Thread: Insulating homes from heat n the future?

I'm working on a sci-fi story set in the distant future where the average daily temperature ranges from 100-120 degrees F. The idea is to have most outdoor activity occur at night, when temps are lowest, with people staying indoors during the day.

Is there a way of existing indoors without A/C when its 120 degrees outside, such as unique building/insulation techniques, building into the earth (presumably cooler). Obviously, it's possible to cool off a home at night (down to 100 degrees) simply by opening the windows, but can I hold that temperature indoors until the next night? I'd like it to be marginably realistic but my knowledge in this area is marginable at best.

If appropriate, please let me know if there is a forum where I should cross-post to (where they won't get annoyed by a sci-fi question).

Thanks.
D

Underground homes in Coober Pedy in devastatingly hot (and freezing cold at night) outback desert South Australia hold a steady temperature year round.

Other forms of building earth covered buildings have had similar success. Green roofs are a less extreme version of these.

In Tunisia (and other regions near the Sahara desert), they have building painted white with a half-spherical shape : the idea is to reflect as much sun radiations as possible.

Traditional colonial buildings in Carabinean regions, for instance, seem fresh : permanent natural ventilation, large volumes of rooms, an open and shadowed patio is build in the center of the house with plants, trees and fresh water (fonts, pools, dousing ...). A very pleasant architecture.

Perhaps worth noting that, from the point of view of insulation, keeping the house cool in a hot environment is exactly the same problem as keeping it warm in a cold environment.

But I agree that fully/partly underground is the best idea.

thanks again
last question if I may. since I need to accommodate millions of people. would it work to build my buildings underground? such as apt buildings built deep into the earth? I'm imagining buildings below ground with a simple white dome at the surface entrance and exit. im trying to compare this to inventing some fancy building materials and windows that reflect heat.



p.s. android tab 2 is really bad with this site.
Dirk

im trying to compare this to inventing some fancy building materials and windows that reflect heat.

Mylar is a very good material that could be used easily and is cheap to reflect away sunlight. You could also put it on rooftops using shingles with it on the surface but remember that when it gets cold you can't remove those tiles so it will not be helpful in getting the dwelling warm.
mylar - Google Search

ast question if I may. since I need to accommodate millions of people. would it work to build my buildings underground? such as apt buildings built deep into the earth? I'm imagining buildings below ground with a simple white dome at the surface entrance and exit.

You don't need to be more than a couple of metres deep in the right kind of rock to start with. Once you go really big, there are all sorts of issues with ventilation, mildew and other hygiene management as well as the serious issue of fire suppression/ fighting, but so long as the entrance/exit points are large enough and properly designed to act as sufficient buffers to ensure that none of the outside heated air ever gets in without adjustment to the set inside temperature, you'd be OK. (I might add that the fire/flood issue is the one that gives me most concern.)

From the other forum members (thank you, btw), there seem to be some practical problems with creating large buildings underground. What about insulating large buildings from heat above ground? Obviously, we get a lot heat (and cold) through windows, but I wouldn't be surprised if some heat enters buildings through outside building materials (porous brick or cement?)

Naturally, there is also the problem of getting fresh air in and carbon dioxide out.

thanks again,
Dirk

Originally Posted by dbaezner

From the other forum members (thank you, btw), there seem to be some practical problems with creating large buildings underground. What about insulating large buildings from heat above ground? Obviously, we get a lot heat (and cold) through windows, but I wouldn't be surprised if some heat enters buildings through outside building materials (porous brick or cement?)

Naturally, there is also the problem of getting fresh air in and carbon dioxide out.

thanks again,
Dirk

Hi Dirk, I having been giving your post some though and some ideas and questions spring to mind, my first thought was that to reduce your internal temperatures with outside levels at 120 you really are going to need some sort of internal air conditioning, but you kind of rule this out. So ok there are other ways to go about this but here I have a few questions about whether you are ruling out all types of inter cooling or just the standard types of A/C units, is that you are seeking a way of keeping internal temperatures down without the use of say? I can probarbly give you are few inervative suggestions if we can narrow down a little your requirements. Also it may be useful to know how the high external temperatures are being generated, one would assume through extremely long periods of direct sunlight, I only ask because this makes a difference about possible ways to reflect solar radiation and heat from residential structures.

