A thermostat showing that the temperature is 63

Eco heating: what are the options?

With soaring energy bills and worse to come, is eco-heating the answer? Discover sustainable ways to heat your home, without heating the planet. Mike Childs, Head of Science, Policy and Research at Friends of the Earth, reviews the pros and cons of the best options for home-owners and renters, including heat pumps, insulation and smart controls.
Picture of Mike Childs
By Mike Childs    |      Published:  11 Oct 2018    |      Last updated:  23 Nov 2021    |      11 minute read

Your gas or oil boiler – which will heat your radiators and water – will already be costing you a fortune in heating bills, or it will when the price cap on energy bills is lifted next April. It will also be undoing your attempts to slash your climate-wrecking emissions.

For example, an ordinary small, terraced house with a well-insulated loft and a modern gas-fired boiler will produce around 2.75 tonnes of planet-warming greenhouse gases a year – the same amount as driving 11,770 miles in an average car or flying 11 round trips to and from Rome.

Eco heating is all about reducing carbon emissions, protecting our environment and keeping you warm. So, if you’re lucky enough to be a homeowner, and you want to cut your home’s carbon footprint and cut your energy bill, what are your options?

Save energy: 12 easy tips

Starting with insulation is the best bet.

You can pay about £50 for an energy performance assessor to identify the insulation options suitable for your home (the government has a list of accredited assessors). But many options aren’t rocket science so you can also just make your own choices. The Energy Savings Trust also has a wealth of independent advice on its website.

Here’s my 12 tips for energy saving (cheapest first).

1. Use your boiler efficiently

Doing this will save money and carbon emissions. If you have a combi-boiler that heats radiators and provides hot water on-demand, then set the heating control to around 60-65C because this is the optimum temperature for boiler efficiency. The hot water can be set to a lower temperature because there is little point in heating the water so hot that you need to add cold water to cool it. The exception is if you have a hot water tank, then you need to heat it to around 60C to prevent legionnaires disease, otherwise 45-50C should be fine.

2. Adjust your thermostat

Try setting your thermoset to 18oC or lower and see how that works for you. Turning your thermostat down one degree can reduce your energy use by 10% and save around £80 a year on your energy bill. Getting a plumber to fit thermostatic radiator valves to your radiators will also enable you to keep the homes you use most warmer and the other rooms a bit cooler.

3. Consider draft-proofing

Draft-proofing is a cheap, easy, and cost-effective option. There’s a short explainer video on what to do on the Simple Energy Advice website.

4. Explore loft insulation

Around a quarter of heat can be lost through the roof. Loft insulation, like draft-proofing, can be a DIY job. It should pay for itself in under two-years.

5. Treat your exterior walls

A cheap measure is also to paint your exterior walls with a transparent cream called Stormdry. This stops brickwork soaking up rain which reduces heat loss by around 10%. It should pay for itself within five years.

6. Try money saving smart devices

illustration of smart heating controls - remote, radiator and wall theremostat
Credit: Russell Hardman/Friends of the Earth

Technology to help our homes to use energy more efficiently is developing fast. A smart thermostat learn how your home heats-up and cools down, adjusts heating based on the weather, and can switch your heating on or off depending on if you are at home or not. It will reduce your energy consumption by 5% or more and the payback is around 5 years. There’s a recent review of options here. You can even buy smart radiator valves to programme when individual radiator are on or off in different rooms. These are quite pricey – around £60 each - so will have a longer payback but may be worth it depending on how you use your home.

7. Insulate your walls

Homes built after the 1920s are likely to have cavity walls – two layers of bricks with a gap in between. Filling the cavity with insulation is a professional job but will pay back in around 4 years.

illustration of thermal wallpaper and paint
Credit: Russell Hardman/Friends of the Earth

8. Insulate your underfloor

For most people underfloor insulation is also a professional job. It involves either removing floorboards and hanging insultation between the joists or placing a small robot under the floor and spraying insulation. The payback will be longer, perhaps up to 10 years, with an upfront cost of between £500 and £1,500 depending on your property.

9. If you live in a home with solid walls, there's still great insulation options...

There are around 8 million solid wall properties in the UK. These are harder to insulate. The two traditional options are external wall insultation, which will cost around £10,000, or internal wall insulation which will cost around £8,000. But a much cheaper alternative is internal thin wall insulation which can be as much as 70-80% as effective and can be DIY fitted. A recent government report rated 1.3cm thick high-tech aerogel best of the bunch (much better than the latex rolls I’ve fitted) and only costs around £80 per M2. Woodfibre (Pavadry or Diffutherm) works just as well, is cheaper and has a lower carbon footprint but has to be double the thickness to deliver the same energy saving. You can DIY following the manufacturer’s install guidelines or go for a trained retrofit coordinator (PAS 2035 Accreditation). Insulating solid walls will make a serious dent in your carbon emissions and energy bills.

