Investa Commercial Developments awarded a contract to Thiess for the design and construction of the landmark "Ark" office tower on 40 Mount Street in the heart of North Sydney CBD, New South Wales.

The project comprises 28,500m² of A-Grade commercial office space over 20 floors with floor plates up to 2,000m². It features a unique and complex facade with larger cantilevered floors at the upper levels facing Mount Street and a stepped western facade integrating external terraces.

Thiess took on the challenge of constructing an office building that would be highly efficient in both water and energy consumption compared with a conventional office building. The Ark includes a greywater recycling system that captures and stores the rainwater from the roof, stormwater, fire sprinkler test water and air-conditioning condensate water for reuse.

The building’s primary source of power is an on-site trigeneration plant that uses gas turbines to provide energy for electricity and heating/cooling for the base building. Trigeneration reduces carbon dioxide emissions by producing heat, cooling and power simultaneously from a single energy source. Ark is among the first buildings ever to be equipped with a trigeneration system.

The building had its official opening in May 2010, and was awarded a 6 Star Green rating from the Green Building Council of Australia (Office Design v2 Certified Rating) representing world leadership in environmentally sustainable design.