Heating in Buildings: Heat Loss During Nighttime

[rootX]

I was wondering if a heating device is installed in a building, and the building is good enough(no open windows). And would there be heat loss during the night time when all the doors are closed?

 

[Astronuc]

I was wondering if a heating device is installed in a building, and the building is good enough(no open windows). And would there be heat loss during the night time when all the doors are closed?

Well what does one think that closing doors/windows will do? There are three heat transfer properties: conduction, convection and radiation. How will each be affected by a sealed building? How are each affected by temperature differential between the building and the outside air and ground temperatures.