Design impact measures
Design impact measures are used to qualify projects for various rating systems and to guide both design and regulatory decisions from beginning to end. Some like the greenhouse gas inventory may also be required globally for all business decisions. Some like the LEED point rating system are used only for its own ratings, and the qualification for 'points' may include some physical measures to qualify, but the points do not represent measurements. Others like the Athena life-cycle impact assessment tool attempt to add up all the kinds of measurable impacts of all parts of a building throughout its life and are quite rigorous and complex.
The general field also includes environmental impact assessment and environmental accounting, and to tie them together, systems ecology, cost estimation models and cost–benefit analysis.
For sustainable design the number and types of methods and resources that have become available in 2008 is suddenly much larger than before. Because they help you with it, all these tools also require beginning to think about real complex processes. The reason for the sudden appearance of so many new methods appears to be the natural rapidly increasing complexity of the physical design problem we confront as our interactions with the earth become larger, more complex and more critical to account for.
Simple online calculators
The Energy Star building energy calculator & targeting tool based on the US IEA and CBECS data from long term US nationwide energy use surveys. This is the estimator that projects use to qualify for a Green Globes rating. It is solid and simple but tells you less about your particular choices – Easy carbon footprint tools, the UK "Footprinter" and "Build Carbon Neutral" These are the simplest of the tools that estimate the total by adding up the easily visible parts.
Advanced impact and energy analysis tools
US DOE list of "building energy tools" This is a huge list and is probably quite incomplete, but has good concise software reviews. All the design and engineering software packages are also starting to build in energy impact tools and climate modeling, etc. Many of them rely on the move to BIM whole building design data models that allow many consultants to work on the same building or urban design scheme at once.
The "Greenhouse gas protocol" is an intergovernmental data service used by the major international bodies for organizing the greenhouse gas data and reporting requirements. It's organized primarily by industry. – "Athena Eco-Calculator" is an advanced and thorough Life-Cycle impact assessment tool for buildings. This can be read at the US DOE list above.
"EcoFootprinting" provides a way to measure your total use of productive land, or 'ecological footprint'. Its figures are based on studies showing that our burden on renewable resources is significantly greater than the Earth's regenerative capacities, and still increasing. The results may not measured uncertainty, but would probably be comparable to each other.