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Passive Solar Building Design - Passive solar building design |
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Indirect solar gain
Indirect gain, in which solar radiation is captured by a part of the building envelope designed with an appropriate thermal mass (such as a water tank or a solid concrete or masonry wall behind glass). The heat is then transmitted indirectly to the building through conduction and convection. Examples of this are Trombe walls, water walls and roof ponds. The Australian deep-cover earthed-roof, innovated by the Baggs family of architects, is an annualized example of this path.
In practice indirect solar gain systems have suffered from being difficult to control, and from the lack of reasonably priced transparent thermally insulating materials.
Isolated solar gain
Isolated gain, involves passively capturing solar heat and then moving it passively into or out of the building using a liquid (for example using a thermosiphon solar space heating system) or air (perhaps using a solar chimney), either directly or using a thermal store.
Sun-spaces, greenhouses, and "solar closets" are alternative ways of capturing isolated heat gain from which warmed air can be taken. In practice it has been found that some owners use these structures as living spaces, heating them with conventional fuels and therefore significantly increasing, rather than reducing, the environmental impact of the building.
Don Stephens' "Annualized Geo-Solar" (AGS) heating is an annualized example of this option, which offers the advantages of preventing over-heating when living spaces are already deemed warm enough, and of extending time-delays until such heat will be desired. Next Page: Other passive solar design techniques
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