Since heat rises it follows that heat loss through the roof is a large contributor to energy waste in your house. By installing modern 290mm thick insulation in your loft space you could save up to 25% of your heating bill but perhaps more realistically by 20% . By upgrading old thin insulation you may also be able to save an additional 7 or 8% of you bill. The cost of installing the new thick insulation or of an upgrade is fairly modest at about £ 350 for a smaller house and about £ 450 for a larger house.
The effect of only adding loft insulation in the example 3 bed house is shown below with the indicative insulation install of £ 350 to calculate an approximate payback time with several fuel source options.
| 3 bed house* | Approx % energy saving | Approx Energy Saving | Gas |
Electric (Std) | Economy 7 | LPG |
Fuel Oil |
| Savings with thin insulation | 14% | 2800 kWh | £ 87 | £ 330 | £ 112 | £ 151 | £ 120 |
| Saving with modern 290mm insulation | 20% | 4000 kWh | £ 124 | £ 472 | £ 160 | £ 216 | £ 172 |
| Payback time with upgrade from thin to thick insulation | 9.4 years | 2.5 years | 7.3 years | 5.4 years | 6.8 years | ||
| Payback time with thick insulation (no other insulation present) | 2.8 years | 0.7 years | 2.2 years | 1.6 years | 2 years | ||
| *Calculations assume the energy required to heat an un-insulated 3 bed house is 20000 kWh | |||||||
| 5 bed house* | Approx % energy saving | Approx Energy Saving | Gas |
Electric (Std) | Economy 7 | LPG |
Fuel Oil |
| Savings with thin insulation | 14% | 2800 kWh | £ 87 | £ 330 | £ 112 | £ 151 | £ 120 |
| Saving with modern 290mm insulation | 20% | 4000 kWh | £ 186 | £ 708 | £ 240 | £ 324 | £ 258 |
| Payback time with upgrade from thin to thick insulation | 8.1 years | 2.1 years | 6.3 years | 4.6 years | 5.8 years | ||
| Payback time with thick insulation (no other insulation present) | 2.4 years | 0.6 years | 1.9 years | 1.4 years | 1.7 years | ||
| *Calculations assume the energy required to heat an un-insulated 5 bed house is 30000 kWh | |||||||
Is it worth doing?
This is one of the single most cost effective things you can do to save money and the environment. The payback time is very short and the long term reward is great. Many of us are also eligible for grants from the warm from scheme, energy companies and local authorities (check with your local energy advice centre). If you cannot get a grant, supermarkets are also offering good deals and DIY installation will also save a packet! It is almost insane not to insulate your loft and even "top-up" insulation offer a better payback than any renewable energy option.
eg 25% loft
10%windows etc