Comenius

Walls are the largest source heat loss because they represent the largest area in contact with the cold air outside. If the wall has a cavity between the outer and inner wall then it can be insulated at any time. If there is no cavity then the walls can be insulated internally or externally. External insulation is not easy as it also requires weather proofing and will generally require installation by a technical specialist.

Special reflection foils made of aluminium can be stuck to the wall behind the radiators so that they are not visible. Heat will be reflected from the radiator back into the room minimising the heat to be lost through the walls.

The heat loss is greatest for a detached dwelling which has the largest number of outside walls and least for an apartment in a multi-family dwelling.

Windows are responsible for up to a quarter of the total energy loss either through the glass pane directly or by ventilation through any gap between the window frame and the wall. To reduce heat loss it is possible to replace a single glass pane with two (or even three) glass panes within the same window frame. To prevent convection of heat between the panes, the space between is either partially evacuated or filled with an inert gas like argon. Whether it is necessary to replace the window frame will depend upon the type and condition of the frame and how well it is sealed into the opening in the wall.

Typical heat loss in a building

Single panes of glass can also contribute to condensation during the winter as moisture condenses on the inside of the window.

High levels of condensation can contribute to health problems as these can create conditions in which house mites can flourish which can lead to bronchial illnesses such as asthma or allergies. So reducing heat transfer rates through windows has more than one benefit.

Roof and floors

May be responsible for up to 25% of the total energy losses The exact value will depend on the type of building and its level of existing insulation – the loss will be smallest in apartment buildings where t apartments have neighbours with heated flats above and below and highest in individual homes.

A variety of insulating materials exist for both roofs and floors. If there is access to the loft space between the ceiling and the roof, it is generally possible to add additional insulation at relatively low cost for which a grant or subsidy might well be available. If there is no loft, then insulation can only be added beneath the ceiling if height allows or on the roof if it is flat.

It is generally not possible to check whether there is any insulation under the floor unless the house has wooden sprung floors. Only new houses are likely to have insulation under the floor. Floor carpets do provide some level of insulation.