Home Energy Team
Plymouth City Council
Plymouth PL1 2AA
- Loft insulation
- Cavity wall insulation
- What if you have solid walls?
- Draught proofing
- Hot water cylinder jacket
- Ground floor insulation
- Double glazing
If your home isn't properly insulated you will be paying money to heat the air outside your house or flat. For a typical semi-detached house the equates to:
- 35 per cent of energy is lost through walls
- 30 per cent through the roof
- 20 per cent through windows
- 15 per cent through doors and floors
By insulating your home you will save money but how quickly you recoup this money depends on the type of insulation you choose. As a rough guide:
- Cavity wall insulation - payback in less than two years
- Loft insulation - payback in around one year
- Draught proofing doors and windows - payback in around four years
- Hot water cylinder jacket - payback in around six months
- Ground floor insulation - payback in less than three years
Loft insulation is the most cost-effective energy efficiency measure. The most common form of loft insulation is a mineral wool quilt which comes in roll form but other types include sheep's wool and cellulose made from recycled newsprint.
Current building regulations require a depth of 250mm to 300mm of insulation. If you already have loft insulation of 50mm or less you should consider topping it up.
Cavity wall insulation is the second most cost-effective energy efficiency measure.
In general, homes built since about 1930 have cavity walls and the insulation is installed by drilling holes into the mortar between bricks in the outer skin of the wall and pumping or blowing the insulating material into the cavity. The installer will fill holes with mortar that matches the existing colour as far as possible. The height of the building and its exposure to wind-driven rain will determine which material is best.
Cavity wall insulation should be installed by a specialist contractor. Make sure they provide you with a Cavity Insulation Guarantee Agency (CIGA) guarantee.
Most homes built before 1930 have solid walls and are often referred to as 'hard to treat'. The most common forms of solid wall insulation are internal, such as dry-lining, and external, such as thermal render.
External wall insulation is much more costly than cavity wall insulation. Our recent pilot scheme has shown that average costs for a three bedroom semi are between £10,000 and £12,000. The installation process involves fixing insulation boards to the existing walls and applying several layers of render on top. One of the advantages of external wall insulation over internal insulation is it causes minimal disruption to the occupants.
There are several ways of insulating internally, from dry lining to thermal wall coverings.
Although more expensive than cavity wall insulation, the costs will eventually be recouped in reduced heating bills.
Draught proofing doors and windows is a low-cost way of reducing your energy bills Various types of seals and brushes are available for doors/windows and letter box covers can easily be fitted. In the winter putting up heavy lined curtains can help to keep out draughts and keep warmth in the room.
If you have a hot water cylinder and it is fairly new it will have 50mm to 80mm of factory-applied sprayfoam insulation. Older cylinders will require insulation with a jacket, which should be about 80mm thick. It will cost between £10 and £20.
Common forms of floor insulation are mineral wool quilts, rigid insulation boards or blown insulation. Installing insulation - below floorboards for example - can be disruptive. Floor insulation is particularly beneficial in detached houses, where heat loss through the floor perimeter is highest. It is possible to insulate on top of the ground floor, which will be less disruptive. However, you will lose some room height.
Double glazing will improve the energy efficiency of your home. However, you would not replace windows to improve energy efficiency; you would replace them because they are beyond economic repair. It is not therefore strictly an energy efficiency measure, mainly because it is extremely expensive and will never pay for itself in reduced heating bills. Because of this, grants such as Warm Front are not available for double glazing.