Architect and Builder Magazine South Africa Dec 2017 / Jan 2018 - Page 73

To acquire the 6 star Green Rating that was achieved required input from both the civils and structural disciplines. Contributing factors included the reuse of rubble for the complex underfloor drainage system, as well as the use of re-cycled steel, while pushing the reduction in cement contents to above standard industry norms. SUSTAINABILITY CONSULTANT’S REPORT As the sustainability and Green Star consultants on the No 1 Silo job, the Arup team were instrumental in bringing the client team’s vision of a 6 Star rating to fruition. As consulting engineers, Arup prides itself on good design principles, and the team looked far and wide for engineering solutions that would respond to, and harness the environment of the building. Seawater from the Atlantic Ocean is one of the stand-out examples of a green solution; using seawater to reject waste heat, thereby eliminating the need for potable water in the cooling system and resulting in huge water savings. The system draws cold seawater (normally between 14 and 16 degrees) from the harbour through a titanium plate heat exchanger system in the basement. Another key to the 6 star rating is the façade on the building. The largely glass design presents challenges as it needs to remain as transparent as possible, whilst eliminated glare from not only the sun, but the sea as well. Glass can also add to energy usage due to the need for extra cooling in summer and heat loss in winter. To manage this, the building has a double skin façade on the north east and north west elevations. These have a clear glass outer layer, 700mm outside the main façade – which is double glazed. To deal with the No 1 Silo glare, there are automatically controlled blinds, found between the two façade skins, which tracks the sun as it m oves across the sky. Many other alternative solutions were sought, including: • Under floor displacement air conditioning • Solar thermal panels and heat pumps • Energy and water sub metering • Energy efficient lighting and lighting sensors (only using lighting when required) • Sub soil drip irrigation and hardy plants used to reduce landscape water need by 50% • Sustainable use of materials including a reduction of cement usage by 60% and virgin steel to 10% (i.e. 90% of all the structural steel was recycled steel). • Intelligent building management system. 73