10. Replace old doors

If your home has old poorly fitting external doors replacing these will make a big difference. Old doors tend to warp meaning that even draft-proofing can’t keep all the draughts out. Heat is also lost through the door itself. Insulated doors aren’t cheap, mine cost £1,000 each ten years ago! The payback will be measured in decades. But the difference it made to the comfort of our house was enormous and immediate.

11. Replace old windows

Like replacing doors, replacing windows isn’t cheap and doesn’t have a fast payback but the comfort and noise reduction is well worth the investment. The very best windows are A++ rated, triple-glazed with an inert gas such as argon between the glass panes. But if you can’t afford to replace your windows you can install secondary glazing. Professionally made secondary glazing is the best bet and should last 10 years or more, but will be much much less effective than double or triple-gazing. You can buy cheap plastic film from a DIY store to fit yourself, this might stop some draughts but will do very little else.

12. Be an 'early adopter' of Hydro Genie

Lastly, one innovation, that caught my eye, is a system to remove dissolved oxygen from the water in your heating system, and therefore make it much more efficient. Called Hydro Genie, in tests with Energy Systems Catapults, Living Lab, it was installed to 4 homes in Newcastle, it reduced energy consumption & carbon emissions by an impressive 35% on average. The systems cost from £1,865 for a lower fuel user (e.g., less than £1,200 a year for heating) and up to £3,500 for the higher fuel user. But according to the manufacturer you should save this in reduced energy bills, in around 3-5years, if you are a high energy user. It will take a bit longer if you are a lower energy user. This technology isn’t widely used yet (just over 700 installed), so if you install it, you’ll be what’s called an ‘early adopter’. But that also means there aren’t yet lots of users’ real-world reviews available yet, so it isn’t risk free. 

Save money: grants and support

This list above would cost you an arm and a leg if you decided to do it all at once (and you could, except you can’t do cavity wall insulation if you don’t have cavity walls!). How much you can do depends on your financial situation.

If you are a low-income household (e.g., on benefits, less than £30,000 household income) and own your own home you can access some grant schemes. The government requires energy companies to fund energy efficiency measures, including more expensive measures such as external wall installation, as part of its strategy to reduce fuel poverty. There is more information on the energy regulator OFGEM website. The recent government Budget also announced £950 million for homes that aren’t on the gas grid plus additional money for local authorities to target energy efficiency support to low-income households. It is well worth contacting your council and contacting your energy company to see if you are eligible for grants.

If you aren’t a low-income household sadly the government isn’t offering any financial support for energy-saving - although they will offer some support for ditching your boiler and switching to a heat pump, see below – but many of the options above will save you money quickly, as well as reduce your carbon footprint.

Eco heating: 6 options

Burning gas to heat our homes is heating the planet, so as well as saving energy what are the options for ditching fossil fuels altogether in home-heating, and what are the pros and cons of these.

1. Heat pumps

A heat pump is basically the same as a fridge in reverse. Rather than making the inside colder and transferring the heat outside it does the opposite – it extracts heat from the environment outside the house and pumps it into the house. Roughly speaking, for every unit of electricity you use, it will provide 3 units of heat. It's therefore by far the most efficient form of heating there is.

A heat pump can reduce your carbon footprint by two-thirds or more!

I got an air-source heat pump two years ago and it’s kept our home warm, including through a cold north of England winter. It extracts heat from the air outside even when it’s freezing cold and uses it to heat the water in our radiators and in our hot water tank. It doesn’t make the water as hot as a gas-fired boiler, so to ensure our house is warm enough it runs for longer and we’ve increased the size of our radiators. The heat pump itself is in our backyard where it hums away quietly.

Until April 2022 you get financial support from the government’s Renewable Heat Incentive which will pay between £6,000 - £12,000 over 7 years. After April 2022 you will instead get a £5,000 upfront grant. My heat pump and radiator refit cost £11,000, including fitting a new water tank.

There are other types of heat pump.

A ground-source heat pump extracts heat from the soil. It is more efficient but much more expensive, and you’ll need a garden to lay the pipes. The grant available for this type of heat pump will be £6,000.

There are also hybrid heat pumps which works alongside your gas boiler. These may be suitable in homes that can’t be insulated, such as some homes in conservation areas or very old cottages. But there are also high-temperature heat pumps. These are newer on the market and provide can provide hot water at the same temperature as a gas boiler, thereby doing away with the need to install bigger radiators and be suitable in hard to insulate properties. Whether a grant will be available for a high-temperature heat pump or not will depend on the efficiency, which may differ between models. A grant won’t be available for hybrid heat pumps.

There is also air-heat pumps which blows warm air into your house rather than hot water. These might be suitable if you live in a small flat. There isn’t a grant available for this type of heat pump either.

