A siphonic system is a well-known cost-saving solution for drainage of large roof areas. The principle of expelling air from the system means that only water is transported at high speed, making use of the suction pressure created behind the full bore water column. The high speed full bore flow enables smaller pipe dimensions, compared to conventional systems. The elimination of multiple downpipes and a lot of piping in the groundwork translates into a large cost saving and greater architectural freedom for the building design.
This technology, initially developed for large roofs, is also extremely useful when applied to high-rise buildings that have a smaller roof but longer downpipes. Siphonic roof drainage on high-rise buildings enables savings on space and costs by reducing the number of required downpipes. These space savings are even more important on green buildings, where secondary piping systems for rainwater collection and re-use have to be installed in space-constrained service shafts.