56
Sustainability and the built environment
a steady internal temperature. Glass can be given a reflective coating to keep the sun
out, but this is relatively ineffectual when dealing with the massive areas of glass used
in this style of building. When the sun’s glare is fully upon a building its cooling system
is wasting energy cooling the air which has been thus heated.
This energy dependency places cities with a proliferation of such buildings at a
disadvantage; and makes them extremely vulnerable to interruptions in power supply
or changes in climate. Re-cladding façades with smaller glazed panels and shading
is an option, but if the building is orientated to bear the brunt of the sun’s rays there
may be limited impact. In addition, the resulting loss of window area may create
dependence upon artificial lighting systems, which would be counterproductive.
These techniques have limitations in an urban environment where site selection, space
for orientation and access to the sun are limited. Ventilation in cities with poor air
quality is also an issue. Even so, all new buildings and retrofitting should be planned
and designed to take advantage of these benefits where possible.
Building occupancy
By employing the techniques outlined above, passively designed buildings attempt
to reduce fixed energy demand by reducing movable demand. The number and
efficiency of appliances must also be considered.
Use of energy-efficient products and appliances, coupled with moderation in
consumer habits, is encouraged through policy-led incentives which reward such
behaviour. For example, energy demand from electrical appliances can be reduced
by eliminating standby facilities, which account for 11% of total electrical demand in
a typical domestic dwelling. Further measures include timing the use of appliances,
where possible, to coincide with off-peak tariffs and altering the electrical metering
system to enhance visibility of consumption. Energy tariffs could also be set to reward
lower consumption instead of giving ‘bulk use’ discounts, which are still a prevalent
feature of many energy supply deals.
Designers and policy-makers play a significant part in creating low energy consuming
built environments. However, unless there is co-operation from occupants, the
resulting energy savings may be disappointing. Educating occupants is therefore
critical in ensuring that such measures have a positive impact.
Energy generation
To power our built environment, some form of energy generation is required. This
is currently provided by a combination of fossil fuel fired power stations (primarily
gas and coal), nuclear power stations, pump storage hydropower plants, plus other,
renewable forms such as wind and the sun (see Figure 15).
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