How to heat your home sustainably: Can we remove fossil fuels & is it possible without breaking the bank?

by Tony Melvin

We know that there is a lot of pressure to move from burning coal, oil and gas for electricity generation and heating towards use of renewable sources, such as solar and wind. But what can we do about it as individuals? This was our dilemma when we bought a house in rural Norfolk recently. The house was not hooked up to the gas supply, but we could pay to have it connected. It had old, inefficient storage heaters in some of the rooms and a wood burner in the living room, making it too cold for comfort in the winter. So, it was time for us to work out how to heat our home in a sustainable way that wasn’t going to break the bank. Here’s what we found out:

91% of households in the UK have centrally homes heated by gas or oil. This makes up 14% of the total greenhouse gas generation of the UK, which is on a par with the emissions from cars. The difference between this issue and the issue for cars is that we can already see the path forward for cars. There is a massive increase in the sale of electric cars and the government has imposed a ban on new petrol and diesel car sales from 2030. However, for household central heating the future is far less clear. The government has made a move: it has declared that gas should not be supplied to new-build homes from 2025. But this alone won’t be enough for us to reach our UK climate goal of being net zero greenhouse gas contributors by 2050. Therefore, the houses already in existence will need to be quickly converted to low carbon heating and hot water.

So, what would be the options if you were to consider switching away from gas or oil-based central heating and hot water?

There are only three serious options presently (excluding the possible use of hydrogen in future):

  1. Heat pumps (ground-source heat pumps and air-source heat pumps)
  2. Biomass heating
  3. Electric heating from renewable sources

Heat Pumps

These sound like a great idea: you take heat out of the ground or out of the air, heat it up some more (using electricity) and use the ensuing hot water to heat your house. They work rather like a fridge in reverse and look like large air conditioning units on the sides of houses. They can be very effective for new-build houses that have the best levels of insulation. However, existing houses tend to have far inferior insulation and the level of heat that heat pumps can produce is not as good as gas/oil central heating. It is often said that people find that heat pumps need to be left on most of the time and they still find that the house is never quite warm enough. The cost to install heat pumps is high: varying from about £10,000 to £25,000 depending on the type of system and the type of property, although there are currently some government incentives that can ease the up-front costs (descriptions of these can be seen below). You may find that you need to install underfloor heating or change all the radiators to larger models. There are also some maintenance costs because there are moving parts that do wear out. The pumps are also somewhat noisy outside the house, a bit like hearing a large fridge or air conditioning unit. So, these don’t appear the perfect solution considering the huge cost.

Biomass heating

These are typically wood or pellet burners in the house. They may have a back-boiler attached in order to heat water for central heating and domestic hot water. Biomass heating is potentially sustainable provided the sources of the wood or pellets are known to be sustainable, e.g. when the felled wood is fully replaced or when the pellets are created from organic waste. Burning biomass does generate CO2 but it is a lot less than fossil fuels.  However, if many UK households were to adopt biomass heating then it would become very unsustainable because there would not be enough organic material to go around (i.e. not enough room to replant that much biomass!). There are some practical issues to consider with these heating systems, such as space, smoke, and storage of fuel. Biomass boilers can be large, requiring a hopper next to the boiler in order to provide a continuous feed of fuel. Also, you’d need to store the fuel somewhere as it usually gets delivered in large quantities. Finally, it’s important in built-up areas that the boiler is certified exempt in areas where air quality controls are in place. Installing biomass heating systems is expensive: typically £11,000 – £17,000, although there are government incentives to either ease the upfront cost or provide for ongoing savings (more details below). Essentially, when it comes to fixing the heating of a whole country, the issues with biomass are difficult to get around.

