Into the harbour. Every air conditioned building has the same problem. The heat it removes from people, lights and equipment has to go somewhere. Most buildings push it out through cooling towers on the roof, evaporating large amounts of water to do it. Jørn Utzon's 1957 winning design took a different approach: a heating and cooling system using seawater from Sydney Harbour. When the building opened in 1973, cold water drawn straight from the harbour was circulating through