AHEC’s decision to commission a comparative Life Cycle Assessment (LCA) of American hardwoods and competing materials has not been taken lightly. LCA is a complex and time-consuming process, particularly when dealing with a range of internationally traded materials. Data collection will be required in a variety of sectors and geographical regions.
To be meaningful, LCA studies must compare like-with-like. Comparing the energy used to produce one tonne of wood with the energy to produce an equivalent mass of steel is of little relevance if three times as much wood is required to perform the same function. Therefore the LCA must compare equivalent “functional units”. For example, in the case of external cladding, the functional unit may be one square meter of wall that satisfies building regulations.
Because environmental implications vary from location to location, LCA models must incorporate relevant local conditions. For instance, electricity is used to varying degrees in the manufacture of most materials but there could be a significant difference in the environmental effects of electricity produced from coal versus electricity produced from water power.
The durability of products in use is also a key factor in LCA. The environmental impact of a product that needs to be replaced three times during the lifetime of a building is effectively three times that of an equivalent product that needs to be replaced.
To do well, LCA requires independent third party expertise, a labour-intensive data collection exercise, and a deep understanding of industrial processes and the long-term performance of materials. LCA is also partly a negotiation process requiring that practitioners engage in an unbiased, open and honest manner with the wide range of interests that might be affected by the outcome.