Tonight I have been looking into this and I found the Australian Life Cycle Assessment Society (http://www.alcas.com.au/). They have a useful page that discusses what a 'life cycle assessment' is and here is their explanation:
"assesses the environmental aspects and potential impacts of a product, process or service by
- compiling an inventory of relevant energy and material inputs and environmental releases;
- evaluating the potential environmental impacts of those inputs and releases
- interpreting the results to better inform decision-making".
The ALCA has a basic methodology of how someone would undertake a life cycle assessment, but so far I don't know how you as a general member of the public would actually obtain the information required to be inputted into such an assessment so that any sort of judgement or comparison of products could be undertaken. Will keep you posted.