Thermal Mass

Thermal mass is a key part of good passive solar design. Thermal mass makes use of certain materials to retain or store heat produced by the sun.

How It Works

Summer

Winter

This is not the exposed surface (often tiles) but the material below or behind that surface. Thermal mass stores heat by changing its temperature which can be done by storing heat from a warm room or by converting direct solar radiation into heat. The more thermal mass the more heat can be stored.

Thermal mass works as heat moves from warmer materials (mass) to colder ones (air) until there is no longer a temperature difference between the two.

The thermal mass warms up during the day and releases that heat as the day cools.

Thermal mass often uses material like exposed concrete, tiles (on concrete slab) or other masonry materials. Water has also been used as thermal mass.

Thermal mass can be easily incorporated into the materials used in the construction and the design of your home. This requires consideration from the outset of the design of your home.

Thermal mass can be added to an existing building as part of a renovation by:

• Incorporating a concrete floor or solid concrete wall, either of which are exposed to direct sunlight
• If you have an existing concrete floor then remove any floor covering and replace it with tiles or leave the concrete exposed (grind and finish the slab)

Alternatively you may wish to consider installing a conservatory with windows through to the main house. Although this is not thermal mass it can have a similar effect