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 | £ 115 | £ 384 | £ 129 | £ 207 | £ 174 |
| Saving with modern 290mm insulation | 20% | 4000 kWh | £ 164 | £ 548 | £ 184 | £ 296 | £ 248 |
| Payback time with upgrade from thin to thick insulation | 7.1 years | 2.1 years | 6.3 years | 3.9 years | 4.7 years | ||
| Payback time with thick insulation (no other insulation present) | 2.1 years | 0.6 years | 1.9 years | 1.2 years | 1.4 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% | 4200 kWh | £ 172 | £ 575 | £ 193 | £ 311 | £ 260 |
| Saving with modern 290mm insulation | 20% | 6000 kWh | £ 246 | £ 822 | £ 276 | £ 444 | £ 372 |
| Payback time with upgrade from thin to thick insulation | 6.1 years | 1.8 years | 5.4 years | 3.4 years | 4 years | ||
| Payback time with thick insulation (no other insulation present) | 1.8 years | 0.5 years | 1.6 years | 1 years | 1.2 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. There are some grants from 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.
This seemed too good to be true and of course it was. Our annual bill is £1500 but taking out the standing charges and estimated gas usage for hot water we were left with £822 as a good estimate of what portion of the bill is actually heating. This equates to a possible £164 PA @ 20% saving due to cavity insulation which I think is more realistic. This is still a substantial saving and awaiting quotations to calculate possible payback period.
I was quite suprised to see that we use on average less than half the energy consumption for a 3 bed house than your estimator is using.
well actually me , because i love this kind of thing !
THANK YOU GOD FOR CREATING PHYSICS
now to watch universitychallenge and antiques roadshow !!
hurrah !!
eg 25% loft
10%windows etc