Heating

domestic heat loss

Most people rely on gas and/or electricity to heat their home and to provide themselves with hot water. Around one sixth of the carbon dioxide that the UK generates comes from the gas and oil boilers that we use to heat our homes. This section concentrates on how to save gas and electricity used for heating.

Heating tips:

  1. Learn how to programme your heating

  2. Manage your central heating controls

  3. Manage your hot-water heating and storage

  4. Replace a 10-15 year old boiler

  5. Generate your own renewable energy

 

Overview 

The best way to reduce greenhouse gas emissions from fossil-fuel energy used in the home is to follow these three steps in turn:

1) reduce energy consumption (this may cost nothing to do and generally saves you money)

2) use energy more efficiently (this may cost money initially but makes a bigger impact on climate change)

3) use or generate energy from renewable sources (this can be expensive but it will make the biggest impact).

The Energy Saving Trust is an excellent source of advice on these topics.

 

Typical energy use in the home

In most homes, the use of electricity for appliances and cooking is fairly steady throughout the year and only varies slightly with the seasons as the demand for lighting varies. However, if you have electrical storage heaters or oil-filled heaters, your electricity consumption will depend on your heating needs as well. Similarly, gas consumption will vary with the seasons if you have a central heating gas boiler; a typical profile of cumulative gas use over a year is shown in the diagram. Your electricity consumption will follow a similar pattern if you have electrical heating.

Find out where your gas and electricity meters are and use them to monitor your consumption during the year (gas and electricity companies often estimate their meter readings; do not rely on your energy bills for this information). If you read the meter regularly you can make a plot like the one above. To manage your gas and electricity consumption you need to measure and monitor it first.

CO2 impact

For every kilowatt hour (kWh or unit) of electricity you consume at home, on average 0.590 kg of carbon dioxide (CO2) is emitted at a power station. Similarly, burning the equivalent of 1 kWh of gas emits 0.227 kg of carbon dioxide. However, even though electricity is two and a half times more polluting per kWh than gas, in general in a year homeowners are responsible for the emission of more carbon dioxide from using gas (mainly for central heating) than electricity.

If you consult your gas and electricity meters, you will be able to work out exactly what your household emissions are (allow 0.590 kg CO2/kWh for electricity and 0.227 kg CO2/kWh for gas).

Money aspects

If you look at the diagram above (and your energy bills) you can see that much more energy is used during winter than in the summer. Therefore one way to save a significant amount of money is to cut back on heating. This can be done without being colder by improving the heating control system and insulation of your home.

Energy prices are changing rapidly at the moment and, because companies offer so many different types of contract, it is hard to estimate what you will pay for gas or electricity. I have used the prices for the marginal cost of gas (4.4 pence/kWh) and electricity (13.3 pence/kWh or unit) from  mid-2013 bills in the calculations below. Remember that when estimating any payback time that energy prices are likely to continue to rise in future. Grants are available for some energy saving measures.

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1. Learn how to programme your gas-guzzling boiler (if you have one) or other heaters

Central heating boilers are invariably fitted with a timer-programmer; if your electrical heaters haven’t got a timer-programmer, buy one or get an electrician to fit one. Set the boiler and heater timer-programmers so that they heat the home only when needed; for example, there is no point in having the heating on during the day if the home is unoccupied or at night when you are tucked up in bed. Many timer-programmers can be set for different times on different days of the week to match your lifestyle. It may also be appropriate to change the timer-programmers ON/OFF times with the season of the year; in many cases a central heating boiler can be switched off completely from about April to about September although you may need it to generate hot water.

CO2 impact

Suppose you have a condensing (non-condensing) gas boiler that operates at an output of around 15 kW. This means that if it has an efficiency of 90% (60%) it will emit the equivalent of 3.4 (5.2) kg of carbon dioxide for every hour it is burning gas. So, if you save one hour of boiler burning-time per day for half the year you will save over 600 (900) kg of carbon dioxide per year!

Similarly, if you have two electric storage heaters each rated at 3 kW, a one-hour per day reduction in heating for half the year will save about 650 kg of carbon dioxide per year.

Money aspects

The above suggestions generally cost nothing to implement and will immediately save you money. Even if you need to buy a timer-programmer, it shouldn’t take long to pay for itself.

Suppose you have a condensing (non-condensing) gas boiler that operates at an output of around 15 kW and has an efficiency of 90% (60%). If you can save one hour of boiler burning-time per day for half the year you will save 3042 (4563) kWh or around £135 (£200) per year!

Similarly, if you have two electric storage heaters each rated at 3 kW, a one-hour per day reduction in heating for half the year will save 1095 kWh or around £145 per year.

