Evaluation of the Indoor Air Quality Procedure for Use in Retail Buildings

Abstract

California's building efficiency standards (Title 24) mandate minimum prescribed ventilation rates (VRs) for commercial buildings. Title 24 standards currently include a prescriptive procedure similar to ASHRAE's prescriptive "ventilation rate procedure", but does not include an alternative procedure, akin to ASHRAE's non-prescriptive "indoor air quality procedure" (IAQP). The IAQP determines minimum VRs based on objectively and subjectively evaluated indoor air quality (IAQ). The first primary goal of this study was to determine, in a set of California retail stores, the adequacy of Title 24 VRs and observed current measured VRs in providing the level of IAQ specified through an IAQP process, The second primary goal was to evaluate whether several VRs implemented experimentally in a big box store would achieve adequate IAQ, assessed objectively and subjectively.For the first goal, a list of contaminants of concern (CoCs) and reference exposure levels (RELs) were selected for evaluating IAQ. Ventilation rates and indoor and outdoor CoC concentrations were measured in 13 stores, including one "big box" store. Mass balance models were employed to calculate indoor contaminant source strengths for CoCs in each store. Using these source strengths and typical outdoor air contaminant concentrations, mass balance models were again used to calculate for each store the "IAQP" VR that would maintain indoor CoC concentrations below selected RELs. These IAQP VRs were compared to the observed VRs and to the Title 24-prescribed VRs.For the second goal, a VR intervention study was performed in the big box store to determine how objectively assessed indoor contaminant levels and subjectively assessed IAQ varied with VR. The three intervention study VRs included an approximation of the store's current VR [0.24 air changes per hour ( Calculations of IAQP-based VRs showed that for the big box store and 11 of the 12 other stores, neither current measured VRs nor the Title 24-prescribed VRs would be sufficient to maintain indoor concentrations of all CoCs below RELs. In the intervention study, with the IAQP-based VR applied in the big box store, all CoCs were controlled below RELs (within margins of error). Also, at all three VRs in this store, the percentage of subjects reporting acceptable air quality exceeded an 80% criterion of acceptability.

Developing evidence-based prescriptive ventilation rate standards for commercial buildings in California: a proposed framework

“…With support from the California Energy Commission, researchers at Lawrence Berkeley National Laboratory (LBNL) are performing extensive research exploring relationships between VRs, indoor contaminant emission rates, indoor contaminant concentrations, exceedances of contaminant concentration guidelines, and associated chronic health risks (Apte et al 2012;Chan et al 2012;Dutton et al 2013;Parthasaranthy et al 2012bParthasaranthy et al , 2013. Also, the direct relationships of VRs with several human outcomes are being studied.…”

Should Title 24 Ventilation Requirements Be Amended to include an Indoor Air Quality Procedure?

“…The authors concluded that indoor pollutant source reduction, air cleaning, and local ventilation may be needed at reduced VRs, and even at the current recommended VRs. Dutton, Chan et al (2013) describe research to evaluate indoor air quality in a large Big-Box retail store using both the objective and subjective IAQP assessments. In addition, the report describes application of the objective IAQP assessment to 12 additional retail stores.…”

“…The 100 µg/m 5 limit is from a committee of the World Health Organization and the 120 µg/m 3 limit is from Health Canada. The subsequent two studies , Dutton, Chan et al 2013) applied generally stricter CLs, including, for formaldehyde, the California Environmental Protection Agency's 9 µg/m 3 limit (California EPA) and the 16 µg/m 3 limit of National Institute for Occupational Safety and Health. These studies found that IAQP VRs were generally higher than the minimum VRs specified in ASHRAE's VRP and California's Title 24 standards.…”

“…These studies found that IAQP VRs were generally higher than the minimum VRs specified in ASHRAE's VRP and California's Title 24 standards. Dutton, Chan et al (2013) and Mendell and Apte (2011) have pointed out limitations of ASHRAE's IAQP. At present, the users of the ASHRAE IAQP have complete flexibility to select "critical contaminants" and CLs.…”

Energy and IAQ Implications of Alternative Minimum Ventilation Rates in California Retail and School Buildings

“…Modeling in prior studies [9,10] found that indoor particle concentrations are not highly affected by minimum VRs because particles are present in outdoor air as well as being emitted from indoor sources. In addition, the high removal rates of particles by filters and substantial loss of particles by deposition on indoor surfaces lessen the influence of VRs on indoor concentrations of particles.…”