CHAPTER 5 - PASSIVE HEATING AND COOLING

Abstract

Passive solar design uses solar energy naturally by involving the conventional building elements for solar energy collection, storage, and distribution. Unlike the active systems in which a carefully designed and relatively complex solar collector is connected to fans or pumps, storage or heat exchange units to provide heating, the passive system uses natural convection, conduction, and radiation. This chapter discusses the passive heating and cooling. The various different approaches to passive solar energy collection have been categorized into five basic groups, namely, the direct gain approach, the trombe wall or thermal storage wall, the solar greenhouse, the roof pond, and the natural convective loop. Solar space heating in buildings can save very considerable amounts of energy. In the design stage of the direct gain approach, a fundamental principle was that the control of the internal environment should be obtained by a combination of solar energy and a heat pump system to provide heat and cooling, together with hot water supply and refrigeration. The trombe wall is both a heat collector and a heat store. As solar radiation passes through the glass, it is absorbed by the surface coating which heats the wall. As the long wave reradiation from the wall is trapped behind the glass, the air between the wall and the glass becomes heated. Ducts at the top and the bottom of the wall allow the heated air to be fed into the room at ceiling level, while the colder air from the floor is drawn in at the bottom.