In developed countries, almost half of carbon emissions come from the built environment in one way or another. What we build and how we use our buildings will determine whether or not we get anywhere near our carbon targets and maintain a liveable climate. And yet, even when we set a high bar for new buildings, we routinely fail to meet it. Studies show that carbon emissions from a new home are on average 2.6 times higher than the architect planned for. A zero carbon home on the drawing board is almost certain to perform worse than that in reality.
It’s not just carbon emissions either. Britain has a big problem with new-build homes that are substandard, with insulation that isn’t fitted properly or smart home technologies that haven’t been configured correctly. Often these flaws go unnoticed because nobody thinks to check. The problems aren’t fixed, and builders and designers don’t get the feedback that could improve their work in the future.
To improve homes, we need those feedback mechanisms, and Fionn Stevenson’s book is all about ‘building performance evaluation’ (BPE). There are various ways to do this – it could be surveys and interviews with occupants after they’ve lived in the house for a year. It could be live monitoring through smart home technologies. It might involve thermal imaging scans, or tests of heating and ventilation systems. There are a host of techniques, some more invasive than others for inhabitants. The main point is to get information on both how the building is functioning technically, and how it’s working out for the people living in it.
You don’t know what you might find. For example, a family were observed living in a prototype house and the designer realised that only 5 of 21 openable windows had ever been used. (You’ll probably know in your own house which windows never get opened, and where one doesn’t open that should.) That’s useful information for the next iteration of the home, saving money and improving efficiency and security by just putting openings where they’re needed. Or another study found that builders had forgotten to put insulation in the cavity between terraced homes, creating a cold gap between them. Fixing a problem like that can save thousands of pounds in heating costs over the lifetime of the homes.
Unfortunately, these sorts of post-occupancy studies are rare, and house builders are actually reluctant to do them. They represent a cost and they can create liabilities. But if they can be priced in appropriately, there are lots of benefits – business reputation and trust, learning is captured and designs are improved, houses perform as expected and carbon emissions come down, and homes get more convenient and comfortable as architects and builders improve their work.
The book makes the case for better evaluation, describes good examples of where it’s been done before, and sets out the basics for doing it. It’s written for practitioners, so it will be most useful to architects and engineers, planners and developers. Councils could be taking a lead on BPE and should take notice, especially since there’s a primer on carrying out a building performance evaluation at the back of the book – a publishing first in an emerging field, apparently. There are detailed case studies, useful notes from the author’s own experiences, and it’s a richly illustrated and high quality book all round.
There’s no legal requirement to carry out building performance evaluation. Most house building associations don’t require it. Architects don’t necessarily learn about it in training. It’s time that changed, as it’s obviously very important in raising Britain’s poor quality housing stock. The Royal Institute of British Architects, who’ve published Housing fit for Purpose, are recommending it for all members from 2020. RIBA declared a climate emergency this year, and BPE has a role in meeting that challenge to the industry – capturing learning to reduce costs, improve designs, and ensure that low carbon homes actually are low carbon.