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Instead of relying solely on air conditioning, which often adds to greenhouse gas emissions if run on fossil power, there are a number of passive solar design s
by 35mm 4y ago
Instead of relying solely on air conditioning, which often adds to greenhouse gas emissions if run on fossil power, there are a number of passive solar design strategies that work without additional energy:
- Solar chimneys draw cool air in when it’s sunny via pressure differential
- Building orientation along with natural shading from deciduous trees prevent excessive solar insolation heating the building
- Building on top of a thermal slab to provide enough thermal inertia to prevent excessive heat during the day
I wrote more details on this on my blog: https://uplevelgreen.com/passive-solar-cooling-in-hot-humid-climates/ https://uplevelgreen.com/passive-solar-cooling-in-hot-humid-...
- MomoXenosaga 4y agoThere is nothing worse than spending a heatwave in one of those valleys of concrete and glass we call "office towers".
- hdjjhhvvhga 4y agoYeah, and everybody turns AC to maximum, we have record energy consumption for each heatwave, whereas at home I feel more comfortable with just a big fan.
- the8472 4y ago- paint that has high emissivity in the IR window and high reflectivity in the rest of the spectrum. - thermochromic windows
- 4gotunameagain 4y ago> - paint that has high emissivity in the IR window and high reflectivity in the rest of the spectrum. Does such thing exist? And, doesn't high emissivity in the IR mean high IR absorption as well ?
- the8472 4y agoIt's a fairly recent development[0], a few years before that the principle was demonstrated as a special surface coating on smooth surfaces rather than paint. And it's about the IR window[1], which is smaller than the whole IR spectrum. And sunlight delivers most of its energy in visible light and near IR, so there isn't a problem with reflecting the incoming light while radiating away into cold space in the IR window[2]. [0] https://ceramics.org/ceramic-tech-today/materials-innovations/new-reflecting-paint-achieves-full-daytime-sub-ambient-radiative-cooling https://ceramics.org/ceramic-tech-today/materials-innovation... [1] https://en.wikipedia.org/wiki/Infrared_window https://en.wikipedia.org/wiki/Infrared_window [2] https://www.researchgate.net/figure/Illustration-showing-desired-low-absorptivity-over-Solar-Spectrum-relative-to-desired_fig10_326902771 https://www.researchgate.net/figure/Illustration-showing-des...
- ekianjo 4y ago> - paint that has high emissivity in the IR window and high reflectivity in the rest of the spectrum. paint is not free and needs replacement every few years. hardly a solution.
- rowanajmarshall 4y agoNo solution is free and needs no replacement.
- sschueller 4y agoThe surface finish of walls may also make a difference. Rough vs smooth and something like that doesn't fade as quick as paint itself.
- hutzlibu 4y agoSo you are looking for a free magic solution? I mean, I like houses made from big stones but it is probably cheaper to paint an existing house, instead of tearing it down and replacing with stonewalls.
- ekianjo 4y agoProbkem is that it does not scale globally if you can only rely on short term efficacy
- anthropodie 4y agoAlso I think this needs to be deployed an large scale. It uses passive radiative cooling http://skycoolsystems.com/ http://skycoolsystems.com/
- sschueller 4y agoSomehow this has been lost over the years. I can especially see this in Zürich Switzerland where new office buildings being built are awful and there seems little thinking about temperature. Everything is managed by complex air systems to move air from one area to the other. On the other hand you go into a 200+ year old building and you notice it's cool in summer although there is no air conditioning. The building is positioned in such a way that it stays cool for the most of the day, the walls and windows are placed to optimized for this. It's not 100% but if you added a cooling system you would have a perfect setup. We rely to much on technology to build these ugly boxes instead of also considering the building shape and position itself.
- KingOfCoders 4y agoI would assume it's mostly the thicker walls, at least it was this case in Berlin with older buildings staying cool for a long time because it took months to heat the walls. Then those walls were warm in winter and it took months to cool them down (though it didn't work very well in the last very hot summers that were hot early on)
- theobeers 4y agoThis is still sometimes done. The newest section of the Freie Universität Berlin campus (the “Holzlaube”) was built so that the inside remains comfortable with no A/C and minimal heating. Thick walls, as you said. I don’t know how applicable architectural cleverness will be in densely populated cities in the developing world that are threatened by global warming. That seems like an impossible situation.
