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A house is surrounded by text describing where most heat is lost and how we can stop it. U-values are included measured in W/m2K, in which a lower value is better.
A red arrow pointing away from the house shows that up to 15% of heat is lost through the roof – existing (no loft insulation) 2.30 W/m2.K. This can be reduced by insulating the roof, exemplar 0.12 W/m2K.
An arrow shows that up to 40% of heat is lost through uninsulated walls – solid uninsulated walls 3.00W/m2K. This is reduced with external, cavity or internal wall insulation, exemplar 0.15W/m2K.
An arrow shows that up to 15% of heat is lost under the floor. This can be reduced by insulating between joists – uninsulated suspended timber floors 1.00W/m2K, exemplar 0.15W/m2K. It can also be reduced by excavating and insulating below a solid uninsulated floor, exemplar 0.15W/m2K.
An arrow shows that up to 10% of heat loss is through drafts, pressure test 25 m3/m2/h @ 50Pa. This can be reduced by fixing seals throughout and re-lining walls, exemplar 3 m3/m2/h @ 50Pa.
An arrow shows that up to 20% of heat loss is through windows – single glazing 4.80 W/m2K, double glazing 2.00 W/m2K. This can be reduced by improving or replacing windows, exemplar 0.80 W/m2K.