Upstream Solutions to Downstream Problems: Working with the HVAC and Efficiency Communities to Improve Field Performance of Small Commercial Rooftop Units

Small commercial HVAC systems are notorious for consuming more energy than necessary to properly heat, cool, and dehumidify buildings. Several studies have confirmed poor performance of the equipment. Key findings include failed economizers, cycling fans, refrigeration charge variations, higher unit external static pressure, and reduced air flow rate. These problems result in a reduction in unit efficiency under field conditions relative to rated conditions and, in some cases, inadequate ventilation to meet occupant needs or building standards. The energy wasted as a result of these problems in newly installed packaged units in California alone is on the order of 830 GWh of electricity, 245 MW of coincident peak demand, and 2.31 million therms of natural gas each year, and compounds each year as new buildings are added to the stock. This paper focuses on a market transformation effort aimed at HVAC equipment manufacturers to encourage improvements in the overall reliability and maintainability of their product. Enhanced component reliability, fault tolerant design, and/or on-board diagnostic systems are possible solutions being considered under this initiative. The goal of these efforts is to encourage the development of advanced rooftop units with improved reliability that can be identified and promoted by a network of market transformation and energy efficiency programs. The paper discusses the early involvement of the efficiency and manufacturing communities and the evolution of these efforts. The outcomes of these industry-to-industry communications are highlighted to provide valuable information for future efforts to improve infield performance.