Save hundreds of pounds on your energy bills with these top insulation tips

23 November 2017

Are you wasting hundreds of pounds each year on heat and energy that is escaping from your home? Then pick up our top tips on draught proofing and insulation. Not only will these ideas help save you money, they’ll reduce your CO2 footprint too.

Ever heard the saying: ‘An Englishman’s home is his castle’? Well, it’s true in more ways than one. Much like a castle, many of our properties leak energy.

We may as well be throwing money out with the rubbish because that is just what we are doing if our home is not well insulated and draught proofed. If you want to check heat loss from your home, the easiest way is to employ someone with a thermal imaging camera (or you can hire one from £102.90 at This will give you a thermal image of the outside of your home, highlighting any points where excess heat is lost.


The highest proportion of escaping energy is through your walls – an incredible 35%. So what can you do to prevent the loss?

Homes built after 1924 generally have a space between the internal and external walls called the ‘cavity’. This acts as a barrier to stop rain reaching the inside of the building, but it also is a perfect space to fill with insulation to reduce heat loss Since 1982, it has been compulsory to install cavity wall insulation into all new-builds, but if your home was built between 1924 and 1982 it may not have this.

See the box below to find out how to tell if you have cavity wall insulation already installed. If you are unsure whether your home is of cavity or solid wall construction, you can check how the bricks are laid – see illustrations below. If you have cavity walls and would like to check if they are insulated, look for tell-tale marks in the brickwork (see below).

Above: If you have cavity walls and want to check if they are already insulated, look for these tell-tale marks (see arrows)

If you need cavity wall insulation, you may qualify for a grant – visit or call 0800 015 4759 to see if you’re eligible.


Once you have sorted out your walls, pop into the loft to check if it is adequately insulated. There are many types of roof and loft insulation (you can see all these at roof-and-loft-insulation.html), but the most common is rolls of glass and mineral wool laid between the ceiling joists. This should be 270mm thick, but you may be surprised to find a flimsy layer of non-descript material or nothing at all in your loft. There goes another 25% of lost heat and a wad of money up into the sky.

The first thing to check once again is whether you are eligible for a grant. Go back to or call 0800 015 4759.

If you are not eligible for a grant and are reasonably nimble on your feet, then have a go yourself. Just make sure you wear the correct personal protective equipment such as a mask and goggles.

When buying material, look out for the Energy Saving Trust Recommended logo to ensure you are buying insulation products that have been through a quality-control process and comply with building regulations.

Here are indicative savings for insulating the loft in a typical semidetached house:


Your home could lose up to 10% of its heat through the windows. Ideally, you should change those old, leaky windows to double- or triple-glazed units. However, this can cost thousands of pounds, so from an economical point of view it may not make sense. As an alternative, you can install secondary glazing.

Secondary glazing is a secondary pane of glass and frame, which can be fitted inside the existing window reveal. This won’t be as well sealed as a double-glazing unit, but will be much cheaper to fit, and will still save energy. If this is still too expensive, then even a sheet of clear plastic film stretched over the window reveal will help reduce wasted energy and money.

Other simple ideas to reduce heat loss through windows are curtains lined with a layer of heavy material or special thermal lining. However, do not let your curtains hang over a radiator as this will stop the heat from radiating into the room.

Hollow blinds, fitted into place with a sealed frame, and sealed shutters will also help cut draughts and keep your heat in for longer.

Make sure you close curtains and blinds before it becomes dark (and cold) outside. Conversely make sure they are open in rooms which face the morning sun so that they can be heated by solar power.


This is one of the cheapest and most efficient ways to save energy – and money – in any type of building.

There are two sources of fresh air entering your property, ventilation and draughts. While ventilation helps reduce condensation and damp, draughts if left uncontrolled can let in too much cold air, leading to heat wastage.

To draught-proof your home, you should block up unwanted gaps that let cold air in and warm air out. Keeping in warm air means you’ll use less energy to heat your home and save money at the same time.

Draught proofing shouldn’t be much of a problem if you can handle simple DIY jobs. Most products should be available from good DIY shops.


For windows that open, buy draughtproofing strips to stick around the window frame and fi ll the gap between the window and the frame.

There are two types:

  • Self-adhesive foam strips. Cheap, and easy to install, but may not last long.
  • Metal or plastic strips with brushes or wipers attached. These are longer lasting, so cost a little more. Make sure the strip is the right size to fill the gap in your window. If it is too big, it will be crushed and you may not be able to close the window. If it’s too small, there will still be a gap. Sliding sash windows are known to be draughty, and foam strips do not work well. It’s best to fi t brush strips or consult a professional. For windows that don’t open, use a silicone or foam sealant. This special type of foam can be sprayed into gaps around windows or doors. Draughts also occur in cracks between the window frames and the surrounding walls – in this instance, use sealant or putty for best results.


