Coping with heat

Is it still hot over there? -6C here this morning. I've switched from keeping heat out to keeping it in. I'll probably remove the tarps over my south-facing windows today to hold off having to fire up my heater.

I heard that eastern Canada had its heat dome collapse.

Yes, all those heat-absorbing surfaces in cities makes a difference. I wonder how much of a difference it would make if the pavement in a city was concrete rather than asphalt.

Someone should do a study of the total economic effects for a city if the council mandated roof colour or types. Even with white granules, asphalt shingles absorb a lot of solar heat. White metal roofs would not be much more expensive to install than asphalt shingles (and the price would drop due to increased demand and supply), and might make a significant savings in cooling costs for all buildings in the city, and make the city air a bit cooler for everyone. I don't think anyone's life would be dramatically worse if they couldn't choose dark red asphalt shingles for their house.
 
Mij said:
And planting trees on top of buildings or just paint the roofs white?
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I'm not sure of the cooling effect of trees. They will absorb more heat than a bright white surface, and raise local humidity levels. Maybe someone has done a comparative study? Trees also trap heat below them. The area under my spruce trees is significantly warmer than the ground around it.
 
Google AI suggested this 2024 review on the cooling impact of street trees:

Abstract

Urban planners and other stakeholders often view trees as the ultimate panacea for mitigating urban heat stress; however, their cooling efficacy varies globally and is influenced by three primary factors: tree traits, urban morphology, and climate conditions. This study analyzes 182 studies on the cooling effects of urban trees across 17 climates in 110 global cities or regions. Tree implementation reduces peak monthly temperatures to below 26 °C in 83% of the cities. Trees can lower pedestrian-level temperatures by up to 12 °C through large radiation blockage and transpiration. In tropical, temperate, and continental climates, a mixed-use of deciduous and evergreen trees in open urban morphology provides approximately 0.5 °C more cooling than a single species approach. In arid climates, evergreen species predominate and demonstrate more effective cooling within compact urban morphology. Our study offers context-specific greening guidelines for urban planners to harness tree cooling in the face of global warming.

Cooling efficacy of trees across cities is determined by background climate, urban morphology, and tree trait​

See https://www.nature.com/articles/s43247-024-01908-4​

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my bolding
 
PrairieLights said:
Heat is one of those things that leaves me struggling more. I have no access to air conditioning.

I thought maybe if there are others who also struggle we could share some tips or ideas that help us.

Last year I bought these window heat reflecting things for the window. I have them in my bedroom. They do reduce the temperature a bit in my room.

https://amzn.eu/d/avhjlAa
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Solidarity with you struggling with this. Can you be more specific about how heat affects you? In my case, at its worst, it leads to a feeling of swelling around my sinuses that ends with a terrible migraine in the worst cases. I’ve started trying to prevent heat-related-PEM by regularly rubbing an ice cube all around my forehead and temples until it’s fully melted (though usually for me the big problem is some sort of exercise at the same time as being in hot conditions). And drinking big gulps from a half gallon container of ice water through a straw throughout the day (which seems to cool the blood flowing by, helping reverse the feeling of increases in heat in my head). And plunging my head in a giant cooking pot of cold water regularly (I’m in the Deep South so our summers are long and unbearable even for fully healthy people - and even with AC). But that’s tailored specifically to my own issues with heat. Sharing in case it helps you figure out your own protocol tailored to you.
 
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Peter T said:
Google AI suggested this 2024 review on the cooling impact of street trees:


my bolding
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As someone in the Deep South I can confirm the neighbourhoods covered in enormous Live Oak trees are significantly cooler than the ones without during our epic summer heat. If you roughly calculate the vast surface area of the leaves on a large tree (with each leaf furiously absorbing solar energy for photosynthesis) you start to get a sense of how they can be powerful coolers of the area around.
 
Long time tropical dweller here. Trees definitely work, in two ways: Keeping sunlight off the ground/buildings/you, and cooling the air around them through transpiration.

There is also some interesting work going on developing a new class of reflective paint that are more selective in the wavelengths of light they radiate back out, maximising a certain infra-red range that the atmosphere is transparent to so the heat gets radiated away much more effectively. Apparently they can actually reduce the temperature under the roof to below the ambient air temperature.
 
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Surely it would make sense to install solar panels on all roofs. Then anyone should be able to cool their homes, and businesses, when it's hot.

It's madness to leave it to individuals. I've been trying to get government-assisted panels on my roof for years, and am trying to save enough to pay for them, and I am now relatively well-off.
 
MeSci said:
Surely it would make sense to install solar panels on all roofs. Then anyone should be able to cool their homes, and businesses, when it's hot.

It's madness to leave it to individuals. I've been trying to get government-assisted panels on my roof for years, and am trying to save enough to pay for them, and I am now relatively well-off.
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They pay for themselves in about 7 years usually. Because you save money on your bills rather than really make money its also effectively a tax free reduction in living costs and one of the few capital investments that does so. We ought to be splattering every house and business building with them because combined with enough battery this will cut much of our need for oil and gas and it saves people an absolute bucket tonne of money.

One of the good things about summer time AC need is it pretty much always aligns with high amounts of sunshine. The only problem is the heat sticks around after the sun goes down so it does require batteries to completely deal with it from your own solar. But in the Uk our power needs through the summer are about 20GWs less than in the winter, the capacity exists to be using a lot more AC.
 
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That study seems to be about trees vs no-trees (and dark surfaces), so of course trees are better. I'd like to see a comparison between treed streets and streets with white surfaces of equivalent area. While I love trees, and the ecosystems that accompany them, for solving the problem of urban heat, maybe there's a better solution. However, if white canopies proved to be a few percent more effective at reducing heat, I wouldn't consider it worth the loss of ecosystem and the psychological benefits. Educational benefits of trees too, especially for kids.
 
