Indoor carbon dioxide concentrations have played a role in discussions of ventilation and indoor air quality (IAQ) for centuries. Those discussions have evolved to focus on the use of indoor CO2 as an IAQ metric, estimation of ventilation rates using CO2 as a tracer gas, control of outdoor air ventilation based on CO2 concentrations, and impacts of CO2 on building occupants. More recently, the measurement of indoor CO2 has been discussed in the context of airborne infectious disease transmission. However, many applications of indoor CO2 do not reflect a sound technical understanding of the relationship between indoor CO2 concentrations, ventilation and IAQ. Some applications have actually been technically flawed, leading to significant misinterpretations of indoor CO2. In response, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) has recently issued a Position Document that discusses the role of indoor CO2 in the context of building ventilation and IAQ based on ASHRAE’s long involvement with those topics. The stated positions address the use of CO2 as a metric of IAQ and ventilation, the impacts of CO2 on building occupants, indoor concentration measurement, the use of CO2 to control outdoor air intake rates, and the relationship of indoor CO2 to airborne infectious disease transmission. This position document recommends research into the impacts of CO2 on occupant health, comfort and performance and on the application of indoor CO2 concentrations in building operation, as well as the development of guidance on the measurement and practical use of CO2 concentrations.
AIMS AND SCOPE
Aim #1: To explain the motivations behind the ASHRAE Position Document on indoor CO2.
Aim #2: To explain the positions and recommendations contained in the Position Document.
Aim #3: To engage the attendees in a discussion to identify topics that might not have been well-covered in the position document, to capture disagreements with the positions and reasons for those disagreements, and to generate additional ideas for future research and guidance.
Aim #4: To discuss other activities to clarify the roles of indoor CO2 in the field of ventilation and IAQ, to improve practitioner understanding of those roles, and to reduce misapplication of indoor CO2.
Overview of position document
Andrew Persily NIST
CO2 as an indicator of ventilation and IAQ
Lan Chi Nguyen Weeks La Cité College
Health and cognitive impacts of CO2 exposure
Howard Kipen Rutgers University
CO2 as an indicator of infection risk
William Bahnfleth Pennsylvania State University
Other issues for the future?
Pawel Wagocki Technical University of Denmark
Quantitative health impact assessment applied to schools’ indoor pollution
Hulin, Marion Sante Publique France
Considerations for updating European estimates of IABOD
Hänninen, Otto THL, Finland
Discussion on the ways forward