The NHS has set itself the ambitious challenge of being the world’s first Net Zero national health service. To meet this challenge, NHS England will need to decarbonise its complex hospital sites.

Low carbon heating solutions such as heat pumps are critical to achieving estate decarbonisation and ground source heat pumps (GSHPs) are particularly well suited to large complex sites like NHS hospitals.  Although they are more expensive to install than air source heat pumps (ASHPs), they are cheaper to run as they are more efficient, particularly during very cold weather.

NHS England, Energy Systems Catapult, and the British Geological Survey were awarded funding by the Knowledge Asset Grant Fund to develop a screening tool for England which will guide initial feasibility studies for using GSHPs as a low carbon heating alternative. The Department for Energy Security and Net Zero (DESNZ) have also provided funding, enabling further development so the tool would work for all public sector building types including schools, prisons and courts.

The aim of the tool is to reduce the barriers to installing GSHPs therefore increasing the uptake across the public sector estate.

The tool can be found here.

The challenge

The NHS is the largest employer in Britain and is responsible for around 4% of the nation’s carbon emissions. In October 2020, the NHS became the first health service to commit to reaching Net Zero.

The ‘Delivering a Net Zero Health Service’ report set out a clear ambition and a more challenging Net Zero target for the NHS than nationally set decarbonisation targets.

The NHS has set itself two goals:

• For the emissions controlled by the NHS directly (the NHS Carbon Footprint), the organisation will reach Net Zero by 2040, with an ambition to reach an 80% reduction by 2028 to 2032;
• For the emissions influenced by the NHS (our NHS Carbon Footprint Plus), the organisation will reach Net Zero by 2045, with an ambition to reach an 80% reduction by 2036 to 2039.

To deliver on such ambitious decarbonisation goals, the NHS needs to explore alternative methods for meeting the energy needs of its sites. Removing fossil fuels and tackling heat decarbonisation is likely to be achieved in part through the adoption of heat pumps, including GSHPs.

The challenges for the NHS when looking to deploy GSHPs are both the variation of the NHS building stock and the variation in geothermal properties across the country. The ground type below an NHS site will have different thermal properties, resulting in differing GSHP performance and variations in how easy it is to drill the necessary boreholes.

The temperature across the UK landmass also varies by several degrees, being around 10°C on average in the upper 100m and warming by ~2.8°C every 100m. Therefore, the depth of drilling or total length of borehole required to provide a certain rate of heat extraction will vary depending on where you are located and how deep you are prepared (or have space) to drill.

Without this tool, public sector organisations would need to engage consultants, even to get an initial understanding of the areas suitability. This barrier and the higher installation costs compared with ASHPs (despite the cheaper running costs) means that the public sector has not historically explored this option further, missing out on potentially better outcomes in the long term.

The innovation

A proposal for grant funding was put forward by NHS England in collaboration with Energy Systems Catapult and the British Geological Survey to the Knowledge Asset Grant Fund, run by the Government Office for Technology Transfer, funded by the Department for Science Innovation and Technology (DSIT), and administered by Innovate UK.

The grant was used to develop a national scope screening tool for England which will guide initial feasibility studies for GSHP as a low carbon heating resource option for individual NHS trust buildings and heat networks. The toolkit aims to assist users in establishing the availability of ground source heat in their area, potential benefits specific to their location and potential challenging ground or drilling problems that may be present.  DESNZ also provided funding to enable the tool to be expanded to model all public sector building types, significantly increasing the applicability and value of the tool.

The screening tool uses geological information and user provided data to calculate the energy demand for building heating and how much of the heating demand can be provided by closed loop GSHPs. It evaluates and presents the primary factors that influence geological feasibility and uses the calculated results to present estimated installation (CAPEX) and operational (OPEX) costs, comparing them to both the current heating system and an equivalent installation of an ASHP.

The tool also provides an indication of the potential for open loop GSHPs in the location as well as presenting the effect of potential building fabric improvements on the results.

Energy Systems Catapult was responsible for the above ground (building related elements) parts of the tool and the development and hosting of the web-based tool. The British Geological Survey was responsible for the underground (geology related elements) parts of the tool.

The envisaged tool users are estate managers, energy managers, the consultancy market and others who want to know whether GSHPs are a feasible option for decarbonisation.  The tool is currently live, and Energy Systems Catapult will continue to seek funding to further improve the tool.

The outputs are indicative, broad estimates of costs, carbon and energy savings, feasibility of installing GSHPs, site limitations, heat energy required with current buildings’ fabric and with fabric improvements and a percentage of heat that can be met by the GSHPs. It is intended that, for sites where a GSHP is feasible, the tool user will contact relevant designers or experts to move the project through to the design phase.

The impact

The project aims to help the NHS and other public sector organisations determine the feasibility of using GSHPs on their sites, overcoming the existing cost and time barriers to doing this.

The impact of this will be to enable cost-effective heat decarbonisation across the public sector through the installation of more GSHPs on suitable sites.

Next steps

We will be promoting the tool across the public sector and aim to further develop the tool.  This further development would cover adding other non-domestic buildings and improving the tool by adding cooling calculations. GSHPs can also provide effective cooling to buildings which has the benefit of “charging up” the ground with the heat taken from the building. This reduces the capital cost and improves the GSHP efficiency, further strengthening the business case for installing a GSHP.