The Building
The installation site is a multi-building commercial complex in a coastal Mediterranean city. The complex includes 14 buildings with flat concrete rooftops, a total roof catchment area exceeding 3,000 m², and conventional gravity drainage discharging into the municipal stormwater network.
The buildings were constructed with standard waterproofing membranes and roof drainage infrastructure sized for local design rainfall. The municipal drainage network serving the area was experiencing capacity constraints during significant rain events, leading to localised surface flooding at downstream points.
The Stormwater Challenge
The site faced a specific stormwater management challenge: during high-intensity rainfall events (common in Mediterranean climates, where a significant portion of annual rainfall occurs in a small number of intense events), the simultaneous discharge from all building rooftops overwhelmed the downstream drainage network.
The municipal authority identified building-level retention as a potential mitigation strategy — if peak discharge from the rooftops could be reduced and delayed, the downstream infrastructure could process the same total volume of water over a longer period without surcharging.
The engineering requirement was to install a system that could temporarily retain stormwater on each rooftop, control the release rate, and provide documented performance data — without modifying the existing roof structure or drainage pipe sizing.
SmartFlow Monitoring System
The SmartFlow platform was selected for the installation. Each building received a SmartFlow unit installed at the primary roof drainage outlet. The unit consists of a compact hardware assembly including a motorised valve (normally-open design), an ultrasonic water depth sensor, and a cellular communication module.
The units connect to the SmartFlow cloud platform, which provides a multi-site dashboard showing real-time status of all 14 buildings, configurable release profiles matched to the site hydrology, automated rain event detection and logging, and performance reports showing retention volume and peak flow reduction per event.
Implementation
Installation was completed across all 14 buildings over a period of approximately three weeks. Each unit was installed at the existing roof drainage outlet without modification to the drainage pipe system or roof structure. The motorised valve assembly mounts directly to the standard drain fitting.
Site-specific release profiles were configured based on the local hydrological assessment, taking into account the building roof area, structural load capacity, downstream drainage capacity, and the target peak flow reduction specified by the municipal authority.
The system was commissioned remotely via the cloud platform after physical installation, with each unit verified for sensor accuracy, valve operation, and communication reliability.
Results
The installation has been operational through multiple rain seasons. The observed performance includes the following outcomes.
- Peak runoff reduction — during monitored rain events, the controlled release from equipped buildings reduced peak discharge rates compared to uncontrolled drainage from equivalent rooftops in the area.
- Controlled drainage — the motorised valves operated as configured, detaining water during peak rainfall intensity and releasing it gradually during post-event periods when downstream capacity was available.
- Infrastructure visibility — the cloud platform provided continuous monitoring across all 14 buildings, with event logs and performance data available for review by both the site operator and the municipal authority.
- Operational reliability — the normally-open valve design ensured that in the small number of communication or power interruptions observed, the system defaulted to free drainage, maintaining structural safety at all times.
- Non-invasive installation — no structural modifications, drainage re-piping, or waterproofing alterations were required at any of the 14 buildings.