(a)
The exterior wall of a timber-framed house is constructed as follows from the inside out.
.
Internal surface convective coefficient B W/m°K.
13mm plasterboard k = 0.25 Wimk
1150 mm insulation (k = 0.04 W/mK). making up 85% of the area between 150 mm
timber studs (k = 0.13 W/mK)..
12 mm sheathing plywood (k = 0.13 VimK).
.
A 75mm air cavity of thermal resistance 0.18 m*K/
.
100mm block outer leaf (k = 0.57 Wimkj
.
20mm render (k = 0.57 W/mK).
External surface convective coefficient 25 W/m°K
Taking into account the bridging of the insulation by the timber studs, calculate the overall heat transfer coefficient for the wall
(15 Marks)
(b)
For a building with a perimeter of