiring dynamic modelling, all that is required is the Passivhaus Planning Package as a design tool, and these results are achieved in a building that doesn't even go as far as achieving Passivhaus Certification.