ELEMENT:
Breezway Louvres with timber and glass blades
AIM:
A passive ventilation system is used in place of electrical energy intensive
climate control devices such as air conditioners. The louvred window openings
give a greater control over the direction and velocity of air entering
the building.
STRATEGY:
Optimise Passive Design
In moderate warm climates the purpose of ventilation is to provide fresh
air to the occupants, cool the building fabric and cool the occupants
though air movement and heat loss. Cross ventilation is horizontal and
is usually wind driven. Stack ventilation is usually vertical and driven
by thermal difference.
Clerestory windows provide for a stack ventilation effect in the house.
The positioning of clerestory windows high in the building envelope adds
to the natural airflow effect from low to high with the warmer air escaping
through the high window opening.
In periods of calm, stack ventilation is used; air rises into the atrium
and siphons through popup roof monitors. To facilitate this type ventilation
system a pavilion form is used with the building split into two sections
connected by a breezeway. The portal frame structure allows the building
to be open inside to facilitate air movement without the need for bracing
walls.
Louvered windows provide a potential 100% surface area opening for airflow
into the building. Adjusting the angles of the louvred blades can also
control airflow direction which provides for a greater control over the
desired air movement.
Timber louvre blades are used for the clerestory windows facing north
to reduce the solar penetration through the window. Glass louvre blades
are used for the clerestory windows facing south to increase the natural
daylight to the atrium space. This lighting is diffuse (reflected) light
rather than direct sunlight so the heat gain from this type of light is
negligible.
REFERENCE:
Breezway Louvres Techinical Information. June 1999.
Hyde, R, Climate Responsive Design. A Study of Buildings in Moderate and
Hot Humid Climates. E and FN Spon, London 2000.
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