To meet stormwater requirements and ensure the homes achieve net zero energy performance, a combined solar-green roof system is installed on the townhouse roofs. To guard against leaks in the roof itself, an Electronic Field Vector Mapping (EFVM) system is installed under the roof membrane. Consisting of a stainless steel wire mesh connected to an exposed copper wire, this allows the membrane to be tested for leaks by applying a charge to the mesh through the wire, and “sweeping” the roof with a copper bristle broom. Holes are detected when an electrical connection is made to the copper bristles through any holes in the membrane.
The green roof assembly on top of the roof deck integrates solar racking bases made by German-based company Optigreen. The Optigreen system allows the solar racking system to be ballasted by the green roof media, avoiding the need for penetrations in the roof membrane. Low-maintenance ‘sedum’ plants are selected for their hardiness, with shade-tolerant species placed under the PV panels. This green roof-solar combination offers the additional benefit of improving solar generation from the panels; the evapotranspiration of the green roof plants effectively cools the panels in hotter summer months, which studies suggest improve solar production by 8-12%.