Erin Darling

Benefit‐cost analysis of commercially available activated carbon filters for indoor ozone removal in single‐family homes

This study involved the development of a model for evaluating the potential costs and benefits of ozone control by activated carbon filtration in single-family homes. The modeling effort included the prediction of indoor ozone with and without activated carbon filtration in the HVAC system. As one application, the model was used to predict benefit-to-cost ratios for single-family homes in 12 American cities in five different climate zones. Health benefits were evaluated using disability-adjusted life-years and included city-specific age demographics for each simulation. Costs of commercially available activated carbon filters included capital cost differences when compared to conventional HVAC filters of similar particle removal efficiency, energy penalties due to additional pressure drop, and regional utility rates. The average indoor ozone removal effectiveness ranged from 4 to 20% across the 12 target cities and was largely limited by HVAC system operation time. For the parameters selected in this study, the mean predicted benefit-to-cost ratios for 1-inch filters were >1.0 in 10 of the 12 cities. The benefits of residential activated carbon filters were greatest in cities with high seasonal ozone and HVAC usage, suggesting the importance of targeting such conditions for activated carbon filter applications.

Analysis of the cost effectiveness of combined particle and activated carbon filters for indoor ozone removal in buildings

This study involved the development of a model for evaluating the potential costs and benefits of ozone control with combined particle/activated carbon filtration (referred to here as activated carbon filtration) in buildings. The modeling effort included the prediction of indoor ozone and ozone reaction products with and without activated carbon filtration in the HVAC system. Benefit-to-cost ratios were estimated for various types of buildings in 12 American cities in 5 different climate zones. Health benefits were evaluated using disability-adjusted life-years attributed to the difference in indoor ozone concentration with and without activated carbon filtration, and included city-specific age demographics for each simulation. Costs of activated-carbon filters included capital cost differences when compared against conventional HVAC filters of similar minimum efficiency reporting value rating (e.g., minimum efficiency reporting value 6–8), energy penalties due to additional pressure drop, and regional utility rates. When assuming a single-pass ozone removal efficiency of 60%, carbon filtration during the ozone season was beneficial and economically viable in commercial office buildings, long-term health-care facilities, and K–12 schools. Residential activated carbon filtration could be economically viable for conditions of higher ozone removal efficiencies, lower filter costs, and lower pressure drop across the filter.