Eight low-tech ways to keep cool in a heatwave (2013)
bbc.co.uk
bbc.co.uk
I think this is personal. Ice cold showers help me immensely and consistently in multiple climates. My wife (originally from another country) prefers to take hot showers. Although that sounds awful, if I feel her skin afterward, it's cool to the touch, so I know it works for her. So I of course tried it and it was a nightmare. Never again.
Where I live it was 40C/105F yesterday and we don't have air conditioning. It's actually not bad when you have a strategy in place. In college I lived on the 10th floor of concrete building that also lacked air conditioning. I think the list in this article is good mainly for short term relief. It's also optimized for situations that aren't very applicable to most of its readers.
In France, it's standard for windows to have white exterior shutters that both repel sunlight and prevent it from entering a home through the window. They are controlled easily from a handle indoors next to the window. This should be standard in homes and buildings worldwide. If you prevent heat from entering in the first place then you can greatly reduce the "need" to use air conditioning. I can personally attest to how effective they are.
Simply opening the windows at night helps a lot since where we live it gets cool enough. Whole house fans (run in the early morning or late evening), ceiling fans, and cool drinks are enough to keep me comfortable indoors no matter the temperature.
Italy too, although in most newer places, they have the roll-down ones -they're fantastic! On the other hand, the idea of mosquito netting hasn't caught on, which is bizarre.
Unfortunately I can't install rolling shutters on my windows because the gap between the top of the window and the roof outcrop is too short, and existing products are just way overpriced anyway since it's such a niche product. Maybe we'll make something ourselves that produces the same effect.
I think exterior rolling shutters and white rooftops are the two most effective changes we can make.
Rolling shutters are great against summer heat, but IMHO their biggest advantage is the ability to let you have a totally dark room for optimal sleep.
They are also really good at preventing thermal leaks during very cold weather, and provide extra protection against storms and hail. Lastly, really good shutters can be locked into window frames to keep thieves away.
I don't understand why they are not more popular. Coupled with mosquito nets, they are a really convenient and energy-efficient all-weather solution.
Their aim is to avoid sunlight in summer and keep warm in winter.
If you have mosquitos try different brands of mosquito repellant that don't smell that bad. They have been very effective for me. I'm not sure about the health concern of the toxic they produce, however.
I drive on some recently paved roads and they were all paved black. Seems that if we mixed the asphalt with a small amount something light and unwanted (plastic bottles?), but light in color, we could put a dent in both the garbage problem and the heat absorption problem.
Doesn't have to be full white, as that would glare worse than dark black. But a few shades lighter could help some.
Years ago the freeway maintainers were applying rubberized asphalt to the freeways in the metropolitan Phoenix area. The newly-rubberized freeways were very, very black. "Brilliant, just brilliant", I thought.
Some time later I read that while rubberized pavement gets hotter than plain asphalt during the day, it cools much, much quicker at night. The article had infrared aerial photos of the Phoenix metro area pre-rubberized freeways and post-rubberized freeways. Before the project the freeways were all lit up. After the rubberized surface was applied, the freeways were entirely black on the infrared photos.
Rubberized asphalt, applied to Valley freeways to
minimize noise, has an unintended benefit: It's cooler
at night than other pavement, according to the Arizona
Republic.
That's because air holes constitute 20 % of rubberized
asphalt, said Kamil Kaloush, an assistant professor of
civil and environmental engineering. Those pockets of
air allow heat to escape, something that dense concrete
can't do.
https://www.popsci.com/la-is-painting-its-streets-white-to-k...
Although, minisplits have become more prevalent.
You could fill a tub with ice though.
The last two days I hung up two wet towels as "curtains" on the outside of (open, curtainless) window in the living room, which face the sun during the day. They blocked the sun, and air coming into the house through the window was notably colder.
They dried out so quickly that I had to soak them again twice during the day. Given how much energy it takes to evaporate all that water I think that little hack got rid of a lot of heat.
It's called a swamp cooler. It simply evaporates water and the heat of vaporization causes the air to cool to the dew point.
I live in a place with abundant water, but I would expect this approach to be kind of "frowned upon" in a desert. Isn't saving water a high priority in those environments?
You'd miss on the evaporation cooling though. Maybe a two-layer approach would work best of all low-tech hacks! :)
In the past, when I was living in an apartment with a wider windowsill, I used to put a reflector made from cardboard covered with aluminium foil on the inside and sun-hungry plants inbetween, creating a miniature greenhouse. Open windows were a requirement of course, because it would still trap heat otherwise.
