Ground-Source Heat Pump Project Analysis

Background

Maintaining a comfortable temperature inside a building can require a significant amount of energy. Separate heating and cooling systems are often used to maintain the desired air temperature, and the energy required to operate these systems generally comes from electricity, fossil fuels, or biomass.

Considering that 46% of sun’s energy is absorbed by the earth as shown in Figure 1, another option is to use this abundant energy to heat and cool a building.

In contrast to many other sources of heating and cooling energy which need to be transported over long distances, Earth Energy is available on-site, and in massive quantities.

Because the ground transports heat slowly and has a high heat storage capacity, its temperature changes slowly—on the order of months or even years, depending on the depth of the measurement. As a consequence of this low thermal conductivity, the soil can transfer some heat from the cooling season to the heating season as presented in Figure 2; heat absorbed by the earth during the summer effectively gets used in the winter.

This yearly, continuous cycle between the air and the soil temperature results in a thermal energy potential that can be harnessed to help heat or cool a building.