Brightly painted asphalt was supposed to be a breakthrough in the fight against urban heat islands. Los Angeles has implemented such a solution on hundreds of kilometers of streets, investing millions of dollars. However. doubts are arising.

Verification of assumptions

10 years later, we can now say that, however, according to the latest research, these types of pavements may be cooler on their own, but they can actually make people feel much more warm.

Why? Scientists found that reflected sunlight did not disappear, but... was absorbed by people. This means that on a hot, dry day, a person can feel more than 7 degrees more heat in such a place compared to ordinary asphalt pavement. Unfortunately, this tool, intended to help solve the problem of urban heat islands, seems to have an undesirable side effect.
On a typical summer day, with a maximum air temperature of 31°C, the average radiant temperature on such streets was more than 7°C higher before noon compared to black pavement, and in the afternoon the difference remained above 3°C. This was mainly due to solar radiation reflection, which in the case studied was 130 W/m², corresponding to an additional about 10% of direct sunlight.
Measurements carried out on exposed, shadeless streets confirm that the effect of reflected radiation can worsen the thermal comfort of pedestrians, increase sweating and the risk of dehydration, and in the case of vulnerable groups - promote serious health problems, including heat stroke.

Does it clothe and harm?
It is also worth mentioning that such materials also reflect ultraviolet (UV) radiation, which is a major cause of melanoma and other skin cancers. In addition, it causes burns, accelerated skin aging and eye damage. Creating completely bright spaces can increase UV levels by up to 300 percent compared to non-reflective surfaces.
 
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Mij said:
I'm guessing painting or using white materials on roofs is healthier than painting the street white?
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if you look at places like Greece where white is commonly used then it is more matte and also often on buildings and surfaces with more rounded edges too and are thick stone so any that does turn into heat has a thick mass to get through.

the just making tarmac white idea reminds me of the warnings when going skiing that you can get bad sunburn because it reflects the light but the snow doesn't melt etc.

On @Creekside mentioning about the lack of specificity in certain papers pushing for trees I suspect they are correct too, I'm cynical - my very basic tomato growing so far has a stage where apparently we should remove the bottom leaves so the plant itself get cool air and ventilation and so do the fruits in hot weather; it makes utter sense that in different environments (like humidity varying or the environment they are in being narrow or built up or whatnot) means that what helps vs hinders needs to be a lot more forensic than 'any tree will make it better'. Particularly when you hear of certain trees being very water hungry, fire issues where a tree is oily or dries out or sheds causing other problems and their roots and so on, but also dispersal of light and air being important.

So it probably needs carefully made-fair plans that tackle it so it isn't one poor person also getting none of the benefit and all of the damage/problem because someone didn't want to think of something that worked for both.


it's sad but true but it sometimes seems a lot of those pushing for certain things in the name of green via supposedly academic papers are ruining the reputation/way forward for the rest as they can at least write manifesto-type papers in a way that comes across biased and/or illogical vs there must be a range of options etc in things they write like those who pushed that if they use an LTN to close down their own side road so there aren't side roads to 'use as rat runs' then it isn't just causing congestion and therefore more idling as people are stuck in jams and more pollution because that's the most polluting mode to be in + everyone has to go further because of some rude idea they can hand-waive it by saying 'well that'll put people off driving so the traffic will reduce'. Suggesting 'disabled people will find a way if they are forced to get used to it' is just an attitude problem of those who for some strange reason not only decided not to bother doing the work to find a way, but somehow found something rather strange that caused an issue that probably was never needed, then closed their ears pretending they didn't cause it. etc.

So I've learned sadly a lot there needs to be read with as careful an eye as we are used to here. In case it is one of those topics. But I expect there is some brilliant stuff I'd hope from people who are real engineers who actually want to solve the problem and actually want to understand the causes and how they are best tackled (rather than a bit opportunist as an idea to 'change others behaviours/fortunes' etc - it's always behaviourists isn't it, never look at their own).

Pulling problem-children up/pointing it out where it crops up is very much something someone who wants things to be better and isn't 'anti-green' is doing and should do, as that type give the real ones a bad name and makes things actually being better without causing disadvantage that wasn't needed seem a harder and more uninviting job than it actually is
 
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Creekside said:
White metal roofs would not be much more expensive to install than asphalt shingles
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A good idea is to install a roof on top of the existing roof. As air is an excellent insulator.
I think that double roofing is a traditional practice in Portugal.
Then there is the duct dug into the ground in Provence, a source for a constant temperature of 11°.
We can already draw inspiration from what has been working for thousands of years in warmer regions.
 
Axel said:
A good idea is to install a roof on top of the existing roof.
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Maybe that's for uninsulated ceilings? Modern houses here have thick ceiling insulation--up to R60--so the roof is just to keep rain, birds, etc, from harming the insulation. A simple air layer is better than nothing, but air-trapping insulation is far better.

Axel said:
Then there is the duct dug into the ground in Provence, a source for a constant temperature of 11°.
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Geothermal heating/cooling. That cool air is only constant as long as you aren't drawing too much warm air through it. To be effective for a full summer, it needs a fairly expensive amount of buried duct, and mold can be a problem. Ground-sourced heat pumps might be cheaper in the long run.

Since my solar power system is presently too small to run a fridge, I use passive cooling (put containers of water outside in the evening, and in the morning swap out the ones in my insulated cooler). That kept my food <12C this summer. I now have pots of ice in their from the previous frosty morning. In all too short of a time, I'll have to switch to keeping food from freezing.
 
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