LCA’s are widely used in designing both products and systems. The procedure is straightforward. The initial design of the proposed system is modeled as if it existed using the best available data. This forms the starting benchmark against which subsequent modifications are judged. The results of this initial modeling exercise can then be inspected to see if any of the parameters are bigger than expected or desired. The design may then be modified and remodeled to see if the changes have produced the desired effect and also to see if any undesirable characteristics have been introduced accidentally as a result of revising the design.
Ideally this procedure should be carried out at a very early stage of the design process since subsequent economic or manufacturing problems will need to be incorporated later to see how they affect the environmental characteristics.
The iterative process of “change, model, change, model” can be carried out almost indefinitely since it is almost always possible to introduce improvements. However, eventually the stage is reached where the design must be finalized and although it may not be perfect, it can be regarded as the optimal design when any further changes in design produce only very small changes in the inventory parameters. In general, the major changes occur early on in the design process assuming there is no drastic re-think of the design after the initial concept has been sketched out.
For products, the major parameters that affect the environmental characteristics are choices of materials and production processes. For products with a short lifetime, such as packaging products, the effect of a lifetime use is usually insignificant. However, for capital goods such as washing machines or building materials, their lifetime use may produce significant contributions to the environmental parameters. For example, wooden windows may seem to be attractive because they use a renewable resource but in their lifetime they will need repainting at regular intervals to ensure long life. This repainting may, under certain circumstances, blur their advantages over windows made of materials such as PVC or aluminum that do not need repainting.