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Thermal Mass in Clay bricks

Physical objects have mass and as a general rule, the larger or more dense the object the greater the mass. Understandably a house or any other building will have considerable mass, which will absorb higher temperatures throughout the day and feed them back into the building as the surroundings cool, usually at sunset and night time. Much the way a tar road gives off steam after a cloudburst.
This is not to be confused with insulation, which is exclusionary when it comes to heat.
Thermal mass delays the transfer of heat and makes for improved consistency in internal temperature.

Comparing different materials

The heavier and denser a building material is, the higher the it's potential thermal mass.
Below is a comparison of a number of building materials taking into consideration the material, it's thickness and the resulting thermal mass.


Adobe/Mudbrick 200 200
Concrete 100 221
Claybrick 113 187
10.01Regular brick 90 151
Plasterboard 10 8


Clay bricks help lower energy costs

In South Africa temperature differences between night and day are rather large and as such Thermal mass can go a long way towards energy conservation. During the day the external walls and open concrete or clay flooring that is exposed to the sun absorb the heat and as day turns to night the heat then radiates back into those living spaces keeping temperatures indoors warmer and more stable as the outside temperatures decrease.

Based on how the house is situated, the periods in which heat is absorbed by the clay bricks of the walls as well as similar floor surfaces will vary as the angle of the sun changes with the seasons.

In South Africa a north facing structure will be able to harness the sun's energy effectively in summer.
In summer the house will react slower to changes in outside temperature enabling a saving in energy used to operate machines used for cooling.

Likewise in winter the sun should be able to enter the house allowing it's heat to be stored in the internal mass. Enabling you to make use of the free heating nature provides in conjunction with your clay bricks, whilst simultaneously decreasing your carbon footprint.

Avoiding the hot box effect.

Unlike other materials used for building walls, clay bricks have the ability to absorb heat creating a very important time lag between the peak hours of the sun shining on the exterior wall of the house, and when the interior has reaches its peak temperature for the day preventing what is commonly termed
the “hotbox” effect.