Three out of four office buildings in Singapore are wasting energy because of inefficient air-conditioning systems, according to media reports. A Singapore building of 20,000 square metres spends us $41,250 each month on air-conditioning, when an energy-efficient building would require only us $12,650. "Most owners don't have a clue as to how their offices are energy inefficient,' said Lee Siew Eang, an associate professor at the National University of Singapore.