I had all new replacement windows (softlite banbridge) installed this summer. Today it is 40 degrees and I feel a lot of radiating "cold" coming from them. It is also very windy (the hurricane is closing on us) but there is no drafting from any window that I can tell via the match test.
What should be expected? I thought low-e and gas filled would insulate but I am concerned that as temps drop this winter, my expectations will not be met. Are there tests to determine what is within expected ranges for insulated glass? Is there a ratio of internal to external temp that I can reference? Any and all info and suggestions welcome.
Thanks
Expectation of radiating cold from new windows
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Windows on Washington
- Posts: 5457
- Joined: Fri Oct 27, 2006 11:23 am
- Location: DC Metropolitan Area-Maryland/Virginia/DC
Re: Expectation of radiating cold from new windows
Copied one of Oberon's posts regarding temperature statistics.
Some real numbers:
When it is 0°F outside and 70°F inside and you have very little wind, the interior surface temperature of a single pane of glass is going to be right about 16°F; which is definitely going to contribute to those convection currents.
Add the second lite, be it storm or dual pane and you increase the interior glass surface temperature to 44°F. That is a very significant improvement. And once again, that is not simulation, it is real measurement data.
Add the LowE coating in a dual pane and the temperature of the glass surface increases to the mid 50’s F (53°F – 57°F) depending on the coating and the glass surface that has the coating.
Keep in mind that the wind will speed convection to the outside and therefore increase the radiant and conductive heat losses.
Some real numbers:
When it is 0°F outside and 70°F inside and you have very little wind, the interior surface temperature of a single pane of glass is going to be right about 16°F; which is definitely going to contribute to those convection currents.
Add the second lite, be it storm or dual pane and you increase the interior glass surface temperature to 44°F. That is a very significant improvement. And once again, that is not simulation, it is real measurement data.
Add the LowE coating in a dual pane and the temperature of the glass surface increases to the mid 50’s F (53°F – 57°F) depending on the coating and the glass surface that has the coating.
Keep in mind that the wind will speed convection to the outside and therefore increase the radiant and conductive heat losses.
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HomeSealed
- Posts: 3064
- Joined: Mon Feb 15, 2010 3:46 pm
- Location: Milwaukee, Madison, SE Wisconsin
Re: Expectation of radiating cold from new windows
That is great info. You can test the temperature of your glass to see if it is within the range that can reasonably be expected. Keep in mind, that even the most efficient windows are still going to be the weak link in the overall wall assembly as energy efficiency is concerned.
Re: Expectation of radiating cold from new windows
Thanks for the info... Guess now I wait for a day with 0 degrees. I am doing rough math but a double pane window should be about 65% warmer than the outside temperature when the room is 70 degrees and there are calm winds. I will post what I find out for my windows for all to see asap.