Energy Efficiency
If you have gas central heating, your boiler will account for around 60% of your home's CO2 emissions, according to the Energy Saving Trust. This makes boiler efficiency a key priority if you're looking to cut your carbon footprint and your energy bills.
The age and type of boiler you have will affect how efficient it is. The efficiency of a boiler is normally expressed as a percentage.The table below illustrates how a modern condensing boiler could cut the cost of heating your home, whatever size house you've got.
Annual fuel costs with different boiler types (source: Sedbuk) | ||||||
|---|---|---|---|---|---|---|
Boiler type | Efficiency | Flat | Bungalow | Terraced | Semi-detached | Detached |
Old gas heavy weight | 55% | £267 | £341 | £354 | £397 | £550 |
Old gas light weight | 65% | £231 | £293 | £304 | £340 | £470 |
New non-condensing | 78% | £197 | £249 | £258 | £289 | £396 |
New condensing | 88% | £178 | £224 | £232 | £259 | £355 |
(A boiler that's 15 years old or more is classed as 'old' in these calculations. A lightweight boiler can be attached to a wall; a heavyweight boiler is floor standing.) Suggested savings of between £160 and £360 per year depending on the size of your house.
Condensing boilers
A high efficiency Dimplex condensing boiler is a good choice if you're looking for a greener and more efficient boiler. Conventional boilers are around 66-81% efficient, while condensing boilers are between 85% and 91% efficient. Condensing boilers make better use of the heat they generate from burning fuels such as gas or oil. With a conventional boiler, some heat is wasted in the form of hot gases released from the flue. A condensing boiler captures some of the heat from these gases and uses it to heat water returning from your central heating system. It therefore requires less heat from the burner and is more efficient.
Boiler efficiency?
The efficiency of a boiler can be measured or calculated in a number of ways for different purposes. For simple guidance it is sufficient to look at the SAP 2009 annual efficiency, which is an percentage estimate of efficiency when installed under typical conditions in Britain, taking into account climate, housing conditions, occupancy patterns, and controls.
SEDBUK and SAP 2009
SEDBUK is an estimate of the seasonal efficiency of a boiler installed in typical domestic conditions in the UK, and is used in SAP assessments and the building regulations. SEDBUK stands for 'seasonal efficiency of a domestic boiler in the UK', and has lettered ratings from A (efficiency more than 90%) to G (efficiency less than 70%). This was the boiler equivalent of the energy label found on domestic appliances such as washing machines, fridges and dishwashers.
Although SEDBUK is expressed as a percentage, an A to G scale of percentage bands was also in use until October 2010. This has been withdrawn to avoid confusion with the proposed European energy label using similar ratings based on different principles.
New building regulations require that only gas boilers with Sedbuk A and B ratings (ie. high efficiency ratings) can be installed, unless it's too difficult or expensive, in which case an exception procedure must be completed and certified.
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Could I save money on my fuel bill?
It's estimated that the average efficiency of boilers in UK homes is about 60%. This means they waste up to 40% of the heat they generate in the form of hot flue gases. Using more of this escaping heat to warm your water, rather than the outside, would reduce the amount of gas you need to burn to keep your central heating piping hot. Using less gas will obviously save you money on your gas bill.
The table above illustrates just how much a modern condensing boiler could cut your gas bills, suggesting savings of between £160 and £360 per year depending on the size of your house.
How to improve energy effciency
Being more efficient with your boiler doesn't just stop at the type of boiler you choose - there are also easy ways to cut your heating bills and optimise boiler efficiency.
Use a programmer - Heating programmers save you the hassle of having to manually switch the heating on and off and will help you to minimise unnecessary use. You can predetermine the times your heating is on in advance, set different programmes for different days of the week and set your heating system before you go away.
Room thermostats - Installing a programmable room thermostat in your home allows you to easily and accurately manage the temperature of your home. Wireless thermostats are now available, which makes the location of your thermostat more flexible. Position your thermostat away from electric fires, televisions or lamps, which could stop it from working properly.
Thermostatic radiator valves - Managing your radiators will help your central heating system to heat your home more efficiently and only in the areas of your home that require warmth. Thermostatic valves allow you to easily adjust the temperature of individual radiators and turn radiators off or on according to whether you're using a room or not.
Turn it down - Turning your central heating down by a degree can cut your heating bills by up to 10%.