Gas Boiler Alternatives Index: The greener options to consider to replace your old boiler

In 2019, the UK government pledged to bring all greenhouse gas emissions to net-zero by 2050 and as part of this, announced that ‘fossil-fuel heating systems’ such as gas and oil boilers, would not be installed in any domestic new build properties from 2025 as part of the Future Homes Standard.

But what are the alternatives to these? And how do you go about replacing them with something greener?

Why should I replace my gas boiler?

It’s estimated that 8 out of 10 dwellings in the UK and Wales currently use mains gas to power their central heating, so it’s clear that we have some way to go in cutting down on our use of these fossil fuel-hungry appliances, which burn lots of gas and oil that enters the atmosphere, contributing to global warming.

Using gas has been an easy option for the UK for many years due to plentiful supplies from the North Sea, but if you want to do your bit in the fight against climate change, then one of the best things you can do is to replace yours with a greener alternative.

The Options

Heat pumps

As the name suggests, a heat pump takes low-temperature thermal energy from outside your home and pumps it up to a higher level, to be used throughout your house.

There are many types of heat pumps, but the ones that you’re likely to see heating homes are the air source pumps, ground-source pumps and hybrid systems.

Air source pumps use a fan to pull in cold air from outside the home and warm it up to be used in your radiators and hot water, while ground-source pumps do the same using underground pipes.

The hybrid systems act as a middle ground, allowing you to continue using your existing gas boiler alongside a heat pump and crucially means that you don’t have to replace your current boiler, while still cutting your emissions substantially.

While heat pumps can cost more to install upfront than a gas boiler, over time they usually work out cheaper to run, especially if your house is well insulated.


-One of the most energy-efficient alternatives to gas boilers

-No combustion required, with natural heat being replenished by the sun

-Can recoup some of the cost through the Domestic RHI

-Can be combined with solar panels


-Relatively high initial cost to set up

Biomass boilers

Biomass boilers work similarly to gas ones, with the obvious difference being that they burn materials from plant-based organisms rather than gas, usually in the form of something like wood chips or pellets or logs.

While this does release carbon into the atmosphere, it’s considered to be a carbon-neutral process, as the carbon being released is only that which the trees have absorbed during their lifetimes, rather than being sent to landfill.

Of course, this option will require a lot of effort on your part though as you’ll have to manually fill the boiler with fuel as and when required and will also require regular cleaning too.



-Carbon neutral as you’re burning the same CO2 that the wood has absorbed over time

-One of the cheapest fuel sources available

-Could recoup some of the cost through the Domestic RHI (pellet stoves only)


-Take up a lot of space

-Flue must meet regulations and be professionally cleaned once a year

-Have to be manually filled and cleaned

-Can be expensive to install

Solar power

Solar panels mounted on roofs are becoming increasingly common sights in the UK and they can be an effective and eco-friendly way to heat your home.

These panels collect heat from the sun throughout the day and use that energy to power your electric boiler, storage heaters, and so on.


-Uses heat from the sun so no fossil fuels are burned

-Require little maintenance

-Can recoup some of the cost through the Domestic RHI


-Rely on good weather to be fully effective

-Don’t generate enough energy to fully power your house, just to supplement existing sources

-Relatively high initial cost to set up

Infrared heating panels

Rather than using energy to power existing heating systems like your radiators, infrared heating panels actually directly heat up the people and objects in the room rather than the air around it, meaning that the room stays warmer for longer, without producing any emissions.

They’re also extremely quiet to run and as they don’t circulate air and dust particles throughout the room, are perfect for allergy sufferers.


- Operate almost silently

- Can be mounted on walls so don’t take up space

- Require little to no maintenance

- Ideal for allergy sufferers


- Because they don’t warm the air in the room, the room will go cold as soon as they’re turned off

- Can’t be placed behind objects or facing a window

- Only effective up to around three metres

Electric boilers

Obviously, all boilers require some form of electricity to run, but these boilers actually use it as the energy source, as opposed to gas.

Not only is this a much greener option, but because no actual fuels are being burned by the boiler, there’s less room for something to go wrong.

These boilers are best suited to smaller properties such as flats, where they won’t have to meet such high demands.

The cost

Generally speaking, these alternatives to gas can have higher upfront costs to install than a gas boiler but will see savings in the long run.

However, the government offers a grant called the Domestic Renewable Heat Incentive (RHI) which can help to keep the costs down.

The grant offers quarterly payments to those who are eligible for up to seven years. Those who have an air or ground source heat pump, solar thermal panels or certain biomass boilers can apply and doing so could allow you to significantly recoup some of those initial costs.

But how much do these alternatives cost to install and how much could they save you?

Air source heat pumps

Air source heat pumps can be expensive to install, with the Energy Saving Trust estimating that the cost is between £7,000 and £13,000.

However, it also had one of the highest annual savings, with an estimated £255 per year for a four-bedroom detached home.

The high efficiency of air source heat pumps means that they’re very cheap to run and you may also be able to benefit from the government grant to offset the costs too.

Ground source heat pumps

Ground source heat pumps are the most expensive alternative to gas boilers, with an estimated installation cost of between £14,000 and £19,000, but they also offer up the greatest potential savings, at £330 per year for a four-person household.

As with air source heat pumps, you can make use of the RHI scheme to make these costs more manageable.


Biomass boilers are similarly priced to air source heat pumps (at around £9,000 to £15,000) but the real advantage here is in how cheap the fuel itself is, which can usually be purchased for less than £300 a tonne, although you do need somewhere to store them. The financial savings with biomass are decent, at around £140-£150, but where biomass really sees significant savings is in the amount of CO2 that you produce.

Solar panels

Solar panels are a little more complicated than the other alternatives to gas when it comes to cost and savings for a couple of reasons.

Firstly, with solar panels, if you produce more electricity than you actually use, you can export it back to the grid, which you’ll be paid for through the Smart Export Guarantee (note that all savings below refer to systems using the SEG).

When it comes to how much you can save, unlike with other energy sources, the amount that you can save with solar panels is dictated in part by where you live, due to varying degrees of sunlight.

Below are the estimated annual savings for five locations around the UK, ranging from £105 in Belfast (where the SEG doesn’t apply), up to £244 a year in London.

Here’s a breakdown of the average installation costs and savings for different alternatives to boilers according to the Energy Saving Trust, which are based on a typical four-bedroom detached house with basic insulation and are compared against an old (G-rated) boiler.

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Estimates of installation costs and annual savings sourced from the Energy Saving Trust and refer savings against an old (G-rated) gas boiler and are based on fuel prices as of June 2021.

The saving you can expect will depend on the size of your home, and the cost of replacing your old heating system, depending on its age.