Warm air often goes to the upper parts of the house.
Whar is the name of the process by which air moves and carries heat energy with it ?
Since this is not my area of expertise, I searched Google under the key words "heat convection" to get these possible sources:
http://sol.sci.uop.edu/~jfalward/heattransfer/heattransfer.html
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html
http://en.wikipedia.org/wiki/Heat_transfer
(Broken Link Removed)
I hope this helps. Thanks for asking.
Convection