Open-loop ground source heat pumps
Groundwater-sourced heating and cooling — among the most efficient renewable heating systems available. Ideal for larger residential and commercial properties.
How open-loop systems work
An open-loop system abstracts groundwater from one or more boreholes, passes it through a heat pump to extract thermal energy, then returns the water to the ground via a second “recharge” borehole or discharges it to a watercourse.
Each system is individually designed, accounting for the heat required, available groundwater volumes, abstraction and recharge methods, and the heat pump itself. Open-loop systems can deliver some of the highest efficiencies of any GSHP type.
Because open-loop systems abstract and discharge water, they typically require an Environment Agency abstraction licence. Our licensing team — Nicholls Licensing & Consulting — works closely with the EA to manage this process from start to finish.
Key specifications
- Water source
- Groundwater from boreholes (aquifer-dependent)
- System sizes
- 10kW to 1MW+ for commercial sites
- Discharge
- Recharge borehole or surface watercourse
- Efficiency
- COP 4.0–5.0+ (among the highest of any GSHP)
- Licensing
- EA abstraction licence typically required
- Cooling
- Can provide passive or active cooling in summer
Built-in licensing expertise
Open-loop systems require EA abstraction and discharge licensing. Our in-house licensing division handles the entire regulatory process — you don't need to engage a separate consultant.
Learn about our licensing services →When to choose open-loop
Open-loop is a good fit when…
- ✓Your site sits above a productive aquifer with sufficient groundwater flow
- ✓You need heating and cooling (open-loop systems can provide both efficiently)
- ✓Higher system efficiency (COP) is a priority — open-loop typically outperforms closed-loop
- ✓Your building has a larger heat demand (50kW+) where the efficiency gains are most significant
- ✓You want passive cooling in summer without additional equipment
Consider closed-loop instead if…
- →There is limited groundwater availability beneath your site
- →Geology makes water abstraction impractical or uneconomic
- →You prefer to avoid the EA licensing process (closed-loop is typically licence-free)
- →The property is smaller (domestic, under 20kW) where the efficiency difference is less material
- →Water quality is poor — iron, manganese or other minerals can cause fouling in open-loop systems
Design and installation process
Open-loop projects involve additional hydrogeological and regulatory steps compared to closed-loop. Our combined drilling and licensing expertise means we manage the entire process.
Hydrogeological assessment
We assess groundwater availability, aquifer properties and water quality to confirm open-loop viability at your site.
EA pre-application
Our licensing team engages with the Environment Agency early to confirm abstraction and discharge requirements.
System design
Heat loss, flow rates, abstraction volumes and discharge method are all calculated to design the optimal system.
Test pumping & licensing
We drill test boreholes, conduct pumping tests to confirm yield, and prepare the full EA licence application.
Installation & commissioning
Abstraction and recharge boreholes, pipework, heat pump installation, system commissioning and MCS certification.
Ongoing compliance
We support your EA licence compliance including monitoring, returns and condition reviews.
Applications
Large residential
Country houses, estates and multi-dwelling developments where high efficiency justifies the additional investment.
Commercial offices
Heating and cooling for office buildings, with the dual-mode capability reducing the need for separate HVAC systems.
Healthcare & education
Hospitals, care homes, schools and universities with consistent year-round heating and cooling demands.
Hotels & hospitality
Hotels, leisure centres and spa facilities — open-loop systems can also pre-heat swimming pools.
Industrial & manufacturing
Process cooling and heating for manufacturing sites with significant thermal loads.
Data centres
Open-loop groundwater cooling for data centre facilities — highly water-efficient compared to evaporative cooling.
Could open-loop work at your site?
Contact us for a groundwater feasibility assessment and no-obligation estimate.