Preparing for extreme heatwaves.

[adam2]

With a warming climate, and society subjectively becoming less resilient to out of course events, it might be well to review preparations for exceptionally hot conditions.

Consider not just yourself but also friends and relatives. The elderly, the very young and those already in poor health are at particular risk.
Some actions to reduce the risk of heat illness are common sense, examples include
Keep out of the sun, limit exertion, drink plenty of water, wear lightweight cotton clothing, and so on.

If your home is uncomfortably warm in a normal summer, then that suggests that it could become dangerously hot in a heatwave.
Take steps to reduce solar gain such as external awnings, shutters, and sunshades, the planting of vegetation and the whitewashing of walls and flat roofs.

Electric fans do not normally reduce the actual temperature, but can greatly improve comfort by causing air circulation and the evaporation of perspiration. Electric fans are cheap and widely available, but may be in short supply in a heatwave, make certain that you have at least a couple to hand.
Standard desk fans are of course reliant on the mains electricity supply which might fail. Consider at least one good quality, full sized fan that works from a 12 volt battery. A vehicle battery will serve in a short term emergency.

In the warmer parts of the UK, and in particular in an urban "heat island" you may need air conditioning.
A basic portable air conditioner costs from about £300 and costs in the region of 10 pence an hour to run.
Evaporative coolers are of very little use in UK conditions and should not IMHO be considered.

Edit to add that the above was true when written, but electricity has now nearly tripled in price A modest portable air conditioner can be purchased for about £200, but will cost as much as 30 pence an hour to run.

[kenneal - lagger]

Mind you, in an extreme heat wave the electricity is quite likely to go off and your aircon unit will then not work!

[adam2]

Mind you, in an extreme heat wave the electricity is quite likely to go off and your aircon unit will then not work!

Certainly a risk of which one should be aware, though in the UK, winter heating demand still outstrips summer air conditioning demand. Lack of generating capacity is therefore unlikely to be a Summer problem, though random breakdowns can happen at any time.
Although total UK electricity demand has been falling, it is still increasing in the London area, increasing the risks of transformer and cable failures.
Remember the Great Auckland power failure ! Hot weather, rather optimistic assumptions about cable capacity, delayed upgrades and renewals, together with increased air conditioning demand ended very badly.

Ideally buildings should be designed so as not to need air conditioning, but this is increasingly challenging.

Whilst new records for daytime temperatures make good headlines, increasing NIGHTIME temperatures are of great concern since buildings with good thermal mass now get hotter and hotter during a heatwave rather than cooling at night.

Large shops and offices would be unusable without air conditioning in the warmer parts of the UK.
Some homes in the South East are borderline without active cooling.

[clv101]

Heat (as well as cold) is something we should be taking far more seriously in new buildings.

Our rented 1933 semi, with southwest facing bay windows would get uncomfortably hot in periods of good weather (around 30C) yet the same room would be 13C on a winter's morning after being 20C the night before.

Our new self-build house with it's good insulation (U value around 0.13 for walls, floor and roof) and many tons of internal clay plaster is far more comfortable in both hot and cold weather.

As an aside, we also have a couple of big 250W, 20 inch fans. They shift a serious amount of air. Having one at a downstairs doorway sucking in, and another on an upstairs window sill blowing out does a fantastic job of ventilating the place. A cheap, quick approach.

[woodburner]

In very hot weather it is better to close windows to keep the heat out, not to suck hot air in and blow it out somewhere else. Most people have the delusion that opening windiws is the fix for high temperatures. This might apply at night when the outside air is cooler than the inside, but during the day when the outside temperature is high, it could be several degrees cooler inside if the windows are kept shut.

[adam2]

In hot weather, ventilation should be limited when it is hotter outside than inside.
When it becomes hotter inside than outside, then ventilation should be maximised, either by convection or fan assisted.

If despite sensible control of ventilation, and other steps to reduce heat gain, it is still too hot, then air conditioning will have to be considered.

It is of course possible to work electric air conditioning from a battery and inverter but this needs to be very generously sized.
A small air conditioner with an input of 700 watts will probably need at least a 3,000 watt inverter to reliably start it.
The running current from a 12 volt battery will be about 70 amps, entirely doable with a large battery bank.
Non electric air conditioning does exist but is almost unknown in the UK, it burns alarming volumes of natural gas and only finds favour in places with cheap and plentiful natural gas and expensive or unreliable electricity.
LPG powered air conditioning used to be popular in hot but remote parts of the USA that lacked utility service. The falling price of PV and rising cost of LPG has made the idea uneconomic.

[adam2]

And right on time, the first heatwave alert of the season.
https://www.theguardian.com/uk-news/201 ... or-england

I find the lack of awareness of heatwave dangers to be very concerning.
Most members of these forums can no doubt survive with only a bit of discomfort, by following advice and applying common sense.

The position is very different for residents of old peoples homes, and those lacking the physical or mental abilities to apply common sense.

"use the cooler rooms of you home" most residents of care homes often have no choice, but are herded into the "day room" on a rigid schedule. (this room often faces south and has large windows)

"wear lightweight cotton clothing and use cotton sheets" Care home residents often have no choice, polyester being compulsory.

"you may be cooler outdoors in the shade" Fat chance in most institutions, "safeguarding issues" or other rules often prevent this.

For these reasons I believe that most such places should have air conditioning, and a standby generator.

[emordnilap]

And right on time, the first heatwave alert of the season.
https://www.theguardian.com/uk-news/201 ... or-england

Yesterday, 24/6/18, my outdoor thermometer registered 30� in the shade. This device is usually fairly accurate and, even if not, it was still incredibly hot.

I took a foot out of a shoe to remove a stone and could not put my bare foot on the ground, it was burning hot.

[fuzzy]

Yes here, and again today. You know it's scorchio when you water your fruit every night and by the afternoon your raspberry leaves are shriveling up. Pity the nightshift and outdoor workers.

[adam2]

I have admitted defeat and started using my air conditioner, reluctantly due to the power consumption and the noise.
Uses a bit less than 1KW and claims to produce over 2KW of cooling.

My home has solid stone walls that retain heat or cold for a long time. It remains comfortable during brief hot spells, but during the present more prolonged hot weather indoor temperatures have steadily increased to uncomfortable levels.

Living room yesterday afternoon was 28 degrees, without air conditioner and 23 degrees with it running. The humidity is also much reduced.

[kenneal - lagger]

Have you been opening the windows at night, Adam? Our cob house is about 23-4 and comfortable.

[woodburner]

We don’t have an air conditioner. We have to put up with it.

[adam2]

Yes, so far as possible I have been opening windows at night, but this helps only marginally when it is very warm at night.

[kenneal - lagger]

It might help to use your fans then to push the warmer air out.

[RenewableCandy]

Chateau Renewable remains a cool 23 degC inside, as outdoors it's gone up to about 28.

My measure of The Ultimate Heatwave is this:

Is it too hot for RC to put milk in her tea?

At about 37 degC I find myself resorting to Jasmine or Peppermint or somesuch. So far, I think we're safe from that.

Also, I've never before heard of full-house air-com being used in the UK in an actual house (as opposed to an office). I suppose it's a South thing.