My friends Alon and Ron just published a new paper on a nice measure of sustainability that they came up with called EcoTime. EcoTime (not to be confused with peanut butter jelly time) addresses a number of issues with the current ways we think about sustainability and it has such a sexy name too!
The basic idea of EcoTime is to measure the resource consumption due to a product in time units rather than carbon, water or pollution units. So driving to Maine from Boston and back might equal 14 EcoTime hours, meaning that you used 14 hours worth of resources by driving (***I chose 14 hours arbitrarily and it does not reflect any real calculation of resource use). If I drive up to Maine to pick up a package and turn right around then I’ve used 14 hours of resources in about 4.5 hours, meaning that I’ve been pretty damn wasteful. If, however, I spent 5 days skiing up in Maine (and I didn’t leave the engine running) then it’s a pretty reasonable use of resources.
What’s nice about EcoTime is that people have no trouble thinking in time units. We’re capable of reasoning about quantities of time ranging from seconds to years, whereas energy and even mass units can get pretty confusing. Moreover, units like energy, carbon or mass are hard to grasp intuitively because most people don’t know how much carbon is a lot. How much is 10 tons? Is that a lot? Unlike most other measures of sustainability, EcoTime is a relative measure that can include many ecological factors including carbon, nitrogen, water, land use and pollution of various types. Once you define what the maximum acceptable yearly consumption of these various resources is, EcoTime allows you to express complex environmental calculations with a single, intuitive number.
Sustainability indicators strive to convey the impacts of human activities on natural resource utilization, yet many fail to express these impacts in a simple relatable manner. We introduce a new sustainability indicator, EcoTime, which recasts an environmental burden of a process or item (e.g., the emission of 10 kg CO2associated with a car trip) in time units (seconds, days, etc.). The EcoTime units represent the burden’s share of a benchmark quota calculated according to location or context. For example, a developed country’s average yearly CO2 emissions of 11 ton per capita would translate to 365 EcoTime days in which case the 10 kg CO2 mentioned above would equal ≈8 EcoTime hours. Since time units are commonly used the EcoTime indicator is easy to communicate to a varying audience alleviating challenges often associated with existing sustainability indicators. It leverages our innate ability to easily grasp contrasting time units over several orders of magnitude, ranging from seconds to years. Another key advantage of EcoTime is that its value shifts attention from the absolute environmental impact, which may not be meaningful to most people, to impact magnitude relative to world resource availability or usage, thus giving the burden an intuitive, intrinsic context. In addition, EcoTimes of different impact types can be conveniently and succinctly grouped as a vector (e.g., GHG emissions, water, or land footprints), or, because of the similar units, as a composite scalar. We provide several case study examples of the methodology.
Shepon, A., & Israeli, T. (2013). EcoTime—An intuitive quantitative sustainability indicator utilizing a time metric. Ecological Indicators, 24, 240–245. doi:10.1016/j.ecolind.2012.06.018
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