A system comprising: first and second heat exchange panels each comprising: a main body comprising a sealed cavity in which is provided a fluid in both liquid and gas phases and being configured to communicate heat energy by allowing evaporation of the liquid at one location and condensation of the liquid at a different location in the cavity; and at least a first heat exchanger part (130, 131, 210a, 210b, 211a, 211b) including an inlet and an outlet for allowing the passing of fluid through the first heat exchanger part, the first heat exchanger part being thermally coupled to the main body so as to communicate heat energy between fluid flowing through the first heat exchanger part and the main body and thus the environment in which the main body is present; a heat pump; a controller; a heat tank (213, 214), for providing a heating fluid for a central heating system or for providing hot water, plural controllable valves; and one or more fluid pumps (261, 217), wherein the controller is configured to cause control of the pumps and the valves to as to cause the system to operate in a number of different modes of operation, wherein the system is operable in an active heating mode of operation in which the controller controls the heat pump, the one or more fluid pumps and the valves to provide the system with: a first fluid circuit in which fluid is pumped through at least one of the heat exchange panels and a first side of the heat pump, a second fluid circuit in which fluid is pumped through the heat tank and the second side of the heat pump, and transfer by the heat pump of heat energy from the first fluid circuit to the second fluid circuit, and wherein the system is operable in a thermal transfer mode in which the controller controls the heat pump, the one or more fluid pumps and the valves to take in heat energy from one of the heat exchange panels and to expel heat energy through the other of the heat exchange panels. first and second heat exchange panels each comprising: a main body comprising a sealed cavity in which is provided a fluid in both liquid and gas phases and being configured to communicate heat energy by allowing evaporation of the liquid at one location and condensation of the liquid at a different location in the cavity; and at least a first heat exchanger part (130, 131, 210a, 210b, 211a, 211b) including an inlet and an outlet for allowing the passing of fluid through the first heat exchanger part, the first heat exchanger part being thermally coupled to the main body so as to communicate heat energy between fluid flowing through the first heat exchanger part and the main body and thus the environment in which the main body is present; a main body comprising a sealed cavity in which is provided a fluid in both liquid and gas phases and being configured to communicate heat energy by allowing evaporation of the liquid at one location and condensation of the liquid at a different location in the cavity; and at least a first heat exchanger part (130, 131, 210a, 210b, 211a, 211b) including an inlet and an outlet for allowing the passing of fluid through the first heat exchanger part, the first heat exchanger part being thermally coupled to the main body so as to communicate heat energy between fluid flowing through the first heat exchanger part and the main body and thus the environment in which the main body is present; a heat pump; a controller; a heat tank (213, 214), for providing a heating fluid for a central heating system or for providing hot water, plural controllable valves; and one or more fluid pumps (261, 217), wherein the controller is configured to cause control of the pumps and the valves to as to cause the system to operate in a number of different modes of operation, wherein the system is operable in an active heating mode of operation in which the controller controls the heat pump, the one or more fluid pumps and the valves to provide the system with: a first fluid circuit in which fluid is pumped through at least one of the heat exchange panels and a first side of the heat pump, a second fluid circuit in which fluid is pumped through the heat tank and the second side of the heat pump, and transfer by the heat pump of heat energy from the first fluid circuit to the second fluid circuit, and a first fluid circuit in which fluid is pumped through at least one of the heat exchange panels and a first side of the heat pump, a second fluid circuit in which fluid is pumped through the heat tank and the second side of the heat pump, and transfer by the heat pump of heat energy from the first fluid circuit to the second fluid circuit, and wherein the system is operable in a thermal transfer mode in which the controller controls the heat pump, the one or more fluid pumps and the valves to take in heat energy from one of the heat exchange panels and to expel heat energy through the other of the heat exchange panels.