Glazing type	U-value (W m-2 K-1)
Single glazing	4.8
Double glazing (normal glass, air filled)	2.7
Double glazing (hard coat low-e, emissivity = 0.15, air filled)	2.0
Double glazing (hard coat low-e, emissivity = 0.2, argon filled)	2.0
Double glazing (soft coat low-e, emissivity = 0.05, argon filled)	1.7
Triple glazing (soft coat low-e, emissivity = 0.05, argon filled)	1.3

i.In a house with a 3.5 m single glazed window, what is the combined rate of heat loss through the window on a day when the outdoor temperature is 5C and the indoor temperature is 20C?

Data may be assumed to have been supplied to 2 significant figures (SFs).

1 mark

ii.Assuming the temperature difference remained the same throughout a 24-hour period, what would be the total heat loss in kWh over the day?

1 mark

iii.What would the heat loss be over a 24-hour period if the single glazed window were replaced with a triple glazed window?

1 mark