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CNT Green Values™ Stormwater Toolbox


The Center for Neighborhood Technology (CNT) in Chicago has developed a set of web-based tools, collectively called the Green Values Stormwater Toolbox, which supports the evaluation of urban stormwater management options. The toolbox consists of a series of ‘Green Values’ calculators (National, Original and Chicago), as well as project case studies, a green infrastructure web mapping portal and a manual for understanding and implementing green stormwater management (Water: From trouble to treasure).


The purpose of the Green Values calculators is to help people assess the costs and benefits of green solutions against conventional infrastructure. The calculators are freely available to use and are in the format of online forms and tabs, which produce instantly updated results tables when modified. The calculators model the conditions in a neighbourhood or lot defined by the user. Variables such as size of site and lots, street width, roof size, tree density, average slope and soil characteristics are controlled by the user. The calculators then use a number of assumptions, for example concerning landuse runoff values or rainfall patterns, to produce an assessment of stormwater dynamics for a particular urban landscape. The results show a comparison of the amount of money spent and saved over the life cycle of a conventional system vs. a system improved with green solutions. They also demonstrate the amount of runoff produced in the defined scenario and by how much it could be reduced if using green infrastructure.



Main website – http://greenvalues.cnt.org/

Green Infrastructure mapping – http://www.greenmapping.org/