See the 8/2008 article ZH General Construction Company AG in German from Radius showing photos of the Betonwerk Eisack, Varna. Learn about Optigr?n international AG / Optigreen in The Greenroof Directory.
The greening of a cement factory in Varna, Italy uses the Optigreen “economy roof” and the Optigreen “solar-greenroof.” Construction of the circular concrete bulkheads was performed by ZH General Construction Company AG.
In 2005, the Betonwerk Eisack Headquarters located approximately 25 miles from Varna had greenroofs installed with major slopes. See the Betonwerk Eisack (Concrete Factory), Klausen project profile here.