Just off the top of my head I think what is probarbly called for is buildings with as few angles as possible, either white heat resistant ceramic tiles, mirrorised surfaces or solar panels on every surface, possibly dome shaped, but with flush fittings for windows and doors, basically trying to limit anywhere heat could build up externally. Obviously internally the more insulation the better, but possibly also some like a series of tubes or pipe work within the walls to act as a giant refrigeration system to draw heat away from the air, people and objects inside. Also a heat sink to bleed off heat and possibly an evaporation and extraction system, this would use water to enter the air absorb heat and then be collected and expelled, again though some of this technology will very much depend on whether up not you are wanting to use a powered system or not.

Another thing to consider is that, depending on how far in the future it is, people in that environment may have developed biological adaptations to help them tolerate the heat better.

Originally Posted by Alec Bing

Another thing to consider is that, depending on how far in the future it is, people in that environment may have developed biological adaptations to help them tolerate the heat better.

Yes, thanks to McDonalds and the Big Gulp.

Wow! Great feedback so far. Thank you.

I'm trying to come up with multistory dwellings (for a very large population) that can be kept down to about 100 degrees (the average nightly low temperature) with minimal use of electricity (global warming -> can't burn fossil fuels anymore -> electricity is a luxury most can barely afford, etc.). Time period is about 4000 AD/CE. Daytime temps rise to an average of 120 degrees. It's possible to cool off homes at night (down to 100 degrees) by simply opening the windows. The question is how do I keep most of that "cool" air inside while the outside daytime temp rises to about 120 degrees.

I suppose by then, solar technology will be sufficiently advanced to coat every building (sides and rooftops) with solar panels. I'm not sure if that will generate enough electricity for all of the residents in a building to run fans, A/C, fridges, lights, etc. Obviously, I can also put wind turbines on every rooftop as well.

I'm also assuming a much larger population than today (many more billions), so land is at a premium making solar/wind farms much more expensive and, therefore, less cost-effective. Naturally, if demand outweighs supply, the price goes up, hence electricity becomes a luxury that can't be wasted. Or so the reasoning goes.

Also, what do I do about windows? Is there a type of glass (I have no clue here) that keeps heat out and cooler air in? Or should I assume much smaller/fewer windows as well? Would white mini-blinds help? :-)

Hope that helps.
Thanks again
Dirk

I almost forgot. Smog is rampant above big cities. Pretty much a permanent fixture, so solar panels will be far less effective.

Might be tempted to go the other direction from those suggested. Build the house high off the ground, on sturdy stilts for example with reflective roofs, good insulation and enough thermal mass to hold temperatures near the early morning minimums (average lowest temperature is usually soon after sunrise).

And all this implies a dry place-- with temperatures range between 100-120F daily, the wet-bulb will be more important than temperature to determine if people can survive outside.

Windcatchers and Yakhchals come to mind. Windcatcher - Wikipedia, the free encyclopedia Yakhchal - Wikipedia, the free encyclopedia

Come to think of it, you might find some interesting leads if you were to look into the vernacular architecture of desert communities. For example, many of the older Middle-Eastern cities traditionally constructed tall buildings close to one another because it shaded the cities from the sun.

with minimal use of electricity (global warming -> can't burn fossil fuels anymore -> electricity is a luxury most can barely afford, etc.). Time period is about 4000 AD/CE. Daytime temps rise to an average of 120 degrees. It's possible to cool off homes at night (down to 100 degrees) by simply opening the windows. The question is how do I keep most of that "cool" air inside while the outside daytime temp rises to about 120 degrees.

