When deciding on what materials to use for your house many only think about factors such as cost and aesthetics. But when it comes to creating an energy efficient home the performance of a material and its ability to store heat needs to be taken into consideration. Thermal mass will help regulate the indoor temperature in summer as well as in winter and will reduce the need of mechanical heating and cooling.
In winter, thermal mass works like a heater: it absorbs radiant heat from the sun through north, east and west-facing windows, and also stores heat from mechanical heating. The thermal mass will slowly release the heat which reduces the need for heating. Even when the heaters are turned off, the house will stay warmer for longer. Furthermore, the air and the exposed surfaces have the same temperature (Mean Radiant Temperature), which means there are no unwanted draughts, and the Relative Air Velocity is low; these will increase the thermal comfort of the occupants.
Materials such as concrete and brick are cooler in summer than the surrounding air temperature, so they are able to absorb heat, which consequently lowers the room temperature and the need for additional cooling. At night the thermal mass will slowly release stored heat. Natural ventilation, via open windows, ceiling or exhaust fans, are an effective way to let cool air in and to let heat – collected during the day – out. In extreme hot periods, when it doesn’t cool down at night, air conditioning may be required to regulate the room temperature. The greater the difference between day and night temperature, the more beneficial the thermal mass.
How can you add thermal mass into your home? A concrete slab is ususally the most straight forward solution. If solar access is great and windows are in the right position the winter sun can heat up the concrete floor and help to warm up a home. Other options are internal thermal mass walls, like brick walls, hempcrete or concrete, just to name a few. For external walls either double brick walls or reverse brick walls.
Alternatively you can add tiles to your timber flooring, or maybe a concrete bench top.
Please be aware, that a standard brick veneer home will not give you any benefits for your indoor temperature, as the thermal mass is located externally, and separated from the indoor climate via insulation.