What is thermal mass ?

Due to its thermal mass, concrete allows for less heating and cooling in buildings thereby
improving the energy efficiency of buildings, and lowering CO2 emissions.

Thermal mass is a property that is unique to heavyweight building materials: when it is hot outside, concrete can absorb any unwanted heat and help prevent the building from overheating. This heat is then released in the evening when it is cooler outside. Thanks to this effect, room temperatures remain
relatively stable throughout the year, and as a result, less energy is required to heat or cool rooms.

“Thermally activated” building systems can further enhance the effect by the use of water pipes (warm and cool water) embedded in the concrete (so-called “integrated heating and cooling systems”).