The Empire State Building -- one of the favorite places in the world to try to impale strangers by tossing change off the observation deck -- is getting a major retrofit, according to the Environmental Leader. Energy efficiency will constitute $20 million of the overall $500 million modernization project for the iconic building. Ideally, it will result in $4.4 million in energy savings annually. The payback on green building projects like this are typically faster than in solar, where payback can take eight or more years. Some of the improvements include: 6,500 thermal windows, individual power management consoles for tenants and a retrofit of the chiller and ventilation controls. (Air conditioning is one of the big power consumers in the U.S. -- read here for an overview of several startups in the field. The retrofit in part is being orchestrated by Johnson Controls, one of the old guard in building maintenance and management. When startups talk about companies doing more "traditional" technologies, they often mention Johnson. But the company is not lying down and over the next few years could become one of the major purchasers of startups.