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Wall Contruction, Temp At Each Layer

Wall Contruction, Temp At Each Layer

Wall Contruction, Temp At Each Layer

(OP)
Hi All,

I have a wall that i have calculated the u-vlaue for but i now need to find the temperarure at each of the layers that build up to make the wall. I have the internal and external temperatures and the resistances of the components that build up to make it. Is there any kind of formula?

Cheers

RE: Wall Contruction, Temp At Each Layer

It's just a series resistance problem.  The total series thermal resistance and the overall delta temperature gives you the power per unit area.  Then you simply run that power through each layer.

TTFN



RE: Wall Contruction, Temp At Each Layer

(OP)
Ok thank you,

So my calc will look like this

R1+R2+R3+R4+R5

=Rt (Toal Series Resistance)

My delta T is 23c

Rt / delta t = power per unit

Resistance of layer / power per unit = Temp at that layer!?

RE: Wall Contruction, Temp At Each Layer

Almost there. R=1/U, and the resistances to heat flow are additive, and q/A (the power/area) = U*dT = dT/R. From the power, which is the same rate through each component of the wall, dT(for component)=power/r(for component). Expressed differently, the fraction of the overall dT through each component is (1/r)/sum(1/r).

If you are doing this for a house design, bear in mind that what the insulation nominal R values are and what you actually get in service vary considerably. Without good air barrier installation, a cold windy day can cut an R-19 nominal value in half. Then there is thermal bridging through all that wood connecting inside to outside, anywhere from 12 to 18% of the total wall area. But there are plenty of sites with good info on good wall design for thermal efficiency.

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