Co-benefits 

Beyond financial returns, what other benefits can be expected from a greenspace heat scheme?

Range of typical co-benefits

Figure 1 depicts 6 key co-benefits of greenspace heat schemes. This is not an exhaustive list: those who know a greenspace and its users may be able to identify other valuable co-benefits (or, conversely, non-financial costs that should be taken into account). These co-benefits can be considered in relation to the greenspace heat scheme as a physically or strategically “standalone” system. The greenspace scheme can also be considered in terms of its contribution to and compatibility with a wider transformation through district heating (to which it might or might not be physically connected) and other forms of heat decarbonisation in surrounding areas.

Carbon savings and independence from fossil fuels

The carbon emissions associated with each unit of electricity supplied by the national grid have fallen markedly in recent years and are forecast to continue to reduce – meaning that electricity consumption is becoming greener. When assessing the carbon savings offered by heat pumps – which consume electricity which is created through mixed sources – there is a choice to be made regarding how to account for the carbon emissions from grid electricity. Should the most recent official emissions factor be used? A forecast emissions factor for the scheme’s first year of operation? Or an average emissions factor from the forecast figures that span the scheme’s expected lifetime? The choice may be driven by an organisation’s established standards, or by the requirements of funders – or it may simply be a question of deciding which approach makes most sense for the opportunity under consideration.

Carbon emissions factors for electricity, and for the heating fuels that would be replaced, are available both for the recent past and future (as a forecast) from BEIS. Conversion factors for greenhouse gas reporting from recent years are available here: https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting 

Carbon savings = Carbon emissions under business-as-usual minus carbon emissions with the greenspace heat scheme operational.

Alternatively, the EXCEL tool provided with this toolkit includes calculations on Carbon Dioxide equivalent (CO2e), Nitrous Oxide (N20) and Nitrogen oxides (NOx) reductions 

Air quality

As road vehicles become cleaner and transport is increasingly electrified, gas boilers are gaining increasing attention from city administrations seeking to reduce air pollution, particularly nitrogen oxides (NOx) and particulates. Heat pumps emit zero emissions at the point of use - so when they replace fossil fuel boilers, they improve air quality.

Air pollution legislation is placing strict requirements on the emissions performance of new boilers, so Ecodesign limits (for smaller boilers: less than 400kW) and Medium Combustion Plant Directive limits (for larger boilers) can give a guide to the worst-case emissions performance of a new boiler.

For older plant, in-service NOx emissions – as opposed to the emissions levels that might be reported on boiler datasheets – vary widely depending on the boiler type, age and how it is used. As a starting point for understanding the order of magnitude of NOx savings from heat pumps, a value of 100 mg/kWh could be used.

As long as the UK’s electricity generation mix continues to feature combustion power plants, the production of electricity to run heat pumps will cause emissions of airborne pollutants. However, these power plants are typically located far from centres of population and are increasingly good at controlling the pollutants that are emitted or reducing the creation of pollutants in the first place; meanwhile the share of non-polluting renewables continues to grow. What’s more, because heat pumps are so efficient, the overall pollution created is less than that emitted by the alternatives: fuelled boilers or direct electrical heating.

Local energy

An intangible benefit, that may nevertheless be very important to those considering deploying heat pumps in green space, is the potential for shifting the balance within an area in favour of local consumption of local resources. Although the electricity consumed by heat pumps is normally generated outside the local area, the renewable heat that is harvested from the ground or water and amplified by the heat pump is very much a local resource – and it represents 65 – 85% of the heating that is delivered to users. If local electricity generation is also developed, the local proportion of energy production can rise to up to 100%.

Greenspace protection

One possible benefit of deploying ground or water source heat is the potential to ‘protect’ greenspace from the threat of development by virtue of it hosting critical energy infrastructure. In other contexts, the word “sterilisation” is used to describe this effect – but in the case of greenspace heat, the ability to continue to use the ground or water above the heat collector for its original purpose means that “sterilisation” can be misleading. It should also be borne in mind that the reduction of development potential is not absolute: a change of land use is still possible, but the economics will be somewhat shifted in favour of maintaining green space.

Public/community engagement

The development, construction and operation of a greenspace heat scheme provides an opportunity for public and community engagement. For example:

• Raising organisational profile and reputation by demonstrating climate action

• Awareness-raising about sustainability

• Providing a learning opportunity for schoolchildren and adults

Key principles are discussed in the module “public relations and community engagement”.