The recent UK heatwave caused stories like this BBC News article to be written about how ill-prepared the country is for combating extreme weather.
Blowing hot and cold
The Environmental Audit Committee, author of the report mentioned in the article, wants “tougher rules” that will prepare homes for extreme heat. As things stand, the problem of buildings overheating is not being tackled, and nothing in current regulations helps to prevent it.
A typically meaningless and detail-free response from a Government spokesperson talks about continuing to take “robust action”, and refers to a long term plan for climate change adaptation. The article quotes the removal of funding for local authority officers who would have worked on that exact issue.
Of greater concern is the disparity in attitudes towards hot and cold extremes. Deaths due to cold weather are reported regularly, but statistics for hot weather fatalities are less common. The extent of the disparity is encapsulated by the BBC’s mention of insulating homes to keep them warm in winter, but failing to acknowledge how the effects of insulation work in reverse during summer, helping to keep homes cool.
The future is ever-present
In early June, the NHBC Foundation published their own report. Futurology: the new home in 2050 predicts features that will be common to new-build homes in three decade’s time.
Among the more reassuring ideas is greater flexibility of living accommodation, with rooms and spaces that can be adapted to suit the changing needs of families. I can certainly get behind that. Other ideas, like ‘smart letterboxes’, sound like something we’re more likely to see in three years than thirty.
In separate coverage of the Futurology report, an NHBC spokesperson is quoted saying that homes in 2050 will make use of thermal mass and effective ventilation to avoid overheating.
There’s just one problem with that statement: 2050 is too far away. Perhaps implicit in the NHBC’s choice of year is an acknowledgement of the glacial pace of change in regulations and construction practices.
Thermal mass
In early 2017, I helped present a CPD to a London architectural practice. The subject was thermal performance of building materials and construction products, and one attendee asked about thermal mass. Not my strongest subject, I’ll admit, but I genuinely believed there was no single correct right answer. To my mind, the choice between light and heavyweight construction was a question of the designer’s philosophy.
This excellent write-up on thermal mass by GreenSpec goes some way to supporting my stance (albeit from a much-better informed point of view!). Reading it, several points jump out:
- Both masonry and timber frame structures can take advantage of thermal mass.
- Thermal mass depends on context - what the building is used for, and the climate in which it is used.
- Buildings that experience significant fluctuations in temperature are best placed to utilise thermal mass.
- Housing in the south of England benefits from thermal mass, combined with shading techniques, when looking at a future warming climate.
The knowledge and understanding exists to utilise thermal mass now; the homes of the future can be built today. The London Plan - addressing part of the country where the impact of higher temperatures will be felt most keenly - mentions thermal mass in its ‘Overheating and cooling’ policy.
Perhaps the key is finding ways to disseminate that knowledge and understanding to a wider audience, rather than waiting on regulation changes and long-term climate adaptation plans.
The winds of change
In winter, thermal mass can absorb heat inside the building during the day, then release it at night when the external temperature drops. A comfortable internal temperature is maintained with minimal use of the heating system.
By contrast, opening windows during summer nights is necessary to flush out the absorbed heat and stop the internal temperature from getting uncomfortably high.
Last summer, I stayed in a Passivhaus where the ventilation was designed to partly rely on opening windows. Being a light sleeper and wary of noises from outside, I closed the bedroom window before going to sleep - and promptly woke up part way through the night because I was too hot.
As with so many aspects of building design and specification, arguably the biggest hurdle to overcome is occupant behaviour. Even as someone with some understanding of building physics and the benefits of Passivhaus, I couldn’t put aside my ingrained attitudes and habits for one night in the interests of letting the building work as it was designed to.
People are fallible. Daily life and unexpected changes in routine get in the way. We put things off for a minute, and a minute turns into an hour or two or more. We forget to open windows, or we open them and we forget to close them again. We can learn to use an overly-complicated letterbox, but we struggle to operate our buildings properly.
We can build the homes of the future today, and we should be doing just that. But I’m starting to think the thirty-two years between now and the NHBC’s vision of 2050 is for us to learn to change our patterns of behaviour!