 This means that the temperature differential is lower, leading to higher efficiency.Well maintained ground-source heat pumps typically have COPs of 4.0 at the beginning of the heating season, with lower seasonal COPs of around 3.0 as heat is drawn from the ground.The tradeoff for this improved performance is that a ground-source heat pump is more expensive to install, due to the need for the drilling of boreholes for vertical placement of heat exchanger piping or the digging of trenches for horizontal placement of the piping that carries the heat exchange fluid (water with a little antifreeze).