UK homes are cold - what are the most cost effective insulation methods - Chimney Balloon

What is the most cost effective insulation measure?

Homes in the UK are notoriously draughty. It takes a lot of effort and money to retrofit them to be better insulated, and it can be confusing to work out which measures offer the best value for money. What are the most cost effective insulation measures?

We had a look at the measures recommended by the Energy Savings Trust and assembled them in a table comparing the cost of installing them versus the payback time in terms of savings on the heating bill.

MeasureCost to fitCost saving per yearPayback time
Hot water tank lagging£15£1301.5 months
Chimney draught exclusion£20
(Chimney Balloon Co)
(Chimney Balloon Co)
6 months
Loft insulation
(where there hasn’t been any at all)
£340£18023 months
Pipe lagging£20£1024 months
Cavity wall insulation£465£15037 months
Suspended timber floor insulation£525£60105 months
Loft insulation top up£275£20165 months
Internal wall insulation£8,750£245429 months
External wall insulation£15,000£245735 months
Double glazing£11,420
(The Eco Experts)
£801713 months

All data is taken from the Energy Savings Trust website except where stated otherwise. Figures are averaged over the various house types given.


Households are increasingly switching to combi-boilers so hot water tanks are becoming a thing of the past, but if you have a hot water tank then this absolutely should be lagged, or you will be wasting significant amounts of heat, and consequently money.

Chimney draft stopper

Having an open chimney is like leaving a window open all the time. BRE state that 80 cubic metres of air travels up a chimney per hour. It is difficult to quantify the energy savings of most draught exclusion products but with chimneys this can be calculated. A chimney balloon will prevent around 87% of airflow up a chimney, reducing other draughts as a consequence and saving around £40 per year off your heating bill.

Virgin loft insulation

Up to 25% of heat is lost from the home via uninsulated lofts. If you don’t have any loft insulation the this should be a priority.

Pipe lagging

It is surprising how many hot water pipes are left un-insulated. Pipe lagging is cheap and easy to fit, so it is well worth the effort.

Cavity wall insulation

Of the “bigger” measures, this is the cheapest and easiest to do, but it is important that it is fitted correctly.

Suspended timber floor insulation

Up to 15% of household heat is lost through the floor and although payback would be nearly nine years, it will make your home more comfortable. There are products that draught-proof the gaps between floorboards, and it is well worth installing this, but there is no data available to say what the carbon savings are for this draught proofing measure.

Loft insulation top-up

Although it’s not going to save nearly as much as putting insulation into a loft that has never been insulated before, it’s still going to make your home a lot cosier for a relatively low out-lay.

Internal wall insulation

Up to 35% of household heat is lost through uninsulated walls. It is an expensive measure though, so it is not really a case of installing it in order to save money, but to make your home more comfortable.

External wall insulation

As internal wall insulation.

Double glazing

The Energy Savings Trust had figures for how much it could save, but no estimates for fitting it (which they did for the other products, except for draught excluders). The lifetime of double glazing is around 20 years, so whichever way you calculate the costs, double glazing will save you some money off your bills, but never pay for itself. They will make your home more comfortable, reduce draughts, and look nice if you get the right sort.