Question

Consider a basement wall that is completely below grade. Will heat loss through the upper half of the wall be greater or smaller than the heat loss through the lower half? Why?

Answer 1

first of all lets consider a basement wall of say 10 feet, and this wall doesnt have any insulation what so ever to trap the heat inside. concrete being a good conductor of heat allows heat to escape easily through it.

on chilly days the temperature near the ground surface is considerably less than the temperature 10 feet below the surface. the heat from the basement readily escapes through the concrete which is nearer to the ground surface that is the upper half of the wall, as there is a considerable temperature difference between the ground surface and the basement. whereas the lower half doesnt loose much heat through it because the ground 10 feet below surface is already at a higher temperature than the ground surface. this happens because heat has a tendency to travel from hot body to a cold body until they reach an equilibrium.

whereas if its hot outside and the basement is at a lower temperature than the surrounding temperature then heat flow from the surrounding to the basement takes place more in the upper half of the wall than the lower half,