Insulation of an attic with wood fiber: 14 or 20cm?

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CedLux
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Insulation of an attic with wood fiber: 14 or 20cm?




by CedLux » 12/03/12, 16:06

I plan to insulate the attic floor with wood fiber panels.
The attic is 65m².

I am thinking of using "SteicoFlex" panels which have the following characteristics:
Lambda: 0.038 W / (m * K)
Density: 50kg / m³
"Phase shift": 2100 J / (kg * K)

Solution A: thickness 14cm
R would be 3.68 (= 0.14 / 0.38)


Solution B: thickness 20cm
R would be 5.26 (= 0.20 / 0.38)



Questions:
    The larger R, the better. But what exactly does R mean?
    What is its unit of measure?
    What is the difference between the two results?
    Can someone calculate the phase shift for the two thicknesses? (and explain the calculation)?
    Is it economically profitable to install 20cm instead of 14? (knowing that the additional cost would be +/- 7 € / m²)



thank you in advance for your help : Idea:
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Gaston
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Re: Insulation of an attic with wood fiber: 14 or 2




by Gaston » 12/03/12, 18:01

CedLux wrote:Questions:
The larger R, the better. But what exactly does R mean?
R represents the power which crosses a certain insulating surface for a temperature difference between the two faces.
CedLux wrote:What is its unit of measure?
R is expressed in m² * K / W.
CedLux wrote:What is the difference between the two results?
The power passing through the insulation (and therefore that to be provided by the heating to avoid the drop in temperature) is:
P = surface * temperature difference / R

For example, for a temperature difference of 10 ° and an R of 5, each m² of insulation lets in a power of 1 m² * 10 ° / 5 = 2 W.

Going from 3.68 to 5.26 means reducing losses through this insulator by a factor of about 1.4 (precisely the thickness ratio : Mrgreen:)


CedLux wrote:Can someone calculate the phase shift for the two thicknesses? (and explain the calculation)?
Estimating the transfer time requires knowing the density and the heat capacity of the material.
However, the transfer time is proportional to the thickness.
The phase shift produced by a 20cm layer will therefore be 1.4 times greater than with a 14cm layer.
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CedLux
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Registration: 09/05/09, 14:26




by CedLux » 12/03/12, 19:16

Thanks for the answers.

If I'm not mistaken, the density is 2100.
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bidouille23
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by bidouille23 » 12/03/12, 19:49

slut, boula there is nobody who reads the post already created it is necessary to believe :) .

so look at the other posts not far from yours and you will have all your answers, otherwise you have to learn to be precise in its descriptions is better, then 14 cm on the low floor, 20 cm on the ridge or 20 cm on the walls and 14 under roof etc

: Mrgreen: : Mrgreen:

come on we make efforts we don't open our mouths like a baby bird waiting for its food.

a clue the title of the post is:

Need insulation for advice for my future work


;) good reading
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