Electric heating

Heating a house and hot water purely from electricity was very popular in the past, with many homes (including ours) using overnight storage heaters and immersion heaters for water. The proportion of houses in the UK that still use storage heaters had dropped to only 3% by 2019. Storage heaters are still for sale and updated models are now more effective at retaining heat for longer during the day. Nevertheless, the concept is surely fundamentally flawed. Storage heaters are ‘charged’ at night using a cheaper tariff and then they release their heat during the day. By the evening, when we most need the heat, there’s almost nothing left to give, leaving the house pretty chilly in winter. Once gas central heating became available most people quickly abandoned their storage heaters.

There are also electric radiators providing room heating. Radiators suitable for extended use tend to be either oil-filled or clay-core. This gives them a high thermal mass which means that they provide steady heat without continuously drawing electric current. With today’s technology electric radiators can be very efficient and easy to control. There are models that learn the patterns of movement of people in the household and predict when and for how long they will need heat in each room. Rooms which are not frequently used are then automatically set down to a lower temperature. Because each radiator is individually controllable (often via your mobile phone), there’s no juggling with a central heating set-point that does not quite work for all rooms in the house.

The installation of electric radiators is relatively cheap compared to biomass boilers and heat pumps, amounting to a few thousand pounds to buy and install for a whole house. However, the operating costs can be high. The unit cost of electricity is much higher than gas; currently (February 2021) about 16p per kWh versus about 3p for gas, although it is projected that these costs will decrease with time.

It is possible to guarantee that your electricity supplier is buying their supply from renewable sources by signing up to a ‘green’ tariff. This either means that the supplier supports the generation itself or else they pay for green credits so that somebody else does.

So, what did we choose to do?

Coming back to our dilemma of heating the house in Norfolk. Having understood the short- and long-term costs, including considering connecting the house to the gas supply and installing a gas boiler and wet heating system, we decided to go for electric radiators in each of the rooms combined with improved loft insulation. The upfront cost is relatively low but the ongoing costs, although still an unknown at this point, could be high due to the price of electricity. In order to make the cost of using the radiators cheaper, we are now also looking into the installation of solar panels and a battery. Solar electricity generation is a whole topic with several options and considerations. We’ll cover solar generation and storage in a future blog post.

Finally, it was decided that an all-electric heating and hot water solution is the most sustainable solution that can still keep an older house warm enough. This situation may change as new technology becomes available or as the government rolls out new financial incentives to replace existing fossil fuel systems.

Government Incentives

There are mainly 2 government incentive schemes at the moment:

  • Renewable Heating Incentives (RHI)
  • Green Homes Grant (GHG)

RHI consists of quarterly payments made by the government for up to seven years for generation from heat pumps, biomass boilers and solar thermal units. Solar thermal is a technology to support the heating of domestic hot water by the sun (it is not the same as photovoltaic cells that generate electricity from the sun). Payment levels depend on the energy efficiency of your house (as shown on its EPC document), the amount of heat generation and the heating technology used. Payments are typically between £400 and £4000 annually. The RHI payments sound great, but if the heating technology itself is not fit for purpose for an older home then it is of little real value.

The Green Homes Grant is a recent initiative to subsidise the upfront costs to install renewable technologies, including vouchers of up to £5000 to install heat pumps, biomass boilers, solar thermal panels, and certain forms of insulation.

However, there have been major issues with this voucher scheme. By 26 January 2021, only about 17,000 vouchers had been issued out of more than 100,000 voucher applications. The government then announced in February 2021 that the £1.5bn promised to help 600,000 homes make energy-saving improvements will only be available until the end of March 2021. Between March 2021 and March 2022 only around £320m of funding will be available. The scheme will close at the end of March 2022.

Finally, it’s note-worthy that any money received from GHG will be deducted from any following RHI payments. This effectively means that you can’t benefit from both schemes. Another big issue is that neither of these two schemes apply to solar photovoltaic generation which is unarguably the most popular and effective form of home renewable power generation. This seems to be a huge oversight when it comes to trying to encourage individuals to convert their homes to sustainable electricity. Perhaps, as the 2050 Net Zero deadline looms, the government will be forced to reconsider its position on incentives.

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