The thermal phase shift what is it ???

[Adrien (ex-nico239)]

So I do not really know what to think.

Take the analogy of the swell: the top of the wave is the daily peak of heat, the hollow is the minimum night temperature.
The phase shift is the speed of the wave.
The heat flow (hot or cold) flows through the wall at the speed of the wave.

To prevent the heat or the cold to pass is different (it is the lambda).

Ok, well ...

In thermal building, the thermal phase shift is the capacity of the materials composing the envelope of the house to slow heat transfer, including solar summer radiation. This thermal phase shift is particularly useful in summer to prevent the penetration of energy from solar radiation during the day and reject it at night.


Here again in the definition of wikipedia they only mention the summer radiation


It remains to know how to combine the two for my goal ...

[Adrien (ex-nico239)]

As we say ENERC, the title probably does not match what you're looking for. You have two distinct problems: holding back the heat and letting it pass. On the first point, it is the inertia which is to be sought, on the other, it is more complex according to the considered season: at the moment, it is easy: you open the orifices ...
This is the context in which your questioning is, if it is not indiscreet?

Yes you're absolutely right Ahmed I mislabeled the title but not easy.

The frame always the same (but it is on the wire agri) a search for material for vegetable chests.
So, preserve the best possible temperatures in a small, unheated place (especially in winter of course).
This has nothing to do with a house that is based in particular on the criterion (which I do not have to do) to preserve heat.

If I want to isolate I guess it must use the best lambda material will it keep me both hot and cold (which for the cold is annoying)

And in case there is 10h phase shift the chest never warms up.

This is where I am a little lost

Does a super lambda heat up but prevent it from cooling?

Does a short phase shift let in both hot and cold quickly?

We only find examples of phase shifts (all the time with hot) that praise the long periods: but I on the contrary that does not interest me.

It is necessary that the hot one returns quickly and slowly

And be careful there is no talk (addition) of adding material (water or other) to release (possibly) accumulated heat
We just focus on the materials of the trunk

Go make a title with that

[Adrien (ex-nico239)]

However, this phase shift may have a certain importance in very light constructions (eg MOB, inhabited attic) which will experience a relative peak of heat before they can be ventilated effectively.

Exactly this is the case with a wooden chest 4 double partitions with a window (for simplicity) from above.

What can I put in the double walls so that the inside of the chest warms up quickly but slowly cools down.

Among natural materials, after using straw (but losing a lot of its capacity when it is wet) I thought of sheep wool that can be easily purchased quite easily.

But as we can see, I still wade a lot

[Ahmed]

In short, you are looking for a thermal diode *! Because, in physics we can not distinguish the cold from the hot, since we can speak only of level of heat (even if, in practice, this way of perceiving the reality does not seem to me absurd and works pretty well).

* This exists in the greenhouse effect, for example, since the difference in wavelength between the initial and the reflected one makes it possible to retain the heat, by means of an ad hoc filter.

[Adrien (ex-nico239)]

In short, you are looking for a thermal diode *! Because, in physics we can not distinguish the cold from the hot, since we can speak only of level of heat (even if, in practice, this way of perceiving the reality does not seem to me absurd and works pretty well).

* This exists in the greenhouse effect, for example, since the difference in wavelength between the initial and the reflected one makes it possible to retain the heat, by means of an ad hoc filter.

And in practice (feasible) what gives?

[Ahmed]

I do not see an opaque insulation that can match what you're looking for ... It seems contradictory to me ...

[Remundo]

However, this phase shift may have a certain importance in very light constructions (eg MOB, inhabited attic) which will experience a relative peak of heat before they can be ventilated effectively.

Exactly this is the case with a wooden chest 4 double partitions with a window (for simplicity) from above.

What can I put in the double partitions so that the inside of the chest warms up quickly but slowly cools

you want to make a greenhouse, in this case forget the thermal wave ... your problem is to slow down the thermal conduction of the walls.

the ideal is air (better thermal insulation) and also aluminum films to block the output of infrared rays.

also think to cover the glass wall at night, with an aluminum film + foam thickness over it. Avoid drafts around the box.

There are thin insulation multilayer foam / aluminum: https://www.castorama.fr/isolant-mince- ... lsrc=aw.ds

[Adrien (ex-nico239)]

I do not see an opaque insulation that can match what you're looking for ... It seems contradictory to me ...

So I'm not looking for an insulator for the chassis: there I am constrained by the existing (or the costs): it is P30 (for example) + greenhouse cover.

But an insulating structure for the walls: currently wood and straw.

I will test wood and sheep wool.

I was also told about polyurethane which would be nice too.


But it does not prevent that even if the empirical it is well I would like a little to understand the technical processes of the trick.

lambda high or low?
allied to a
significant phase shift or not?

[A.D. 44]

I still do not really understand what you want to do ...

A chassis, a greenhouse ???

I have the feeling that your heat stock will be that of the earth, right? Once this one heated the day under the trunk by greenhouse effect, it is then necessary to slow the thermal exchanges with the surrounding air but also and especially with the surrounding cold land which it was not heated under the trunk.

You have to find a way to isolate not only the trunk itself, but also the deep ground on the periphery of your frame, cork plate (or extruded poly or other ...) descending vertically in the ground in line with walls of your chest ...

A small diagram, or a sketch even freehand of your project?

[Adrien (ex-nico239)]

However, this phase shift may have a certain importance in very light constructions (eg MOB, inhabited attic) which will experience a relative peak of heat before they can be ventilated effectively.

Exactly this is the case with a wooden chest 4 double partitions with a window (for simplicity) from above.

What can I put in the double partitions so that the inside of the chest warms up quickly but slowly cools

you want to make a greenhouse, in this case forget the thermal wave ... your problem is to slow down the thermal conduction of the walls.

the ideal is air (better thermal insulation) and also aluminum films to block the output of infrared rays.

also think to cover the glass wall at night, with an aluminum film + foam thickness over it. Avoid drafts around the box.

There are thin insulation multilayer foam / aluminum: https://www.castorama.fr/isolant-mince- ... lsrc=aw.ds

Ah, you have preceded my previous answer ....

So to slow the conduction of the walls ... that is to say?

If it's braking the cold entrance yes
If it's braking the entry of the hot no
If it's braking the exit of the hot no
If it's braking the exit from the cold no

Do you see the problem?

But maybe it's impossible?

For the aluminum Didier had spoken to me and I agree entirely that it is the ideal.
But in practice for the moment for me I first thought that it was impossible to use the chests must remain closed during the day because of the cold.
And so the alu be removed in the morning.
So impossible to include in the construction of the chassis.
The only solution would be to make a chassis cover which is quite different.
But in this case would it play its role?

If yes it's him who, choosing the right thickness, could play the role of doormat that you describe, knowing that under him there would not be a glass but (for example) 4 layers of P30 taken in a greenhouse cover (top - bottom).

If despite this "filter" the aluminum still plays its role then it can do it.

For the air however I do not understand well.
This would mean that the 6cm partitions would be more insulating empty (knowing that one should not rely on a total waterproofness of these partitions that are made of wood by me) that with straw, sheep wool or polyurethane?