How important is thermal mass and building design?
Thermal mass is the ability of a material to retain heat energy when subjected to a temperature differential. Clay brickwork and concrete floors have relatively high thermal mass. In summer, a high thermal mass wall can reduce the transfer of heat by absorbing the heat energy flowing in from the outside. This process is slow and results in a delay called thermal lag. Maximum external air temperature is usually reached between noon and 2pm. A lag of six hours, which is typical for brick construction, means the maximum heat flow would not reach the interior until six hours later. By then external air temperature will usually have dropped and thermal flow will reverse, allowing the building to cool for the following day. Buildings with high thermal mass “iron out” the temperature variations naturally, allowing temperature ranges more consistent with the ideal human comfort zone. This is important to the environment, as the building has a reduced need for artificial heating and cooling, me
