4.5. Heating II http://www.ck12.org
U-values of walls, floors, roofs, and windows.
power (watts)=CN
1 hV(m^3 )∆T(K) (E. 1 )= ( 1. 2 kJ/m^3 /K)N
3600 sV(m^3 )∆T(K) (E. 2 )=1
3
NV∆T. (E. 3 )
Energy loss and temperature demand (degree-days)
Since energy is power×time, you can write the energy lost byconductionthrough an area in a short duration as
energy loss=area×U×(∆T×duration),and the energy lost byventilationas
1
3
NV×(∆T×duration).Both these energy losses have the form
Something×(∆T×duration),