The solar thermal collection and radiant heating system for a spa comprising upper and lower absorber members having fluid passageways and in thermal communication, a skin member encasing said upper and lower absorber members and an insulative member located therebetween the upper and lower members and a solar collection device located on the skin member.

In one aspect the invention provides a heat transfer apparatus which includes a transmitter object which defines an external collection surface and an internal transmission surface. Also provided is a receiver object displaced from the transmitter object, the receiver object defining an internal receiving surface and an external heat delivery surface. A thermal conduit is provided which incorporates at least one side wall connected between the transmitter object and receiver object, this at least one side wall spanning the distance between the transmitter object and receiver object and enclosing a volume between the transmitter and receiver objects. This side wall or walls enclose the internal transmission surface of the transmitter object and the internal receiving surface of the receiver object. The transmitter object, receiver object and thermal conduit are configured to promote heat transfer predominantly towards the receiver object.

A gas receiver configured to heat a working fluid is disclosed. The receiver comprises an aperture, a light absorber, and a pre-heater interposed between the aperture and light absorber. The pre-heater is transparent to visible light and opaque to infrared. The pre-heater in the preferred embodiment comprises quartz in the form of a plurality of quartz plates or quartz tubes, for example, that are oriented substantially parallel to one another. The quartz plates are separated from one another by a gap to permit air to pass into the receiver cavity, while the quartz tubes are hollow to permit air to pass therethrough. The quartz plates or tubes are configured to transmit visible light from the aperture to the light absorber, and to absorb infrared radiation passing from the light absorber toward the aperture. Since the quartz structures absorb infrared, they serve to capture blackbody radiation emitted from the absorber and use that energy to pre-heat air before it passes into the absorber.

A system and method for a passive thermal diode (PTD) to be disposed on a pipeline that inhibits heat transfer from the pipeline to the environment below a threshold temperature and promotes heat transfer from the environment to the pipeline above a threshold temperature.

A building envelope, in particular a wall, a floor, or a roof of a building with at least two shells spaced some distance apart from one another, which encloses an intermediate space, said space being essentially empty with the exception of weight-bearing and/or construction-engineering elements or being filled at least in sections with porous, open-celled material and sealed from the interior and exterior of the building, wherein controllable sealing means are provided for sealing the intermediate space from the interior and exterior and optionally separated building envelope sections from one other.