Global Warming

Insulation of buildings

About one and a half thousand million people live in cold climates where some heating in
buildings is required. In most countries the energy demand of space heating in buildings is far
greater than it need be if the buildings were better insulated.
Table 11.3 provides as an example details of two houses, showing that the provision of
insulation in the roof, the walls and the windows can easily lead to the energy requirement for
space heating being more than halved (from 5.8 kW to 2.65 kW). The cost of the insulation is
small and is quickly recovered through the lower energy cost.
If a system for circulating air through the house is also installed, the number of necessary
air changes with outside air is less and the total heating requirement further reduced. In this
case it is worthwhile to add more insulation to reduce the heating requirement still further.

Table 11.3Two assumptions (one poorly insulated,and one moderately well insulated)

regarding construction of a detached, two-storey house with ground floor of size 8 m×8m,

and the accompanying heat losses (U -values express the heat conduction of different

components in watts per square metre per◦C)

Moderately well

Poorly insulated insulated

Walls (150 m^2

total area)

Brick+cavity+blockU-value

0.7

Brick+cavity+block with

insulation in cavity of 75 mm

thickness:U-value 0.3

Roof (85 m^2 area) UninsulatedU-value 2.0 Covered with insulation of

thickness 150 mm:U-value 0.2

Floor (64 m^2 ) UninsulatedU-value 1.0 Includes insulation of thickness 50

mm:U-value 0.3

Windows (12 m^2

total area)

Single glazing

U-value 5.7

Double glazing with low

emissivity coating:U-value 2.0

Heat losses (in kW) with 10◦C

temperature difference from

inside to outside

Total heat loss (kilowatts) 4.2 1.05

Add heat (in kilowatts) needed

for air changes

(1.5 per hour) 1.60 1.60

Total heating required

(kilowatts)

5.8 2.65