Analysis of Thermal Bridges - Scottish Energy Systems Group ...
Analysis of Thermal Bridges - Scottish Energy Systems Group ...
Analysis of Thermal Bridges - Scottish Energy Systems Group ...
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BRE 497 Ro<strong>of</strong> junction boundary condition<br />
conventions (Not CEPH conventions)<br />
U`R<br />
Ro<strong>of</strong> eaves<br />
(insulated at ceiling)<br />
T e<br />
T L<br />
U`C<br />
• It is usual to take T i<br />
=20 0 C and<br />
T e<br />
=0 0 C<br />
• A heat balance between U`R and<br />
U`W<br />
ψ =<br />
l c<br />
T<br />
l i<br />
w<br />
L − l × U′<br />
− l × U′<br />
W<br />
W<br />
C<br />
C<br />
U`C can give T L<br />
• For ventilated ceilings T L<br />
~T e<br />
but<br />
ventilation component <strong>of</strong> U`R is<br />
not generally known. T L<br />
is taken<br />
as 1 0 C for such cases.<br />
• R se<br />
<strong>of</strong> 0.10m 2 K/W is taken for the<br />
upper surface <strong>of</strong> the l<strong>of</strong>t space.<br />
<strong>Scottish</strong> <strong>Energy</strong> <strong>Systems</strong> <strong>Group</strong><br />
samuel@esru.strath.ac.uk
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