Dual pane window infrared….normal?
Greetings all,
We’ve just finished building a home along the So Cal coast, and are surprised at how cold the house is. As a longtime follower of this site and others, I was diligent about air sealing (10 cases of caulk, 25+ cans of foam) and ended up re-doing at least 1/3 of our insulation myself because the subcontractor was so sloppy.
Any by “cold” I mean the temp will say 74-75F, but it feels like 65F the moment the FAU shuts off. We’re going to do a blower door test soon. I’ve walked around with a FLIR and while our (many) IC recessed lights are clearly offenders (10F colder than the room), I don’t see any large likely air leaks or cold areas.
That brings me to glass. I’ve attached an IR pic of a window. Interior temp was 72F, outside temp was 50F, center of glass 65F, and the edges were mid 50F range. Is this normal?
Thanks for any insight.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
What is the outside temperature. Windows will run colder than the room depending on their quality
Oh, and my Cardinal glass with the interior coating will reflect your own temperature back at you
thermal camera gives a nice heat signature of your reflection
50F outside.
They're Cardinal glass as well.
Ok missed that, I don't trust your thermometer. seems unlikely that there would be that kind of temperature when there is that little Delta T
[Edit]
Just checked my windows
The worst 30+ year old glass had edge of glass numbers about 49 degrees
It is 20 degrees out thermostat set to 69
Interior surfaces[walls floor] read 65-67 degrees
That or image looks pretty normal to me. The frame is cold because of thermal bridging, the glass is cooler than the walls because of lower R value.
If you want to measure the surface temperature of the glass, an IR thermometer won’t give accurate results because of the reflective solution. The solution is to put a piece of masking tape on the glass, then measure the temperature of the tape.
Bill
Hmm. Besides the FLIR IR, the only other tool I have is a thermal spotlight that can only tell you if what's in its read area is 5F cooler or warmer than a base reading. I do have a Thermapen, but I don't think I can go stabbing the wood!
The FLIR does show the center glass about what you'd expect? 7F below room temp, +15F vs outside. Edges not so much at ~20F below room? Last night, with the shades down, I was shocked how cold it was between the shades and window.
It certainly sounds like the discomfort you are experiencing is due to radiant heat loss. Do you have very large areas of glass? Do you know window specifications?
Who is the window manufacturer?
Do you know what coating you have on the glass?
Do you have a surface 4 coating?