SOLAR serdar Thermal mass and cooling
Materials used in walls, floor and other sun-exposed parts of the house should have adequate thermal storage or reflectance, that is, thermal properties able to respond to the needs of the climate where the building is located.
In cold climates the capacity of quickly absorbing solar heat and the capacity of providing a slow release of stored heat during the night, can be important when choosing constructions materials: masonry and stone for floors, walls, and roofs are materials that pose that issue. In other words: in cold climates, passive heating demands high thermal mass materials.
Obviously, passive cooling techniques demand mostly low thermal mass materials…
Low thermal mass materials
Low thermal mass walls and structures are a very common option in hot-humid climates with high nighttime temperatures.
Materials like metals and wood have that low thermal mass and are adequate to passive cooling techniques. Metal roofs and wood frames are very common in passive cooling precisely because they don’t heat well and cool quickly, when the sun disappears.
Reflective exterior surfaces
The use of highly reflective exterior surfaces is also advantageous and crucial in passive cooling, due to the large amount of the sun’s heat that can be reflected away by reflection. Reflective roofing is particularly effective.
Color and texture are also important in this case. White or close-to-white colors are good options for reflectance. Shinier and smoother materials are also good options, since they are more reflective.
High mass materials for hot dry climates with cold nights
The use of high mass materials – materials that hold heat well and cool slowly, like masonry and stone for roofs, floors or walls – are adequate in hot dry climates, with cold or relatively cold nighttime temperatures.
Recent studies also show that high thermal mass elements can be used with advantage either in temperate climates and some hot climates. Low thermal mass materials aren’t the only solution.
In hot and humid tropical climates, with small day/night temperature amplitude, natural ventilation isn’t a good option. But in most other cases natural ventilation is an excellent passive cooling technique.
Obviously it demands a correct location of the windows, and a proper orientation of the building (which in some cases may collide with other solar heating or cooling strategies).
The windows design (double-hung and casement windows) and placement, as well as the shape and orientation of the building are crucial for natural ventilation strategies.