ET25SWE0035 - Multifamily CHPWH Fault Detection Diagnostics (FDD) and Load Shift Controls

As multifamily buildings adopt heat pumps and other sophisticated technologies, they are encountering problems with maintenance and operations. Multifamily buildings tend to have no central controls and either no permanent maintenance staff or very low-skilled maintenance staff. Problems with the operation of complex systems are difficult for them to identify and address without outside support. This leads to loss of performance in CHPWH systems. At the same time, time of use (TOU) rate schedules are emerging and CHPWH systems provide opportunities for load shifting. However, there are no readily available controllers which can optimize the timing of load-up and shed activities in response to utility pricing. CHPWH and controls manufacturers are beginning to respond to this opportunity, but there are no clear guidelines for how to accomplish load shifting in a measurable, repeatable, reliable manner. This will likely lead to confusion, complexity, under-performance, and inflated costs.

Ecotope has developed a lab-tested, field-demonstrated, simple and reliably response to load shift commands that is universally applicable to all products on the Northwest Energy Efficiency Alliance Commercial HPWH Qualified Products List (over 100 systems). Multiple manufacturers including Mitsubishi and Small Planet Supply have already adopted this control strategy through minimal, simple updates to their control hardware and sequences. A standardized control sequence like this is needed which can take a range of inputs from system sensors and data from the utility rate structure and deliver control signals to building equipment to optimize load-up and shed operations to minimize utility bills. This would allow an equivalent quantification of load shift capacity for different systems. This same control system could also provide automatic Fault Detection and Diagnostics (FDD) to alert maintenance staff when problems arise and provide specific instructions for response in a timely manner before problems lead to equipment failure or occupant complaints.

This effort will partner with a previous CalNEXT participant to serve as the host site for this project, in an effort to streamline the recruitment process and leverage previous experience with the site and hardware to efficiently deploy the added layer of FDD and load-shift controls. One potential site that has been identified is the Tenderloin Neighborhood Development Corporation (TNDC), which is a low-income multifamily building currently equipped with a CHPWH system, located in a Disadvantaged Community (DAC) and PG&E territory in San Francisco. The existing CHPWH at this site was designed and commissioned by a third-party vendor outside the scope of this study (AESC, ASK Energy, and Ecotope were not involved). The FDD system will be designed to be extremely cost effective and simple, to identify issues with system performance as they arise and notify maintenance staff exactly how to respond. The load shifting algorithm will be designed to track hot water load shape and optimize controls over time to minimize utility costs from TOU schedules. The project will demonstrate the load shift optimization using the local utilities TOU rate schedule and the most up to date version of rates within the California Energy Commissions Market Informed Demand Automation Server (MIDAS). Performance metrics will be gathered to assess the effectiveness on the CHPWH system, and although not part of the scope, general comments will be made regarding how the controller might be expanded to add to other common systems in multifamily buildings such as solar PV, batteries, car charging, or pre-heating or pre- cooling of thermal mass.