Relating actual and effective ventilation in determining indoor air quality

Sherman, Max H.; Wilson, D.

doi:10.1016/0360-1323(86)90022-3

Cited by 51 publications

(45 citation statements)

References 2 publications

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“…To make this comparison we follow the convention, used by Sherman and Wilson (1986) and others, that two ventilation strategies are equivalent if they lead to the same contaminant exposure. We do not need to know what the contaminant of concern is; for a constant air change rate of A eq, we will get a steady state concentration of C eq .…”

Section: Appendix: Defining Equations and Simplified Physical Modelingmentioning

confidence: 99%

“…Sandberg and Sjoberg (1984) developed much of the nomenclature used in this field to deal principally with spatial variation. Sherman and Wilson (1986) followed by Yuill (1986Yuill ( , 1991 have already solved the continuity equation for the general case and defined (temporal) ventilation effectiveness, 2 ε, as a measure of how good a given, time-varying, ventilation pattern is at providing acceptable IAQ. As in those cases, we limit our analysis to contaminants with a linear dose-response and no other loss mechanism (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Efficacy of intermittent ventilation for providing acceptable indoor air quality

Sherman¹

2004

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Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available. This report develops a model of efficacy that allows one to calculate how much intermittent ventilation one needs to get the same indoor air quality as a the continuous value specified. We have found that there is a simple relationship between three dimensionless quantities: the temporal ventilation effectiveness (which we call the efficacy), the nominal turn-over and the under-ventilation fraction. This relationship allows the calculation of intermittent ventilation for a wide variety of parameters and conditions. We can use the relationship to define a critical time that separates the regime in which ventilation variations can be averaged over from the regime in which variable ventilation is of low effectiveness. We have found that ventilation load-shifting, temporary protection against poor outdoor air quality and dynamic ventilation strategies can be quite effective in low-density buildings such as single-family houses or office spaces. The results of this work enable ventilation standards and guidelines to allow this extra flexibility and still provide acceptable indoor air quality.

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Section: Appendix: Defining Equations and Simplified Physical Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficacy of intermittent ventilation for providing acceptable indoor air quality

Sherman¹

2004

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“…The intermittent ventilation algorithms cited above are based on the work of Sherman and Wilson (1986), which looked at ventilation time variations on a fixed schedule. To generalize to ventilation rates that are not on a fixed schedule, we need to develop an equivalent way to determine IAQ.…”

Section: Intermittent Ventilationmentioning

confidence: 99%

Meeting residential ventilation standards through dynamic control of ventilation systems

Sherman

Walker

2011

Energy and Buildings

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Existing ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outdoor pollutant levels are high, the importance of minimizing energy use particularly during times of peak electricity demand, and how the energy used to condition air as part of ventilation system operation changes with outdoor conditions. Dynamic control of ventilation systems can provide ventilation equivalent to or better than what is required by standards while minimizing energy costs and can also add value by shifting load during peak times and reducing intake of outdoor air contaminants. This article describes the logic that enables dynamic control of whole-house ventilation systems to meet the intent of ventilation standards and demonstrates the dynamic ventilation system control concept through simulations and field tests of the Residential Integrated Ventilation-Energy Controller (RIVEC).

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“…Generalized ventilation efficiency as defined by Sherman and Wilson (1986) is based on the simple average over the time period in question. The reference for our infiltration efficiency will be the longest term (i.e.…”

Section: Ventilation Effectivenessmentioning

confidence: 99%

“…This requires numerical modeling. The Sherman-Wilson (1986) approach to effective ventilation can be used to determine the steady-state ventilation rate that would provide the same dilution as the physically occurring, time-dependent infiltration. In this study we calculated hour-by-hour infiltration rates using simplified models and weather data.…”

Section: Introductionmentioning

confidence: 99%

Infiltration as Ventilation: Weather-Induced Dilution

Sherman

Turner

Walker

2011

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The purpose of outdoor air ventilation is to dilute or remove indoor contaminants to which occupants are exposed. It can be provided by mechanical or natural means. In most homes, especially older homes, weather-driven infiltration provides the dominant fraction of the total ventilation. As we seek to provide good indoor air quality at minimum energy cost, it is important to neither over-ventilate nor under-ventilate. Thus, it becomes critically important to evaluate correctly the contribution infiltration makes to the total outdoor air ventilation rate.Because weather-driven infiltration is dependent on building air leakage and weather-induced pressure differences, a given amount of air leakage will provide different amounts of infiltration.Varying rates of infiltration will provide different levels of contaminant dilution and hence effective ventilation. This paper derives these interactions and then calculates the impact of weather-driven infiltration for different climates. A new "N-factor" is introduced to provide a convenient method for calculating the ventilation contribution of infiltration for over 1,000 locations across North America. The results of this work could be used in indoor air quality standards (specifically ASHRAE 62.2) to account for the contribution of weather-driven infiltration towards the dilution of indoor pollutants.

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Relating actual and effective ventilation in determining indoor air quality

Cited by 51 publications

References 2 publications

Efficacy of intermittent ventilation for providing acceptable indoor air quality

Efficacy of intermittent ventilation for providing acceptable indoor air quality

Meeting residential ventilation standards through dynamic control of ventilation systems

Infiltration as Ventilation: Weather-Induced Dilution

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