Civil Engineering Reference
In-Depth Information
Whilst most organic materials have this healthy environmental profile, there
are a few exceptions. Cultivating some plants can involve the use of insecticides,
fungicides, hormone additives and artificial fertilizers, which lead to environ-
mental problems such as increased erosion, poisoned ground water and the
damage or destruction of local ecological systems. This type of cultivation can
produce defects in the product, e.g. enlarged and mouldy cell growth in timber.
The finished products can also be impregnated or given a surface treatment,
which pollutes the indoor climate. Such products need special dumping
grounds when they become waste, in turn reducing the chance of recycling
either as a new product or fuel. Gene manipulation has been suggested as a
solution to these problems. By adding genes of a more resistant plant, it is pos-
sible to reduce the amount of insecticide sprayed on a crop during cultivation.
This gives the modified species an 'unfair' advantage over other species in the
ecosystem, however, and may lead to the collapse of the whole system. This
solution is at present too dangerous to accept as a long-term environmental
strategy.
Generally it can be said that it is desirable to increase the use of organic
materials in the building industry. Only a small percentage of the potential
organic building materials available are used today. Timber is the most com-
mon structural element in building. The use of more varied species will stim-
ulate different methods of application and a richness and diversity of species
within forestry and agriculture. This is beneficial to both the farmer and to
nature.
Living plants
Plants that can be used in buildings in their living state include grass or turf,
climbing plants and hedges. Many indoor plants bind dust and absorb gaseous
pollution, which makes them especially useful in towns and heavily polluted
indoor climates. Besides carbon dioxide, many other gases that can be absorbed
or broken down by plants, e.g. benzene, formaldehyde, tetrachloroethylene and
carbon monoxide. Green plants produce oxygen.
Turf
Turf roofs represent the oldest-known form of roof covering in the northernmost
parts of Europe, and are still in use. In towns and cities in central Europe there is
a renaissance of the turf roof and roof gardens. Turf has also been used as insu-
lation in walls. In Iceland, the construction of pure turf walls with structural
properties was widespread right up to the twentieth century.
