Heat transfer.

Determine the percentage reduction in winter heat loss through the windows of an office building if double glazing is used instead of single glazing. Assume that:

(i) The conductivity of the single glazing = 10 W/mK

(ii) The thermal resistance of the air cavity of double glazing = 0.18 W/m^2K

(iii) The convective heat transfer coefficients for the inner and outer surfaces of the window are 12 W/m^2K and 50 W/m^2K respectively.