A greenhouse, for cold weather climates, is configured with a gable that is offset toward the north wall and therefore the south extension of the roof, from the gable to the south wall is longer than the north extension. A greater amount of light can enter through this south extension and the inside surface of the north wall is configured with a reflective surface to allow light to be more uniformly distributed around the plants. The north wall may have no widows and may be thermally insulated to prevent the greenhouse from getting too cold during the night. A ground to air heat transfer (GAHT) system may be configured to produce a flow of greenhouse air under the greenhouse for heat transfer, to moderate the temperature of the greenhouse. A thermal medium may flow to a thermal reservoir for heat exchange with the conduits of the GAHT system.

An air temperature regulating assembly is provided having a packed rock bed through which air may flow between outer and inner spaces by way of interstices between rock units in order to transfer heat to or from the rock bed, in use. Dampers control the flow of air between the outer space, the inner space, an enclosed air space the temperature of which is to be regulated by raising or lowering it and the surrounding atmosphere. A fan moves air within the assembly. The rock bed is in the form of a pile of rocks having an upper surface that is inclined and directed in the general direction of the sun to directly absorb solar energy. The outer space is defined between the upper inclined surface of the rock bed and a transparent cover spaced upwardly from the surface of the rock bed.

A fenestration assembly comprising a sliding glass assembly that slides between a fully closed position and a fully open position in which the sliding glass assembly is received into a pocket of the fenestration assembly. The pocket is covered on at least one side with insulation. The fenestration assembly may have two sliding glass assemblies. The fenestration assembly may be used in an energy efficient building system.

A heat exchanger battery comprising an insulated container containing a first heat transfer medium having a first temperature; a plurality of cells in the container for contact with the first heat transfer medium; each cell comprising a conductive casing surrounding a compressible core (if required), and a volume of a second heat transfer medium having a second temperature; wherein circulation of the first heat transfer medium through the insulated container effects a transfer of thermal energy between the first heat transfer medium and the second heat transfer medium in a direction according to a difference of the first temperature and the second temperature; and wherein the compressible core prevents damage to the conductive casing by deforming in response to expansion of the volume of the second heat transfer medium.

A greenhouse, for cold weather climates, is configured with a gable that is offset toward the north wall and therefore the south extension of the roof, from the gable to the south wall is longer than the north extension. A greater amount of light can enter through this south extension and the inside surface of the north wall is configured with a reflective surface to allow light to be more uniformly distributed around the plants. The north wall may have no widows and may be thermally insulated to prevent the greenhouse from getting too cold during the night. A ground to air heat transfer (GAHT) system may be configured to produce a flow of greenhouse air under the greenhouse for heat transfer, to moderate the temperature of the greenhouse. A thermal medium may flow to a thermal reservoir for heat exchange with the conduits of the GAHT system.