Hexagon could be first theatre in country to use ground source heat pumps to keep audiences warm

• 120m deep boreholes have been drilled
• Exploration work found water flow is suitable for use
• Ground source heat pumps could be used to heat and cool the theatre

The Hexagon could be the first theatre in the country to be heated by using naturally occurring warm water from underground.

Ground source heat pumps work by harnessing heat from water which flows naturally underground. This is pumped to the surface where heat is extracted using a heat pump and transferred for use in a building. The cooler water is then returned underground. It is like a fridge in reverse.

This form of renewable energy is one of the sustainable initiatives being used in the redevelopment of The Hexagon.

The old inefficient high carbon gas boilers are set to be removed and the ground source heat pumps will reduce the carbon emissions of the theatre. This method is a sustainable and low carbon way of heating the building which fits the Council's ambition to create a carbon free Reading by 2030.

Over the summer contractors conducted an exploration of the Queen's Walk site to see whether the area would be suitable for extracting the water found in the chalk aquifer running under the town.

Two 120m deep, 35cm wide boreholes have been drilled and tests were conducted to see if the flow and the temperature of the water are sufficient to support the heating needs of The Hexagon complex.

Results show that 15 litres of water per second can be extracted and raised to the surface to a heat pump which will extract the heat and use it in the building before replacing it at a lower temperature further downstream.

The geology of the area means that water can flow through the fractures in the chalk, making it particularly suitable for the new way of heating buildings. The water levels returned quickly after extraction throughout the testing process meaning it will have minimal impact on the surrounding area, which forms an important part of the test.

The Council has now applied to the Environment Agency for a licence to use the boreholes for this purpose.

The heat pump system will be funded through the Public Sector Decarbonisation Scheme through Salix who work on behalf of the Department for Energy Security and Net Zero.

Air source heat pumps will also be installed at The Hexagon if any more heat or cool air is needed in addition to the ground source in periods of higher use.

Councillor Liz Terry, Leader of the Council, said: "We are committed to using innovative ways to make our buildings carbon neutral for the future of Reading and our residents.

"The Hexagon could be the first theatre which uses water which is naturally running many metres below us to heat and cool the space to make it comfortable for audiences who come and watch the wide range of shows we have to offer."

Richard Lane, Director, Drift Services Group, which carried out the exploratory work, said: "Drift Services Group (Drift) is delighted to have played a key role in delivering this landmark project for Reading Borough Council, which will be one of the first of its kind in the UK to utilise open-loop ground source heating for both heating and cooling of a theatre.

"Our drilling and testing of the boreholes at The Hexagon confirmed the presence of high-quality water in the aquifer, ensuring not only the required flow rates but also the efficient return of water to the aquifer - an essential factor for the system's performance and the sustainable nature of this clean, green energy solution.

"The rigorous testing process included verifying the aquifer's capacity to supply and reabsorb the required water volumes through separate, rigorous procedures. All tests were successfully completed, and the boreholes have been securely capped, ready for the next phase of permanent pump installation following the heat pump deployment."

Ian Rodger, Director of Programmes at Salix, which delivers and administers grant and loan funding on behalf of the Department for Energy Security and Net Zero, said: "We look forward to working with Reading Borough Council on this project, which builds upon years of dedicated work to reduce their carbon emissions in a bid to tackle the climate emergency.

"The ambitious project at The Hexagon theatre will transform this iconic community venue in the heart of Reading and offer significant benefits to both the council and community."

The redevelopment will be at the heart of the new Minster Quarter and has been made possible by a £19.1 million grant from the government's Levelling Up Fund.