In the UK, the most common methodology for measuring the environmental performance of buildings is the BRE BREEAM scheme. This has been adapted for homes to become the government-owned Code for Sustainable Homes.
Common to most assessment schemes is the basic concept of looking at the whole building, measuring impacts in various categories then weighting the scores in some way, adding them up and giving an overall score. Categories considered usually include energy and water use, impact of materials, waste, health and future adaptability.
Condensing the performance into a single score is a complex task and requires that the relative importance of the various issues is addressed by allocating more points to the more important areas. Energy for example is a key topic and is usually given greater weighting than other criteria.