Regardless of how well insulated your home is the boiler will burn fuel and supply heat to your radiators until the temperature set on this thermostat is reached, before switching itself off. This does not mean that all of the rooms in the house are at the main thermostat temperature, their temperature will be dependent on the heat loss from the room, the radiator heat output of each room and the individual radiator thermostat (if you have them fitted). So the more you can do the reduce heat loss from your home the more rapidly the desired temperature will be reached and the earlier the boiler will switch off, ultimately reducing the amount of fuel you burn and amount you pay.
This is all fairly obvious, what is less easy to determine is what you should look at first to reduce heat loss, which will be the most cost effective for you, and how much should you look to invest to get a sensible return on your investment.
Where is the heat loss?
Some of the areas where heat is lost in the average home, with some of these contributing much more to overall heat loss than others are as follows, Roof/loft; The walls; The floor; The windows; Gaps in the doors; Air vents **; Clothes Dryer; Vents; Fire places; Attic hatch. The percentage heat loss attributed to various areas of your house is usually quoted by most commentators on the subject, the numbers generally accepted are :-
|Doors and Drafts||15%|
**Please note that some air vents are important for your health!
As an observation a percentage is not a helpful way to consider heat loss, since no matter how well your house is insulated ultimately all the heat will eventually dissipate from the property, given that it is cooler outside. It is more instructive to consider how much energy each insulation measure will save and to calculate how much money that will save depending on the fuel you are burning to keep warm, and then to calculate a payback time for any investment you have made. Throughout this section this is the method used.
Relatively old un-insulated houses (perhaps 1930’s) are used as examples in this section of the site, since newer houses are likely to have insulation pre installed. Two sizes have been chose, a 3 bed and a 5 bed house; clearly a 4 bed house will lie in the middle somewhere. Keeping each of these warm for most of the year given that they have no effective insulation installed will use approximately 20,000 kWh of energy for the three bed house and for the larger house about 30,000 kWh. The table below shows how much this energy costs with several fuel source options.
|House size||Estimated energy use to
heat house for a year
||Electric (Std)||Economy 7
|3 bed||20,000 kWh||£ 780||£ 3740||£ 1880||£ 1400||£ 880|
|5 bed||30,000 kWh||£ 1170||£ 5610||£ 2820||£ 2100||£ 1320|