4.2.4 Microclimate – tempering the intake air temperature
Even when the humidity is right, it is not possible to adopt natural ventilation when the outdoor air is very hot. To increase
the chance of success in a naturally ventilated shopping mall, it is necessary to ‘cool down’ the air near the building.
Special attention should be paid to the microclimate surrounding the shopping mall building.
Depending on its colour tone, temperature of external paved surfaces can reach up to 75°C or even more on a hot sunny
summer afternoon. Air travelling over these hard paved areas picks up the heat and transfers it to the building during
natural ventilation. This is not desirable. The following are a few methods to avoid this:
Strategies for cooling in the microclimate of shopping malls
A. Cooling by greenery
The temperature of living plants and grass is always below 37°C.
Proper planting of canopy trees provides shade, which reduces
heat gain, and evapotranspiration of plants helps cool the air
intake to the building.
Compared to a concrete pavement, a landscaped area is always
cooler. Breezes blowing across landscaped areas before entering
the building will bring in cooler air compared to those the blow
across a simple hard paved area.
s
will also provide a
similar benefit.
B. Cooling by evaporation
Evaporating water also takes away heat from the atmosphere.
This is the additional value of a water feature apart from its visual
aesthetic. Apart from water features, there are also successful
examples of integrating permeable hard paving material with a
built-in water supply system where water is evaporated through
the hard-paved surfaces during hot summer days. This system
requires careful engineering design for optimum performance
with minimum energy consumption. As with water features,
harvested rain water or recycled
should be used to
avoid excessive consumption of potable water.
C. Cooling by creating shading
Where regulations and gross floor area permit, using building
elements to create shading can also lower the temperature
around the building.
Figure 73 Water mist systems in ifc mall, Central
Figure 72 Green wall in Citywalk, Tsuen Wan
(Source: Sino Group)
Figure 74 Canopy in Citywalk, Tsuen Wan
(Source: Sino Group)
4
Green design for shopping malls and shop spaces
4.2
Natural ventilation for shopping malls and shop spaces
104 Hong Kong Green Shop Guide
