Ground Source Heat Pumps are more efficient than air source as the earth is a constant heat source that doesn’t fluctuate with day or night and summer or winter. Heat is collected via bore holes which are drilled vertically down and filled with brine or a ground array which are pipes filled with brine laid in horizontal trenches usually dug 1.2m deep and two metres apart. Depending on how much heat is needed for the property depends how much land is needed for the ground array but on average we need about 700 square metres. The design of the ground collectors is vital to an effective heating system. A ground source heat pump can expect a SCOP of around 4.5 (meaning 4.5kW of heat for every 1kW of electricity) and works best with under floor heating. Ground Source Heat Pumps cost more to install compared with an Air Source Heat Pump due to the cost of the bore holes or ground array.