In the 1930's the Empire State Building was considered energy efficient but now it costs about $11 MILLION for the annual energy bill. The building is now being renovated to be more green and reduce their 105,000 metric tons of green house gases over the next 5 years. The workers are doing things like changing the windows to let in less cold weather so that they can lower the energy for heat that they use. Changes like these could really help out energy reduction and also bring down gas emissions if every business or huge buildings did what the Empire State Building is doing to become energy efficient.
Information from Popular Science