Climate control

If you’re in the UK this week, you’ll hear a lot of people muttering darkly about the big yellow ball in the sky, and how they’re having to mist the bed with water in order to get it cool enough to sleep, or steal fans from their children’s bedrooms, or make makeshift beds on the cool tiled floor in the kitchen out of cushions. (All overheard at Pi Towers yesterday.)

And Jon is wearing three-quarter length trousers.


The UK, you see, does’t really do summer. So this week’s egg-cookingly hot heatwave has had us all wishing we had air conditioning – while it’s pretty standard these days in offices, nobody (apart from my mother, who has a mobile unit she calls Mr Freeze because she is awesome like that) really has one at home, unlike those of you in countries whose summers last longer than the standard British week. Mark my words. Next week it’ll be raining again.

The outlay for an air conditioning unit at home is pretty big – they’re unusual, so not very cheap here – but there are options. You can build your own 12v evaporative unit very cheaply, with a PC fan, a bucket, an aquarium pump and some inexpensive electronics and bits and bobs from the homewares shop: this version comes in at about £40. You can take it a step further and add a cheap thermostatic switch.


And, of course, now you’re equipped with an air conditioner that you have made with your own hands, you can start to automate your house. Because that’s what we do here when we’re not spraying the bed sheets and wearing trousers which display our calves.

If you’re taking cooling seriously, you should be looking not just at active cooling like the orange bucket swamp cooler; but also at stopping the heat from building up in the first place. Chris Rieger from Australia has a neat and simple home automation project that controls his blinds as well as his air conditioning. (If you have curtains, you can automate those too – see this project from Jamie Scott, which would be easy to incorporate into Chris’s system in place of the blinds mechanism.)

Chris has made a neat little GUI you can use to control the system over a web interface, with the ability to automate by time or temperature, or to manually turn the system on or off. Full instructions are available at his website.

So really, Great Britain, you’ve got no excuses to keep complaining. I expect to see you all ripping out old PC fans and buying buckets at Homebase this weekend.



Neil avatar

Meanwhile it has been so COLD here in Brisbane, Australia today (southern hemisphere, you know) that I amost thought about putting on a jumper. Heaven forbid!

Ian Hollis avatar

Many houses here in Western Australia have roof mounted units and owners say they need to keep a window open to keep the humidity from getting too high.

As we get summer temps in the high 30s to low 40s (celsius) we need some form of cooling to make summer more comfy.

Looks like a great little unit. I’d make one for my garage/workshop but I inherited an old Window-mount refrigerated unit last year and I use that when it gets too hot – up to 50°c under the tin roof.

pbat avatar

Nice try but not for the UK: by the time you finish building it, in the UK is cold again. In fact, yesterday temperature already dropped from 37 to 22 C.

Sorry I wanted to say:

Nice try but not for the UK: as far as I know evaporative units are useful in *DRY* climates. The only thing that dries up in the UK is my bank account.

(but it’s a great idea for the rest of the world)

whheydt avatar

When the rains return…if you get more than you want, please send some of it here to California. It would cause a lot of comment this time of year…

Spencer Allen avatar

He here in the southwestern USofA (New Mexico in my case) evaporative A/C (“Swamp coolers”) are very common. But those of you in other climates should remember that they only work in areas of low humidity. 10% to 20% is good. Also you must have air flow. I don’t think the UK would qualify.

I could never understand how a country like the UK couldn’t make cars that would run in wet climates. I had 2 MGs and an A-H Sprite and all would quit running at the least hint of moisture. I finally learned to replace anything that said Lucas on it.

jdb avatar

Typically in the UK during heatwaves, the humidity does drop into the 20-30% range. In the south of England, it’s typically higher and ends up with thunderstorms coming across the Channel from the continent.

As for breezes, strong anticyclones sitting on top of us during heatwaves mean a steady but light waft.

yvant avatar

They are used as well in high rise buildings here in Quebec, CAnada.
They work even when the humidity goes high.
I don’t know if it happens in other part of the world but these towers has to be cleaned once in a while.
As a bacteria tends to develop in them and it affect peoples.

yertiz avatar

Down here in the West Country we are wondering what all the fuss is about.

Tuesday was pleasantly sunny but the temperature never got out of the 20s. A pleasant summer’s day but no heat wave.

Wednesday was cloudy with light rain showers. 18 C. Not even a pleasant sunny day.

Thursday was cloudy with very heavy rain showers. 14 C in the rain. OK for Spring?

I’m with Neil. Forget the Air Con bring on the jumpers.

tim Rowledge avatar

I live on Vancouver Island, which is very much like a more-rugged UK; the wether is so similar that when we listen to BBC radio Solent on t’internet the weather forecast is pretty much what we get.

What we have for heating *and* cooling is an air-source heat pump; it does both jobs pretty darn well. Typically you get around 3-5 times as much heating as power put in and it’s efficient to a decent level all the way to -15C or so. There are units even more efficient at even owed temps, but I don’t think I ever saw much worse than that when growing up in the UK.
You can do ground-source, but you need suitable ground (duh!) and the capital cost can be a bit alarming.

Serge Schneider avatar

I, for one, thought the weather has been quite nice. No idea why you’re all melting. =)

ian avatar

to re-iterate the above, these are not really suitable for the uk

bms doug avatar

I was worried that the temperature on Wednesday was going to be too much for the AC systems at work, we were ready to run hosepipes across the dry air coolers to try to bring the temperature down a bit.

37 degrees condensor water return temp is a bit outside of the design specifications for a UK chiller system as it doesn’t happen often enough to justify the cost of designing for it. (that’s right, the system is designed so that it will breakdown when you need it most, because its cheaper that way).

tai avatar

I rather think that’s how *everything* is engineered. :)

Well, not necessarily *break down*, you’re right. That’s a flaw; it should just continue to do its inadequate best outside the design envelope.

So how was it, in the end?

Nicholas Harris avatar

How hot, exactly?

Anything under 85 F is cold for us. Average is about 100-115 F

-from CA in the US

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