An Architectural Agenda for Decentralized Storm Water Buffering
Cities facing the dual environmental crisis of deteriorating water quality and threats of flood from increased rain are realizing the limits of centralized infrastructural capacity, projecting the need for temporary storage of large water volumes for both retention and detention. The notion that many sites should store a certain volume of water for periods from 24-72 hours for landscape- based treatment or delayed delivery to centralized systems—a buffering strategy—drives climate adaptation policies that connect building sites into the performance of urban ecosystems. Emerging urbanisms for decentralized storm water management usually follow standard parameters: e.g. retaining the first 1-inch (2.54cm) of rain during a storm, based on historic data and studies of water quality. As these standard parameters become concretized in the design of individual sites, rain events larger than 1-inch overflows into the centralized system, limiting capacity of the system to historical data and limiting the resilience of the system to future projections. As future rainfall projections intensify, sites will need to expand their buffering capacity. But while buildings still constitute the largest percentage of urban surfaces, their aesthetic, social and performative capacities for storage remains limited. When analyzed against urban scale storage needs, the standard measures of vegetated walls and roofs fall short. Explorations of the potential for buildings to temporary store larger volumes of water on site is fertile territory for new forms of urban architecture integrated to decentralized urban ecologies. This paper seeks to elucidate the idea of stormwater buffering at an architectural scale. A literature review provides various definitions and uses of the term buffering at a landscape scale, reveals the most relevant policy challenges that promote or limit strategies for buffering at various scales, and identifies the most common technical strategies and performance criteria to evaluate their capacity, environmental, experiential and aesthetic effects.