Sustainable Building and Construction - International Environmental ...

Sustainable Building and Construction
of pagodas constructed out of burned bricks in Myanmar (Burma) e.g. has turned a
former forest into a steppe. In the Kathmandu Valley in Nepal the urbanisation and
burning of bricks, which traditionally used as building materials has lead to
deforestation. Today imported brown coal is used, which causes heavy air pollution
(by transport and the burning process itself) and leads to respiratory diseases of
inhabitants as well as to forest dieback and the corrosion of buildings by acid rain.
Regarding the minimisation of the total mass and energy flow in the “main
stream” building and construction sector, it is crucial to use “smart” building
products if products out of renewable materials are not appropriate or available.
Looking, e.g. at concrete, which is used in many present construction projects, there
are two main materials available, common concrete, which is made out of cement,
water and gravel, and gas concrete (or Autoclave Light Concrete (ALC) or Autoclave
Aerated Concrete (AAC)), which is made out of cement water and sand, frothed up
with aluminium powder (only 0,05 - 0,1% of weight) to build up the porous structure
and hardened in autoclaves. While Concrete is very massive, resource and energy
intensive, ALC is comparable very light and much less resource intensive. For the
production of 5m³ ALC only 1m³ of raw materials is required. The accumulated
primarily energy demand for the production of 1m³ ALC (~220 kWh/m³) is about 3
times smaller than for the same amount of concrete (~660 kWh/m³). (According to:
Hullmann, H., Weber, H.; “Porenbeton Handbuch”; Germany 1998) For many
applications in building construction especially for interior and exterior walls, ALC is
a more appropriate building material than concrete because it is much easier to handle
and has a much better insulation effect than massive concrete.
Illustration 22a: Examples of primary energy content for building materials.
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