Author: Oliver Wakefield-Smith, Founder Digital Signet. Reviewed against DfE Sustainability Strategy (Mar 2025) and Education Estates Strategy (Feb 2026). Verified 22 June 2026.
GSHP installed CAPEX in the £2,500 to £3,200 per kW range including borehole field. Borehole drilling alone is £800 to £1,400 per kW; the heat pump and distribution kit accounts for the balance.
GSHP installed CAPEX in the £2,500 to £3,200 per kW range including borehole field. Borehole drilling alone is £800 to £1,400 per kW; the heat pump and distribution kit accounts for the balance.
Where seasonal coefficient of performance is steady at 3.5 to 4.2 (versus an ASHP design-day 2.9), and where electricity tariffs rise above the Ofgem Q3 2026 cap, GSHP can recover the CAPEX premium inside the 25-year design life. The break-even crosses faster for secondaries with long heating seasons.
Closed-loop borehole field at 100 m depth requires roughly 10 m linear between boreholes; a 480 kW secondary array sits on around 0.5 to 0.7 hectares. Open-loop schemes need permission from the Environment Agency and are uncommon outside chalk aquifer regions.
GSHP projects within PSDS Phase 4 typically pair with significant fabric uplift to limit the heat-pump size and the borehole-field footprint. Refer to Salix's published case studies for verified outturn data.