Other benefits

Cutting back on heating may reduce the temperature of your home. We’re not suggesting that you should reduce the temperature so much that you feel cold – this could harm your health, particularly if you are elderly. However, it is simple to keep warm by wearing appropriate clothing or by putting on an extra layer of clothes. Also, your home doesn’t need to be warm if there’s no one there.

If you use your boiler less it will extend its life, but it will still need regular maintenance.

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2. Manage your central heating controls

Ideally, central heating boilers should have a 2-channel programmer that allows the central heating and hot water cycles to work independently. Some 2-channel programmers will fit the same wall socket as a 1-channel programmer and can be changed by the home owner.

As well as the timer-programmer, the central heating boiler is usually controlled by thermostats that sense a) the temperature in the water leaving the boiler and b) the air temperature in the home. Boilers work most efficiently at a particular temperature; chose a water temperature setting suitable for your boiler. The air temperature or room thermostat should be set as low as is comfortable. If you feel cool, put on another layer of clothing. Turn the thermostat down (or the heating off) before you go to bed.

If you have lost the handbook for your boiler, ask the manufacturer for another one. Sometimes such information is available on the internet.

You may not need to heat all rooms to the same temperature – there’s no need to heat rooms that no one is using. Individual room temperatures can be controlled by thermostatic radiator valves (TRVs) or by (programmable) air thermostats. (TRVs can be fitted by a competent DIY enthusiast although this may involve draining the radiators.) If a TRV is fitted to a radiator close to an air thermostat it should be removed or set to maximum otherwise the boiler may ‘hunt’ to reach a room temperature which the TRV is preventing it from ever achieving.

CO2 impact

Turning down the room thermostat by 1°C could save you around 350 kg per year.

Money aspects

A 2-channel boiler programmer costs around £50. Consult your boiler manufacturer to find one that suits your model.

Changing settings costs nothing. A recent report from the Energy Saving Trust indicated that turning down the room thermostat by 1°C could save you up to 10% of your heating bill, around £60 per year for an average property.

A thermostatic radiator valve costs between £5 and £20.

Other benefits

Cutting back on heating may reduce the temperature of your home. We’re not suggesting that you should reduce the temperature so much that you feel cold – this could harm your health, particularly if you are elderly. However, it is simple to keep warm just by wearing appropriate clothing or by putting on an extra layer of clothes. Also, rooms don’t need to be warm if no one’s using them.

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3. Manage your hot-water heating and storage

This tip only applies to those homes with hot-water cylinders; homes with combi-boilers don’t have a cylinder.

All hot-water cylinders should be insulated by a factory-applied foam outer layer or by a jacket installed on site or both. Make sure that your hot-water cylinder has a jacket at least 75 mm (3 inches) thick. Ensure that the hot water pipe work around the cylinder is insulated with special purpose pipe wrap.

If you use an electric immersion heater to deliver hot water, consider fitting it with a timer-programmer; this could allow the heater to operate twice a day and even at different times on different days of the week to match your lifestyle.

Many hot water cylinders have a water temperature thermostat strapped to the outside which is wired back to the central heating boiler. When the water in the cylinder reaches the set temperature the boiler stops providing hot water until the temperature drops again. Check that the temperature is set to 60°C or less depending on the height of the thermostat up the cylinder. Alternatively, just test the water which comes out of your hot tap – is it so hot that you need to mix it with cold water to be safe or comfortable? If so, then it is too hot and you are wasting energy.

CO2 impact

Fitting an insulating jacket at least 75 mm (3 inches) thick to your hot water cylinder can save 160 kg of carbon dioxide per year.

Money aspects

An DIY insulating cylinder jacket costs around £15-20, but can reduce your gas bills by around £20 a year so it quickly pays for itself.

A hot-water cylinder thermostat costs around £13 and an immersion heater timer costs around £15. Wiring and fitting the thermostat will cost extra if you don’t do it yourself. In any event you must have the wiring checked by a competent electrician.

Other benefits

We all need hot water for washing and showering but there is no point in heating up water unnecessarily or to too high a temperature.

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4. Replace a 10-15 year old central heating boiler with a 90% efficient condensing boiler with modern controls and sensors

A condensing boiler is one which extracts and re-cycles heat from the flue gases to make the boiler run more efficiently. Therefore the vented gases are cooler and partly condense into water vapour on leaving the flue. At present, condensing boilers are of interest to many home owners because they are much more efficient than boilers installed before the late 1990s and because by law most new or replacement boilers (whether using gas, oil or liquefied petroleum gas) must now be a condensing boiler. Modern boilers are also more ‘intelligent’ and may incorporate wireless sensors around the home and adjust their heat output according to the indoor and outdoor temperatures. Both ordinary boilers and combi boilers can be replaced by an appropriate condensing boiler.

