Radiator dial set to sleep
36

Change your heating

Room heating and hot water account for well over half of domestic energy consumption. Fully insulate your home and upgrade to an efficient modern heating system. If you use fossil fuels, consider changing to something with far lower emissions, such as wood/biomass, biogas, sunshine or a heat pump.

Image of person holding the sunset.

How much heat do you need?

In the long run, the cheapest and best option is to significantly reduce heat demand via energy efficiency. Before you invest in any new technology, find out how much energy you currently use and do all you can to reduce it (see Action 40: 'Warm your home efficiently'). Better insulation and an efficient boiler can halve heating needs in typical UK homes, twice the reduction from installing an air source heat pump. Best of all, do both; the highest insulation standards combined with heat pumps can reduce heating energy needs by 95%. 

Fuel

The table below compares the carbon emissions of the main domestic fuels. Oil, liquid petroleum gas and coal have unacceptably high carbon footprints and should be replaced. Electricity is high carbon unless you use a renewable supplier or generate your own (for an explanation read Action 23: 'Choose renewable energy' and Action 10:  'Generate your own electricity'). Wood, heat pumps, geothermal, biogas and heat from the sun are all low-carbon choices.

Fuel

 

Efficiency

 

Grams of CO2 per Kilowatt hour

Notes

 

Oil boiler

 

Least efficient

         550

Replace!

 

Most efficient

        310

Replace!

Coal

 

        360

Replace!

 

Liquid Petroleum Gas

 

 

        230

 

Replace!

 

Electric heater

 

Electricity at 370 gms/ kwh

 

        370

 

Entirely dependent on the carbon footprint of the electricity used...

 

 

Electricity at 100 gms/ kwh

        100

 

...so replace where you don't have access to low emission electricity.

 

Gas boiler

Least efficient

        380

Replace!

 

 

Most efficient

        210

 

Natural gas is the cleanest fossil fuel, and is cheap, efficient and easy to use. But it still emits a lot of CO2!

Ground source heat pump

Electricity at 370 gms / kwh

 

     70-190

 

Uses electricity to bring warmth from outdoors inside. Produces 3-4 units of heat for every unit of electricity, much more efficient than electric or gas...

 

Electricity at 100 gms / kwh

     20-50

 

...but more expensive than a new boiler, though grants may be available; it takes 5 to 15 years to pay for itself.

Air source heat pump

Electricity at 370 gms / kwh

     90-250

 

Cheaper and easier to install than a ground source heat pump, but less efficient.

 

Electricity at 100 gms / kwh

      30-70

 

 

 

 

Biogas

 

 

     20-100

Bio-methane is generated from food waste in a bio-digester. See Action 45 'Use innovative technology'

Biomass boiler

 

    Under 100

Good replacement for oil or coal, although a pellet boiler system is expensive to install.

Geothermal

 

 

 

         10

 

Unless you live near a volcano or hot spring, it’s not practical. If you do, it’s the perfect heat source.

Solar thermal

 

 

     10-35

A system where pipes on the roof allow the sun to directly heat domestic hot water. (Not PV panels).

Wood logs

 

 

       15

 

Wood is carbon neutral. But transport isn't, and smoke lowers air quality. Great if you have your own source of wood. 

Source

Wood Shed With Solar Panels Attached To Roof

Sunshine

A great carbon-neutral fuel source which is entirely free is sunshine. You can 'harvest' this by adding a solar greenhouse or conservatory to your home to capture and store the sun's heat (passive solar gain). Build it along the sunniest external wall of your house, allow the heat to circulate into your house, and add thermal mass to store the heat. Include venting and screens so it doesn't overheat in summer.

A simple ‘bread box’ solar water heater can be constructed from recycled materials. It consists of black tanks mounted inside an insulated box. The lid should be well sealed and of transparent glazing material. Cold water enters the tank near the bottom, heats and rises to the top where it is piped back into the home.

Heating systems

Which technology is best? There’s no definitive answer. It depends on your heating needs, the efficiency of the model you buy, the amount you spend, the local climate, your area’s power grid, and how well you maintain the system. Before you spend any money, research widely on-line and consider paying for professional advice.

Central heating radiators are expensive to install, depending on what system you are installing and the size of the property. However, the savings can be quite dramatic and they provide very good thermal comfort. Using mains gas, biomass, a heat pump or solar thermal will all generate significant savings. The best way to work out just how much is to employ an expert.

Underfloor heating is efficient because it turns the whole floor into a radiator. The large surface area means it doesn’t have to be a high temperature to warm the room. It can be expensive to install (especially if retrofitted) but uses 15-40% less energy than traditional radiators. Source.

District heating systems

Also known as heat networks, these generate heat in a central location then distribute it to multiple buildings. They are best suited to dense urban areas and new builds. Low-carbon heat sources can include waste heat, heat pumps, geothermal and bio-methane. Some European countries provide the majority of their energy from district heating.

Open fire/stove

These may look lovely but are generally inefficient and won't heat a whole house. An efficient wood stove with heat recovery and a back boiler might do the job, and you can cook on it as well. Rocket stoves are super efficient as they burn the smoke as well as the wood. When thermal mass (clay or bricks) is added to store and circulate the heat they can provide high thermal comfort.

Micro-CHP

Micro combined heat and power generates heat and electricity simultaneously, from a special boiler. A typical domestic system can generate up to 1kW of electricity per hour, enough to power the lights and appliances. It costs about double a conventional boiler, but generates free electricity.

A Buyers Guide to Renewable and Low Carbon Technologies

Picture credits: 1) TBI Toni - pixabay.com 2) Babin Shrestha - unsplash.com 3) Manfred Antranias Zimmer - pixabay.jpg 
Action
SIMPLE ACTION

Do a home energy assessment

EVERY DAY ACTION

Replace fossil fuel with a low-carbon fuel source

COMMUNITY ACTION

Suggest neighbours and family follow your example

GLOBAL ACTION

Campaign for subsidies for energy efficient home improvements

Earth Care icon
EARTH CARE:
Using less fuel for heating means using less of the Earth’s resources
Fair Share icon
FAIR SHARES:
Subsidies for improved heating systems help poorer households keep warm
People Care icon
PEOPLE CARE:
A warm home is healthy and comfortable for family and friends