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.

Source

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