Biomimicry insulation

Discussions on the interactions between components of the environment and their effects on all types of organisms.

Biomimicry insulation

Postby zetreque on June 10th, 2014, 11:57 pm 

I was thinking about posting this in my house building thread here http://www.sciencechatforum.com/viewtopic.php?f=23&t=26323, but I think it deserves a new thread.

I was reading a book about arctic animals today, and also how arctic human inhabitants dress in layers which made me think about biomimicry for building. Good insulation has pockets of air inside of it, and it does no good to compress insulation material you put in the walls of your house because it just makes it more solid for heat and sound transfer.

I want to build my house out of concrete/rock, and I was thinking how it can act as a thermal mass (that's what rocks and bodies of water do), but it also transfers heat. So even though it works good as a thermal mass to not cool or heat as fast, and have a more stable temperature within the house, it is still lacking on insulation technology.

Coffee and hot drink/soup thermoses use the concept of air, and high tech containers for storing liquid nitrogen and whatnot use a vacuum barrier. Air is a poor conductor of heat and sound, and a true vacuum or no air will not transfer heat or sound

Where biomimicry comes in, animals use this concept in their tissues but also that's why hair helps. Not only does hair gain energy out of the wind by moving in the wind, but it also creates air pockets....

So why don't we see hairy houses in cold climates?

This works in hot climates too. In the place I currently live, I do something like this. I have an overhang outside of my front door, and I hung a large bamboo window blind on it. When it gets hot in the summer I drop the window blind down over the front of the house and the sun beats on it instead of the house. There is that air pocket in between the blind and the house. I swear this keeps my house about 10 degrees cooler than otherwise just by this one window blind over a part of the house that gets afternoon sun!!! Ever since I started doing that a few years ago I no longer run fans in the house during the summer.

I still want to build out of concrete, but if the siding we put on our houses was away from the house by several inches, or even a second wall open to the atmosphere. This would reduce heating and cooling bills heaps. I also think of it as how heat sinks work. Computer, engine/motor, and other heat sinks have fins or blades all over them. This increases surface area to help cooling these conducting materials. Well, large surface area also increases air pockets and shadows to keep the direct sun from absorbing.

Would be interesting to experiment with siding materials that have rough, porous, high surface area, exteriors and how well they insulate a house against heat from the sun, or the cold air in winter.

If you are living in a house in a hot climate, and one or more of your walls gets direct sunlight, I think you should try experimenting by creating some sort of extra layer with air between it and the wall, then post back on this thread. :)

Imagine how much energy/money we could be saving by implementing a simple concept like this. It seems only recently buildings are starting to use white roof tops. Go figure!

My dad painted all his tools white that he used on construction job sites that lay out in the sun all day while working, and he was the only one ever to have metal tools he could leave out and grab without burning his hands. You still don't really see tools for sale in hardware stores painted white. What is wrong with the world? lol

Anyone else have any thoughts on this idea?
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Re: Biomimicry insulation

Postby Braininvat on June 11th, 2014, 10:25 am 

In a sense, fiberglass insulation has a kind of "hairy" quality. Rather like plastic hair, with many air pockets in the material. The loose stuff they blow into unfinished attics is put in that way so that it lands in uncompressed fluffy piles. Again, more air pockets. As I understand it, the key is to have good vapor barriers so that moisture doesn't get into the piles and compress them.

For siding, seems like more "foamy" materials would give you more R-value...maybe a concrete or stucco that approaches a more pumice-like consistency (but not so light that it's easily damaged), with more air pockets in it?
Cinder blocks have an interior cavity, which would be somewhat helpful, esp. if you fill those spaces with insulation.

A layer of air, by itself, doesn't have as much R value because the air will have currents and also there is more radiative heat loss across the gap. That's why old houses, with just air between int. and ext. walls, tend to be chilly. You need "hair" - an insulating material with lots of tiny air pockets in it.

The subject is of interest to me, as well, because I will soon be renovating an old house in the Black Hills. Insulation is fairly important in South Dakota. Hope you will keep us posted on how it goes with your proposed house.
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Re: Biomimicry insulation

Postby zetreque on June 11th, 2014, 2:13 pm 

Braininvat:

Do you think that having an air pocket material along the surface of the building would be better than say a window blind hung about 5 inches from the surface?

In the case of heat, it seems like the air blowing through that void cools the outter blind, and will only heat the inner surface to the temperature of the air. The void, or complete air pocket between them would prevent transfer of heat through the material since air is a much more poor conductor than materials.

After writing that last night I was thinking of some sort of moss or sponge material put onto a house. Like lichen or moss. Not only good insulation, but good camouflage.

Like you said water is very important though. Evaporation cools on the good side, but also the dampness causes mold, decomposition, and compressing them or making them more dense like you said. I think there are more downsides, so we would want to keep water out. Plants have a natural waterproofing on leaves..... not just vapor barrier, but leaves create a lot of air pockets and micro-climates. We need houses with, hair, tree limbs and leaves :)
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Re: Biomimicry insulation

Postby Braininvat on June 12th, 2014, 4:51 pm 

Do you think that having an air pocket material along the surface of the building would be better than say a window blind hung about 5 inches from the surface?



Not sure. Maybe depends on the overall strategy for cooling - I can see the use of the Roman shade (I think that's the word for an exterior window blind), so the sun is striking something that has some separation from your walls. I hope someone else, with more experience of this, will chime in.

In the winter, stacking cats on yourself is quite warming.
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Re: Biomimicry insulation

Postby zetreque on June 12th, 2014, 5:16 pm 

I am curious if maximizing the number of different air pockets or macroclimates.. microclimates? while minimizing the solid/conductive material that makes up the framework of those pockets/climates increases insulation.

There is probably a magic number where you don't want too many air pockets, or too few air pockets.

Also curious about the difference for heating insulation vs cooling insulation. It gets tricky when you add the sun shining onto your wall/roof into the mix. In the winter you want the most conductivity for that heat, while in the summer you want the least.

That's where these air pockets seem interesting. Maybe they work as insulation in both situations.
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Re: Biomimicry insulation

Postby zetreque on July 22nd, 2015, 4:26 pm 

Still wondering about how to maximize air pockets for the ultimate insulation.
It looks to me like this company insulshell's main advantage is how perfect they cut the blocks of insulation to fit between the frame. They also appear to overlap pieces in such a way to prevent conduction through the most conductive materials like screws and brackets.
https://youtu.be/d7ByGnJcyQY?t=1m31s

I also want to make note in this thread of a related thread. viewtopic.php?f=128&t=15877&p=284619#p284619
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