Ground-air heat exchanger

Ground-air heat exchangers are becoming increasingly popular in the UK, in particular in the Health and Education sectors.  Ventilation is simply drawn through a network of underground pipes (1.5m deep), which pre-cools the sir in the summer and pre-heats the air in the winter.

Typical COP's for this efficient system range from 20-50 for a commercial project and even higher for a domestic project.