An introduction to eco friendly heating systems

Heat pumps are billed as the renewable heating systems of the future. It is often stated that they are more than 100% efficient - but is this really possible?

Are they really the most environmentally friendly heating method?

In this article we dive into the facts about how energy efficient they are and the other options available for lower carbon heating. 

The Need for Eco-Friendly Heating

50% of greenhouse gas emissions in the UK are domestic and this comes almost exclusively from our use of of fossil fuels for heating and hot water (source: Carbon Footprint of Heat Generation by the Parliamentary Office of Science and Technology).

Most domestic heating in the UK remains powered by fossil fuels and thus a key target for reducing the nation's carbon footprint is to transition our homes to sustainable heating systems.

Eco-Friendly Heating Options: what is the best form of eco heating?

Changing from a gas or oil boiler requires homeowners to understand a more about the choices available to them as some of these technologies work very differently than the gas boilers most of us are familiar with.

Heat Pumps for greener home heating

Heat pumps are a device that work using a small input of electric energy to move heat from one location to another.

They can be used to heat or cool a home using a refrigeration cycle to extract renewable energy from air (air source heat pumps), water (water source heat pumps) or the ground (GSHPS). 

A Heat pump can be more than 100% efficient because it moves heat from one place to another, rather than generating heat. It is much easier to move heat than generate it. This means that the system can move more heat than the energy required to operate the system, resulting in an apparent efficiency greater than 100%. 

In fact, air source heat pumps can frequently work at 300% efficient or more and ground source heat pumps at 400% or more - whilst water source heat pumps can reach even higher levels of efficiency. Find out more detail about how heat pump systems work here.

Moreover, if a heat pump system is linked to solar PV panels and thus most of the electricity also generated by the renewable energy of the sun, it becomes even more independent of fossil fuels and fluctuations in energy bills caused by energy market. Solar thermal panels can also be linked to eco heating systems so that hot water from them can be used when that is the most efficient choice.

As they do not burn anything to generate heat and can be linked to solar collectors for even lower carbon use, we would argue that heat pumps are the eco friendly choice for most homes. 

Extracting heat from the environment with a refrigeration cycle

Funding to make homes greener with heat pumps

As they are such a well proven form of eco heating, local and national government funding is available to incentivize homeowners to switch their space heating and hot water generation to heat pumps.

Various low carbon heating grants have been made available in recent years such as the renewable heat incentive, now replaced by the boiler upgrade scheme.

You find can out details about the latest funding options here.

Ground source heat pumps (GSHPs)

GSHPs are often called geothermal heating systems, because they gather the heat stored in the earth from the sun, precipitation and water table. They have a heat collector loop - either a horizontal or vertical system of pipes which transfers heat via a liquid medium pumped to the heat exchanger. 

Find out more about ground source heat pump installation here.

Air source heat pumps

Air source heat pumps draw heat from the air by using a fan to pass air directly across a heat exchanger. You can find out more about air source heat pumps here.

Air source heat pumps are the most popular type in the UK because they are relatively easy to install and cost a little less than a ground source heat pump installation. 


An air source heat pump is usually installed outside, though models for producing domestic hot water only are available for indoor installation. 

Decentralised electric space heating and water heating

Another alternative to traditional gas boilers are electric convector, radiant or infrared heaters. Obviously, these can produce heat for space heating but not hot water. 

These can have the same benefits as heat pumps in terms of using clean energy at the point of use and, potentially, home generated solar power for a lower carbon footprint than a boiler.

However, as they use more electricity to provide the same level of heat, they do not cut costs in the same way and the level of renewable energy they use will be dependent on the levels used by your electricity supplier. 

They can be a good choice for small and very well insulated homes where a heat pump may be impractical. There is also no reason that they cannot be combined with solar water heating to create a low carbon heating system. 

It is also an option to use very highly efficient electric decentralised electric water heating in such a heating system. 

With point of use electric water heating you can save both water and energy as they remove the standby losses of large stores of water and also the water wasted by having to run the tap until the water runs hot.

Centralised electric space and water heating

Electric combi boilers and heating boilers are a potential option to provide a more familiar central heating system without gas or oil. They sound like they might be an easy and clean option for low carbon heating; but they do have limitations

Electric boilers are more expensive to run and your carbon emissions remain higher much more dependent on the profile of your mains electricity supply than a heat pump. 



Electric combi boilers, whilst avoiding energy losses from large stores of water, do still have the issue of water being wasted by the delays caused by long pipe runs (unlike point of use electric heaters). An electric boiler with a storage tank will of course face the issues both of energy losses from the centralised hot water supply and the higher fuel costs of electricity compared to gas or heat pumps. 

