A Pilot study of the accuracy of CO2 sensors in commercial buildings

TitleA Pilot study of the accuracy of CO2 sensors in commercial buildings
Publication TypeConference Proceedings
Year of Publication2008
AuthorsWilliam J Fisk, David Faulkner, Douglas P Sullivan
Conference NameIAQ 2007 Healthy and Sustainable Buildings
PublisherAmerican Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA
Conference LocationBaltimore, MD
Keywordsair handlers, commercial buildings, controls, indoor air quality equipment and products

Carbon dioxide (CO2) sensors are often deployed in commercial buildings to obtain CO2 data that are used to automatically modulate rates of outdoor air supply. The goal is to keep ventilation rates at or above design requirements and to save energy by avoiding ventilation rates exceeding design requirements. However, there have been many anecdotal reports of poor CO2 sensor performance in actual commercial building applications. This study evaluated the accuracy of 44 CO2 sensors located in nine commercial buildings to determine if CO2 sensor performance, in practice, is generally acceptable or problematic. CO2 measurement errors varied widely and were sometimes hundreds of parts per million. Despite its small size, this study provides a strong indication that the accuracy of CO2 sensors, as they are applied and maintained in commercial buildings, is frequently less than needed to measure typical values of maximum one-hour-average indoor-outdoor CO2 concentration differences with less than a 20% error. Thus, we conclude that there is a need for more accurate CO2 sensors and/or better sensor maintenance or calibration procedures.