Is it possible to determine the R-value of windows with an IR thermometer?
AlanB4
| Posted in Energy Efficiency and Durability on
I have 10-year-old vinyl windows and have tried e-mailing the manufacturer to no reply, and i have an IR temperature reader.
If one knows the outdoor temperature, indoor temperature, and glass temperature, can that data be used to determine its R value?
For example, right now indoor is 20.5 C, outdoor is -4 C and the windows are registering 13.7 C on the temp reader.
The vinyl frame is about the same temp, maybe 0.3 C higher.
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Replies
You'd have to take the window to a test lab and have them do it--they have the controlled conditions needed, and they can't be duplicated in the field. You're probably not even getting very good temperature measurements with an IR thermometer unless you know how to adjust for emissivity, background temperature, and so on.
In the meantime, if you know the thickness of the glass panes, the air space, whether or not there is low-e coating (and where it is), you can get very close to the u-factor for the glass by looking at the Cardinal specs in their residential glass guide. Ideally, you would use a low-e detector like those from EDTM to check the glass, and even then, you only get the category of coating, not the exact type... and you have to guess about whether or not there is argon gas. The vinyl itself is probably a slightly better insulator than the glass. EDTM makes a couple of other tools that could help narrow it down.