10 Detecting Energy Leaks in Your House

I have been working on turning down the heat in our house but my suspicions are that what the thermostat says and reality are two very different things. So today I got my nerd on. I walked around the house with a temperature gun zapping everything and recording their temperature readings. You can measure the temperature of anything. Anything.

The results are interesting and confusing. I measured each spot twice, once during the day and once at night. The thermostat was at the same temperature the entire time. In some cases the temperature reading was higher at night than it was during the day. Which honestly, I don't understand so I am going to have to take more readings to rule out any flukes. 

I measured walls, floors, ceilings, outlets, doors and windows. The most shocking reading was our master bathroom shower which read 10C/50F. I'm thisclose to taking a sledge hammer to it to find out what is causing it to be so cold. 

By far I saw the largest variance with outlets. I don't know what made me think to measure them but I was zap happy and was just recording everything and anything. I had outlets on exterior walls measure at 11.5C/53F, one on an interior wall read 9C/48F and other interior wall outlets were in the 16-18C/61-64F range. Having safety covers in does not seem to make any difference. 

Doors and Windows
Our doors and windows are crap, especially considering they are only 8 years old. The doors and windows themselves had very cold readings and so did all the areas around them.  Our front door was probably the most interesting. The door itself measured 14.5C/58F, the window panes inside the door were 9.5C/49F and the window pane right beside the door was 9C/48F. The floor in front of each door....freezing.

The Plan
We cant do a whole lot until the weather changes and the snow melts. At that point we can tackle looking for cracks outside. In the meantime I will be sealing any leaks I can find in the outlets and windows and replacing the weather stripping on the doors and windows that open. 

Do you want to detect leaks but don't have a temperature gun? Follow these simple steps from the US Department of Energy:

  1. Turn off your furnace and shut all doors, windows and fireplace flues.
  2. Turn on all fans you have that vent outside like your bathroom fans, dryer and kitchen exhaust. 
  3. Use a lighted incense stick to find leaks. The smoke will pull out of the house if you have a leak. If you don't have incense you can use your hand to feel the cold air. 

Have you ever taken temperature readings in your house or used other methods to detect leaks? 

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photo credit: eryn.rickard via photopin cc


  1. My husband uses heat guns at work, so he brought one home not long ago. Our house has zero insulation (in Boston! We just moved and will insulate in the spring). We saw much colder temps than yours. I wouldn't worry about subtle temperature differences. Also, you may not have leaks, but instead thermal conductance or thermal bridging which can lead to heat loss- especially if you have insulation.

  2. You may not have an insulation behind your shower wall. In addition, you can go to a hardware store and buy felt outlet covers for inside the outlet. Major leaks come from outlets.

    You might want to see if your door sweep is leaking air. Turn off the lights and shine a flash light under the door from the outside. If you see light, your door sweep may need to be adjusted or is missing.

    1. I would be surprised if there wasn't any insulation behind the shower wall because it is code and would have been inspected by the building inspector prior to closing it in. But it could very well be that it has slumped down and is not providing the full protection any more.

      I didn't know about the felt covers...that is a great idea!

      The door sweep is good. One problem is that I actually bent the bottom of the door when it was frozen shut a few years ago.

  3. Ok, I now want a temperature gun and just go crazy in my house! That is a great challenge to try to find energy leaks.

  4. Well this is interesting. I've noticed, just like you, that even though our thermostat is consistent, there's a real difference at night ... and, surprisingly, not colder. I've often wondered why we feel hotter at night than during the day ... could it be because we close curtains and turn on lights? Hm! I know that our windows, doors, and insulation are terrible ... we live in an apartment so there's not a lot we can do about it short of using draft blockers and bundling up. I've got to check out one of those energy guns ... but then, I'd probably drive myself crazy with the thing. :-)

    1. Having the curtains closed will help to retain the heat you built up during the day so that could be accounting for the temp not dropping as much as you would expect at night.

  5. great tips... we have lived in old and new homes and it always amazes me how each house has its own unique footprint... and set of challenges!

  6. Great post! We had our house professionally read and the results were pretty interesting! Our fireplace was the biggest draw and the person reading the temperatures told us that when the fireplace is not in use, stuff a bag of unused clothes up there to seal it. It works, we just HAVE to remember to pull the bag out when wanting to start a fire.

    1. What kind of fireplace do you have Heather?