Estimation of bias with the single‐zone assumption in measurement of residential air exchange using the perfluorocarbon tracer gas method

Ryswyk, Keith Van; Wallace, Lance; Fugler, Don; MacNeill, Morgan; Héroux, Marie-Ève; Gibson, Mark; Guernsey, Judith Read; Kindzierski, Warren B.; Wheeler, Amanda

doi:10.1111/ina.12171

Cited by 13 publications

(11 citation statements)

References 23 publications

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“…When the whole dwelling is considered as a single zone, errors arise from the assumption that the CO 2 concentrations in other bedrooms are consistent with those of the measured space. A study found that the error from the single and well‐mixed air zone assumption could be 16% …”

Section: Discussionmentioning

confidence: 99%

Air change rates in urban Chinese bedrooms

et al. 2019

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The ventilation modalities in most Chinese residences are infiltration and opening windows. We measured infiltration rates and air change rates at night, with no attempt to change occupants' behaviors, of urban residences in five climate zones of China during four seasons. Using the CO 2 decay method, we found the median infiltration rate for 294 residences to be 0.34 h −1 . Using occupant-generated CO 2 as tracer gas, we determined air change rates over the course of 1 year in 46 bedrooms at night from mass balance considerations. In 54% of the measurements, windows were closed, so ventilation was only by infiltration. Windows were mainly closed when the outdoor temperature was below 15°C and above 26°C. The median infiltration rates did not differ appreciably among seasons and climate zones and were always less than 0.45 h −1 .

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Section: Discussionmentioning

confidence: 99%

Air change rates in urban Chinese bedrooms

et al. 2019

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“…In using tracer gas measurements to determine airflow rates among zones, we have assumed that each zone could be represented as a single well‐mixed volume. That type of assumption is common in studies of indoor environmental quality; however, its validity is not often scrutinized . In this study, we have explored the extent to which the well‐mixed approximation is a valid representation of the living zone of the studied house and its impact on estimated air change rate values using tracer methods.…”

Section: Resultsmentioning

confidence: 99%

“…That type of assumption is common in studies of indoor environmental quality; however, its validity is not often scrutinized. 4,10,36 In this study, we have explored the extent to which the well-mixed approximation is a valid representation of the living zone of the studied house and its impact on estimated air change rate values using tracer methods. We did so by having a different tracer steadily released in the upper and lower living zones, respectively, for portions of the summer and winter campaigns ( Figures S5 and S6).…”

Section: Mixing Between the Upper And Lower Living Zonesmentioning

confidence: 99%

Detailed investigation of ventilation rates and airflow patterns in a northern California residence

et al. 2018

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Building ventilation rates and indoor airflow conditions influence occupants' exposure to indoor air pollutants. By making time- and space-resolved measurement of 3 inert tracers steadily released in a single-family house in California for 8 weeks in summer and 5 weeks in winter, this study quantifies the air change rate of the living zone with 2-hour time resolution; estimates airflow rates between the living zone, attic, and crawlspace; and characterizes mixing of air in the split-level living space. Occupant behaviors altered the air change rates, primarily through opening windows and secondarily through operating the heating system. The air change rate correlated with the number of window openings, accounting for 57% of the variability measured across 2 seasons. There were substantial upward interzonal airflows between the crawlspace, living zone, and attic; downward airflows were negligible by comparison. More than 70% of the airflow entering the living zone in the winter and at night during summer came through the crawlspace, rather than directly from outdoors. The airflow from the living zone to the attic increased with the attic-outdoor temperature difference, indicating that buoyancy associated with solar heating of the attic induced airflow from the living zone, increasing the air change rate.

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“…The importance of airflows from the basement to the living area has been noted in both VI and radon studies (Hernandez and Ring, ; U.S. EPA, ). However, most studies have assumed that the whole building, including the basement, is a single and well‐mixed zone (Holford and Freeman, ; Nazaroff et al., ), which likely results in under‐predictions of AERs (Ryswyk et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…EPA, 2003). However, most studies have assumed that the whole building, including the basement, is a single and well-mixed zone (Holford and Freeman, 1996;Nazaroff et al, 1985), which likely results in under-predictions of AERs (Ryswyk et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Air exchange rates and migration of VOCs in basements and residences

Batterman

Godwin

et al. 2015

Indoor Air

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Basements can influence indoor air quality by affecting air exchange rates (AERs) and by the presence of emission sources of volatile organic compounds (VOCs) and other pollutants. We characterized VOC levels, AERs and interzonal flows between basements and occupied spaces in 74 residences in Detroit, Michigan. Flows were measured using a steady-state multi-tracer system, and 7-day VOC measurements were collected using passive samplers in both living areas and basements. A walkthrough survey/inspection was conducted in each residence. AERs in residences and basements averaged 0.51 and 1.52 h−1, respectively, and had strong and opposite seasonal trends, e.g., AERs were highest in residences during the summer, and highest in basements during the winter. Air flows from basements to occupied spaces also varied seasonally. VOC concentration distributions were right-skewed, e.g., 90th percentile benzene, toluene, naphthalene and limonene concentrations were 4.0, 19.1, 20.3 and 51.0 μg m−3, respectively; maximum concentrations were 54, 888, 1117 and 134 μg m−3. Identified VOC sources in basements included solvents, household cleaners, air fresheners, smoking, and gasoline-powered equipment. The number and type of potential VOC sources found in basements are significant and problematic, and may warrant advisories regarding the storage and use of potentially strong VOCs sources in basements.

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Estimation of bias with the single‐zone assumption in measurement of residential air exchange using the perfluorocarbon tracer gas method

Cited by 13 publications

References 23 publications

Air change rates in urban Chinese bedrooms

Air change rates in urban Chinese bedrooms

Detailed investigation of ventilation rates and airflow patterns in a northern California residence

Air exchange rates and migration of VOCs in basements and residences

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