Alternative heating sources - what you need to know

With carbon emissions from heat up for the second consecutive year in the UK, we urgently need alternative heating sources. So how do we switch from fossil fuel reliance to renewable energy heat?

Over 85% of us burn oil and gas for our heating needs. So finding low-carbon alternatives is essential if we’re going to reduce global warming. Renewable heat options are best, including biomass boilers and ground and air source heat pumps.

But not all solutions will fit all houses. So what renewable energy heating options could be right for you?

Heating large homes or several buildings

Burning wood is good. Using local, renewable fuel is a great way to support the local economy and improve the ecological status of our woodlands. It’s also low carbon.

Biomass boilers are a wood-fuelled alternative to your gas boiler. They burn biomass fuel (wood chips, logs, wood pellets) and work best with medium to large heat loads. They’re a great option if you have a big space to keep warm such as a business or a larger country home.

Biomass boilers can also heat several homes connected through a pipe network. This is called a heat network, where several properties are heated by the same boiler. A district heat system therefore supplies heat to homes so bills are based on heat used rather than fuel burnt. Biomass systems are automated but you do need a large, dry area to store the fuel.

Wood pellets have a high energy density so need less storage space. But they can be more expensive. They’re also often imported from overseas, so it is worth checking with your local supplier both the country of origin and also delivery reliability. Logs are far cheaper to buy and widely available but do require manual handling. So the choice of boiler and feed stock depends on your space for delivering and storing wood fuel, as well as how mechanised you want the system.

Heating homes which are off the gas grid

If you are off the gas grid (not connected to mains gas), heat pumps are a far better alternative to oil or LPG and work out cheaper to operate than continuing to buy fuel

Heat pumps work by extracting heat from outside – either from the air or the ground – to use to heat your home and hot water. They operate at a lower temperature than a traditional gas boiler so they work best by heating a larger area such as under-floor heating. Your home will need to be well insulated before a system is installed. 

Heat pumps do use electricity for the pump, which is more expensive than mains gas per unit and at peak times, such as winter evenings, it can be quite carbon-intensive.So it’s not 100% low-carbon heat. However, if you’re off the gas grid, heat pumps are a far better alternative to oil or LPG and could work out cheaper to operate than continuing to buy fuel.

Air source heat pumps: for a wide range of properties

Air source heat pumps are the most versatile and easy to install options, making them suitable for a wide range of properties. The pump itself is still powered by electricity, so to make it a fully renewable option you’d need to ensure your electricity supplier is a clean energy provider. But the heat itself comes from the sun, so it’s classed as a renewable source. Air-to-water systems heat water which is then brought to radiators and under-floor heating systems. Air-to-air systems use fans to heat the air in the home but can’t be used to heat water.

According to the Centre for Sustainable Energy, air source heat pumps cost from around £5,000 to install, plus installation fees. The installation shouldn’t be too disruptive, but, CSE suggests, “you may want to carry out this work at the same time as other home renovations”. Once installed though, the heat pump can save you money each year, especially if you are using off-grid oil and gas or have solar heated water – in which case you wouldn’t need to have the heat pump on at all in the warm months.

Ground source heat pumps

Ground source heat pumps tend to be more efficient than air source heat pumps because of the more consistent temperature, but they cost more to install so they require a larger upfront payment. Ground source heat pumps work using a pipe network in the ground. This is either created by drilling a borehole which is quite deep down into the ground or a “slinky system”, which is a network of pipes under the lawn in your garden (or a neighbouring field). A slinky system is cheaper than a borehole to install. But the choice depends on how much space and access there is to work with.

Solar hot water heaters

Heating hot water from the sun is a great way to use sunshine to replace burning gas. Solar thermal panels on your roof capture heat during day light hours. This heat is transferred in a twin coil cylinder system to warm water for washing in your home. In the UK the systems are not yet big enough to heat your home in the winter.

Solar hot water heaters cost on average between £4,000 and £5,000. You can make great savings on hot water in the summer; less in the winter.

Wood burner stoves for space heating

Wood burner stoves are very popular but like all renewable forms of energy they rely on choosing the right technology for the right location. There are very real health issues regarding air pollution from burning wood, particularly tiny particles, known as particulate matter. Air pollution is a big issue, especially in cities such as London that have lots of traffic and people burning wood in open fires.

A simple rule of thumb is to avoid burning wood if there is already a serious air pollution problem, especially in an open fire place. If you live in rural areas, then Ecodesign ready stoves could be ideal to provide ambient space heating for your home. Always use dry (seasoned) wood and never, ever burn contaminated wood, which is painted or treated with chemicals.  This is to keep you safe and prevent toxic fumes entering the air you breathe. You can also look for SIA and DEFRA approved fuel for your stove:

Passive House

Passive homes are ultra-low energy houses. In the UK the sun rises in the east and sets in the west 365 days of the year. So a house that is designed with large south facing windows and smaller windows on the north gains the most passive solar heat. An extremely well insulated house will then help store this heat for as long as possible. That is the basic principles of a passive house. This efficient way of building homes ensures very little additional renewable heating sources are required so their running costs are very low. Also, because they are very well insulated they help to keep the heat out during very hot summer days so are cooler than most homes during heat waves.

Renewable heat – the one to watch?

If you use renewable sources of heat then you could qualify for a Government subsidy called the renewable heat incentive (RHI). The RHI is to encourage you to switch to low-carbon heating sources and help offset the higher costs of installing a renewable heating system. Securing the RHI is dependent on using a qualified installer. The amount of money you will receive depends on the type of technology used and the year it was installed.

Installers will be able to provide you with more details of the potential RHI payments and the payback for your original investment. And you can find out more about it here. 

Warm homes always start with the most insulation possible to reduce carbon emissions and save bills. Then there are several ways to heat your home without using oil, LPG or even mains gas. Renewable heat sources still have a way to go before they can work in every type of property. But if you live or work in a place that uses oil or LPG or is suitable for conversion, it’s really well worth considering.

Ultimately you can make a huge difference to the planet and could benefit financially as well. The cost savings and suitability are very site specific, but with the RHI and a need to cut carbon emissions, alternatives to fossil fuels for heating are increasingly popular. And given that other forms of renewable energy have become more and more cost effective over time, renewable heat is definitely an area to watch.

Featured image: Gill Alker, AMP Clean Energy

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