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IAQ and Energy Impacts of Ventilation and Source Control in a Big Box Retail Building

Published

Author(s)

Lisa C. Ng, Andrew K. Persily, Steven J. Emmerich

Abstract

Heating, ventilating, and air conditioning (HVAC) systems in buildings are designed to provide thermally comfortable conditions and to maintain acceptable indoor air quality (IAQ). At the same time, the operating costs of HVAC systems are often a large percentage of the total energy consumption of buildings, which constitutes 40 % of the primary energy consumed in the U.S. As efforts are pursued to reduce building energy use, some of which may include reductions in outdoor air ventilation rates, it is important to consider the impacts of these measures on IAQ. To better understand the IAQ and energy trade-offs of various approaches to reduce the indoor concentrations of CO2, formaldehyde, ozone, particulate matter, and a generic volatile organic compound (VOC), a series of simulations was performed using the multizone airflow model, CONTAM, for a big box retail store in two different climates. Simulations included ventilating at the minimum outdoor airflow rate prescribed by ASHRAE 62.1 and at a lower rate for 24 hours a day. Additional cases included increasing the base outdoor air intake rates by 50 %, as well as a leakier building envelope. Annual airflow and contaminant simulations were performed using emission rates estimated from previous studies of retail buildings. The impact of changes in ventilation rates and building airtightness on contaminant concentrations and energy use were evaluated to investigate how both energy and IAQ goals can be met. This study demonstrated that ventilating at a lower rate for 24 hours a day saved energy compared with ventilating at the higher prescribed 62.1 rate during occupied periods without indoor contaminant concentrations exceeding several common benchmarks or health guidelines. Nevertheless, when considering different energy-saving measures, tightening the building envelope could significantly save more energy than reducing ventilation rates alone.
Citation
Building and Environment

Keywords

ASHRAE Standard 62.1, CO2, CONTAM, contaminants, energy, EnergyPlus, formaldehyde, indoor air quality, ozone, PM2.5, retail buildings, ventilation, volatile organic compounds

Citation

Ng, L. , Persily, A. and Emmerich, S. (2015), IAQ and Energy Impacts of Ventilation and Source Control in a Big Box Retail Building, Building and Environment, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917842 (Accessed April 14, 2024)
Created June 10, 2015, Updated February 19, 2017