Of the two types of ground source energy system, an open-loop borehole array is best suited to meet high heating and cooling demands of larger buildings, developments and district heating schemes, where the site is overlying a productive aquifer (found below most of UK's major population centres).
Open-loop systems pump water from the aquifer and return it with a small change in temperature and typically, a fairly modest groundwater flow of 10 litres/sec can provide 200 kW of heating load. Less boreholes are needed compared to closed-loop systems, but they are significantly greater in diameter and are more complex to construct and commission, therefore requiring specialist knowledge and in most cases larger machinery.
In the England and Wales, the Environment Agency (EA) regulates abstraction and recharge of groundwater to protect the resource which is critical for public and private water supplies. However, as open-loop schemes are net-zero in terms of groundwater consumption, new applications would normally considered favourably by the EA. It is important that boreholes and pumping systems are installed, commissioned and maintained by an experienced contractor to ensure compliance with consents and licences. Given the capital cost of installing a system, it is imperative to ensure best practice is followed to reduce the risk of a system not continuing to performing in decades to come. The experts as Subsurface Hydro can point to an enviable track record of practical involvement in successfully delivered schemes, working alongside the industry's most renowned ground source energy consultants.
