Keeping the heat out
Jul 10, 2015
Bishop Hill in Climate: WG3

An article in the Mail tells the story of the number of people - apparently large - who are choosing to decamp rather than continue to live in their ecohouses.

When Emma Taylor was offered a two-bedroom apartment in an award-winning block of flats, she couldn’t wait to move in.

Newly built, she was informed the building had been constructed to such high eco-standards that it would cost just £1 a week to heat. Unfortunately, as she’s discovered to her extreme discomfort, keeping warm is the least of her problems.

Because unlike most Britons, 23-year-old Emma has come to dread the summer months. Her ground-floor flat in Coventry is so well insulated that when the sun shines the temperature inside rockets — regularly over 25C, a point at which experts say health can suffer.

The Mail article seems to suggest that this can be a lethal problem:

To understand the impact heat can have on mortality rates, turn the clock back to 2003.

That August, much of Europe sweltered under a heatwave, with temperatures in northern France exceeding 40C.

The result was 15,000 heat-related deaths, the vast majority among older people. Research later revealed at least half could have occurred due to exposure to heat in people’s homes.

However, there is research out there that claims to have shown that as far as the 2003 deaths in France are concerned it was lack of insulation that was a risk factor. The UK government seem to concur and official advice is to get your walls insulated to keep the heat out.

The National Housebuilders organisation have looked at this question too, but their report raised more questions than it answered:

There is increasing evidence that new and refurbished properties are at risk of overheating, especially small dwellings and flats and predominantly single-sided properties where cross ventilation is not possible.  However, there is also evidence that prototype houses built to zero carbon standards are suffering from overheating, which shows that overheating may also become an issue where cross ventilation is not achievable in lightweight, airtight houses with little or no solar shading.

In many cases the lack of ability to reject the heat build-up from normal occupant activities means that a risk of overheating exists in summer.  However, in some instances the gains are such that the overheating occurs for most of the year and is therefore independent of the external temperature.

I'm guessing that because of the relatively low numbers of people who live in eco-houses at present, their risk of frying the occuptants alive was not picked up by studies of the French heatwave. Certainly, the one cited above only had a category for buildings "Built after 1975".  It may be that there is an optimum level of insulation, above which the risks of overheating outweigh the benefits in lower fuel bills.


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