1.9-Years
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 | £ 126 | £ 406 | £ 204 | £ 216 | £ 185 |
| Saving with modern 290mm insulation | 20% | 4000 kWh | £ 180 | £ 580 | £ 292 | £ 308 | £ 264 |
| Payback time with upgrade from thin to thick insulation | 6.5 years | 2 years | 4 years | 3.8 years | 4.4 years | ||
| Payback time with thick insulation (no other insulation present) | 1.9 years | 0.6 years | 1.2 years | 1.1 years | 1.3 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 | £ 189 | £ 609 | £ 307 | £ 323 | £ 277 |
| Saving with modern 290mm insulation | 20% | 6000 kWh | £ 270 | £ 870 | £ 438 | £ 462 | £ 396 |
| Payback time with upgrade from thin to thick insulation | 5.6 years | 1.7 years | 3.4 years | 3.2 years | 3.8 years | ||
| Payback time with thick insulation (no other insulation present) | 1.7 years | 0.5 years | 1 years | 1 years | 1.1 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.
then go to page 6
http://www.confusedaboutenergy.co.uk/index.php/heat-loss-and-insulation/loft-insulation
http://www.energysavingtrust.org.uk/Insulation/Roof-and-loft-insulation/Loft-insulation-materials
hope they helped and good luck!
why is loft insulation needed?
how loft insulatn reduce heat loss?
how tha thickness of the loft insulaton affects heat loss?
please answer these questions:
why loft insulation is needed
how loft insulation reduces heat loss
how the thickness of the loft insulation affects heat loss
thanxs..xx
How does the thickness of the loft insulation affect heat loss??
The thicker the loft insulation is the more heat loss will be reduced as if it is thicker the more air is trapped between the layers of insulation and thermal energy cannot pass through trapped air causing it to not leave the house. Different materials hold in heat at different rates. The higher the R-value of the material, the better it will be at holding heat in.
hope this helped im doing my science gcse too. here is some extra information about loft insulation:
What is Loft insulation?
Loft insulation is method for many people to make their houses energy efficient. To prevent heat loss, loft insulation acts as a blanket trapping rising heat in the house. Without loft insulation a house would loose 25% of heat through the roof. Using Loft insulation benefits many people as it reduces heating bills in an effective way. When combined with wall insulation, adequate heating and controlled ventilation loft insulation also helps to prevent the formation of surface condensation, damp and mould growth.
How does loft insulation prevent heat loss?
Loft insulation works by preventing the movement of heated air through the insulation material, by trapping the air in the fibres.
More detailed:
The ceiling is a conductor and energy is transferred into the loft. If there is no insulation, the air at the base of the loft warms up and then a convection current of warm air moves through the roof space and escapes through the tiles. If the loft is insulated, the air in the insulation cannot move around the loft by convection. Loft insulation acts like a blanket, helping prevent heat escaping through the roof. Convection currents can transfer heat energy in the loft to the roof tiles. It has trapped air which is a poor insulator.
why is loft insulation needed?
how loft insulatn reduce heat loss?
how tha thickness of the loft insulaton affects heat loss?
essentially insulating materials are poor thermal conductors. The density of the atoms and molecules in the materials greatly effects conductivity as heat is transferred effectively by 'packets' of energy moving from atom to atom. Metals are very dense and conduct heat very well and are not good thermal insulators. A Vacuum (the big bit in space or the bit surrounding a a thermos flask) is void of matter and does not conduct heat. air trapped in a woolly jumper or loft insulation is not a dense material and does not conduct heat well and so is a good insulator.
density is not the only factor by the way
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.
It is amazing the variations, last month we had someone write in to say they were using 33,000 kWh per year to heat their three bed bungalow. You are using less than 9000kWh for heating and yes 20% of this corresponds to about £200 at your charge rate.
In the article we state this:-
*Calculations assume the energy required to heat an un-insulated 3 bed house is 20000 kWh
(assumptions are here: http://www.confusedaboutenergy.co.uk/index.php/heat-loss-and-insulation/heat-loss)
Uninsulated is the key word here. If you already have loft insulation and double glazing the proportional effect of adding cavity wall insulation will be lessened, the heat flow through the wall remaining static and being governed by thermal gradient and wall materials.
From you email, do you live in Jersey? 12p per kWh for gas, wow, is it really that much! Is it LPG?
the 20000kWh number comes from UK averages, and includes all climates by the way.
would you consider putting you data on our survey?
http://www.confusedaboutenergy.co.uk/index.php/the-real-house-survey
cheers
Richard
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