The thermal phase shift what is it ???

[Adrien (ex-nico239)]

It must be the vacation period but I can not pick what exactly the thermal phase shift (probably because I want to use it in reverse of its most common use ...)

So as I know there are experts here I ask the question: what is the thermal phase shift?

[A.D. 44]

Hello,

https://conseils-thermiques.org/contenu ... hasage.php

Here is something to see more clearly.

[Adrien (ex-nico239)]

Thank you I have not consulted the net but they do not speak exclusively of phase shift to prevent the heat to enter the house in the summer.

But it's the opposite that interests me
- store (let in) heat during the day
- leave it out as little as possible at night

So I do not really know what to think.

I have to look for the material that has the least good coefficient of phase shift?
MAIS
The best lambda?

[A.D. 44]

You seek to store the daytime heat to restore it in the evening and at night!

This is the principle of inertia in a building, combined with good insulation it allows to smooth the yoyo temperature and provides optimal heating in winter.

[Adrien (ex-nico239)]

You seek to store the daytime heat to restore it in the evening and at night!

This is the principle of inertia in a building, combined with good insulation it allows to smooth the yoyo temperature and provides optimal heating in winter.

Yes it would be ideal ....

Or if the heat is welcome during the day and it escapes as little as possible at night.

But most subjects on the net deal with the phase shift in terms of protection against heat, especially in summer
https://fr.wikipedia.org/wiki/D%C3%A9phasage_thermique

[ENERC]

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).

[Remundo]

well, it takes a lot of mathematical skills to explain it all, but I will try to make it understandable.

A wall, or the ground, undergoes a sinusoidal evolution of temperature, between Tmin and Tmax and over a period equal to one day.

The temperature is instantly transmitted to the exposed solid surface, but not instantly in depth
* first the thermal wave is attenuated, far below the floor, there is almost no temperature variation (eg 10 ° C constant, a little variable depending on the region, but typical in France, deep cellar temperature)
* then: phase shift This is the time that the wave propagates to a certain depth. Thus the peak temperature on the surface takes time to propagate in depth.

to be more precise: look for courses on thermal diffusion - thermal wave.

[Ahmed]

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?

[A.D. 44]

In very big ... To summarize very summarily.

You have an old stone building?!?!

you open to the south (as far as possible) with occultations and summer protection, you isolate the walls from outside (the techniques and materials are multiple), you install insulating sidewalks, you perfect the insulation of the roof in and finally you places the most central (and if possible backed by a heavy slit) a wood stove.

Voili voilou

[Bardal]

The phase shift, in this case, is the time that separates the external thermal wave from the internal thermal wave. This difference is dependent on the one hand on the inertia of the wall concerned and on the other hand with the thermal resistance of this wall (more precisely of their square root): the greater the inertia of the wall and the greater its resistance. thermal, the greater the difference.

Attention, this has only a distant relation with the capacity of the wall to isolate the room, ie to decrease the amplitude of the thermal wave; we can find very insulating walls but rather little phase shifter (a thick polyurethane for example) and conversely a phase wall much degraded but very insulating (wall of stone, or concrete). Which means that we can have a wall that allows a lot of thermal energy to pass, but with a lot of delay, and another phase-shifting wall with very little heat energy.

In fact, in today's houses (highly insulated and built with other materials, receiving a light insulation) the phase shift becomes a notion largely losing its importance; when the heat flow reaching the inside has been diminished by 10, there is little concern about when it reaches its maximum; incidentally, whether the insulator is internal or external has no influence on the phase shift (which does not mean that the thermal behavior is the same). 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.

To answer your question, do not count on the phase shift in winter to bring in heat to your home (we do not see where it would come from elsewhere), and it is thermal inertia which is capable of retaining daytime heat at night. To my knowledge, the simplest and most efficient way to recover and store heat in winter is an appropriate solar radiation collector heating an interior thermal mass (slab or wall); a bay window overlooking a slab is an example, widely used in the rt2012 (the solar gain can in some regions reach 40 to 50% of the needs), but the phase shift is then zero, the solar rays instantly bringing energy . That said, no one is prevented from imagining more elaborate and more efficient devices (the "Trombe-Michel" wall is an example).

An abundant "scholarly" discussion had taken place on the forum Futura-Science there is 3 or 4 years (which I tried above to summarize the conclusion).

Good reflection.