The volume of hot water produced by an electric combi boiler will be constrained by the electricity supply that you have. On ordinary single phase domestic supply this may mean that they will power a shower but not a bath. 

Thus, whilst electric combi boilers and heating boilers with tanks have the advantage of being a more familiar technology, and are relatively cheap to install compared to renewable options, they are only as efficient as decentralised electric heating which is far cheaper to install and hot water produced this way is likely to be more expensive  than decentralised electric water heating. 

The low carbon heating grants do not apply to electric combi boilers, although some funding may be available for a combi boiler to those on low incomes to replace an older, inefficient, gas boiler. 

Biomass boilers

Whilst a biomass boiler uses a renewable energy source (usually in the shape of wood pellets) and are generally considered carbon neutral, they are not the most eco friendly heating solution in terms of their emissions at the point of use as they generate heat by burning natural materials. 

Burning wood pellets in biomass boilers obviously releases pollutants into the air, which is not ideal, particularly in urban settings. 

Wood pellets are also bulky and require storage and handling which is not ideal for many properties and owners. There is also a carbon impact of transporting the heavy fuel for biomass boilers which must be taken into consideration when evaluating whether they are truly a low carbon option. 

Large scale biomass boiler use also carries the risk of deforestation; so it is important to know the source of the fuel is sustainably managed. 

Bear in mind that because of the challenges of producing enough wood sustainably biomass boilers are unlikely to be a mainstream option. This means that biomass boilers will not have the same benefits of enhancing the value of your home that may enjoy from a truly renewable option like a heat pump. 

Biomass boilers, like other renewable options, have a relatively high initial cost of installation. 

Biomass boilers also have the disadvantage of requiring constant maintenance with weekly cleaning of the combustion chamber and disposal of soot and ash required. 

The electrification of heat

STIEBEL ELTRON have a clear vision of the future of the future of heating systems as powered by electricity as the cleanest and most practical way to heat your home without fossil fuels.

Our recommendation is thus to choose one the electrically powered options for preference and this is all we sell.

Smart controls are allowing us to use and store solar energy in new ways that allow us to make the most of the times when the sun shines. 


Battery storage is improving all the time to allow us to harvest the sun's energy for use at the times we need it, extending our ability to use low carbon electricity generated by solar panels or wind turbines on our own land. 

Batteries can store electrical energy but also heat. A heat battery uses phase change materials to store energy as heat for use in your home at a later date. 

Alternative or emerging technologies for low carbon heating

It is worth mentioning here that there are other technologies that are being marketed as "renewable" or "low carbon" heating which do not fully displace fossil fuels, still involve an element of combustion at the point of use or are not yet fully proven. 

For example, micro combined heat and power (CHP) units generate heat and power simultaneously but burn gas and have low levels of adoption.

Hydrogen boilers are also often touted as a potential greener solution for home heating; but in reality many barriers exist to the mass production and safe distribution of hydrogen and these technologies may never be widely adopted for domestic use.

Whilst these methods may yet prove themselves for certain applications, none yet rival the electric or biomass options supported government incentive schemes for reliable, future proof low carbon heating.

Cautious consumers are best advised to choose from among those or existing direct acting electric heating solutions.  

Insulation and Energy Efficiency

A truly eco friendly heating system not only displaces a gas or oil boiler but takes into account the need to make a home energy efficient by insulating as far as is practical for the age and type of building.

Whether you choose some form of biomass boiler or heat pump, an electric combi boiler, solar panels or an auxiliary heating system using electricity your home heating will be more energy efficient if you insulate. 

It is of course worth being energy efficient by insulating even if you keep gas or oil as the heat source to heat your home and any easy measures that you can take should always be done whilst investigating a low carbon heating option!

The Energy saving trust has lots of information on where to start with reducing energy loss from your home to reduce energy bills and create a low carbon home.

Choosing the Right System for Your Home

There are a number of factors when choosing a future proof method to heat your home. Do you have the roof space for solar panels, the outdoor space for heat pumps or the storage required by biomass? Do you have the money to invest in low carbon system or do you need something that can be installed at low upfront cost like direct electric heating? 

Choices will also differ dependent on the age of your home and your existing heating systems.

We offer a free specification service to help you make the right choices for an effective system for your home  and our partner installers are highly experienced in integrating various low carbon technologies into homes. 


o save our environment we must transition away from fossil fuels for heating our homes. This means replacing gas boilers and oil boilers with low carbon alternatives. 

Low carbon options include  an an air source heat pump, ground source, solar thermal panels, biomass boiler, electric combi boiler, direct acting electric heating or a combination of these. 

Whilst this change currently remains optional for both UK new build and existing homes it is likely to be mandatory at some point in coming years if targets for low carbon heat are not met organically.