Feasibility studies and design testing for an open loop ground source heat pump at Reading Borough Council’s The Hexagon theatre have paved the way for a new scheme that plays a significant part in the council’s 2030 decarbonisation plans.

Carbon Zero Consulting, an RSK Group company, has conducted the studies for a heating and cooling system to provide a peak heating demand of 500 kW and cooling demand of 440 kW, equivalent to the energy requirement for around 80 houses. The system will use an open loop ground source heat pump to supply year-round heating and cooling, supporting the council’s ambitions to decarbonise its buildings and progress sustainability practices across the organisation.

Carbon Zero Consulting Associate Technical Director Anna Hitchmough said: “Open loop systems extract heat from a flow of water taken from bodies of water such as underground aquifers, lakes, flooded mine workings, rivers and estuaries before returning the water to its source (non-consumptive) or, more rarely, discharging the water to another location (consumptive). At this site, a non-consumptive scheme is used to sustainably extract heat from the chalk aquifer under the ground. A few degrees of heat is taken from the water and amplified by the heat pump before the water is returned to the aquifer without the loss of any volume. The temperature of the returned water quickly re-equilibrates in the aquifer.

“The chalk is an excellent source of groundwater, especially where a good network of underground fractures is encountered. This means that a reliable source of groundwater is available. Testing of the aquifer during this project suggests that the aquifer is easily capable of providing the bulk of the theatre’s heating needs, and it is hoped that the scheme will be enlarged to heat the whole Minster Quarter redevelopment.”

Following the successful installation of a pair of boreholes, licensing has been sought from the Environment Agency for the abstraction and injection of groundwater into the system.

Anna said: “We worked carefully with the client to reduce their risk by starting consultation with the Environment Agency early and progressing stages of drilling only once initial test results provided confidence that the scheme was likely to be economically viable. The site is located above relatively shallow groundwater, which reduced the space available for reinjection. Therefore, a reinjection test was carried out on the first borehole drilled, which provided confidence that a single borehole doublet would be effective to recirculate the required flow of water into the chalk. These positive early results meant that the second borehole got the go ahead.”

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

“The Hexagon is one of the first theatres to use water that 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.”