Tradeoffs among indoor air quality, financial costs, and CO2 emissions for HVAC operation strategies to mitigate indoor virus in U.S. office buildings

Faulkner, Cary A.; Castellini, John E.; Lou, Yingli; Lorenzetti, David M.; Sohn, Michael D.

doi:10.1016/j.buildenv.2022.109282

Cited by 12 publications

(3 citation statements)

References 29 publications

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“…Following this way, Faulkner et al raised new metrics to evaluate improvement in IAQ relative to costs/emissions. Using dynamic building simulation, the trade-offs' comparisons in a medium office building system model in different climates in USA were accounted for regarding four different operation strategies among IAQ, financial costs, and CO 2 emissions [22].…”

Section: Learned Lessons From the Aspect Of Simulation And Modelingmentioning

confidence: 99%

Enhancing Indoor Environmental Quality and Sustainability in Post-Pandemic Office Settings: A Study on Displacement Ventilation Feasibility

Shen,

Chen,

Rajagopal

2023

Buildings

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The COVID-19 pandemic has catalyzed global efforts toward transitioning to a sustainable society, driving rapid innovation in building technologies, working practices, building design, and whole life cycle environmental impact consideration. In this pursuit, this study explores the enduring impact of these on an alternative ventilation approach for both existing building renovations and new building implementations. Comparing displacement ventilation to mixed-mode ventilation in a Finnish office building with varying occupancy densities, this study examines indoor air quality (IAQ), thermal comfort, total building energy performance, and embodied carbon. The findings reveal that the basic case of mixed ventilation has a specified system primary energy value of 38.83 kWh/m2 (with 28 occupants) and 39.00 kWh/m2 (with 24 occupants), respectively. With the displacement ventilation alternative, it reduces this by 0.3% and 0.1%, enhancing thermal comfort and decreasing turbulence as well as having a marginal decrease in embodied carbon. In general, the study offers three-fold contributions: insights into post-pandemic office mechanical ventilation design with an emphasis on sustainability and ecological footprint considerations, a concrete case study addressing climate action and human-centric IAQ design, and a multifaceted analysis using the Environmental, Social, and Governance (ESG) paradigm, contributing to the groundwork for associated future research and policy progress.

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Section: Learned Lessons From the Aspect Of Simulation And Modelingmentioning

confidence: 99%

Enhancing Indoor Environmental Quality and Sustainability in Post-Pandemic Office Settings: A Study on Displacement Ventilation Feasibility

Shen,

Chen,

Rajagopal

2023

Buildings

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“…5,7 The indoor air CO 2 concentration is often used as an indicator of the adequacy of the ventilation flowrate with the occupant density. [12][13][14][15][16] A maximum hygienic concentration of 1000 ppm is recommended. 17 European and French regulations set limits of CO 2 concentration at 1000 and 1300 ppm respectively.…”

Section: Introductionmentioning

confidence: 99%

Improving the ventilation of a classroom to achieve heating energy savings and better indoor air quality

