High density materials such as concrete, bricks, and tiles require a great deal of heat energy to change their temperature and are therefore said to have high thermal mass. Lightweight materials, on the other hand, such as timber, have low thermal mass.
Thermal mass is particularly beneficial where there is a big difference between day and night outdoor temperature. Appropriate use of thermal mass moderates internal temperatures by averaging day and night (diurnal) extremes, which in turn improves comfort and reduces energy costs.
Thermal mass acts as in the same way as a battery, except that is stores heat instead of electricity. During summer it absorbs heat, keeping a building comfortable. In winter the same thermal mass can store the heat from the sun or heaters to release it at night, helping the building stay warm. However, thermal mass is not a substitute for insulation. Thermal mass stores and re-radiates heat. Insulation stops heat flowing into or out of the building. A high thermal mass material is not generally a good thermal insulator.
Related category• BUILDING AND ARCHITECTURE
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