" Comparing the ecological level of products is an evolving and young discipline. Neverthelesss, thanks to the information it generates, it is possible to identify some trends that are favourable for the wood. Besides, it is a generality that has few exceptions. In any case, timber benefits the comparison, In any case, timber is confirmed as the "environment-responsible" choice :

Wood exploitation proves to be much less polluting than the extraction of others raw materials.

As regards the transformation in building product, timber displays a clear superiority in terms of energy consumption. The production of one tonne of wood needs 10 to 50 times as few energy as the same wheight of steel, and 50 to 100 as few as a tonne of aluminium. With equal performances, a concrete beam represents an energy cost 5 times as expenseive as a timber beam.

Wood transportation during its life cycle, shows very few risks in comparison with others materials.
When you add the energy needed by the different building steps, timber proves to be twice as cheap as steel and more than three times as cheap as aluminium coated iron.

Building a steel structure rejects 5 times as many CO2 in the atmosphere as a comparable timber structure.

For parts making and building, timber requires much less water as the others materials.

With equal thickness, timber is 15 times as insulating as concrete, 400 times as much as steel and 1770 times as much as aluminium.

Timber is the most biodegradable building material.

Although these examples are as many assets for timber, none refers to the first step of a material life cycle: the elaboration of it. However, that is at this step that appears the most clearly the superiority of wood, even its unique characteristic. Indeed, during its growth, wood is the only material able to fix the atmospheric CO2, and thus to reduce its concentration. That is the way it limits global warming, that greenhouse effect gas implies. At last, timber is the only material wich elaboration produces oxygen, and everybody would agree that it is more than useful.

It is important to insist on the fact that a forest can only fix CO2 and reject oxygen only if it produces wood. That is to say it is a cultivated and exploited. On the contrary, when the forest is left alone, trees get old, die and decompose, releasing the CO2 to the atmosphere and canceling the positive effects.

Source : G. DAELMANS, l'UCDB general secretary (Extract from " Commerce international du bois " April 99)