Hi.
Outside a heated dwelling, an infrared/thermal camera can perceive where the heat escapes trough cracks, doors, windows, roof, basement...
How can those lossy places be found from inside a dwelling, where everything is warm and no cold air is entering to be found with such thermal camera ? How is it done ?

 

When I built this house over 40 years ago the contract specified that all "cracks" be sealed. I also used 2x6 on 24" centers exterior wall construction plus outside foam foiled sheeting and the Sill Plate was to be sealed to the concrete slab. Well... I also had an interior water-cooled heat pump installed which worked great. That is until in the middle of the night a few years later one of the water pipes broke at the unit. It was then that we discovered that the sill plates had not been sealed as the water inside the house was draining out under the sill plate. That is NOT how I would recommend testing.

 

Reviews Thermal Camera’s

check these, I didn’t go down the rabbit trail but might work. Hopefully at a good price, never thought about it until now but maybe the cheap thermal laser I purchased might show different levels of Temp in my house, just shoot it over and over for fun.

Calculating the thermal loss is different not sure how to do that.

kv

 

Wherever there is heat loss, there is cold. If all if the walls, windows, etc were are the same temp as the air, there would be no transfer of heat.

 

It’s called a ‘blower door’ test. One of your exterior doors is replaced by a fan that draws a low pressure (50Pa). Done on a cool day, after warming up the interior, a thermal camera can show detailed leakage points. CFM of the fan at pressure indicates overall leakage.

 

The major losses are windows and doors. Windows should be sealed double panes and the framing should NOT be aluminum! Best is likely wood framing with acrylic outter coating. In extreme cold areas, winter "storm windows" should be additionally used. Additionally, insulated curtains help. Outside doors should be insulated with tight sealing trim and have a very good quality storm door with double pane glass and tight trim as well. Don't forget the attic pull down steps. They make insulated boxes that go in the attic to help seal them. You can tell when you are getting there when you can't just flip the outside door shut but have to actually push it until it latches.

 

maybe the cheap thermal laser I purchased might show different levels of Temp in my house, just shoot it over and over for fun.

Just remember, the laser is just a guide to the center of the measurement area. IR "thermometers" have a conical field of view. The farther from the measured surface, the larger the target area. The reported temperature is the average of the circular measured area.

 

How can those lossy places be found from inside a dwelling

An IR camera indicates relative temperature, so could detect cold spots on the inside surfaces.

 

GetDevice... Thanks. Yes, that should show thermal air leaks as exterior cold is being sucked-in due to the lower pressure inside. (Not the heat leaked-out)
Would mean the expense of the blower on top of the thermal imager. Perhaps I should explore renting the service.

 

Using a thermal imager as stated without the blower test will show you cold spots. If you can see warm spots from outside, you can see cold spots from inside. The thermal camera is the tool you need. Using the blower will tell you with excellent detail more information than the camera alone, but if all you need is overall inspection, the camera will tell you.
You don't have to get super expensive either. At Adafruit, they have some maker friendly thermal imaging breakout boards. These.
its only 8x8 pixels, but that is enough to find bad spots relative to the surroundings.

 

I can't speak to quality but there are some FLIR adaptors available for smartphones for less than 100 USD. Might be worth checking out. The "good" FLIR cameras are sold for thousands of USD.

 

GetDevice... Thanks. Yes, that should show thermal air leaks as exterior cold is being sucked-in due to the lower pressure inside. (Not the heat leaked-out)
Would mean the expense of the blower on top of the thermal imager. Perhaps I should explore renting the service.

Thermal imaging works great as it can pin point the specific leakage. For static conductance of walls, windows, ceiling, then a single point gauge will work. Energy auditing typically looks at your construction and makes calculated assumptions, along with a blower door / thermal imaging. Any upgrades can then be priortized.