- KingOfCoders 4y agoMany parts of the world the outside will be unhabitable :-(
- bsedlm 4y agomaybe i'm squinting too hard, but I see this as related to a more general attitude of imposing our will while disregarding what is already there. "why would we want to position the building according to where it is? specially when there's an alternative of putting it however we like, and then involving a sophisticated air system which will isolate the building from it's environment (which is going to shit anyways) and also, think of all the jobs, the infrastructure, electricity, generators, coal-mining, ac technicians, etc that come with an AC based building! if the building, just by virtue of where it is, can do without all this then the economy will shrink, we cannot have that."
- zrail 4y agoHow much do these things work when the wet bulb temperature is over 90F?
- baybal2 4y ago
- OccamsRazr 4y agoThis would be my concern too. People fail to understand how in heatwaves there ceases to be cold air to move around. Everything heats up. It's brutal.
- kibwen 4y agoAt that point you need to put your heat exchanger pipes underground, which is more annoying than air-based AC but not insurmountable. The temperature 20 feet underground will be about 50 F year-round. Of course, if a city of millions tried to do this all at once I have no idea how the local ground temperature would react.
- TheCoelacanth 4y ago> 20 feet underground will be about 50 F year-round Is that the case in India? I was under the impression that while underground temperature is consistent across seasons, it does vary considerably across climates, with warmer climates generally having higher underground temperatures. For example, while much of the central US has underground temperatures around 50F, southern Florida, California and Arizona have areas with temperatures in the upper-70s[1]. [1] https://www.builditsolar.com/Projects/Cooling/EarthTemperatures.htm https://www.builditsolar.com/Projects/Cooling/EarthTemperatu...
- kibwen 4y agoI can believe the ground temperature is higher nearer to the equator. At the same time, you don't need the ground temperature to be very low, just low enough for the heat exchanger to function. Alternatively, you can dig deeper until you hit a lower temperature.
- pseudostem 4y agoI deployed my own design (not calculated, eyeballed) of a buoyancy based passive cooling at my parents home near Mumbai, India. It did make a measured difference of approximately (temperature meters aren't very accurate) 2 degrees Celsius. I have been reading a lot in my spare time and your blog looks like a nice read. My point is, is 2 to 3 degrees Celsius enough? From what I read is that I need to really move very large columns of air to make a sizeable impact. TBF my energy bills did come down by ~10%
- dgellow 4y agoI’m not that familiar with hot temperatures but intuitively I would think that a difference of 2-3 degrees (Celsius) when temperatures are already high at around 40-45 to be noticeable. For example if you go from 40°C to 37-38 that’s a quite good improvement if you don’t have to spend energy for this. I don’t know if that also applies to more extreme temperatures like 47°C, I cannot really imagine how that feels like.
- ianai 4y agoAt those temperatures heat stroke isn’t far away regardless of humidity. These aren’t temperatures to target 2-3c reductions as a safe goal, either. Ref: lived in LV,NV for a decade.
- dgellow 4y agoFrom what I understood 2-3°C is not a safe goal but something you can get from the passive cooling solution the initial commenter mentioned. I would guess you can add extra active measures on top?
- ianai 4y agoAt some point the thing to do is give people shovels and tell them the roof of their new dwelling has to be at least 2 meters/6 feet below the surface. Or use modern tech.
- 4y ago
- th3iedkid 4y agoVery good ideas but as far as India goes, adoption might have to consider monsoon, winter-snow in some, which again might require more tweaks based on more tests. Another aspect is how real-estate and building construction works in India, across rural and urban regions.Some of the regions have strong clouts of companies that control building/development in urban spaces, while supplies and other aspects in rural region. Can see the realties changing and newer construction projects taking in newer & greener designs, in both urban and rural regions, but its got a long way to go!
- drieddust 4y agoThanks for the excellent resource. A big part of this problem is self inflicted. We used to have thick mud walled houses which stayed cool during scorching heat. People who could afford would go with stone constructions. Things such as sun and wind direction were also considered while constructing the houses. All that knowledge is discarded in favour of high rising concrete jungles. But all that is replaced with concrete based constructions with almost no insulations. This makes inside even more uncomfortable than outside once the wall have absorbed heat. Commercial construction is even worse with lots of glass.
- ricardobayes 4y agoSpanish houses are made of ventilated brick without insulation so they stay really nice even when outside temps are touching 40C. Of course the price to pay is it's 'freezing' between Jan-March.