I'd be a bit disappointed in the progress of engineering if electricity weren't being generated for near nothing after 2000+ years of development of solar collection and associated storage technologies. Let alone wind, tidal and geothermal. And there's no way of knowing how many new technologies can be developed in each thousand years that follow us.

As for structural features of such buildings, there are the wide verandahs of Australian homesteads, the traditional Queenslander on stilts, tropical and desert palaces, the internal courtyards of the Mediterranean region, the arches and thick adobe walls of the southwest of North America. I'd say your biggest design issue would be how to manage airflows within and between multiple residences within large buildings.

Some of these might give you some ideas. Energy Efficient Buildings You'll need to track down the full technical details of each one. CH2 is pretty impressive going from memory.
And something along these lines might work in some areas. Cliff dwelling - Wikipedia, the free encyclopedia

Had an idea about a building that stands in pool of water, with large air vents that draw air into the building through large pipes that take the air through the water, thus cooling it down, this air then replaces the warmer air in the building which rises and exits through roof vents. The warm air exiting the building creates less air pressure in the building effectively taking heat with it outwards and then vacuum effect would help 'suck' in fresh, water cooled, air from outside helping to absorb more heat and lower the internal termpertures. Since warm air rises natually then it shouldn't require pumping out of the building, so it should all work without requiring any power.

Ascended, you would make Isaac Asimov proud.

Ascended, I was trying to think of where I saw a report of someone doing something similar in an ordinary house. The basic idea is that you have a cool, moist greenhouse on one side of the house. The surprising feature was that you cooled the house by lighting a fire in a fireplace on the other side of the house. I presume this fire would be set a bit higher than your normal warm-the-room fire. You basically set up a draught which took warmed air up a chimney and the only available source of replacement air came from your cool, moist room - and that air had to travel through the house to get to the exit point. So all the air in the house would move towards the heated chimney and be replaced by more comfortable air.

All very wonderful if you live in the country with your own wood supply. Not very useful for dbaezner's multiple housing units in large buildings - though having balconies (miniature greenhouses) covered in cooling greenery would be a useful component for some designs.

Originally Posted by dbaezner

Ascended, you would make Isaac Asimov proud.

Cheers Dirk, I enjoy a good ego stroking as much as the next person but that is compliment of a very high magnitude indeed.

Originally Posted by adelady

Ascended, I was trying to think of where I saw a report of someone doing something similar in an ordinary house. The basic idea is that you have a cool, moist greenhouse on one side of the house. The surprising feature was that you cooled the house by lighting a fire in a fireplace on the other side of the house. I presume this fire would be set a bit higher than your normal warm-the-room fire. You basically set up a draught which took warmed air up a chimney and the only available source of replacement air came from your cool, moist room - and that air had to travel through the house to get to the exit point. So all the air in the house would move towards the heated chimney and be replaced by more comfortable air.

All very wonderful if you live in the country with your own wood supply. Not very useful for dbaezner's multiple housing units in large buildings - though having balconies (miniature greenhouses) covered in cooling greenery would be a useful component for some designs.

Just curious was it is that would keep a greenhouse cooler than normal wood/brick/insulation materials in other parts of the house?

Thanks.
D

A properly set up greenhouse - not a glasshouse, though you can also use those to warm a house - is a cool, shady, moist environment. Suitable for growing ferns and similar forest floor plants that thrive in a consistently moist, cool environment where the temperature changes very little throughout the day.

It usually has a gravel, or similarly porous, moisture retaining floor and, if you're sensible, a method for both drip and spray watering. Some people set up pools for more evaporation and to collect drips or add in small, constantly recirculating fountains to imitate the natural, high humidity, almost dripping, environment of many rainforests - though the important feature is the constant, consistent moisture of the soil.

Largish verandahs and small shaded courtyards on a suitable side of a house can function as a de facto greenhouse if they're well protected from winds and crowded with well-watered plants. The important question is whether the design of the house allows free flow of that cooler air into other areas without promoting the incursion of hot air. Sometimes it's enough to just cool one or two rooms right next to that external area.

