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Title: Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation

Abstract

Previous research has shown that under-ventilation of classrooms is common and negatively impacts student health and learning. To advance understanding of contributing factors, this study visited 104 classrooms from 11 schools that had recently been retrofitted with new heating, ventilation, and air-conditioning (HVAC) units. CO 2 concentration, room and supply air temperature and relative humidity, and door opening were measured for four weeks in each classroom. Field inspections identified HVAC equipment, fan control, and/or filter maintenance problems in 51% of the studied classrooms. Across 94 classrooms with valid data, average CO 2 concentrations measured during school hours had a mean of 895 ppm and a standard deviation (SD) of 263 ppm. Ventilation rates (VRs), estimated using the daily maximum 15-min CO 2 in each classroom, had a mean of 5.2 L/s-person and a SD of 2.0 L/s-person across 94 classrooms. Classrooms with economizers, with or without demand control ventilation (DCV), tended to have lower mean CO 2. Improperly selected equipment, lack of commissioning, incorrect fan control settings and maintenance issues (heavily loaded filters) were all associated with under-ventilation in classrooms. Many classrooms in this sample were frequently too warm to support learning. There were 23 out of 103 classrooms thatmore » had indoor air temperature above 25.6 °C for more than 20% of the school hours. Better oversight on HVAC system installation and commissioning are needed to ensure adequate classroom ventilation. Periodic testing of ventilation systems and/or continuous real-time CO 2 monitoring (either as stand-alone monitors or incorporated into thermostats) is recommended to detect and correct ventilation problems.« less

Authors:
 [1];  [1]; ORCiD logo [1];  [2];  [2];  [2]; ORCiD logo [2];  [2]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of California, Davis, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1580428
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Building and Environment
Additional Journal Information:
Journal Volume: 167; Journal Issue: C; Journal ID: ISSN 0360-1323
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION

Citation Formats

Chan, Wanyu R., Li, Xiwang, Singer, Brett C., Pistochini, Theresa, Vernon, David, Outcault, Sarah, Sanguinetti, Angela, and Modera, Mark. Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation. United States: N. p., 2020. Web. doi:10.1016/j.buildenv.2019.106426.
Chan, Wanyu R., Li, Xiwang, Singer, Brett C., Pistochini, Theresa, Vernon, David, Outcault, Sarah, Sanguinetti, Angela, & Modera, Mark. Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation. United States. doi:10.1016/j.buildenv.2019.106426.
Chan, Wanyu R., Li, Xiwang, Singer, Brett C., Pistochini, Theresa, Vernon, David, Outcault, Sarah, Sanguinetti, Angela, and Modera, Mark. Wed . "Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation". United States. doi:10.1016/j.buildenv.2019.106426.
@article{osti_1580428,
title = {Ventilation rates in California classrooms: Why many recent HVAC retrofits are not delivering sufficient ventilation},
author = {Chan, Wanyu R. and Li, Xiwang and Singer, Brett C. and Pistochini, Theresa and Vernon, David and Outcault, Sarah and Sanguinetti, Angela and Modera, Mark},
abstractNote = {Previous research has shown that under-ventilation of classrooms is common and negatively impacts student health and learning. To advance understanding of contributing factors, this study visited 104 classrooms from 11 schools that had recently been retrofitted with new heating, ventilation, and air-conditioning (HVAC) units. CO2 concentration, room and supply air temperature and relative humidity, and door opening were measured for four weeks in each classroom. Field inspections identified HVAC equipment, fan control, and/or filter maintenance problems in 51% of the studied classrooms. Across 94 classrooms with valid data, average CO2 concentrations measured during school hours had a mean of 895 ppm and a standard deviation (SD) of 263 ppm. Ventilation rates (VRs), estimated using the daily maximum 15-min CO2 in each classroom, had a mean of 5.2 L/s-person and a SD of 2.0 L/s-person across 94 classrooms. Classrooms with economizers, with or without demand control ventilation (DCV), tended to have lower mean CO2. Improperly selected equipment, lack of commissioning, incorrect fan control settings and maintenance issues (heavily loaded filters) were all associated with under-ventilation in classrooms. Many classrooms in this sample were frequently too warm to support learning. There were 23 out of 103 classrooms that had indoor air temperature above 25.6 °C for more than 20% of the school hours. Better oversight on HVAC system installation and commissioning are needed to ensure adequate classroom ventilation. Periodic testing of ventilation systems and/or continuous real-time CO2 monitoring (either as stand-alone monitors or incorporated into thermostats) is recommended to detect and correct ventilation problems.},
doi = {10.1016/j.buildenv.2019.106426},
journal = {Building and Environment},
number = C,
volume = 167,
place = {United States},
year = {2020},
month = {1}
}

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This content will become publicly available on January 1, 2021
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