What is the difference between insulating a house and double wall insulation in thermos bottles? Couldn’t using that technology conserve energy?
In: Engineering
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Both are the same technology, still air conducts not really well. The problem with making your house as insulated as a thermos bottle is that the thermos bottle contents is sealed, there is no ventilation. This works for coffee, but not for humans.
I suppose is a matter of size, cost and resiliency. Materials used in house constructiom must withstand the elements, must support lots of weight and be cheap enough.
I bet the material used in thermos is expensive in large quantities, or doesn’t carry the same properties in another shape.
On top of that, houses have windows and doors, and what else, they’re hard to keep closed for that kind of isolation be effective.
Ok 2 things need to be addressed. 1 what is a thermos? 2 what makes a house different from a thermos? TLDR it’s mainly about cost and appeal to buyers for homes.
An original thermos (really old style, like 1970s) was a glass vessel wrapped in soft insulation then given a metal skin. An old style (like 1990s) was 2 plastic jackets, sealed together at the top,with insulation between. And a modern (like a yeti) is a skin of stainless steel shaped into an inner and an outer wall, sealed with a chemical tablet inside that then absorbs any moisture and air making a (relative) vacuum. So each of those designs works differently with the last only allowing heat to transfer out where the metal skin lets conduction happen, and please take my word that stainless actually kind of sucks at it compared to copper and other metals.
A house can’t be constructed like a really old thermos (because we won’t make houses out of just glass because cost, material strength, and efficiency) or a modern one (because cost of stainless steel is prohibitively expensive at that scale, isn’t pleasing to buyers, and would cost a lot to make it hold a vacuum while hammering and screwing all the protective siding and drywall pieces on) so construction companies and local and national housing authorities have decided that making a house more like a 1990s plastic thermos is the way to go, because having a cheap material for the walls and structure means building and selling the house are affordable, and we just fill it with insulation and call it good enough, and don’t complain about stapling, nailing or screwing into it because it generally doesn’t affect the efficiency of the insulation.
Ok 2 things need to be addressed. 1 what is a thermos? 2 what makes a house different from a thermos? TLDR it’s mainly about cost and appeal to buyers for homes.
An original thermos (really old style, like 1970s) was a glass vessel wrapped in soft insulation then given a metal skin. An old style (like 1990s) was 2 plastic jackets, sealed together at the top,with insulation between. And a modern (like a yeti) is a skin of stainless steel shaped into an inner and an outer wall, sealed with a chemical tablet inside that then absorbs any moisture and air making a (relative) vacuum. So each of those designs works differently with the last only allowing heat to transfer out where the metal skin lets conduction happen, and please take my word that stainless actually kind of sucks at it compared to copper and other metals.
A house can’t be constructed like a really old thermos (because we won’t make houses out of just glass because cost, material strength, and efficiency) or a modern one (because cost of stainless steel is prohibitively expensive at that scale, isn’t pleasing to buyers, and would cost a lot to make it hold a vacuum while hammering and screwing all the protective siding and drywall pieces on) so construction companies and local and national housing authorities have decided that making a house more like a 1990s plastic thermos is the way to go, because having a cheap material for the walls and structure means building and selling the house are affordable, and we just fill it with insulation and call it good enough, and don’t complain about stapling, nailing or screwing into it because it generally doesn’t affect the efficiency of the insulation.
A thermos works because there is no air (technically there’s a bit) between the two walls of the double wall. Heat needs a medium to conduct through, so if there’s nothing there except a vacuum, there’s nothing to conduct the heat. To do this in a house you’d have to pull a vacuum in the walls, roof, and floor of the house, and then seal it so air never leaks in. That’s way more difficult than using fiberglass.
You could, but the amount of money you would spend in vacuum insulation would be way more than the cost of the energy you would save.
There is also diminishing returns for insulation. After about 6” of typical home insulation the improvements of additional insulation could only be measured in a laboratory setting. In other words having exotic space aerogel or vacuum thermos insulation on your home would only preform a tiny bit better than 5-6” of stuff you can buy at Home Depot.
We actually do similar things with houses when it matters enough to justify the cost- double paned windows, for example.
Double walls in houses are actually a thing, in fact. https://www.finehomebuilding.com/project-guides/insulation/a-case-for-double-stud-walls
We already use it:
For Roofs (And sometimes walls) we use glass wool, which is better than air for that job.
For Windows, we use multiple layers with air pockets between them so the same principle.
Even for (classical) brick walls, we have small holes in the bricks them to use the same principle.
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