Under hot conditions, the source of heat is solar radiation. This can enter the building directly through windows, or it can heat the building envelope to a higher temperature than the ambient temperature, thereby increasing heat transfer through the building envelope. The solar heat gain coefficient (a measure of solar heat transmittance) of standard single-pane glass can be around 78-85%. Solar gain can be reduced through appropriate shading, light-colored roofs, spectrally selective (heat-reflective) paints and coatings, and various insulation types for the rest of the envelope. Specially coated glass can reduce ultraviolet rays to about 10%. Radiant barriers are very effective for attic spaces in hot climates. In this application, they are more effective in hot climates than in cold climates. For downward heat flow, convection is weaker, and radiation dominates heat transfer in air spaces. Radiant barriers must face a sufficient air gap to be effective.
If refrigeration air conditioning is used in a hot and humid climate, then sealing the building envelope is particularly important. Dehumidification of humid air infiltration wastes a lot of energy. On the other hand, some building designs are based on effective cross-ventilation rather than refrigeration air conditioning to provide convective cooling through prevailing breezes.
Technologies in hot climates
In hot and dry climate regions, summer insulation is the main problem. Nearly half of the energy consumption in urban areas is consumed by air conditioning systems, mainly to meet people's demand for refrigeration. There are also many in hot and dry climates due to the increasing use of refrigerators. But if the region suffers from power shortages in summer, that would be a bad start. Therefore, using extruded board insulation can play an effective role in energy saving. In the past, we would use stone-wood insulation materials to improve thermal comfort. Thick insulation layers will produce a time-lag effect, which may slow down the heat transfer speed during the day and keep the indoor temperature within a certain range. (Dry hot) climate regions usually have a large temperature difference between day and night. But after years of technological change and development, we can already achieve a thermal insulation environment through Kunming extruded boards.
Keeping cold is actually the same as keeping heat, both are the same insulation technology, just like the reason we can see foam boxes holding popsicles in summer. It uses temperature-reflective materials to maintain constant temperature. Of course, they can also improve the insulation effect, because in hot regions in summer, in addition to keeping low temperature indoors, we also need to block high temperature, which is also a desirable method in hot periods.
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