Packaged rooftop units (RTUs) serve over 60% of the commercial building area in the United States. Essentially a box that provides hot and cold air and ventilation to a building, RTUs represent a large, untapped potential for energy savings.
What’s under the hood?
Most rooftop units operate using the minimum controls required by code. Fans in the units operate at maximum speed and bring in a constant amount of outside air during occupied hours. Additionally, units often contain basic economizing capabilities to cool by bringing in cold outdoor air when possible. As it is, these controls are still less efficient than many other control strategies available today. While the units may meet minimum code requirements, there is room for improvement in terms of energy efficiency.
Super-charging rooftop equipment?
Not all RTUs are destined for mediocrity. A variety of retrofit kits have become available to facilitate more advanced controls for energy cost savings.
The advanced energy saving control strategies include fan speed control, demand controlled ventilation, and advanced economizer operation. The controls allow the fans to run at lower speeds when possible, eliminate unnecessary outdoor air being brought into the facility, and increase the efficiency of the existing economizer control. A study has shown savings averaging 55%, when these strategies are implemented.
Hit the nitro and fly to the finish!
Above and beyond the energy savings, the RTU advanced controls pave the way for a more networked and centralized building automation system. Data from the advanced RTU controllers can be collected and correlated to show how equipment is operating and allow advanced scheduling of operating times and set points. The controls also help building staff to maintain the units by providing proactive tools to monitor energy use, determine maintenance requirements, and help identify problems when they occur.