What does “thermal mass” refer to?

Thermal mass refers specifically to the ability of a material to absorb, store, and release heat, which plays a significant role in the regulation of indoor temperature. This property is essential in building design as materials with high thermal mass, such as concrete or stone, can help moderate temperature swings within a space. During the day, these materials can absorb excess heat when the temperatures rise, and later, as temperatures drop at night, they release that stored heat, contributing to a more stable and comfortable indoor environment.

In contrast, insulation primarily prevents heat transfer, while thermal mass actively manages heat levels. The total heat generated by appliances does not relate to thermal mass but rather to energy consumption and heat output. Similarly, ventilation rate pertains to air movement within a space and does not directly influence the thermal retention properties of materials. Thus, the correct concept of thermal mass is accurately captured by the ability to absorb, store, and release heat, significantly affecting indoor climate control.