The measurement of sustainability for institutions, businesses, regions, and nations is a complex undertaking. There are many disciplinary approaches but sustainability is innately interdisciplinary and the challenge is to apply these approaches in a way that can best measure progress towards sustainability. The most common methods used by institutions, such as colleges and universities, use indicators that take basic metrics such as energy and materials consumption and translate them into a measure of sustainability.
Greenhouse gas (GHG) inventories are becoming a common measure of environmental impact and sustainability for institutions. A GHG inventory for fiscal years 2004-2008 for the University of Illinois in Chicago (UIC) showed that in fiscal year 2008, UIC's carbon footprint was not significantly higher than the 2004 emissions (275,000 vs. 273,000 metric tons of carbon dioxide equivalents, respectively). For 2008, the largest source of emissions was buildings (83%), followed by commuting (16%) and waste (1%). The variation in the emissions over the five years studied is largely influenced by the amount of electricity purchased and the mix of sources of that electricity (i.e., nuclear vs. coal).
Ecological footprint analysis (EFA) is used to determine the area of land and water ecosystems needed to provide the resources for a given population and process the waste that it produces in a globalized metric (global hectares), generally on an annual basis. An EFA for UIC for fiscal year 2008 was calculated as 97,601 global hectares which comes to 2.66 hectares per total faculty, staff and students. The largest components of the EFA were due to energy for the built environment (73%), transportation and commuting (13%), materials and waste (12%), and food (3%). A sensitivity analysis on the effect of climate change events on the footprint indicated that, if all other factors are held constant, climate change will increase the ecological footprint of UIC.
Greenhouse gas emissions from colleges and universities were found to be a function of the size of the institution (full-time student enrollment and square feet), the amount of laboratory and residential space, whether there is a medical school, and commuting to campus by faculty, staff and students. Laboratory space was found to have 10 times more effect on emissions per square foot than space such as classroom and office, while residential space had about 2 times the effect. The magnitude of the parameters change somewhat when looking at schools that have gross emissions of 50,000 metric tons of CO2-equivalent or less.