Stormwater Attenuation and Green Roof Retrofit
This chapter describes research demonstrating how to assess whether to retrofit with a green roof to attenuate stormwater runoff. Pluvial flooding causes substantial financial costs, disruption and impact on our urban settlements. A range of technical specifications for stormwater roofs and critical issues to consider in retrofitting existing buildings are evaluated. Theoretical frameworks of the distributed benefits of green roofs are presented, and a methodology to estimate potential for stormwater attenuation of green roof retrofit at the city scale level is described in detail. Recent empirical research undertaken in two cities with very different climatic conditions Melbourne, Australia and Newcastle, UK at city scale level is evaluated. Having examined the city scale level, a second illustrative case study at an individual building scale outlines stormwater performance and the assessment process in Portland, OR. A summary of the potential benefits of green roof retrofit for stormwater attenuation is made.