Reduction of heat flux through a roof by water film

Passive cooling by evapo-reflective roof for hot dry climates

“…The relative advantages of evaporative cooling in relation to many other approaches (cavity wall, insulation, whitewash and large exposure orientations, vegetable pergola shading, roof with removable canvas, water film, soil humid grass and roof with white pots as cover) were demonstrated in [10,11]. The reduction of heat gain through the roofs using evaporative cooling systems was extensively investigated with open roof ponds [18,19], on water spraying over the roof, moving water layer over the roof, thin water film and roofs with wetted gunny bags [12][13][14][15][16][17]. Chandra and Chandra [12] have developed a periodic heat transfer model to study the effects of evaporative cooling using water spray and variable ventilation on the temperature control of a non-air-conditioned building.…”

Roof ponds as passive heating and cooling systems: A systematic review

“…Therefore, lower relative humidity is desirable for efficient functioning of cooling roof pond systems [23,44,59,82,85,88]. For an open roof pond designed for cooling purpose in the warm-temperate conditions of New Delhi, Sodha and Kumar [47] found that increasing relative humidity results in larger amount of heat flux into the room.…”

Energy conservation in electrical water heating in buckets

“…It can be seen that he is a function of saturation vapour pressure which depends non-linearly on the temperature. However, Sodha et al (1978) have reported that in a narrow range of temperature variation, it can be represented by a linear temperature dependence, namely…”