Rebuilding outer leaf

[SteamyTea]

Insulation can be thought of as reducing air movement.

The material that the insulation is made from does not make a huge difference, it is picked for its mechanical properties, not it's insulating characteristics. 

 

In reality, well Physics, thermal conductivity is much more complicated and depends on the material's phases and structures.

 

Using

7 hours ago, saveasteading said:

Woozle

as a model, you can think of these little Gnomes (how I see them) passing buckets of heat to one another.  They initially pass them in any direction they like (radiative scattering), but eventually realise to be of any use, they have to take the most efficient path, which is the thermal gradient. Downhill for cooling, uphill for heating.

The shorter the path, the steeper the gradient is, so the Gnomes can pass buckets faster to each other.

[saveasteading]

19 minutes ago, SteamyTea said:

passing buckets of heat to one another. 

I like the buckets analogy. 

Struggling with the hill though. Isn't heating or cooling the same process of bucket passing? Downhill for poor insulation, uphill for good?

 

21 minutes ago, SteamyTea said:

it is picked for its mechanical properties, not it's insulating characteristics.

You mean that it can be woven from rock or glass or paper or oil, but the gas or air bubbles and maze of conductive routes are what matters?

[SteamyTea]

6 minutes ago, saveasteading said:

I like the buckets analogy

Thank you.  I could refine it a bit more and say they transfer the contents between buckets. That is closer to what is happening in the quantum realm (photons and electrons swapping over).

 

10 minutes ago, saveasteading said:

Isn't heating or cooling the same process of bucket passing

It is, except that as things get hotter, they radiate more energy, so heating up, past a certain point, gets rapidly harder and harder. For the same building, the heating and the cooling curves will be different.

 

13 minutes ago, saveasteading said:

You mean that it can be woven from rock or glass or paper or oil, but the gas or air bubbles and maze of conductive routes are what matters

Yes.

If you look up the densities of all the materials that make up the 'insulation', you will find that the solid part is quite a small fraction of the overall mass.

 

I used to have a spreadsheet of material properties (Kaye and Laby, NPL) that was useful for picking desired mechanical properties out.