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« Hot spot or not - Josh 335 | Main | Truth and the green »
Friday
Jul102015

Keeping the heat out

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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Reader Comments (57)

Lots and lots of people claiming that insulation keeps you cool in the summer. I guess these same people believe that a 15 tog duvet keeps you cool in bed in the summer. Yes, if you are a zombie, but household activities are not heat neutral, and won't be until the EU bans cooking, the use of any electrical appliance, or being a human at (roughly) 37 Celsius body heat.

Insulation protects against thermal conduction, and of course there are two other ways of transmitting heat (sorry if I don't get my terms completely correct, but my physics teacher was a paedophile). I guess the correct analogy here would be to wear a really thick parka coat, and stand in front of a very powerful radiant heater, such as an electric fire, or the sun. Radiant heat from the outside, human activities on the inside. No wonder I'm getting hot.

So, it all comes down to ventilation, which means lots of draughts, and big holes in the walls so that air can circulate without letting in any radiant heat ever. I guess we could persuade the late MC Escher to become an architect, then we could have houses with no roof and four north facing walls.

Jul 11, 2015 at 7:26 PM | Unregistered CommenterMax Roberts

MikeN

>"award-winning" architects

You've reminded me of Max Hutchinson, erstwhile president of the Royal Institute of British Architects and a follower of the Norman Foster school of glass'n'concrete design, while himself living in a period thatched farmhouse!

As Max R says above, ventilation is the key, and is a particular problem in modern blocks of flats, where windows often don't open to prevent the hapless occupants from throwing themselves out...

Jul 12, 2015 at 11:34 PM | Registered Commenterjamesp

Fortunately right next to this story is the answer. We see the delightful Gemma Atkinson as she 'flaunts her incredible figure in teeny-tiny white string bikini as she soaks up the sunshine in Cuba'. And looks pleasantly cool as she does it.

Jul 13, 2015 at 2:17 AM | Unregistered Commentermichel

Mooloo " Just install a fan to evacuate the loft space in the hottest days."

Mooloo -didn't you know common sense went out of vogue years ago !! As highlighted by you and Peter Walsh it is always the simple ways that work and seem to get lost the quickest.

BTW. I'm waiting to hear how these ultra insulated houses start to get damp problems because they cannot "breath" properly to get rid of moisture.

Jul 13, 2015 at 3:33 AM | Unregistered CommenterRoss

1. On eco grounds compel plenty of insulation and no ventilation.
2. House overheats.
3. On eco grounds blame man-made global warming.

Job done.

Jul 13, 2015 at 8:14 AM | Unregistered CommenterPunksta

Insulation is by design only a retardation of the heat flow through a wall. HEAT FLOW is dependent on the delta-T - the difference between the temp on one side versus on the other side. This is assuming all other things are equal and no difference in ventilation, especially. Then insulation material itself doesn't know which side the heat is on; it just slows down heat flow by being there. This is all basic materials science stuff.

In winter with 0°C outside, and if 20°C (68°F) is chosen as the desired temp inside (a delta-T of 20°C), in order to minimize heat flow OUT then, then the insulation will do pretty much exactly the same for 40°C outside (ALSO a delta-T of 20°C), preventing heat flow INTO the house equally well. If it is only 35°C outside, the same insulation should definitely keep the interior below 20°C.

I'd say that some things are going on that aren't being spelled out, and people without any grounding in science or problem solving are jumping to conclusions without looking at all the factors.

I've helped build some houses with this sort of super-insulating aims, and I wouldn't live in one if someone PAID me to. The biggest problem was NO VENTILATION, and for me that meant stale air - too much CO2. THAT has a physiological effect of making one breath too hard, which by itself can warm up the interior. And the extra effort may make 25°C feel too warm. Like so many here have said - 25°C sounds pretty GOOD to them!

I wonder if those dwellings were built with windows that can't be open. My guess is that the answer is yes.

Jul 13, 2015 at 11:30 PM | Unregistered CommenterSteve Garcia

About temps in the 25C range being "the point above which health suffers", this weather news video out of British Columbia says the opposite. It says at about the 1:37 mark "...and then temperatures start to drop a little. Now, we are going to get down into the middle 20s, which is really quite comfortable, both in Edmonton and Calgary..."

http://www.theweathernetwork.com/news/articles/favourable-weather-ahead-for-wests-fire-crews-find-out/54106/

One man's "health suffering" is another man's "really quite comfortable."

Forehead smacking time...

Jul 14, 2015 at 8:51 AM | Unregistered CommenterSteve Garcia

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