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Greener Home Heating

Cost and carbon footprint illustrations for a number of options for reducing the carbon footprint from home heating

Over following pages we provide 6 illustrations of the options that are being promoted as ways for reducing the carbon footprint of your home hot water and space heating. The carbon footprint from heating our homes is far from insignificant. A typical Victorian mid-terrace house will use around 12,000kWh of energy for space heating and 2,500kWh for hot water every year. This is even with a well-insulated loft and a modern gas-fired boiler. This will produce around 2.75 tonnes of greenhouse gases, which is the same carbon footprint as driving 11,770 miles a year in an average car, or flying 11 round trips to and from Rome.

To produce the illustrations we have brought together a number of official data-sets. These are:

* Government data on energy consumption for a range of housing types.

* Data provided to the government by consultancy Delta EE on the costs of installing a range of new heating options. The data they provided including a range of costs (low, central, high). These are illustrative costs only – the actual costs will vary depending on how easy the installation is or not, and costs of labour vary across the UK.

* Data from the National Grid on the carbon intensity of the electricity grid now, including at different times of year and different times of day. Carbon intensity is the carbon footprint from producing a unit of electricity. For example, if the electricity at a given time is largely produced by renewable energy the carbon intensity will be low whereas if the electricity is largely produced by gas-fired power stations the carbon intensity will be high.

* Government projections of the carbon intensity of the electricity grid in future years. The carbon intensity is projected to decline as more renewable power is produced.

* Estimates on how much subsidy some of the options may be eligible for under the governments Renewable Heat Incentive. This data is from a 2018 Fact Sheet published by the regulator Ofgem, but is provided as a guide only.

For the heat-pump option we have used reasonable estimates on how much energy they can capture from the surrounding environment. Heat pumps work like fridges in reverse. Rather than cooling the inside and dissipating the heat outside of the fridge the heat pumps capture heat from the environment outside the house (air or land) and transfer the heat into the house.

They work even when the temperature outside is as low as minus 20oC, but they operate more efficiently at higher temperatures. For our modelling we have used a factor of 2.8 for air-source heat pumps (for every unit of electricity consumed they provide 2.8 units of warmth), 3.0 for air-air heat pump, and 3.2 for ground source heat pumps. For the energy costs we have used current costs from one supplier. The costs will differ dependent on your supplier. Our choice of this supplier does not imply endorsement of the company or its practices.

We have also added an additional example of one type of micro fuel-cell CHP. The data the government requested from Delta-EE did not include costs from this new technology which has just come to market in the UK (200,000 units are already installed in Japan). The cost data we are using for this comes from the manufacturer.

See the full 10 page Greener Home Heating briefing.

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