I've experienced this very thing riding a motorcycle through Arizona. Man, it takes some real willpower, but gearing up is what is required when the temps go over about 85F. Just don't stop!
Tip. On a motorcycle, wet your shirt. Zip up your coat. Unzip your wrist cuffs. This slows down the airflow giving time for the water to evaporate and cool you, while providing an intake and exhaust. You will be amazed at how well this works. You can actually regulate the temperature (air flow) by opening or closing the zipper by your neck.
This will not work in areas with high humidity like the deep south.
I also haven't worn clothes at home for awhile.
In contrast, I ride my bike to work, so I start super early in the summer in order to avoid getting drenched in sweat.
The problem here in the Midwest is that it gets cool at night, but with virtually no wind, so we use some window fans to bring the cooler air into the house.
It's simple, low-tech, and effective.
I'm not sure how good that analogy is. Generally a box fan is loosely fit in the window and has an open interior with no shroud, as opposed to server fans which are tightly mounted to a fan-sized hole and have a close-fitting shroud around the blades. This has a big effect on the optimum configuration, because the box fan's suboptimal design happens to be more suboptimal at sucking than blowing (while a server fan is good at both, being closer to an ideal actuator disk)
I have observed that, in general, a box fans work better at blowing out a window than sucking in. At first this confused me. Why should this be the case, given time reversal symmetry?
Here's my hypothesis. The fan produces a high velocity jet of outlet air, but sucks in any air nearby (that's why you can blow paper across the room, but you can't suck paper across the room, another seeming violation of time symmetry). Since the fan is located nearer to the interior of the window, it can either A) blow an outward jet that maintains its momentum through the window, or B) attempt to suck an inward jet of air through the window. That doesn't work, so it mainly intakes warm interior air, resulting in mostly in-room recirculation with very little flow through the window and very little static pressure created to drive whole-house airflow.
Think I'm full of shit? Good, then your skepticism is working! Don't take my word for it. Anyone can test this using a phone with a barometer. Put the phone on a table (for constant altitude) in the room with the fan. Compare the pressure drop (exhaust fan on vs. off) with the pressure rise (intake fan on vs. off). If I'm right, the absolute magnitude of the pressure drop should be greater than the pressure rise, indicating greater airflow in an exhausting configuration.
If you only have one fan, definitely have it pointed out, not in. The moving column of cold air cools the entire place, not just a single room. Also this arrangement keeps the noisy fan in a separate room, while you enjoy the cool air quietly wafting through a nearby open window.
I've transformed many friend's apartments from sweltering to comfortable by implementing this tip.
TL;DR blow out, not in.
You're right - cross ventilation is really important. Generally you want to pull air in as low as possible as it's cooler. And then push out as high as possible. As "cross ventilation" somewhat implies, usually this is across a room or building for the best airflow.
A fan in a regular-height window and an open vent (a higher window, door louver) generally works pretty well. Even if it's the same window, it'll work ok.
>But your body will react to a dramatic change like this by trying to preserve heat.
>"If I'm hot and I go under a cold shower, I'll shut down the blood flow to the skin and trap the heat inside me rather than let it escape," says Tipton.
>As a result, he says, it's better to use water that is in the 20s Celsius than water that is in the 10s.
>"It's better to have a warmer shower that is cool enough to lower the deep body temperature but is warm enough to allow the blood to the surface of the skin."
Is there any proof of this? Even if the body makes adjustments in an attempt to mitigate heat loss, I have doubts that these adjustments manage to make lukewarm water more effective at cooling than near-freezing water. That seems backwards, but maybe it is just contrary to my intuition. If 20 degree water is more effective at cooling than 10 degree water, how does 5 degree water compare? What if you shower in -10 degree liquid? Is 25 degree water even more cooling than 20 degree water because it is even closer to normal body temperature? I would like to see an experiment.
On related note - reading recommendations for when for example a dog gets a heat stroke, you will find that ice or very cold water straight onto the belly may worsen the situation for exactly that reason. Also recommendations to in particular cool the head - pretty straight, not that much depending on blood vessels state, heat transfer from the brain preventing/slowing the damage.
> What if you shower in -10 degree liquid?
that takes blood flow mechanics play even further - you can get a heart attack by quick changes in blood flow caused by the blood vessels constriction (or quick expansion after that if you quickly get back into the warm environment - there was that story about a ship crew rescued from cold ocean water only to all drop dead from heart attack when they were immediately walked into a warm room on the rescue ship). On the good note - being a Russian i like and frequently do hot sauna until my heart can't take it anymore and jump into the cold water (or into the snow or river ice hole back then in Russia) straight after that - great fun enjoyed responsibly :) - the key here is having hot sauna to really expand your vessels so they wouldn't get immediately shut down by the cold water/ice and staying open they provide for efficient heat transfer.
https://biology.stackexchange.com/questions/31566/how-does-t...
