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

Cary A Faulkner; John E Castellini Jr; Yingli Lou; Wangda Zuo; David M Lorenzetti; Michael D Sohn

doi:10.1016/j.buildenv.2022.109282

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

Build Environ. 2022 Aug 1:221:109282. doi: 10.1016/j.buildenv.2022.109282. Epub 2022 Jun 16.

Authors

Cary A Faulkner¹, John E Castellini Jr¹, Yingli Lou², Wangda Zuo^{3

4}, David M Lorenzetti⁵, Michael D Sohn⁵

Affiliations

¹ Department of Mechanical Engineering, University of Colorado Boulder, UCB 427, Boulder, 80309, CO, USA.
² Department of Civil, Environmental and Architectural Engineering, University of Colorado Boulder, UCB 428, Boulder, 80309, CO, USA.
³ Department of Architectural Engineering, Pennsylvania State University, 104 Engineering Unit A, University Park, 16802, PA, USA.
⁴ National Renewable Energy National Laboratory, Golden, 80401, CO, USA.
⁵ Energy Analysis and Environmental Impacts Division, Lawrence Berkeley, USA.

Abstract

Adapting building operation during the COVID-19 pandemic to improve indoor air quality (IAQ) while ensuring sustainable solutions in terms of costs and CO₂ emissions is challenging and limited in literature. Our previous study investigated different HVAC operation strategies, including increased filtration using MERV 10, MERV 13, or HEPA filters, as well as supplying 100% outdoor air into buildings for a system initially sized for MERV 10 filtration. This paper significantly extends that research by systematically analyzing the potential financial and environmental impact for different locations in the U.S. The previous medium office building system model is improved to account for operation in different climates. New evaluation metrics are created to consider the comprehensive impact of improving IAQ on costs and CO₂ emissions, using dynamic emission factors for electricity generation depending on the location. HVAC operation strategies are studied in five different locations across the United States, with distinct climates and electricity sources. In four of the five locations, MERV 13 filtration offers the best improvement in IAQ per increase in costs and emissions relative to MERV 10. The exception is the mildest climate of San Diego, where use of 100% outdoor air provides the best IAQ with a limited increase in costs and emissions. A system not sized for HEPA filtration can lead to increased costs and emissions without much improvement in IAQ.

Keywords: CO2 emissions; COVID-19 pandemic; Climate change; Financial cost; Indoor air quality.