[esp-r] RE : Low-e coatings

Wed Mar 12 22:25:45 GMT 2008

Liam,

The radiation exchanges between surfaces separated by an air gap within a construction are not explicitly modelled / simulated in ESP-r - rather the effective thermal resistance of the air gap in the zone's construction file (.con) can be adjusted to account for various gases and low-e coatings in a sealed glass unit. Using WIS or LBNL's WINDOW, you can derive the effective gap resistance for a given window from the entire unit U value, and individual glass pane thicknesses and conductivities. You should also tweak values to account for framing effects (both in .con and .tmc files).

Hope this helps,

Denis Bourgeois

-----Message d'origine-----
De : esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] De la part de Liam O'Brien
Envoyé : March 12, 2008 5:51 PM
À : esp-r at lists.strath.ac.uk
Objet : [esp-r] Low-e coatings

Hello,

I want to model a low-e coating on a new window construction.  As far as I can tell, materials (i.e. glass) are defined as homogeneous in the materials library, and thus have a single emissivity value.  However, clearly a low-e coating will cause the glass to have two different emissivity values.  Could anyone share how they have modeled this?

Also, it would be useful in future versions of ESP-r to have fill gases other than air.  I know the properties of the air can be changed, but it would save a step to be able to choose argon or krypton, for example.

Thanks!

Liam O'Brien

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