We discuss how sensor technologies have enabled the development of proactive energy management (EM) systems. At the same time, we discuss how these emerging EM systems motivate the development of new sensor technologies. Proactive EM systems integrate advances in weather forecasting, sensors, predictive models, and real-time optimization algorithms to anticipate uncertain factors that affect energy performance and costs and make real-time set-point corrections (supply conditions, ventilation rates, thermostats) to modulate them. Ongoing deployment studies have found that up to 30% HVAC energy savings are achievable with this type of technology. We describe extensions of these systems to exploit emerging sensor technologies including occupancy, ventilation, and air quality sensors.