Brick temperature outside showing as 12C

waqasahmed

Is this normal?

I bought myself a thermal image. It's a fairly cheap one from aliexpress, however I figure it's good to at least get something that can show me how much radiant heat something has

I went outside, and my house was showing as 12C. My walls inside are showing around 18C. The ambient temperature here is about that much too. The outdoor temperature is also 9C currently. Not sure if this means I've got a heat loss of 6C? 

QrizB

waqasahmed said:

Is this normal?

It doesn't sound abnormal.

Energy will be flowing (hopefully slowly) from the inside of your house to the outside. There will be a temperature gradient from hot to cold.

The outside walls will have to be warmer than the outside air, and the inside walls will have to be warmer than the outside ones.

Grumpy_chap

It might be normal.

If the outside air is 9 degC and the camera measures the surface temperature of the brick that 3 degC difference is the heat loss across the laminar zones close to the surface of the brick.

A similar thing happens inside, that the brick is cooler than the air in the room.

Have you tested the accuracy of the indication from the thermal imaging camera against something of a know temperature?

waqasahmed

Grumpy_chap said:

It might be normal.

If the outside air is 9 degC and the camera measures the surface temperature of the brick that 3 degC difference is the heat loss across the laminar zones close to the surface of the brick.

A similar thing happens inside, that the brick is cooler than the air in the room.

Have you tested the accuracy of the indication from the thermal imaging camera against something of a know temperature?

Ahh. That's a fair shout. I'll have to get it onto something where I know the temp of and go from there 

Good to know then that the house is at least already likely not leaking a lot of heat which it shouldn't be if it was built in 1979 but still 

Reed_Richards

If the wall in question has been in the sun at all you would expect it to be warmer than the outside air.

waqasahmed said:

 Not sure if this means I've got a heat loss of 6C? 

No it doesn't because a temperature difference is not a heat loss.  Heat loss is measured in Watts. 

If you had a perfect thermal insulator in your wall then you would expect the outside brick to be the same temperature as the outside air but you would have to find a wall that never sees the sun to avoid solar gain.  If you measured such a north facing wall then the only temperature difference of significance would be the difference between the wall and the outside air temperature.  The higher that temperature difference then the faster that part of your house is losing heat.