Development and validation of a dynamic mass-balance prediction model for indoor particle concentrations in an office
Soo Bhin Park1, Ju-Hyeong Park2, Young Min Jo3
1Department of Mechanical Engineering, College of Engineering, Kyung Hee University, Yong-In, Gyung-Gi Do, South Korea.
Abstract:
The Korean government recommends intermittent operation of air purifiers (APs) as a measure to maintain indoor particulate matter (PM) concentrations below the mandatory standards and reduce exposure to indr PM2.5 (PM with a diameter smaller than ). However, there is no guideline to inform occupants of when and how long APs should be operated to comply with the standards. In this study, we developed a dynamic mass-balance model to predict indoor PM concentrations in an office considering penetration of outdoor particles, change in number of occupants, and operational status of the AP. The model fit and prediction accuracies were verified using the American Society for Testing and Materials (ASTM) D 5157 criteria and the k-fold validation technique. We observed that indoor PM2.5 concentrations were determined by infiltration of outdoor PM2.5, and indoor generation/resuspension by occupants and removal. For , the indoor concentrations were determined by interior door access and indoor generation/resuspension. The operation of an AP effectively decreased indoor PM2.5 concentration but not PM2.5-10. We found that our model accurately predicted indoor PM concentrations. Therefore, using the developed model, a guideline may recommend: 1) start the AP when the predicted indoor PM2.5 concentrations under no AP operation approached the standard (e.g., 90% of the standard); and 2) stop the AP when the indoor PM2.5 concentration predicted under the assumption of no AP operation fell below the standard (e.g., 80% of the standard).
Insights
This study developed a dynamic model to predict indoor air quality. The model guides optimal intermittent operation of air purifiers (APs) to effectively reduce fine particulate matter (PM2.5) while meeting air quality standards.
Area of Science:
- Environmental Science
- Indoor Air Quality
- Aerosol Science
Background:
- Intermittent air purifier (AP) operation is recommended by the Korean government to control indoor particulate matter (PM) concentrations.
- Guidelines for optimal AP operation timing and duration are lacking to meet mandatory air quality standards and reduce exposure to PM2.5.
Purpose of the Study:
- To develop and validate a dynamic mass-balance model for predicting indoor PM concentrations in an office environment.
- To assess the impact of AP operation, occupant presence, and particle infiltration on indoor PM levels.
- To provide a basis for developing operational guidelines for APs.
Main Methods:
- A dynamic mass-balance model was created to simulate indoor PM concentrations.
- Model performance was validated using ASTM D 5157 criteria and k-fold cross-validation.
- Factors considered included outdoor particle penetration, occupant dynamics, and AP operational status.
Main Results:
- Indoor PM2.5 concentrations were primarily influenced by outdoor infiltration and indoor generation/resuspension by occupants.
- Larger particulate matter (PM2.5-10) levels were affected by door access and indoor sources.
- AP operation effectively reduced indoor PM2.5 but had minimal impact on PM2.5-10 concentrations.
Conclusions:
- The developed model accurately predicts indoor PM concentrations.
- A guideline can be established using the model: initiate AP operation when predicted PM2.5 nears 90% of the standard and cease when it drops below 80%.
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