Thermal Mass Explained (2012 update)
This guide explains what thermal mass is, and how best to utilise it.
Concrete and masonry are building materials that steadily absorb any heat that comes into contact with surfaces. The heat is conducted inwardly, and stored until the surface is exposed to cooler conditions and its temperature begins to drop. When this occurs, any heat begins to migrate back to the cooler surface and be released. In this way, heat moves in a wave like motion, alternately being absorbed and released in response to the variation in day and night-time conditions. Exploiting thermal mass on a year-round basis is not difficult, but does require consideration at the outset of the design process when requirements for the building form, fabric and orientation are being established.