Here are the main things to consider when draught-proofing outside doors.

  • Keyhole – buy a purpose-made cover that drops a metal disc over the keyhole.
  • Letterbox – use a letterbox flap or brush, but remember to measure your letterbox before you buy.
  • Gap at the bottom of the door – use a brush or hinged flap draught excluder.
  • Gaps around the edges – fi t foam, brush or wiper strips like those used for windows.
  • Inside doors need draught-proofing, but only if they lead to a room you don’t normally heat, such as a spare room. Keep those doors shut to stop the cold air from moving into the rest of the house and block gaps at the bottom of the door with a draught excluder. You can make one stuffed with rice or bits of spare material.

Loft hatches

  • Put strips of draught-excluding material around the hatch edges.

Electrical fittings on walls and ceilings

  • Use sealants to fill gaps around the fittings.

Suspended floorboards, skirting boards and ceiling-to-wall joints

You can block cracks by squirting filler into the gaps. Floorboards and skirting boards often contract, expand or move slightly with everyday use, so you should use a filler that can tolerate movement. These are usually silicone-based. Look for flexible fillers, decorator’s caulk or mastic-type products.

Fillers for both indoor and outdoor use block gaps permanently, so be careful when you apply them. If there are draughts between the skirting board and the floor, seal as necessary. Ideally, you should insulate the void under the floor.

Cracks in walls

  • Squirt flexible wall filler into crack.

Chimneys and fireplaces

If you don’t use your fi replace, your chimney is probably a source of unnecessary draughts. There are two main ways to draught-proof a chimney if you don't use your fi re:

  • Fit a cap over the chimney pot – this might be better done by a professional.
  • Buy a chimney draught excluder – devices that help stop draughts and heat loss up the chimney, usually fitted within the chimney or around the fi replace.

Old extractor fans

  • Old fan outlets may need to be filled with bricks or concrete blocks and sealed from both the inside and outside.

Disused vents

Disused vents may be left behind after gas fires and old central heating boilers, with non-balanced flues, are removed. These should be sealed up, perhaps with an adjustable vent cover, or you can fill them with expanding polyurethane foam. You should block most of these, but be careful in areas that need good ventilation, such as:

  • Areas where there are open fires or open flues.
  • Rooms where a lot of moisture is produced, such as the kitchens, bathrooms and utility rooms.


If you’ve insulated your walls, loft and windows, you may be feeling a bit smug, but now is not the time to stop. Here comes the fiddly bit, insulating pipes, loft hatches, hot water tanks, secondary glazing, draught proofing and so on. By adding all these you could be saving another 25% of lost energy and significantly reducing your CO2 imprint. None of it is difficult; it’s just a little time consuming, so let us look at each in turn.

Energy-efficient doors


Replacing an old door with a high performance thermal door can keep your home warmer and reduce fuel bills. But like double-glazed windows, economically this is a tricky one. The cost to install a fully insulated composite door may be £400-plus, but the energy saved may only add up to £8 a year so the pay-back period is nearly 40 years. If you have the money, then it is the right thing to do. If it is unaffordable, then it may be better to buy a regular door and ensure that it is properly draught proofed (see page 67 for more on this).

Pipe insulation


This consists of a foam tube that covers the exposed pipes between your hot water cylinder and boiler. It’s usually as simple as choosing the correct size from a DIY store and then slipping it around the pipes. Not only does it save you money but it helps prevent frozen pipes. Speak to anyone who has had burst pipes and you will appreciate why this insulation is such a good idea.

Hot water cylinder


Insulate your hot water cylinder with at least an 80mm lagging jacket – a well-fitted jacket could save you around £25 to £35 a year and only costs £15. For more details on savings, see table below.

Loft hatch


Cooler air in an insulated loft could mean that cold draughts come through the loft hatch. To prevent this, fit an insulated loft hatch or foam board with polystyrene onto the inside of the hatch – small savings but they all count.

Ventilate your home

Air needs to flow in and out of your house so it stays fresh, dry and reduces condensation problems. Make sure you don’t block or seal any intentional ventilation, such as the following:

Extractor fans – take out damp air quickly in rooms where lots of moisture is produced (kitchens, bathrooms and utility rooms).

Underfloor grilles or air bricks – help keep wooden beams and floors dry.

Wall vents – let small amounts of fresh air into rooms.

Trickle vents – modern windows often have small vents above them to let fresh air trickle in.

Keep good ventilation in areas where there are open fi res or flues and in rooms where moisture is produced.

Don’t seal kitchen and bathroom windows, which let out the steam and helps create ventilation. Instead, seal the inner doors to these rooms.

Tony Whittingham is director of, a noncommercial and not-for-profit organisation that helps you save money and the environment in everyday life by minimising waste, pollution and carbon dioxide output.

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