Vale of White Horse District Council
Abbey House, Abbey Close,
Abingdon, OX14 3JE
Email: comments@whitehorsedc.gov.uk
Telephone: 01235 520202

Vale of White Horse District Council

Saving energy - insulation

Cavity wall insulation

Walls are the largest contributor to heat loss in a home; approximately 35 per cent of the heat lost in a home is lost through the walls. Insulating cavity walls is therefore one of the most cost effective ways of reducing heat loss. Cavity wall insulation will create a more even temperature in your home, help prevent condensation on walls and reduce the amount of heat building up inside your home during hot spells. Cavity wall insulation can reduce heating bills by up to £90 per year and usually pay for itself within five years. If your house was built after 1930, it will probably have cavity walls. Cavity wall insulation is straightforward, inexpensive and causes minimal disruption, but must be done by a specialist contractor. The insulation material is injected into the cavity through a series of holes from outside, and usually takes less than a day to complete. 

All approved installers issue a 20 year guarantee provided by the Cavity Insulation Guarantee Agency (CIGA), and the materials they use should be either BBA or BSI approved. The National Insulation Association can supply details of professional installers registered with them. Contact them on 01525 383 313 for more information.

The Council supports two insulation discount schemes and offers residents a grant to put towards the cost of insulation. See Grants and discounts for insulation for more information.    

Solid wall insulation

Houses built prior to 1930 are most likely to have solid walls. Solid wall can be insulated either internally or externally. Solid wall insulation will cost more than cavity wall insulation but the savings to be made are greater as solid walls lose heat more rapidly than cavity walls. Insulating solid walls can reduce heating bills by up to £300 per year.   

The National Insulation Association can supply details of professional installers registered with them. Contact them on 01525 383 313 for more information.   

Internal solid wall insulation

Of the two methods available internal insulation is usually preferred as it is cheaper and will not alter the appearance of a house. Ready-made insulating boards can be fixed to the walls; alternatively, batons fixed to the walls can be in-filled with insulation. A polythene vapour barrier must be fitted between the wall and the insulation to prevent dampness. Depending upon experience you can install internal wall insulation yourself. Given the disruption and cost involved in fitting internal wall insulation, it is recommended you only fit internal wall insulation when undertaking renovation or decoration works. 

External solid wall insulation

To insulate a wall from the outside insulation is fixed to the external wall and covered with a protective weatherproof finish. Applying external wall insulation involves significant structural refurbishment and a specialist contractor should always be used. External wall insulation may require planning permission and may not be suitable for some building given the resulting change to the appearance of the building. Work will take longer and cost more than internal insulation, but creates less disruption. As with internal insulation it is recommended that work be carried out in conjunction with scheduled repairs or renovation.

Loft insulation

The roof is the second largest contributor to heat loss in the home; approximately 25 per cent of the heat lost in a home escapes through the roof space. Loft insulation is therefore a cost effective way to reduce heating bills. Loft insulation can reduce heating bills by up to £110 per year and will usually pay for itself in less than four years. The current minimum recommended depth of loft insulation is 10 inches or 270 mm. If there is less than 8 inches or 200 mm of insulation in a loft is it worth topping it up. 

Loft insultation pic

Insulating a loft can be a DIY job provided that the necessary safety precautions are followed and there is adequate ventilation. Lay the insulation between the joists where possible, and then at right angles to the first layer when it reaches the top of the joists. Take care not to block the eaves, as ventilation is essential to avoid condensation. Make sure the loft hatch is also insulated and draught-proofed and lay insulation under power cables so they remain visible. Ensure any tanks or pipes in the loft space are properly lagged to prevent freezing. 

Alternatively the National Insulation Association can supply details of professional installers registered with them. Contact them on 01525 383 313 for more information.

The Council supports two insulation discount schemes and offers residents a grant to put towards the cost of insulation. See Grants and discounts for insulation for more information.    

Windows, doors and draughts

25 per cent of the heat lost in a home is lost through windows, doors and draughts.

Secondary glazing

The addition of a second pane to an existing window is known as secondary glazing and there are a variety of methods of installing secondary glazing. Cheaper options include plastic sheeting that can be stretched taut and sealed around the edges of the window with tape. More expensive options include pull down or slide across additional glass panes. As long as an effective seal is created between the two layers trapping the air, it will effectively slow down the rate at which heat is lost.

Double glazing

Replacing windows with double glazing can not be justified on the grounds of saving energy alone given the significant costs involved. Therefore double glazing should only be considered if the windows need replacing, or if there are additional benefits for doing so, such as improving the appearance of the house, noise reduction and security.

The Glass and Glazing Federation (GGF) can supply details of professional installers who are members of the GGF. Contact them on 0870 0424 255  for a list of installers in your area or look for membership details on adverts.

Draught proofing

Gaps around ill fitting doors and windows let cold air in and warm air out. Small gaps can be filled in with sealants or fillers, but windows and doors may need special preformed sealing strips. Most are inexpensive and easy to fix and there are a multitude of products that can be matched to individual window/door types. For example, older type sash windows tend to be very draughty and should be fitted with brush or wiper seals, whereas wooden hinge windows are better suited to compression seals. Do not forget to draught proof letterboxes and keyholes.

The National Insulation Association can supply details of professional draught-proofing installers registered with them. Contact them on 01525 383313 for more information.   

Ventilation

Adequate ventilation is essential to allow fuel burning appliances to burn efficiently and safely, to allow waste gases to escape and to prevent condensation. Do not draught proof kitchen and bathroom windows as ventilation is needed in these rooms where excess steam and moisture are created which lead to condensation. You should however seal bathroom and kitchen doors to prevent steam escaping into the house and creating condensation.