CO2 impact

Changing from an old central-heating boiler to a condensing boiler is one of the best ways that an individual can reduce their greenhouse gas emissions.

Boilers that are over 10-15 years old may be only 55-65% efficient yet the latest condensing boilers with a SEDBUK A rating (SEDBUK = Seasonal Efficiency of Domestic Boilers in the UK) are about 90% efficient. This means that to provide the same heat output a condensing boiler will burn only two thirds of the gas used by the old boiler, resulting in an increase in efficiency of one third. So, for example, if your boiler presently consumes the equivalent of 18,000 kWh of gas per year, close to the UK average per household, you will save around 6,000 kWh of gas and 1.3 tonnes of carbon dioxide per year when you fit a condensing boiler.

Money aspects

It is quite expensive to fit a new condensing boiler (around £2000 depending on the rated output and installation) but the savings can be substantial. It is advisable to obtain several quotes from Gas Safe Register or OFTEC heating engineers. At the same time consider upgrading your boiler controls. Grants are available, consult the Energy Advice Centre in Southampton (0800 8048601).

Saving 6000 kWh of gas per year equates to a saving of around £260 per year.

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5. Generate your own renewable energy

Once you have minimised your consumption of gas and electricity for heating and set up your home to use energy in the most efficient way then the next step is to consider ways of using renewable energy.

If you have a chimney and access to a source of logs, then a wood-burning stove is one solution (although a special flue will need to be fitted to some chimneys). Some stoves can even heat hot-water too. For many people a wood-burning stove is an excellent way of keeping warm on those occasional chilly spring and autumn days and evenings when the central-heating system is off. More ambitious systems use woodchip boilers for central heating and hot water or ground-source heat pumps for underfloor heating. To install a wood burning stove, see the National Energy Foundation's  log pile website  for a list of retailers and manufacturers. Or why not give a second-hand stove a home: they are virtually indestructible and sell on eBay for as little as £50!

Solar panels to provide domestic hot-water are the best choice of renewable energy for many people but even so they depend on the availability of a suitable south-facing roof or wall. On 11 June 2012, the Government announced the revised details of the Renewable Heat Incentive Scheme under which householders will be paid a premium for generating solar hot water.

A Feed-in Tariffs (FITs) scheme was introduced by the government on 1 April 2010, under powers in the Energy Act 2008, to allow the government to pay domestic consumers who generate their own electricity from solar photovoltaic (PV) panels.

In summary, a wide choice of technologies is available which is too broad to consider here. More information can be found at Better Generation or in Boyle, G., Ed. (2004), Renewable energy: power for a sustainable future, Oxford University Press in association with the Open University.

CO2 impact

By definition, a renewable heating or hot-water system either emits no carbon dioxide or else the source of energy, such as wood, is sustainable which means that the emitted carbon dioxide is part of a natural cycle of tree growth (which absorbs carbon dioxide), followed by death and decay (which emits carbon dioxide). However it can be argued that some carbon dioxide emissions are embodied in the manufacture and delivery of stoves and solar panels, for example.

Money aspects

The installation of renewable and sustainable energy sources can be expensive, but you will save money on your energy bills so it will often pay for itself in the medium to long term. Often the main incentive is simply to reduce one’s carbon dioxide emissions and carbon footprint.

To ensure that you get the best price when installing renewable energy, always get at least two quotes from installers. The energy saving trust can provide some guidelines for looking for a good supplier.

The government will now pay a feed-in tariff of up to 14.9 p/kWh for new photo voltaic cell produced electricity ( until 1st January 2014). Other forms of renewable energy may also be eligible for the payments of feed-in tariffs.

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If you would like to give feedback on this site, or have any suggestions for improvement, please contact us. We are particularly keen to hear about other organisations and initiatives in and around Winchester which can help people reduce their carbon footprint.

The information on this page is provided in good faith and reflects our understanding of the underlying science and technology at the time of writing, but we cannot guarantee that it is wholly accurate. All figures for costs, savings and other matters are estimates: the actual figures will depend on your particular circumstances and may differ (perhaps significantly) from those shown. Although we have included links to various organisations, we are not recommending these organisations: it is your responsibility to check that they are suitable for your needs. Nonetheless, if you experience difficulties with any of the links or organisations, or believe that any of the information presented here is inaccurate, please let us know and we will update this page if we consider it necessary.