I've just moved into a house where I'm concerned that an energy audit might find problems. The clue is that the windows appear to be old single-pane windows. Once it's cold out I can borrow an infrared camera and go around checking to see how bad things are and exactly where the greatest heat losses are. But it's hard to install new windows in winter. What can I do now to anticipate where the problems will be?

  • If in the winter you would determine that you have an unacceptably large heat loss through your windows, then you would not be under any obligation to immediately install new windows, right? Wait until you get the results of this energy audit. Aug 25, 2019 at 8:17
  • @JimStewart - I get depressed when I am living in a drafty house. Where I live it's a long winter and workmen will not, in my experience, replace a window in winter. Aug 25, 2019 at 15:28
  • Generally, the best energy retrofit (from best to least) is: 1) fixing air leaks, 2) adding attic / ceiling insulation up to 16” - 20” thick, depending on your location, 3) adding wall insulation, 4) adding floor insulation, 5) adding retrofit single pane glass to existing single pane windows, 6) replace single pane windows with double pane windows.
    – Lee Sam
    Aug 25, 2019 at 16:37
  • @LeeSam - Thank you. If I ask a separate question, how to add single pane glass to existing single pane windows, will you post an answer? Maybe you have a link to a good how-to? Aug 25, 2019 at 22:15
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    It’s called “window inserts”. You could probably google that... or, here’s a good site that explains that method of retrofit: treehugger.com/sustainable-product-design/amp/…
    – Lee Sam
    Aug 25, 2019 at 22:38

3 Answers 3


One way is to heat the whole house so it is above the outside ambient temperature, say 24 degrees C, then use a thermal camera to take pictures of the outside walls and roof surfaces of the house.

Those walls, windows etc that are loosing heat faster than other surfaces or parts of surfaces show up. If the camera is calibrated then it will provide a scale showing the relative temperatures.

  • Brilliant. Thank you. Aug 25, 2019 at 15:19

The general principle to use is that actual air leaks are a lot worse than just having poor insulation.

Look around your doors, windows, plumbing, attic/basement/crawlspace access hatches, fireplace, and anywhere else where there's a hole in the wall. Anywhere you feel air movement is an issue. Anywhere you can see daylight (that's not glass) is an issue.

  • So, you're saying that single pane glass is not a deal breaker for keeping warm if I sit on an arm chair or sofa that's placed near the window (as long as there are no gaps around the frame)? Aug 25, 2019 at 15:30
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    Yeah, (well-maintained) single planed glass isn't as bad as people think, to the point where upgrading to double-paned windows doesn't have a great return. It's not as good as double-paned, it's just not worth upgrading in most cases. Aug 25, 2019 at 16:24
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    @user3757614 I agree. We have priced the cost of replacing single pane windows with double pane and the payback is 40-50 years.
    – Lee Sam
    Aug 25, 2019 at 16:27
  • As a side note, really old houses were built assuming people would be wearing sweaters indoors, have heavy curtains, and keep the heat low during winter. Modern construction techniques assume people want to be comfortable in a T-shirt in the dead of winter. While bringing your home up to modern standards would be nice, adjusting your expectations would be cheaper. Aug 25, 2019 at 16:30
  • That is a very good point about thick curtains. I think that is something I neglected to do where I was living last year, which I did do in my previous house. Aug 25, 2019 at 22:14

My answer is old school but it has worked for me many times. Get a roll of that semi clear plastic and tape a piece to the entire inside window frame, basically sealing it. Any air leaking will either bow or suck in the plastic. you can then work on fixing any leaks and will know when you've succeeded because the plastic will quit moving. here is a link to the type of plastic I used. https://www.amazon.com/Premier-Clear-Plastic-Cloth I also used the blue painters tape so i wouldn't damage the walls or frame.

  • Somehow I missed this. This would also be worthy of a green checkmark. Thank you very much. Aug 25, 2019 at 15:29
  • Do this to all the windows. It will definitely stop the drafts. I did it in a house I lived in in Grand Rapids, cut the heating bill in half.
    – JACK
    Aug 25, 2019 at 15:29
  • The plastic taping procedure you're recommending -- is it a diagnostic, or is it a remediation, or both? Can you post a link to the type of plastic and the type of tape? Also, do I tape it to the window frame (not the edge of the wall)? Aug 25, 2019 at 15:31
  • It ended up being both because we were renting and the owner had no intention of installing new windows. I did add some weathering stripping around the doors because we didn't want to keep the plastic up there. You can tape the frame or wall, whichever give you a better seal. If you suspect a leak between the frame and wall, then tape the wall.
    – JACK
    Aug 25, 2019 at 16:09
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    I used the blue painter's tape.
    – JACK
    Aug 25, 2019 at 22:36

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