Laboratory Testing of Performance Enhancements for Rooftop Packaged Air Conditioners

The primary goal of this project was to measure and quantify the relative performance gains that can be achieved by a typical rooftop air conditioner from various enhancement technologies. This involved baseline testing of the air conditioner under a range of operating conditions, and then conducting similar tests with the enhancements applied. The project scope was limited to the collection of performance data, which can be later used to develop models for estimating the potential energy savings in different climates. The testing is not intended to rank similar technologies against each other, but rather to provide perspective on the range of performance changes that can be achieved. Thus, an effort has been made to avoid naming manufacturers. The project report is divided into five phases of laboratory testing: Benchmark testing of an old RTU for comparison with the manufacturer's specifications, Execution of a Quality Maintenance service with follow-up performance testing and comparison with the benchmark to determine savings, Evaluation of the performance of economizers, which included tests for airflow and demonstration of two recently-introduced digital economizer controllers, Performance testing of the RTU with four samples of evaporative condenser air pre-coolers, including one that combined a coil for ventilation air pre-cooling, and Performance testing of the RTU with separate systems for indirect evaporative cooling of ventilation air and direct evaporative cooling of condenser intake air. This study was performed in parallel and/or in sequence with four other studies, all of which assessed the performance of RTUs that employ evaporative technologies in different ways or configurations. These include: • A field assessment at a big box retail store and grocery in Bakersfield, CA of indirect evaporative cooling units from two different manufacturers applied as retrofits to existing RTUs. http://www.etcc-ca.com/reports/indirect-evaporative-air-conditioners-added-existing-rtus • A field assessment of indirect evaporative cooling for a mall in Fairfield, CA in which a new RTU was retrofitted with a direct evaporative pre-cooler at the condenser inlet, and a water to air heat exchanger at the ventilation air inlet. http://www.etcc-ca.com/reports/indirect-evaporative-cooling-shopping-mall • A field assessment of an indirect evaporative unit, serving as a dedicated outside air supply (DOAS) at a restaurant in Rocklin, CA. http://www.etcc-ca.com/reports/indirect-evaporative-air-conditioning-restaurant • Lab and field assessments of a Munters hybrid unitary dedicated outside air supply (DOAS) system. Lab: http://etcc-ca.com/reports/munters-epx-5000-dedicated-outside-air-supply Field: http://etcc-ca.com/reports/climate-appropriate-cooling-grocery-store-hybrid-unitary-doas-system-san-ramon-ca