The reason we have decided to use polished concrete for a lot of our flooring is for it’s use as Thermal Mass.
Materials with high thermal mass, like concrete, help to stabilise temperatures within the house. On hot days, our flooring will help to absorb heat, releasing it slowly during the night with the use of cool breezes which should then transport the heat out of the house. On cold days if there is any winter sun available, because the slab is exposed it absorbs what heat it can and releases it in the evening. This should help us to cut down on our energy bills for both heating and cooling. Thermal mass effectively acts as a temperature battery, soaking up the heat when there is a lot of thermal energy available and releasing it slowly later on.
It’s not just the floor which will help with our temperature control, there are several other factors very important to utilise thermal mass effectively.
House design and orientation is a key factor which had to be considered. We had to make sure that our house was oriented well so that we receive winter sun, yet shaded effectively (with the use of eaves as well as curtains and blinds) so that summer sun is kept out. With design, window placement was very important so that we can catch any available breezes, have them run through our house and exit again. Our design has also incorporated a double layer of windows in the living area, so we can open up both levels of windows at once. The hot air will naturally be drawn out the higher windows, whilst the lower windows draw cooler air in.
Finally, we are required to be active agents in assisting the process. In summer, we need to make sure all blinds are pulled to keep the sun from heating up the floor and absorbing unnecessary heat, and then at night, open all windows to catch any available breezes to assist with removing what heat has been absorbed. In winter the opposite is in effect, we have to ensure our slab is exposed to as much sun as possible during the day in order to gain the warmth needed for the house in the evening.
This is a basic explanation, for more detail check out the Alternative Technology Association website www.ata.org.au