Advanced Green Roof at SAP Headquarters


The advanced green roof at SAP Headquarters in Newtown Square, Pennsylvania is the first intelligently controlled green roof system in the world. It provides a controlled irrigation of a 3,781 square feet of flood irrigated turf grass on the site’s roof.  The system functions during dry weather by maintaining the root zone water level while also allowing depletion of the flood irrigated layer prior to likely rainfall and preventing irrigation during wet weather.

When the water level inside the access chamber is below 1.32 inches, the valve opens, allowing sub-surface flood irrigation of the green roof. When the water level is above 1.57 inches, the valve is closed, discontinuing the supply of water to the green roof. These set points were chosen to keep the water level within the root zone of the turf grass.

Most importantly the system reacts to forecast rainfall by setting the lower set-point well below the dry weather level to dramatically increase wet weather capture and decrease overall water consumption.  The OptiNimbus driven intelligent control system also provides live access to monitor and control the roof through a dynamic web-based browser dashboard environment as well as a means for accessing all stored data.

Results from minute-by-minute monitoring data collected from this project show that the water level control system has been remarkably successful over its 3 year life. In addition to maintaining precise and reliable water levels within the green roof, the system minimizes the occurrence of stormwater overflows while conserving irrigation water by utilizing logic which halts irrigation to the roof when rainfall is forecasted.


Green roofs can be an effective way to achieve multiple low impact development objectives: reduce stormwater runoff, increase rainwater reuse, reduce impervious surface, reduce energy consumption, and increase green space.  The OptiNimbus intelligent control system was designed to maximize the wet weather performance of the roof and reduce water use.

Addition of intelligent control reduced runoff volume 25% and decreased water use 4%, as compared to the same green roof without intelligent control.

Project area and volume: 3,781 sq feet; 97,700 gallons of runoff per year.


County: Delaware County
Watershed: Crum Creek/Delaware Watershed


SAP America
Geosyntec Consultants
Water Environment Research Foundation


$4,175 for 5-years of active OptiNimbus real-time control services after approximately $6500 for retrofit of existing flood irrigated green roof for intelligent control


OptiRTC, Inc
356 Boylston St Second Floor Boston, MA 02116

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