We saw in Advantage 1 how the dense mass of a full brick wall slows the penetration of summer heat through the wall. But what happens in winter?
This is where the inner layer of brickwork comes into its own, absorbing, storing and slowly releasing heat that is generated inside the house.
In a house using passive design principles, the internal brickwork mass can also absorb the warmth of the low winter sun as it enters through large north-facing windows. As the temperature falls at the end of the day, the brickwork slowly releases the stored heat into the house.
The result is a natural level of comfort without having to constantly resort to artificial heating.
Dense materials such as bricks are essential for this process to occur. Insulation has a role to play but it has no effective capacity to store and slowly release heat energy.
A concrete slab also adds to the potential thermal mass. However the ability of a slab to absorb solar energy is reduced if covered by carpet or timber. Ceramic tiles bonded to the slab in the areas struck by the sun will preserve its solar efficiency.
What is passive design?
Passive design is a package of four simple, well-established design principles that allow the maintenance of a high level of personal comfort without having to constantly resort to artificial heating and cooling:
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Orientation The placement of large north-facing windows to capture the low winter sun, but shaded against the higher summer sun.
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Insulation Insulation acts as a barrier to heat flow.
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Ventilation Natural air movement helps minimise heat gain and facilitates heat loss on warm or hot days.
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Thermal mass Dense materials such as bricks help stabilise temperatures by slowing the entry of external heat and absorbing and releasing internal heat in winter.
Like the wheels of a car, all four principles are essential for a passive design to work. Take away any one and the wheels fall off the design!
Ask Austral Bricks or your builder for more information about passive design.
