Real-life examples In Denver, Alliance for Sustainable Colorado exchanged the building's T-12 fluorescent lights for more energy-efficient T-8 fluorescent lamps and installed daylight sensors to regulate the amount of electricity used for lighting based on the amount of sunlight coming through the windows. To make the building's HVAC system more efficient, they digitized the controls and made them remotely accessible through the Internet. To cut water use, they replaced toilets and water fixtures with low-flow fixtures. The results? The energy retrofit (including HVAC and controls) is cutting Alliance for Sustainable Colorado's power bill 8% annually. At a cost of $30,000, the project will pay itself back in five and a half years. The organization's $20,000 water retrofit has reduced water use by 90% a year and will pay itself back in four years. Finally, the $17,000 lighting retrofit is expected to break even in just 2 1/2 years. Adobe Systems ( ADBE), on the other hand, shelled out $1.4 million for a green retrofit of its San Jose, California, headquarters, according to Lockwood. Despite a 35% increase in staff, Adobe saw a 35% drop in electricity use, a 41% decline in natural gas use, a 22% reduction in domestic potable water consumption and a 76% reduction in landscape irrigation water use. So far, the retrofit has generated a 121% return on investment, and the average payback time for each project is just 9 ½ months. The company also received $389,000 in grants and equipment purchase rebates for installing energy-efficient technologies. Plus, the revamped building saves the company $1.2 million in utility costs per year.