Center for Neighborhood Technology: National Green Values Calculator

This tool is designed to quickly compare the performance, costs and benefits of green infrastructure, or low impact development, to conventional stormwater practices. The National Green Values Calculator is designed to take you step-by-step through a process of determining the average precipitation at your site, choosing a stormwater runoff volume reduction goal, defining the impervious areas of your site under a conventional development scheme, and then choosing from a range of green infrastructure BMPs to find the combination that meets the necessary runoff volume reducing goal in a cost-effective way.