Improving the Effectiveness of Commercial Energy Recovery Ventilation Systems
Dave Bohac, P.E., Josh Quinnell, Ph.D. — Jan 2014
The project team completed field monitoring and consolidated data for the final analysis on nine systems that could be divided in to three categories — high-performing, basic-functioning, and low-functioning. The team found that identifying and addressing the issues of the low-functioning units is most important; minor issues don’t always need to be addressed since the opportunity for cost-effective modifications is minimal. Full Project Update
Why this research is needed
Energy recovery ventilation systems exchange energy between the outgoing exhaust air and the incoming outdoor (ventilation) air to reduce heating and cooling energy while meeting ventilation requirements. Energy recovery systems have the potential to eliminate the majority of energy requirements for heating and cooling ventilation air.
Based on systems encountered in CEE’s recommissioning work and participation numbers from utility incentive programs, there are already over 1,500 ERV systems installed in commercial and institutional buildings in Minnesota. Unfortunately many of these systems fall short of achieving their design effectiveness due to a variety of problems including improper design, installation, or operation and maintenance. According to a 2010 Minnesota Market Assessment Report, only 48 percent of systems operated properly immediately after installation, with an overall average efficiency of 42 percent. In addition, very little field data is available on commissioning and recommissioning best practices for ERVs.
Now that ASHRAE 90.1-2010 Energy Standard for Buildings has been adopted over the next year, ERVs will become much more prevalent in Minnesota and identification and resolution of problems inhibiting performance is a key requirement for ensuring their promise for increased energy efficiency.
Project process and expected outcomes
This field research characterized representative energy recovery systems in Minnesota commercial and institutional buildings as well as identified common problems that diminish their effectiveness compared to their design intent. Staff selected 10 ERV systems that are representative of Minnesota buildings and performed visual inspections, functional performance tests, trend data analysis, and continuous monitoring that identified problems that prevent these systems from operating effectively.
After monitoring and documenting ERV performance, recommendations for improving ERV operation will be implemented. During a post-implementation monitoring period, CEE is identifying energy savings and further operational enhancements. CEE will collect independent data to verify savings and use the results to draft operations guides for recommissioning providers, trainings for facility operators, and engage in dissemination work to improve the as-operated quality of ERV systems in Minnesota buildings.
This project supported in part by a grant from the Minnesota Department of Commerce, Division of Energy Resources through the Conservation Applied Research and Development (CARD) program. And with co-funding by CEE in support of its nonprofit mission to advance research, knowledge dissemination, and program design in the field of energy efficiency.