Also there is some theoretical danger associated with the setup of how blood is supplied to the brain: https://en.wikipedia.org/wiki/Danger_triangle_of_the_face
http://www.ailr.com/liquid-desiccant/ld-tutorial/
http://ashraemadison.org/downloads/Meeting_Presentations/jan...
one of those things I can't help but chuckle at. 73 F (23 C) is like my ideal temperature!
Just suck it up, 30c is manageable, even if you're used to it. any humidity? That is the worst
You realize they put out the warnings for a reason, right? Like... people die when temperatures get that hot in northern regions. People actually die. But nah, just suck it up right? Suck it up granny, quit yer dying over there and just buy a fan!
You are discounting the personal factor. I'm 28C inside and 36C outside. Pretty comfy for me and not running Air conditioner yet. In fact I set the Aircon at 20-23 most of the time. A hot day would be 40+ outside.
Nah, but go ahead and laugh when 80F is considered hot. We laugh in our tank tops and shorts when you guys say 50F is cold.
I went back to the Norwegian summer following the summer of Black Saturday in 2009, where we got a few 46c days. That was a shocking summer even by Australian standards. When I got to Norway it was around 35c - unusually hot for them; my family really couldn't handle it. I just found it mild and pleasant... they all looked at me weird.
The reverse was true when I moved to Australia many years before that. Arriving in June, coming straight out of the Norway winter I couldn't understand why Melburnians were complaining so much .. to me the "winter" felt hot!
Of course I also complained that they should close the windows in the office because of the road noise, only to discover that double glazed windows aren't standard everywhere. They really don't know how to build houses here.
I've seen below freezing point temps riding to work now so they really ought to introduce some proper building codes ... it's just sad how much energy is wasted pumping heat through the metre wide gaps under the main doors. Really, Australian builders have NFI about energy.
> These thresholds vary by region, but an average threshold temperature is 30 °C by day and 15 °C overnight for at least two consecutive days.
As a German, I would say anything over 38 °C during the day and over 20 °C overnight is a "heat wave", and I think a lot of people down south, maybe most humans on this planet, may not consider this too warm. I remember visiting the Emirates for a week during summer... or working in the kitchen of a summer camp for disabled people in Oakhurst, New Jersey during the summer, without an AC in my room. The camp's kitchen's giant refrigerator room was a favorite meeting place for anyone who had access. The only way to sleep was with a fan running at full speed blowing right at me. Maybe that experience shifted my view of what a "heat wave" is. Oh, and in the Emirates they have "cooled swimming pools". I thought it was just a joke, but no, they really artificially cool the water of their swimming pools. I went into the Gulf water - for half a minute, then I went straight into the cooled swimming pool that I had scoffed at. Having grown up in East Germany and only knowing the Baltic I never knew that the sea could ever be too warm even to enter for more than a minute.
Yesterday or the day before, reading UK news (BBC or The Guardian) as I often do, I saw the announcement of the "heat wave" and the warning of temperatures over 30 °C(!) and thought exactly the same as OP, even if he got the exact number wrong.
In some places, buildings are designed on the assumption that temperatures at night will be significantly cooler, and give the building an opportunity to shed heat collected during the day. When that assumption is violated, the building remains hot and continues getting hotter each day, which is dangerous to people inside.
By the way, I found by personal experiment that all it takes is one layer of something like cloth in front of the stone to prevent if from heating up. I completely cover my large balcony on the outside now, including the thick stones. In all previous years they always stored to much heat during the day that the balcony remained hot well until morning, heat radiating from all sides, making it almost unbearable to go there (or to open the wide door) even when the outside air temperatures had dropped below 20 °C. The difference this summer is huge. So it does not take anything fancy or expensive at all, just prevent direct sun exposure of those heat sink surfaces (like solid concrete).
Another “trick” is cardiovascular health. I was miserable in heat for some time but thing got a lot better after I picked up cycling - 32 c humid heat produced no discomfort (apart from sweat).
But try putting a reusable cooling pack right on your body, it’s pretty great when you’re overheating.
Back mounted compressor that runs cooling pipes to your underwear, that could be amazing!
Now I have a family member who grew up in Hawaii and consequently with AC turned on alot.