Illustration of ground-source heat pump
Credit: Russell Hardman/Friends of the Earth

Pros:  Air-source and ground-source heat pumps are a very efficient way of providing heating, using roughly 1 unit of electricity to produce 3 units of heat; they are also eligible for a government grant. They will make a massive impact on your carbon footprint, in a good way!

Cons:  Heat pumps do involve some disruption to your house, eg pipework, and some systems will need bigger radiators. You'll need to be happy with a heat pump outside your house making some noise, although it’s only about as loud as a fridge, and will be working hardest in winter when you are less likely to be outside.

2. Heat batteries

New on the scene are heat batteries, which can store the heat produced by your heat pump for later use, or they can be warmed-up by electricity. The stored heat can then be used to provide instant hot water for showers and baths, as well as heat your radiators. Both approaches enable you to keep bills lower by using electricity overnight when the price and carbon intensity of electricity is low. The upfront cost and running cost of the electric heat battery will be much higher, but you won’t need to buy a heat pump.  

Pros:  Heat batteries are much better at storing heat than a hot water tank and therefore more efficient, and they enable you to use low-cost electricity.

Cons: The upfront cost of installation will be higher than fitting a hot water tank, but they will reduce running costs by 30-40%  by using off-peak low-cost electricity and reducing heat losses, so will save money over time.

3. High-heat retention storage heaters

These are much better insulated than the old-fashioned storage heaters. This means they're much better at providing the heat when you need it.

The switch to high-heat storage heaters is straightforward, so long as you have an electric supply near to where you want to fit the radiators. They come with individual room controls and the better models match energy input to weather conditions. High-heat retention storage heaters don’t heat your water.

High-heat retention storage heaters will reduce your greenhouse gas pollution compared to your gas boiler but not by as much as a heat pump.

Pros:  Easy to install and will reduce your carbon footprint. Their gradual release of heat makes them ideal if you're at home most of the day.

Cons: No government grants available and as expensive as a heat pump if you consider the government grant for the latter. Your energy bill is likely to increase.

Illustration of domestic heating radiator
Credit: Russell Hardman/Friends of the Earth

4. Electric radiators

These radiators use electricity to provide you with heat when you need it. They are cheap to buy and fit compared to the options above. They might cost less than a new gas-fired boiler. Many will be programmable and have smart controls.

For at least the next 5 years (and probably longer) they will generate more greenhouse gas pollution than your gas-fired boiler. This is partly because they use electricity at peak times when the grid is mostly powered by fossil fuels.

Pros: None that I can think of.

Cons: Will increase your carbon footprint for at least the next 5 years and your energy bills will go through the roof

5. Infrared heaters

Infrared heaters are new to the market They provide warmth by heating objects rather than the air – like sitting in the sun on a winter’s day, you can still feel warm even though the air is cold around you. We’ve got used to seeing these outside cafes and pubs during the pandemic.

One company selling these heaters (Herschel Infrared) gave us illustrations that suggested heating bills will reduce by around a third compared to conventional electric radiators. If this is true, they will out-perform electric radiators in both costs and carbon footprint, although they still wouldn't be as good as heat pumps for reducing your carbon footprint.

One advantage of these heaters is that they are super thin and light-weight – they can be located on your ceilings pointing down, printed over to appear to be pictures on your wall, or hidden behind mirrors.

The retailers claim they will be no more expensive than fitting traditional electric heaters.

Pros: Can look great, and offer savings compared to conventional electric radiators, according to the manufacturers.

Cons: Because infrared heaters are new on the market there is little or no independent evidence on how well they work in practice. Like conventional electric radiators they will use peak time electricity, not Economy 7, so are likely to be more expensive to run than storage heaters and will increase your carbon footprint for at least a few more years.

6. Biomass boilers and stoves

Biomass boilers have had financial support from the government under the Renewable Heat Incentive, but this is about to stop apart from very limited circumstances (e.g., off-grid, rural and only some types).

At first glance they seem like a great option: what could be better than burning trees that can be replanted and managed sustainably? It’s less clear cut than that (excuse the pun).

The carbon footprint of a biomass boiler or wood-burning stove depends very much on the source of the wood. In some cases it is likely to be worse for the climate than gas-fired heating systems. In urban areas wood burning is coming under the spotlight because of its contribution to air pollution (the intensity of which will vary enormously between models of stoves and burners).

Choosing heating for your home

Opting for a heat pump is the best option if you have outside space. In our well insulated pre-1900 house we've fitted an air-source heat pump and a hot water cylinder (although in hindsight I wish we’d fitted a heat battery instead). For a more modern house an air-source heat pump would also be perfect. In less well insulated homes, a high temperature heat pump might be better.

If you don't want or can’t fit a heat pump, then a heat battery or high-heat retention storage heaters aren’t a bad fall back. Their ability to deliver carbon footprint reductions will increase in line with an increase in renewable energy on the grid.

Whatever your choice, energy-saving and insulation is always going to be the best first move.

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