With the winter chill setting in, most of us are focused on how we can keep heat in our homes – not out.
Yet there is a risk we are concentrating too much on insulating our homes and forgetting the dangers of what potentially awaits us in the summer months – overheating.
We recently hosted our Sustainable Futures Conference, during which Dr Joel Gustafsson, Founder and Director of JG Consulting, cautioned that in the last century, our heatwaves have elevated temperatures to levels akin to the South of France, and our housing infrastructure is entirely ill-equipped to cope with such conditions.
The UK is relatively inexperienced when it comes to energy-efficiency measures compared to our European counterparts. In the UK, we have only really awakened to the need to make our homes more energy efficient in the last decade. So far, much of our efforts have focused on how to keep our homes warm and reduce energy bills, with not as much thought – if any – given to the risks of overheating.
Oxford University recently cautioned that Switzerland and the UK would experience a 30% increase in days with uncomfortably hot temperatures if the world misses the 1.5°C climate target and warms to 2°C – and this is without taking into account extreme events such as heatwaves.
Some may be familiar with the Hot Homes Project – a joint initiative between the Bureau of Investigative Journalism (TBIJ) and the University of Glasgow.
As part of its study into overheating, they installed sensors in 40 homes in one of the hottest places in the UK – the London Borough of Southwark.
During the monitoring period – between August and mid-September – every home in the study rose to at least 25C, with most homes feeling more like 27C. During the study, twelve households experienced conditions that felt like 32.5C – classified as ‘extreme caution’ on the Heat Stress Index and carrying the danger of heat exhaustion and heatstroke.
Some homes the study found were as much as 8-10C hotter at night than the outdoor temperatures recorded at the local weather station.
Interestingly, a number of flats in the study were new builds and described as ‘well-insulated and warm’ during the winter. However, this same insulation posed a challenge in the summer as it prevented the flats from cooling down. The report highlighted that both older homes with low energy efficiency and newer builds with high energy efficiency ended up experiencing higher temperatures.
When you look at countries such as France, for example, they have been building and designing homes to cope with the heat even before the climate emergency. Window shutters on the outside of a property play a big part in keeping European homes cool in the summer. Here in the UK, we tend to just close our curtains, but then the sun still hits the glass and heats up the air behind it.
Ensuring the right amount of ventilation is also crucial in a property. In the UK, we have built various flats and houses with such a small ratio of opening windows to glazing that there isn’t enough air passing through.
In the past, air conditioning might have been a solution to keep homes cool, but this is obviously unfavourable from a carbon perspective.
They may have received somewhat of a bad press, but heat pumps also have a part to play. Despite being misleadingly called heat pumps, as highlighted by Dr Joel at our conference, they can also cool a property by moving heat out as well as in – something I’m sure not many people are aware of.
While building regulations in England were amended last year to include the requirement that new building projects must consider the potential for overheating, this does not address the existing housing stock.
At SDL, we’re positioning ourselves to provide retrofit and energy reporting services to lenders, social housing landlords and homeowners and have so far trained over 100 domestic energy assessors.
Overheating is not something we give much thought to at the moment in this country, but this is going to have to change.
Simon Jackson is managing director of SDL Surveying
First published with Financial Reporter