Labihi,

Benakcha,

Meslem

et al. 2024

Building Services Engineering Research and Technology

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Indoor air quality and heating energy consumption are closely linked, especially in densely occupied spaces, as classrooms. In a classroom of Rennes University, a transient thermal simulation highlights the impact of ventilation on heating consumptions for different cases: (1) without controlled mechanical ventilation (CMV), (2) with a single flow CMV (SF CMV) of a regulatory flow of 18 m3.h−1. person−1 during periods of occupancy, and (3) a double flow CMV (DF CMV) whose flow is during periods of occupancy either equal to 18 m3.h−1. person−1 or (4) to 35 m3.h−1.person−1. The infiltration flowrate was evaluated experimentally using CO2 concentration measurements in the first case, which corresponds to the actual situation. In the normal use of the classroom with 30 persons inside, CO2 concentration exceeds 5000 ppm and the heating energy consumption is equal to 52 kWh.m−2.year−1. In case (2) and (3), CO2 concentration has a maximum level of 1350 ppm and the energy consumption is equal to 65 and 53 kWh.m−2.year−1, respectively. In case (4), the maximum CO2 concentration stays in the range 800-900 ppm without excessive heating consumption (58 kWh.m−2.year−1). Finally, by limiting the fresh air flowrate to 18 m3.h−1.person−1 in DF CMV and coupling it to a façade insulation (extra Case 5), the heating consumption is reduced to 32 kWh.m−2.year−1. These results are valuable within the context of the upcoming energy renovation strategy of the campus. Practical application In most schools, in France and elsewhere, insufficient ventilation flowrates are often observed compared to regulatory requirements. If compliance with ventilation standards and the subsequent revision of CMV installations are necessary to ensure the health of users, it is important to evaluate the energy cost of these renovations, and to identify the best choice to reduce heating consumptions. Our contribution is to compare different renovation choices in terms of two indicators: energy consumption and indoor air quality evaluated using CO2 concentration.

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“…They are especially efficient in simulating large spatial-scale problems. For example, they have been used to assess contaminant transport scenarios in settings ranging from a decaying period time constant wing or floor of a building (Faulkner et al 2022a(Faulkner et al , 2022bMa et al 2022), to an entire building (Li et al 2005;Lim et al 2010), or city and regional scale analyses (Shrubsole et al 2012;Jones et al 2015;Shi et al 2015;Lu et al 2020;Molina et al 2021). Similarly, well-mixed models can also efficiently assess long temporal-scale problems, such as simulations of contaminant concentrations over the course of a year.…”

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Quantifying spatiotemporal variability in occupant exposure to an indoor airborne contaminant with an uncertain source location

2023

Self Cite

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Well-mixed zone models are often employed to compute indoor air quality and occupant exposures. While effective, a potential downside to assuming instantaneous, perfect mixing is underpredicting exposures to high intermittent concentrations within a room. When such cases are of concern, more spatially resolved models, like computational-fluid dynamics methods, are used for some or all of the zones. But, these models have higher computational costs and require more input information. A preferred compromise would be to continue with a multi-zone modeling approach for all rooms, but with a better assessment of the spatial variability within a room. To do so, we present a quantitative method for estimating a room’s spatiotemporal variability, based on influential room parameters. Our proposed method disaggregates variability into the variability in a room’s average concentration, and the spatial variability within the room relative to that average. This enables a detailed assessment of how variability in particular room parameters impacts the uncertain occupant exposures. To demonstrate the utility of this method, we simulate contaminant dispersion for a variety of possible source locations. We compute breathing-zone exposure during the releasing (source is active) and decaying (source is removed) periods. Using CFD methods, we found after a 30 minutes release the average standard deviation in the spatial distribution of exposure was approximately 28% of the source average exposure, whereas variability in the different average exposures was lower, only 10% of the total average. We also find that although uncertainty in the source location leads to variability in the average magnitude of transient exposure, it does not have a particularly large influence on the spatial distribution during the decaying period, or on the average contaminant removal rate. By systematically characterizing a room’s average concentration, its variability, and the spatial variability within the room important insights can be gained as to how much uncertainty is introduced into occupant exposure predictions by assuming a uniform in-room contaminant concentration. We discuss how the results of these characterizations can improve our understanding of the uncertainty in occupant exposures relative to well-mixed models.

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Tradeoffs among indoor air quality, financial costs, and CO2 emissions for HVAC operation strategies to mitigate indoor virus in U.S. office buildings

Cited by 12 publications

References 29 publications

Enhancing Indoor Environmental Quality and Sustainability in Post-Pandemic Office Settings: A Study on Displacement Ventilation Feasibility

Enhancing Indoor Environmental Quality and Sustainability in Post-Pandemic Office Settings: A Study on Displacement Ventilation Feasibility

Improving the ventilation of a classroom to achieve heating energy savings and better indoor air quality

Quantifying spatiotemporal variability in occupant exposure to an indoor airborne contaminant with an uncertain source location

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