Insulating your house reduces heat transfer.

LOFT INSULATION: Thick layer of fibre glass wool laid out across the loft floor and ceiling reduces heat loss by conduction and convection.
HOT WATER TANK JACKET: Lagging such as fibre glass wool reduces conduction and radiation.
DRAUGHT-PROOFING: Strips of foam and plastic around doors and windows stop draughts of cold air blowing in, i.e. they reduce heat loss due to convection.
DOUBLE GLAZING: Two layers of glass with a narrow air gap in between to reduce conduction and convection.
THICK CURTAINS: Big bits of cloth over windows to reduce heat loss by conduction and radiation.
CAVITY WALL INSULATION: Foam squirted into the gaps between the grips stops the convection currents being set up in the gap and radiation across the gap. The insulating foam and trapped air pockets also reduce conduction.