P1 - Keeping houses warm Flashcards
1
Q
How does double glazing insulate houses?
A
There is a space between the two panes of glass filled with air so it does not conduct heat.
2
Q
How does cavity wall insulation work?
A
The foam is filled with trapped air which insulates the house.
3
Q
If air is such a good insulator, why do we need cavity wall insulator?
A
This is because air is a good convector meaning heat can be lost through convection currents.
4
Q
What is the formula for energy efficiency?
A
Efficiency = useful energy output/total energy input x 100
5
Q
What is the formula for payback time?
A
Payback time = cost of insulation/annual saving
