Solve the following problem.
The PasivHaus standard for low energy building requires that the U-values of all outer shell materials be no more than 0.15 W/ m^2*K.
If the area of a PassivHaus standard wall is 18 m^2, how much energy En flows through the wall over a week if the inside temperature is 10 ℃ warmer than the outside?
I believe you want to know the energy that flows through a PasivHaus standard wall.
Now the U-value of the standard PasivHaus low energy building for all outer shell material is to be less than 0.15 W/m^2*K.
So the rate of energy flowing out can be a maximum of 0.15 W/m^2*K. The standard area of the wall is 18 m^2. The temperature difference inside and outside the house is 10 degree C or 10 K.
Therefore the rate of flow of energy is 0.15*18*10 W
= 27 W.
In a week there are 24*7= 168 hr.
Therefore the energy flowing through the building is 168*27 W*hr
= 4536 W*hr
= 45.36 kW*hr.
The required energy flow over the week is equal to 45.36 kW*hr.