According to EPA’s Energy Star program, lighting consumes close to 35 percent of the electricity used in U.S. commercial buildings and affects other building systems through its electrical requirements and the waste heat it produces. Upgrading lighting systems with efficient light sources, fixtures, and controls can reduce lighting energy use, improve the visual environment, and affect the sizing of HVAC and electrical systems. The Green Proving Ground program is investigating the effectiveness of technologies such as Occupancy Responsive Lighting Solutions and Integrated Daylighting Systems in reducing lighting energy usage while maintaining occupant satisfaction.