U Value and SHGC - Window Film

Created by Vicki Marshall, Modified on Mon, 7 Nov, 2022 at 12:04 PM by Vicki Marshall

Region: All States


Assessor Question:


I have a client who would like to use a 3M All Season film instead of using low-e windows.  Can you please advise how this film could be modelled in FirstRate5?

TechLink Response:

  • Film and retrofit options are available in the NatHERS Custom Library options.
  • Where performance figures of those systems cannot be matched it is possible to use the NatHERS procedure set out in clause 8.3 of the Technical Note.
  • Additionally, the values of the suggested product may be appropriate for hot/tropical locations.
  • The very low SHGC figure of 0.32 will cause serious detriment to building fabric thermal performance in cool/cold climate zones.
  • Summer heat issues are best dealt with by external shading not by having glass that stops heat coming in all year round. 

You could also refer to the webinar Window Film, NatHERS and WERS For Film.

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