I can't find anything online about this, but there used to be a common practice in some Australian outback areas of building a an attached or completely separate "cool room". It was made with brush fencing walls to full height and a drip system running around the top of those walls. The constant evaporation cooled the air inside the 'room'. (Of course this was done only in areas with a supply of non-potable bore water. No one would ever be mad enough to do this with rainwater from a tank in areas where you never know when the next rainfall would be.)

I think I'm missing something. In a hot environment (e.g., 120 degrees), wouldn't the sun bake the plants in the greenhouse? In that case, evaporating water would make for moist heat (New York City!). How does the air get cooled under those conditions? I vaguely recall certain types of glass reflect heat - is that part of this?

Greenhouses. are. not. glasshouses.

Greenhouse design and maintenance is about excluding sunlight, cool temperatures, and keeping very high humidity. Greenhouses may use some glass in their construction but it's not necessary and in some places it's totally counterproductive.

Glasshouses are designed both to maximise and to control effective sunlight reaching plants, keeping temperatures warmer than, or much the same as, the surroundings and keeping air circulating. Most plants grown in glasshouses are susceptible to moulds, mildews and insects which like the warm, moist conditions.

If you're trying to grow lettuces and ferns in the same place, one (or maybe both) of them is in the wrong place.

Though of course this conversation is probably people from different latitudes/ environments talking at cross-purposes. I live in a hot, arid place where glasshouses are used to grow tomatoes and other foods year round - but they need strong controls to stop the plants inside from being scorched in hot weather. The old-fashioned method was to whitewash the roof once the outside temperatures rose and it would gradually flake and wash off before the cold weather returned. Modern glasshouses use retractable shadecloth and the like for the same result.

Remember, in most of Australia we get too many sunlight hours for growing traditional vegetables in the traditional ways out in the open. It's more sensible in Australia to plant cabbages, broccoli, kale much closer than elsewhere to protect the soil from overheating by allowing the plants themselves to shade it and to maintain soil moisture more consistently.

Thank you, all. Lots of great ideas. I'll post back with whatever I finally decide.

D

Originally Posted by Ascended

Had an idea about a building that stands in pool of water, with large air vents that draw air into the building through large pipes that take the air through the water, thus cooling it down, this air then replaces the warmer air in the building which rises and exits through roof vents. The warm air exiting the building creates less air pressure in the building effectively taking heat with it outwards and then vacuum effect would help 'suck' in fresh, water cooled, air from outside helping to absorb more heat and lower the internal termpertures. Since warm air rises natually then it shouldn't require pumping out of the building, so it should all work without requiring any power.

In a hot place through, you'd probably want to heat exchange from that moist web-bulb cooled air with relatively dry air so you end up with dry cool air entering the house.

Originally Posted by Lynx_Fox

Originally Posted by Ascended

Had an idea about a building that stands in pool of water, with large air vents that draw air into the building through large pipes that take the air through the water, thus cooling it down, this air then replaces the warmer air in the building which rises and exits through roof vents. The warm air exiting the building creates less air pressure in the building effectively taking heat with it outwards and then vacuum effect would help 'suck' in fresh, water cooled, air from outside helping to absorb more heat and lower the internal termpertures. Since warm air rises natually then it shouldn't require pumping out of the building, so it should all work without requiring any power.

In a hot place through, you'd probably want to heat exchange from that moist web-bulb cooled air with relatively dry air so you end up with dry cool air entering the house.

Yeah many of the new, well designed, office buildings use really good air exchange systems to help with temperature control. They tend to work really well with taller buildings as the hot air rises and can exit buildings on or near the top whilst the cooler air is drawn in nearer the bottom. The idea of the water because in the given scenario the air outside was pretty hot, so even at ground level it would still need cooling down before entering the building, and this was a way of doing it using water which is very good at absorbing heat using the natural, non powered, air flow cycle.