A lot of our clients at Energy Rating Perth prefer a large amount of glazing and usually do not understand the implications of having a large glazing area out of the wall area. Since glass has virtually no thermal resistance, glazing or windows are essentially holes in the building envelope that allow heat gain and losses to occur easily and rapidly.
Our energy assessors always aim to find a middle ground between the client’s preference and the optimum thermal performance in the building. We urge building designers to balance this glazing area along with ensuring the optimum orientation in order to benefit from solar radiation.
In certain climates and times of the day, the building needs to allow solar radiation to enter into the homes and heat the interior space. However, by night time, in the absence of solar radiation, there needs to be a way to store that heat. This can be achieved by having building materials of high thermal mass capable of storing the heat for a long period of time and re-radiating it back into the environment once the interior air is cool. For instance, the brick wall in a reverse brick veneer wall will take a significant amount of time to heat from solar radiation during the day but also due to its high thermal mass will store that heat. During the night, when the air is cooler, and the wall is sufficiently insulated, it will radiate this heat into the interior of a building.
On the other hand, in the summers, a polished concrete floor placed adjacent to north facing glazing will store heat energy from the solar radiation during the day and release it into the air at night time once it is cooler. The warm air will rise and if there is sufficient natural cross ventilation in the building; cool air from outside will rush into the house eventually lowering the internal temperature of the house.
At Energy Rating Perth, we urge our clients especially ones that are building designers to use thermal mass intelligently and incorporated well into the building design. By rendering the thermal mass rather than covering it with plasterboard, wood, vinyl, floorboards, carpet etc, the building can achieve significant thermal comfort due to the thermal mass.