How To Heat Rural Homes

by Bean Beanland, GSHPA

The heating strategy for rural homes must change and the government is looking at multipronged short to medium term solutions.

In 2015 the Saudi oil minister Sheik Yamani said, "The Stone Age didn't end for lack of stone, and the oil age will end long before the world runs out of oil."

Rural communities in the UK are heavily dependent upon oil for heating and domestic hot water, but in an age when cost of living is key, the International Energy Agency's Neil Atkinson says that oil markets could experience more intense price volatility in the coming years because of insufficient investment.

Domestic oil prices have risen from 35.7p/l to 53.3p/l (49%) in the last twenty months. By comparison, the price of domestic electricity increased by 7% in the year to Q3 2017. Many oil consumers will also remember the days of 75p/l, or more, in the 2013 peak.

Oil at 53.3p/l and a boiler efficiency of 88% delivers heat at 6.3p/kWh. Electricity at 12p/kWh and a ground source heat pump operating at a very conservative seasonal performance factor (SPF) of 3 delivers heat at just 4p/kWh.

Combating Climate Change

Cost per kWh of heat is not the only driver. The Clean Growth Strategy of October 2017 recognises the demand for massive reductions in carbon emissions to combat climate change together with a need for clean air because "poor air quality remains the largest environmental risk to public health in the UK".

The Clean Growth Strategy states that heating our homes, businesses and industry accounts for nearly half of all energy use in the UK and a third of our carbon emissions. Meeting our target of reducing emissions by at least 80% by 2050 implies decarbonising nearly all heat in buildings. Reducing the demand for heat through energy efficiency will help, but it will not be sufficient to hit the 2050 target.

This is the challenge and it makes sense to start by displacing the highest carbon factor fuels first. The carbon factor for coal and oil both exceed 315 gCO2e/kWh at 85% efficiency. By comparison, the carbon factors of natural gas and grid electricity (DEFRA data July 2017) are 184 gCO2e/kWh and 352 gCO2e/kWh respectively.

However, the carbon factor for grid electricity has fallen by 29% between 2014 and 2017, and is on a continuing downward trajectory as wind and solar generation capacities increase, and coal-fired generation is withdrawn.

Zero carbon grid electricity remains some way off, but even SAP is likely to recognise the scale and pace of change when the outcomes of the current consultation are published.

The DECC projections in November 2015 suggested parity between the electricity grid and natural gas being achieved around 2022, but this is now likely to be beaten by 2020. On this basis, a ground source heat pump with a conservative SPF of 3 is already 41% more carbon efficient than a gas-fired boiler operating at 92% efficiency. Against an oil-fired boiler operating at 89% efficiency, the carbon saving is 61%.

For a ground source heat pump operating at an achievable SPF of 3.8 in a new build property, the carbon reduction against oil is already 70%. Heat pumps are also zero NOx at the point of use.

Contrary to the vested interest views of the heating oil industry, the Clean Growth Strategy identifies a number of short to medium term options for rural heat decarbonisation, including the electrification of heat. It also calls for district heat networks, improvements to the existing boiler stock under the Boiler Plus, the roll-out of smart metering and investment in the development of new, low cost, low carbon technologies.

Newly build houses are already heat pump friendly by virtue of Building Regulations and extensive use of underfloor heating. However, high levels of insulation and UFH are not required for heat pump efficacy: the retro-fitting of heat pumps to the existing housing stock can be highly successful if best practice is applied.

The deployment of smart meters will provide opportunities for 'demand side response', shifting electricity consumption to times when it is plentiful and cheap: equally beneficial to heat pumps and electric vehicles.

Criticism that the heat pump sector has been heavily subsided is misplaced because the majority of the RHI funding has gone to support biomass boilers and 23% of accredited installations are in social housing.

Deployment of heat pumps is not a significant risk to the oil sector in the short term because it will take time to build the UK supply chain. The real danger for oil boiler suppliers comes from resistive heat, particularly in the new build arena.

If SAP continues to recognise only building fabric and emissions, the default and lowest capital cost option for developers will eventually be electric panel heaters and immersions, notwithstanding their SPF of 1.0 and operational cost of grid electricity. Bio-oil won't get a look-in and consumers will pay the operational price.


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