How come the heat gain from a roof is more than the heat loss?

Question

if Q = UA delta T, and in the winter the delta T is greater, why am I getting a greater load in the summer than in the winter?

Answer 1

You are correct with Q=UAdelta T but you are disregading a form of heat often so slight as to be negliable but here that is not the case. The heat gain in summer is PREDOMINANTLY radient heat not conductive heat from the atmosphere. Do you not get hot laying on a beach in the sun in the summer?? Usually the air temp is lower than your body's surface temp so why don;t you cool off instead of broiling??? Oh thaz right radiant energy from the sun.

Answer 2

Of course you will have more heat load during summer due to the radiant heat from the sun. During winter time, radiant heat is negligible.Often we are considering only the heat load due to convestion and condution. But during summer, heat due to radiation is very influential.

Answer 3

coz heat gain is due to convection above the roof, convection thru the roof and radiation from the sun (Q = Stefan boltzmans constant * (T1^4-T2^4), etc).

Heat loss is due to conduction thru the roof and convection above the roof only.

So for the gain there is one extra force acting for heat gain hence the flux (Q) is higher.

Answer 4

You're not. That may be the way that it _feels_ to you, but if you did proper measurements you would find that the heat flow would be as described.