CH-24-C082 - Optimizing Indoor Air Quality for Facilities that Permit Smoking

Environmental Tobacco Smoke (ETS), even though largely prohibited in buildings, is still allowed in some indoor spaces, such as casinos and bars, in some locations. It is important to manage the smoke in indoor environments and mitigate exposure to occupants as it contains health damaging chemicals. There are little to no guidelines or threshold limits defined on managing ETS. ASHRAE’s current policy is such that ‘Standards and Guidelines’ shall not prescribe any defined ventilation rates or claim to provide acceptable indoor air quality (IAQ) for indoor smoking spaces. With no definitive codes or guidelines, mechanical designers are faced with a wide range of possible design ventilation rates and management strategies for managing ETS. The contaminant removal is typically addressed using high outdoor air change rates or air cleaning technologies. A higher outdoor air change rate is not only an energy burden but also creates a risk of drafts, causing discomfort to the occupants of the room. In this study, a 20,000 sq.ft. casino space in Las Vegas is studied in detail using Computational Fluid Dynamics (CFD). It is assumed that 38% of occupants are smoking at any given time in the case study. This study compares the contaminant removal effectiveness and energy use of various air flow rates using CFD and energy modeling. The smoke is simulated as a nonreactive species and its trajectory is traced within the space. The purpose of this study is to evaluate if ETS can be effectively managed with a lower outdoor air change rate by using ventilation. The results discuss how optimizing ventilation rate against energy use while managing the ETS at breathing zone. This study introduces a novel methodology to demonstrate ventilation optimization and reduction in energy use using CFD and energy modeling techniques in indoor smoking areas. The findings of the study and the methodology will help building design practitioners in addressing ETS exposure in buildings, especially when with the lack of definitive guidelines.