When it gets a little warm/humid and no AC is available, it's absolutely miserable for her. But I'm just fine. I mean it's miserable but I can pretty much function normally. She can't.
Source: Living in South East Asia for years.
Oh Man, when it is hot I love go sleep and use a wet towel as a blanket. Girls hate it.
Unless you're trying to chill the universe, that is.
You take ice, put it in front of the fan, and let the fan blow on you combining several of these low-tech ways to keep cool.
Better only use store bought ice for this trick.
For example:
- ovens: vent outside on hot days, inside on cold days.
- clothes driers: vent outside on hot days, and on warm days either (a) vent inside through a filter or (b) send the exhaust through an indoor heat-exchanger before venting.
- refrigerators: cooling coils cooled with indoor air on cold days, outdoor air on hot days.
We live in the tropics and do not have anywhere to hang clothing to dry.
We use a heat-pump dryer which heats the air on the 'hot' side then through the clothes and then circulates the now-moist air through the 'cold' side which removes the excess heat and condenses the water vapour.
The same air then goes through the cycle all over again. That means no huge amount of hot, wet air escaping into an already hot house which needs to be either vented or cooled.
And because the energy used in heating the air is not thrown away by venting it, but is recaptured by the 'cold' side, the dryer is cheaper to run.
https://en.wikipedia.org/wiki/Pika
Edit: specifically the American Pika
We don't need tech to survive either, so long as we don't mind living like animals!
Depends on the person. If you're used to using A/C and you take it for granted you'll use it a heck of a lot more. I used to sit in DC traffic in a black truck with no A/C every day on my way home and sitting in traffic was the part that sucked. The temperature wasn't an issue because it's what I was used to. I'm fine with box fans around the house.
My girlfriend starts complaining and wants me to put the window A/C in when the temperature hits 80ish.
Guess who was raised where A/C was common and who wasn't.
Temperatures in North America are such that with proper ventilation A/C is in fact optional (though it's certainly nice in some places). Whether or not people use it is mostly based on availability and culture. If you convinced everyone that A/C or heating is for liberals the "A/C vs heating" break-even map in the US would look a lot like the red/blue voting map which would be kinda funny.
If we really get the vast majority of the world using air con we may as well get them to power their homes by diesel generators 24/7 too and be done with the planet, environment and any claims to care for it.
Where I live, the summers are muggy. Having ACs double as dehumidifiers is usually a blessing.
OTOH, when I'm at hotels in the SF Bay area, the AC dries the air out so much that I often shut it off at night, choosing the lesser of two evils.
Let me guess you are not from a region where its hot and humid. That is a deadly combination, your overall efficiency drops with such a combination.
Too much carbon in the atmosphere warming the climate? Of course the solution is to build more air conditioners and blast out more carbon. /s
Why would we opt for air conditioning instead of improving our building practices and performing retrofits to require less energy input?
Thankfully I choose to live in a temperate climate so my heating costs are minimal (gas) and cooling costs are 0.
People forget what a boon to human kind, to the human mind such things like inexpensive artificial light, mechanized temperature control, industrial farming and manufacturing and such really are.
Its fun to play at virtue by switching off the AC and popping open window (thinking that the AC is some sort of sin of weakness) while completely forgetting that you've never had malaria because AC is ubiquitous in your area.
We are, perhaps, rightly gun-shy of trusting too much in technology because of some last century's indiscretions, but I don't think that a return to the age of cholera is the solution. At some point, we're going to have to get over it and have some hope again that we can use the fantastic tools of human science to start fixing some the the big problems.
That's a long way of saying that the answer is not to turn off the AC (and smugly tell the developing world that they're not allowed to have it either), the answer is to find a better way to power everyone's AC without doing the damage to our world that it previously did.
We are up to the challenge.
Running an AC in a warm part of the world consumes vastly less power than heating in a cold part of the world does. Moving south reduces GHG emissions, all else being equal.
This isn't wrong, and even LKY concurs:
> Air conditioning. Air conditioning was a most important invention for us, perhaps one of the signal inventions of history. It changed the nature of civilization by making development possible in the tropics.
> Without air conditioning you can work only in the cool early-morning hours or at dusk. The first thing I did upon becoming prime minister was to install air conditioners in buildings where the civil service worked. This was key to public efficiency.
Also note that we already have energy sources that can let us reliably run air conditioning without dumping CO2: nuclear energy. The climate problem isn't unsolvable, it's been solvable for decades, the only thing between us and solving it is our weird and irrational (burning coal or making solar-panels kills far more people) fear of nuclear fission.