In building design, thermal mass is a property of the mass of a building that enables it to store heat and provide inertia against temperature fluctuations. It is sometimes known as the thermal flywheel effect. The thermal mass of heavy structural elements can be designed to work alongside a construction's lighter thermal resistance components to create energy efficient buildings.
The benefit of thermal mass is shown in this comparison of how heavy and light weight constructions affect internal temperature
A modern school classroom with natural ventilation by opening windows and exposed thermal mass from a solid concrete floor soffit to help control summertime temperatures
An adobe walled building in Santa Fe, New Mexico
Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials.
Mineral wool insulation, 1600 dpi scan
Car exhausts usually require some form of heat barrier, especially high-performance exhausts, where a ceramic coating is often applied.
Common insulation applications in apartment building in Ontario, Canada.
Insulated hot water supply and return hydronic piping on a gas-fired boiler
