Provided is a method of disinfecting a hot water supply system having a plurality of controllable hot-water outlets and a water heating arrangement including an energy store comprising a phase change material that has a phase transition temperature of less than 60 Celsius, the method comprising: informing an operator of a future disinfection event; increasing a hot water supply temperature from a pre-event temperature of less than 60 Celsius to a disinfection temperature; providing a signal to the operator to cause the operator to open a first of the hot water outlets; providing a signal to the operator to close the first outlet after a disinfection period; providing a signal to the operator to open another hot water outlet; providing a signal to the operator to close the another hot water outlet after a disinfection period; and repeating the signalling to the operator to open and then, after a disinfection period, to close each of the plurality of controllable hot-water outlets; reducing the hot water supply temperature to the pre-event temperature of less than 60 Celsius from the disinfection temperature; and indicating to the operator the completion of the disinfection event. A corresponding hot water supply system is also provided, the system preferably including a heat pump.

Building heating and/or cooling methods are provided that can include continuously distributing fluid from within conduits within a concrete floor of a building to conduits within grounds surrounding and/or supporting the building while transferring air to/from the interior of the building via a heat exchanger.

Building heating/cooling systems are provided that can include: a building comprising walls and concrete floors; fluid containing conduit within the concrete floors; circulating fluid within the conduit; a least one heat exchanger operatively associated within the building and configured to transfer air to/from the building; and processing circuitry operatively coupled to fluid circulation controls and heat exchanger controls.

A system and method for heating water are provided. The system includes a first subcooler for receiving a first water flow, a second subcooler for receiving a second water flow, a first condenser in fluid communication with the first subcooler and the second subcooler for receiving water from both subcoolers, and a second condenser in fluid communication with the first condenser. The method involves receiving a flow of water, and transferring heat to the water using the system.

A building heating system, including for heating water, such as tap water and/or utility water, of a building water system. The embodiments also relate to a kit of part to realize such a building heating system. The embodiments further relate to a method for controlling the building heating system.

Provided is a heating installation including an energy store including a latent heat energy storage medium, and a heat pump having a defrost cycle, the heating installation including a hot water supply system arranged to supply instantaneous heated water and space heating to a building, and a processor to control the installation. The processor being configured to: control the supply of heat from the heat pump to the latent heat energy storage medium to store heat for heating water and to a heating circuit for providing space heating; and estimate a likelihood of a defrost cycle by the heat pump. In anticipation of an impending defrost cycle, the processor further being configured to control operation of the installation to store additional energy by at least one of: heating the latent heat energy storage medium to a higher level than a level set for anticipated water heating demand alone and/or heating the building and/or circulating heating fluid of the installation to a higher level than a level set for desired building heating; to compensate for an absence of heat from the heat pump during the impending defrost cycle.