Under current government guidelines, off-grid homeowners will soon need to replace their fossil fuel heating system with a low-carbon option.

However, because there are a wide range of options available, it can be difficult to know which one is most appropriate. Installers play an important role in helping homeowners make informed decisions. Therefore, it is essential to have up-to-date information on different low-carbon technologies.

In this blog, we will provide an overview of the different greener heating options, highlighting the pros and cons to each one.

Renewable ready boilers

For rural homes with an LPG gas boiler already installed, renewable liquid gases could be suitable alternative because they are a 100% green alternative to LPG and produce significantly less carbon than traditional fuels.

For example, bioLPG can be dropped into existing LPG systems, meaning there is no need for an extensive change to heating systems already in place.

Another renewable liquid gas, which is currently being commercialised in the UK, is rDME, produced from renewable and waste feedstocks. Like bioLPG, it also produces significantly less carbon than traditional fuels (up to 85%) and will provide homeowners with another green gas option if they are off the mains gas grid.

Benefits of bioLPG 

A gas boiler can heat a home quickly and bioLPG can be used as a drop-in alternative in a traditional LPG gas heating system, with just some slight adaptations to an existing heating system required. This is beneficial to gas installers because it means no retraining is needed. Gas boilers are generally more suited to older, less energy efficient properties, and in future, renewable liquid gases (RLGs) will be able to fill the gap, once traditional LPG can no longer be used. RLG’s can also be a cost-effective solution for off-grid homes.

Drawbacks of bioLPG 

Gas boilers can take up space and need regular maintenance. They can also lose heat quickly if they are not insulated correctly.

Air source heat pumps

An air source heat pump takes heat from the air and absorbs it at a low temperature, turning it into a fluid in the unit. This fluid passes through a compressor where its temperature is increased and its then circulated to the heating and hot water circuits in the house.

Benefits of air source heat pumps 

Air source heat pumps require virtually no maintenance if installed correctly and are relatively easy to install. They are fully automated and there is no need to order fuel for them to run. They are extremely efficient in well-insulated homes and can save carbon emissions.

Drawbacks of air source heat pumps  

Air source heat pumps are expensive to install and costly to run in poorly insulated homes. In energy inefficient homes, such as older rural properties that are hard to heat and hard to treat, the cost of retrofit can be significant, up to £32,000.

They also can be noisy. As this technology is newer, there are fewer heating installers trained to install this type of system, so it may be difficult to find and access training currently.

Ground source heat pumps

A ground source heat pump works in a similar way to an air source heat pump, except that heat from the ground is absorbed into the fluid, which passes through a heat exchanger into the heat pump. This raises the temperature of the fluid and then transfers the heat to hot water circuits in the home.

Benefits of ground source heat pumps  

Ground source heat pumps are fully automated, very energy efficient and save space. They are also low maintenance and save carbon emissions.

Drawbacks of ground source heat pumps  

Similarly to air source heat pumps, ground source heat pumps are expensive to install, with a large upfront payment, and can require a significant retrofit in poorly insulated homes to perform well. Installation can be disruptive, as it can mean digging up a garden or driveway, and underfloor heating and new radiators may also need to be installed.

This technology is also relatively new, so not all heating installers will be fully trained on how to install this type of system currently.

Water source heat pumps

Water source heat pumps extract heat energy from a water source, such as a lake, river or the sea, and use this to provide hot water and heating to a property. There are two types of water source heat pump systems: open loop and closed loop.

Open loop systems 

An open loop system will extract and filter the water, circulate it through the system, and release it back into the water source, or another alternative, such as a water well or borehole. These systems do not use a heat transfer fluid – the water itself is the fluid that is circulated through the heating system.

Closed loop systems 

A closed loop system continually circulates a mixture of water and refrigerant (also known as ‘brine’) through submerged or buried pipes. The water from the source does not get into the pipes. As the fluid flows through the pipes, it is heated by the water body, before returning to the heat pump.

Benefits of water source heat pumps  

Water source heat pumps are generally more efficient than ground and air source systems because heat transfers better in water.

Drawbacks of water source heat pumps  

Water source heat pumps have a have high upfront cost with an average payback period of five years. The installation of the heat pump can also be quite difficult, as they need to be close to a water source.

Solar thermal heating

Solar thermal panels can be fitted to a roof and contain tubes of fluid that absorb heat from the sun. This hot fluid is then transferred to a hot water storage tank via a heat exchanger.

Benefits of solar thermal heating  

Solar thermal heating uses a readily available and free source of energy from the sun and can be integrated into an existing system. Solar panels have no CO₂ emissions during operation and can provide cost savings.

Drawbacks of solar thermal heating  

Solar thermal heating is intermittent and has a low energy density. Panel installation costs can be high and they require a large amount of roof space.

Biomass boilers

Biomass heating systems burn wood chip, wood pellets or logs to provide heat in a single room or power central heating and hot water boilers.

Benefits of biomass boilers  

Biomass boilers are often a renewable and low-carbon fuel type, which means homeowners can run a heating system with a reduction in carbon emissions. These systems are also very efficient and can be cost-effective to run.

Drawbacks of biomass boilers  

Biomass boilers need a lot of space because the systems are generally large and they have a high upfront cost. There can also be some additional costs associated with maintenance and the price of biomass pellets can vary.

To find out more about different low carbon technologies for off-grid homes, speak to Liquid Gas UK.