The Effect of Internal Door Positioning on the Transport of Airborne Pollutants in a Two Room Building

Collin M. Work, Kaushik K. Shandilya and Andrea R. Ferro

Department of Civil and Environmental Engineering

An important area of indoor air quality is the study of the movement of air indoors, within a single room and through multiple rooms. Since much of the inter-zonal air movement indoors occurs through internal doorways, it is critical to understand the effects that doors have on airborne pollutant movement. This study focuses on the relationship between the area of a door opening and the transport of airborne pollutants between two rooms in a home. Included in this study are the effects of proximity to the pollutant source.

Eleven experiments were run in two adjacent rooms in a naturally ventilated house with no mechanical mixing. Approximately three liters of carbon monoxide (CO) were emitted as a pulse and environmental tobacco smoke (ETS) was emitted for a period of ten minutes from a smoldering cigarette in the “source” room. Approximately three liters of sulfur hexafluoride (SF 6) were emitted as a pulse from the “nonsource” room. Langan model T15d carbon monoxide monitors were placed in the source room, nonsource room, kitchen and the hallway into the kitchen. Polycyclic aromatic hydrocarbons (PAHs) were measured in the source and nonsource rooms with two EcoChem PAS 2000CE monitors. An Innova 1312 photoacoustic multi-gas monitor measured SF 6 in the source room. Three HOBO H8 Loggers were placed in the source room, nonsource room and outside to log temperature and relative humidity (RH) for the experiments duration. For each experiment, the door connecting the two rooms was varied. The door was positioned at fully open, open 40cm, 30cm, 20cm, 10cm, 5cm (twice), 2.5cm (twice) and closed. An additional collocation experiment was run to assure the quality of the results and adjust for instrument bias. Figure 1 provides a floor plan for the experiments.

Figure 1. Floor plan of the area used in the experiments including locations of sources and monitoring equipment.

Figure 2 plots the carbon monoxide concentration in the source and nonsource rooms over time for four different door positions: fully open, 30cm open, 10cm open and 2.5cm open. As the area of the door opening decreases, there is a decrease and a delay in the peak concentration in the nonsource room. In addition, the difference in the source and nonsource room concentrations increases as the opening in the doorway decreases.

Figure 3 plots the concentration of carbon monoxide at three points at increasing distance away from the source: in the source room (1.9m), the hallway (5.1m) and the kitchen (9.5m). In approximately the first 30 minutes after the carbon monoxide was emitted, there was significant concentration differences between the three monitors in relation to their distance from the source. During the remaining decay period, all three monitors measured similar concentrations, indicating that the carbon monoxide was well mixed in the source room and kitchen.

We have found that a closed door or even a slightly open door can be effective in reducing human exposure in a nonsource room. Proximity to the source also has a significant effect on human exposure during the time period soon after the pollutant has been released because the home is not instantaneously well-mixed. Approximately 30 minutes after the source has been released, the home becomes well-mixed, resulting in little variation in exposure due to location.

Figure 2. Carbon Monoxide concentration in the source and nonsource rooms for four different door positions: fully open, open 30cm, open 10cm and open 2.5cm

Figure 3. Carbon monoxide concentration at three distances from the source: 1.9m, 5.1m, and 9.5m

Class of 2006, Biosystems Engineering, Michigan State University, REU, Andrea Ferro, Oral presentation

Graduate Student, Department of Civil and Environmental Engineering, Clarkson University

Assistant Professor, Department of Civil and Environmental Engineering, Clarkson University