Concrete heat transmission U values
Concrete heat transmission U values
(OP)
Hi:
I am comparing the ASHRAE U values for different thickness of concrete to http:// www.combus tionresear ch.com/Inf ra-Spec/in fra-spec/u value.html. and to http:// wiki.answe rs.com/Q/W hat_is_the _R_value_o f_concrete
Can anyone explain the difference?
I am comparing the ASHRAE U values for different thickness of concrete to http://
Can anyone explain the difference?





RE: Concrete heat transmission U values
The second one is showing the relation between R-Value and k-value. How one can obtain the R value from the k value.
Now its sometimes confusing. You have to understand each one
1. Thermal Conductivity - k value - Unit is W/(m.K)
2. Thermal Resistance - R Value - Unit is m2.k/W
it can be obtained from k-Value with the formula described in Wiki Answers
for a Wall(or roof) assembly made of different layers, first thing is to determine individual R-values of each layer. then compute total resistance Rt as
Rt = R1+R2+R3+....
Now U-Value is the reciprocal of Rt (U = 1/Rt)
U value is called overall overall heat transfer coefficient
its units are W/(m2.K)
RE: Concrete heat transmission U values
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