Real-Time Measurement of Rates of Outdoor Airflow into HVAC Systems: A Field Study of Three Technologies

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Technologies for real-time continuous measurement of the flow rates of outdoor air (OA) into HVAC systems are now available commercially. Our prior papers reported on laboratory-based evaluations of these measurement technologies and this document describes the methods and results of a field study of the accuracy of three of these technologies. From the field study data, we determined that neither wind speed nor wind direction have an important adverse impact on measurement accuracy. The field study confirmed that these three measurement technologies can provide reasonably accurate measurements of outdoor air intake rates in field settings, if the pressure signals are measured with high accuracy. Some of the pressure transducers marketed for use with commercial HVAC systems were determined to be sufficiently accurate for this application. Given the significant impact of OA flow rates on both energy use and occupant health, more widespread use of technologies that provide for real time measurements of OA flow rates seems warranted.

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