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Natural ventilation is used to cool buildings and cut energy costs by inducing airflow through building openings without the use of mechanical ventilation and cooling systems. However, prior research has documented increased introduction of particles into indoor environments that are naturally ventilated, with associated health consequences. The recently updated ASHRAE Standard 62.1–2019: Ventilation for Acceptable Indoor Air Quality Natural Ventilation Procedure (NVP) prescribes opening sizes as a function of occupant density and geometry for use as a ventilation strategy, a change from the previous standard. The current work quantifies the indoor air quality impacts of implementing the Standard 62.1–2019 Natural Ventilation Procedure in the United States and compares it to the 62.1-specified ventilation rate procedure. This is done via coupled transient simulation of CONTAM 3.4 and EnergyPlus 9.1. Three pollutant classes were identified to represent a broad range of contaminants: outdoor-generated pollutants, pollutants generated indoors by humans, and pollutants generated indoors by the building itself. With boundary conditions from measured weather and outdoor pollutant data for 13 representative locations throughout the U.S., our modeling first found 41%–185% annual average increase in ventilation rates over its mechanical counterpart if the NVP is used across the geometries and occupant densities in the Standard. Due to elevated ventilation rates, the Natural Ventilation Procedure reduced building-generated and occupant-generated contaminant concentrations during occupied hours by an average of 17%–61% compared to the ventilation rate procedure. Outdoor-generated fine particles averaged 2.1–2.5 times the concentrations indoors when using the NVP as compared to mechanical ventilation with a MERV-8 filter and 7.8–10.4 times the concentration of a mechanical system with a MERV-13 filter. Both ventilation rates and concentrations were substantially climate-specific and somewhat window geometry-specific. We further showed that increased filtration is needed in many cases to keep up with increased effective NVP rates in the 2019 Standard if acceptable levels of indoor particles are to be achieved, and we offer suggestions for improving the Standard.
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Tradeoffs Between Indoor Air Quality and Sustainability for Indoor Virus Mitigation Strategies in Office Buildings
The COVID-19 pandemic has motivated building operators to improve indoor air quality (IAQ) through long-term sustainable solutions. This paper develops a modeling capability using the Modelica Buildings library to evaluate three indoor virus mitigation strategies: use of MERV 10 or MERV 13 filtration and supply of 100% outdoor air into a building with MERV 10 filtration. New evaluation metrics are created to consider the impact of improving IAQ on financial and environmental costs. The mitigation strategies are studied for medium office buildings in three locations in the United States with differing climates and electricity sources. The results show that use of 100% outdoor air can significantly improve IAQ with limited increases in costs in the milder climate, but leads to very high costs in the hot and humid and very cold climates. MERV 13 filtration can improve IAQ relative to MERV 10 filtration with small increases in costs in all locations.
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- Award ID(s):
- 2217410
- PAR ID:
- 10430524
- Date Published:
- Journal Name:
- Linköping Electronic Conference Proceedings
- Volume:
- 186
- ISSN:
- 1650-3686
- Page Range / eLocation ID:
- 136 to 145
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.3384/ECP21186136
