Field Testing of HAN/BAN systems with FDD

In addition to optimizing energy consumption, home energy management systems (HEMS) are now able to diagnose operating malfunctions and respond to peak demand events. This Southern California Edison (SCE) study aimed to verify the fault detection and diagnostics (FDD) and demand response (DR) capabilities of selected HEMS and their ability to communicate alerts to homeowners and technicians. A review of existing HEMS products resulted in the selection of three (Systems A, B, and C) with FDD capabilities and with potential to exercise or add DR event optimization, except System B, to their heating, ventilating, and air conditioning (HVAC) control capabilities. Through a mix of laboratory and field testing, the project team evaluated the ability of the systems to efficiently perform desired FDD and DR functions and to appropriately communicate faults, alerts, and desired actions to homeowners and service personnel. Starting in January 2014, the team evaluated FDD System A on an HVAC unit at a Knoxville, Tennessee, laboratory using ASHRAE standard procedures. Communications were two-way via a wireless network connection requiring internet service. Performance was evaluated with refrigerant-side sensors, air-side sensors, and power and energy monitors. To evaluate the creation of error messages, the team manipulated system conditions to create various faults. System A performed as expected, both in detecting malfunctions and in communicating them to homeowner and technician platforms. The system sent appropriate error messages to the homeowner, with an option to call the service technician. Errors were also displayed at the outdoor unit, with diagnostic details available to the technician. System A’s DR capability was not commercially available at the time of this research and was thus not tested. The team tested FDD System B in the field on an operating HVAC unit in the laboratory starting in January 2014 and at three sites in Southern California starting in July and August 2014. System B monitors and tracks HVAC performance over time to determine if thresholds are crossed or if performance degrades. The system also measures air- and refrigerant-side temperatures and pressures, as well as electric power consumption. Communication occurs via the internet, with repair or maintenance alerts emailed to the homeowner and service company, as well as via an interface that contractors and homeowners can log into to monitor performance. System B uses two-way communication, but is not configured for DR, as it does not have controls capability. Once installed in the laboratory, System B detected two major problems with a compressor/fan contactor and power strips of the HVAC unit, which were both corrected. Testing commenced and the only alerts triggered were for filter maintenance. The alerts prompted a change-out of the filter, which yielded a performance improvement. Five System B units installed at three multifamily residential sites in Southern California (Santa Ana, Ontario, and Whittier), all on the indoor units of split-system air conditioners serving common areas and on individual apartment units. System B detected many problems with the HVAC unit serving the office/common area in Santa Ana, in part because the HVAC units were being adjusted by many users. After prompting corrections of duct problems, closed vents, and dirty filters in initial monitoring, System B continued to send six alerts to facility personnel about this unit. The other four units tested in Southern California had a total of only eight alerts. The team tested two FDD/DR System C units in the office and common area of a multifamily housing complex in Lancaster, California, beginning in September 2014. The system monitored the units using real-time measurements of indoor and outdoor temperatures, system and component runtimes in heating and cooling modes, and thermostat settings. Using dedicated broadband access for remote monitoring and communication of alerts, System C generated emails for routing to the property manager. However, performance monitoring revealed no problems that required attention; therefore no notifications/alerts were transmitted. The DR-capable System C units responded successfully to DR events simulated in May 2015. This simulation included precooling before the event by lowering the thermostat setpoint and an increase in the thermostat setting during the event. Both actions succeeded in eliminating HVAC operation during the simulated demand period. This research confirmed the success of the FDD capabilities of selected home energy management systems in laboratory and field settings, as well as the DR capabilities of one system. Rigorous laboratory testing was effective in exercising the FDD capabilities of System A. Field testing of System B revealed that initial setup of the measurement, monitoring, and communication equipment required to operate the HEMS could reveal HVAC unit installation and operational faults. This project also demonstrated the feasibility of presetting HEMS units (in this case, System C) with DR response capability to minimize demand requirements during DR events. Since HVAC systems tend to operate reliably for long periods of time, thorough evaluation of FDD functions requires a rigorous laboratory test protocol or long-running field tests or both. The difficulty with lab evaluation is the capability to simulate particular faults, and running through the whole series of faults. The next step should be a scaled field placement of these technologies to evaluate their impacts at scale over an extended period of time. Such testing is needed to provide sufficient data to determine a statistically significant impact for these technologies.