Device for heating and cooling, respectively, more than one house, where at least two small houses (1) are connected to a common energy storage (2) in the ground and where a control device (3) is arranged to transport a heat carrier in a pipe work (4) connected to the energy storage (2). The small houses (1) are each arranged to have a separate respective heat pump device, and in each heat pump device is connected to the pipe work (4), so that, firstly, the heat carrier can flow through the heat pump device and, secondly, the small houses (1) are connected in parallel in relation to each other to the pipe work (4).