Heat loss occurs through the envelope of the property (the walls, floor and roof). Insulation is a great way of slowing this heat loss; our external wall insulation systems, for example, dramatically slow the rate at which heat moves through the wall.
How can insulation save you money?
Why does the above save you money on your energy bill? Well, most of us heat our homes with central heating systems (a gas boiler and radiators), or electric heating. When either of these heating systems is turned on, the air is heated up. In an uninsulated house, this hot air escapes quickly through the external walls, the ceiling and the floor. But when you add insulation to any of these different areas, the hot air can’t escape as quickly. It doesn’t need to be constantly replenished by your heating system, so you save money by being able to use the heating less!
How much would insulation save me?
Putting a figure on exactly how much money insulation will save you is tricky though. It depends on your current energy usage, how much insulation is added and the type of insulation added – as well as where on the house it is installed.
For example, some people heat their homes to 25 degrees centigrade even in the middle of the winter and think nothing of it. Others are reluctant to turn on the heating until the end of November! The amount of money you will save on your heating bill is dependent on where on this scale you sit; a high energy user (who likes their home nice and warm) will save more than someone who only turns their heating on 4 days a year.
The thickness of insulation is also important, as the energy savings of 100mm of insulation will be more than the energy savings resulting from adding 20mm of insulation (provided the insulation material itself is the same). More insulation will result in bigger energy savings.
Anyway, lets try and put an approximate figure on the amount you might save on your energy bill when you insulate. Aaccording to the BEIS, in 2016 the average gas bill was £650. Approximately 80% of the average gas bill is normally spent on heating, while the other 20% is spent on heating. Based on this, £520 can be contributed to heating. If 90mm of EPS insulation is added to the wall (meaning the U-value goes down to 0.3W/m2k), then you can expect to halve your heating bill. So you would save approximately £250 per year by installing external wall insulation on your property.
Now as we have mentioned previously, this figure can change dramatically depending on how much you heat your house and the temperature you heat it to. If you are a high-energy user, then you could save nearer £500 per year on your gas bill by installing solid wall insulation.
Basically, what it shows is that while the initial cost of getting some of these works done on your property is high (for external wall insulation you are looking at anywhere between £80 and £120 per m2), the energy savings do make a significant difference to your heating bill. Bearing in mind that in 2005, the average energy bill was just £580 (which included both gas and electricity) and now it is more like £1300, it makes sense to speculate that energy prices in 2025 will be considerably higher than they are now. This means the energy savings from installing insulation measures on your home will continue to rise.