A plant for tempering a building, including an energy storage unit formed by ground heat exchangers coupled in parallel and each including a heat insulated leg and a non-insulated leg in thermal contact with surrounding soil. The heat exchangers are included in a circulating circuit for a circulation fluid which includes a circulation pump and room temperature keeping devices. The energy storage unit has a continuously varying temperature in a depth direction from a cold end to a warm end. The flow direction in the ground heat exchangers is controlled by a reversing valve such that for a warm keeping function, circulation fluid is received from the warm end and for a cool keeping function, circulation fluid is received from the cold end. The circulation pump is controlled such that the circulation flow brings about a temperature difference between the inlet and outlet of the ground heat exchangers that is constant with a value that can be calculated with the aid of the properties of the ground and the actual components.
