Avoiding condensation and mould growth in existing housing with the minimum energy input.

Detailed studies of public sector modernisation programmes show that the principal problem resulting from lack of thermal insulation and inappropriate methods of heating and ventilation is condensation and mould growth. Gives the optimum air change rate (for dwellings with particular heat loss characteristics) at which the heat input necessary to prevent the RH rising is at a minimum. The resulting temperatures are too low to be considered comfortable, so air change rates need to be less than the optimum. Under these circumstances the thermal insulation characteristics of the enclosing walls become important, particularly in the corners of exposed rooms where the surface temperature will be less then the remainder of the room. A wall U-value of 1.0 W/m2K is enough to avoid surface condensation in the corners of rooms.