Here in the Netherlands where we have relatively easy access to the ground and ability to drill, we are starting to make more use of ground temperature. With ei

Here in the Netherlands where we have relatively easy access to the ground and ability to drill, we are starting to make more use of ground temperature. With either narrow 50m deep installs to reach a place with a steady 12 degrees Celsius, or more top layer but wider installs. A heat pump is then used to exchange the heat of ground to the heat of the house. For both heating and hot running water. Then an additional option is to cool the house in summer by extracting the heat from the house and pumping it into the ground to be extracted during winter. This is interesting because, especially in combination with floor heating, this can heat a house on the solar generation in winter. Sadly these systems are expensive to install after building the house. But it can be done, especially the less specialised wider top soil solutions.