120 research outputs found
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Indoor air quality in California homes with code-required mechanical ventilation.
Data were collected in 70 detached houses built in 2011-2017 in compliance with the mechanical ventilation requirements of California's building energy efficiency standards. Each home was monitored for a 1-week period with windows closed and the central mechanical ventilation system operating. Pollutant measurements included time-resolved fine particulate matter (PM2.5 ) indoors and outdoors and formaldehyde and carbon dioxide (CO2 ) indoors. Time-integrated measurements were made for formaldehyde, NO2 , and nitrogen oxides (NOX ) indoors and outdoors. Operation of the cooktop, range hood, and other exhaust fans was continuously recorded during the monitoring period. Onetime diagnostic measurements included mechanical airflows and envelope and duct system air leakage. All homes met or were very close to meeting the ventilation requirements. On average, the dwelling unit ventilation fan moved 50% more airflow than the minimum requirement. Pollutant concentrations were similar to or lower than those reported in a 2006-2007 study of California new homes built in 2002-2005. Mean and median indoor concentrations were lower by 44% and 38% for formaldehyde and 44% and 54% for PM2.5 . Ventilation fans were operating in only 26% of homes when first visited, and the control switches in many homes did not have informative labels as required by building standards
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Healthy Zero Energy Buildings (HZEB) Program Interim Report on Cross Sectional Study of Contaminant Levels, Source Strengths, and Ventilation Rates in Retail Stores
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Healthy Zero Energy Buildings (HZEB) Program Interim Report on Cross Sectional Study of Contaminant Levels, Source Strengths, and Ventilation Rates in Retail Stores
Effectiveness of Urban Shelter-in-Place. III: Commercial Districts
In the event of a toxic chemical release to the atmosphere, shelter-in-place (SIP) is an emergency response option available to protect public health. This paper is the last in a three-part series that examines the effectiveness of SIP at reducing adverse health effects in communities. We model a hypothetical chemical release in an urban area, and consider SIP effectiveness in protecting occupants of commercial buildings. Building air infiltration rates are predicted from empirical data using an existing model. We consider the distribution of building air infiltration rates both with mechanical ventilation systems turned off and with the systems operating. We also consider the effects of chemical sorption to indoor surfaces and nonlinear chemical dose-response relationships. We find that commercial buildings provide effective shelter when ventilation systems are off, but that any delay in turning off ventilation systems can greatly reduce SIP effectiveness. Using a two-zone model, we find that there can be substantial benefit by taking shelter in the inner parts of a building that do not experience direct air exchange with the outdoors. Air infiltration rates vary substantially among buildings and this variation is important in quantifying effectiveness for emergency response. Community-wide health metrics, introduced in the previous papers in this series, can be applied in pre-event planning and to guide real-time emergency response
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Durable Airtightness in Single-Family Dwellings: Field Measurements:
Durability of building envelope is important to new homes that are increasingly built with improved levels of airtightness. It is also important to weatherized homes such that energy savings from retrofit measures, such as air sealing, are persistent. We presented a comparison of air leakage measurements collected in November 2013 through March 2014, with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007-2008. The purpose of the comparison is to determine if there are changes to the airtightness of building envelopes over time. The air leakage increased in all but one of the new homes, with a mean increase of about 25%. The weatherized homes also showed an increase in the mean air leakage (12%). We performed a regression analysis to describe the relationship between prior and current measurements in terms of normalized leakage (NL). The best estimate of the aging factor predicts a 15% increase in NL over ten years. Further analysis using ResDB data (LBNL’s Residential Diagnostic Database) showed the expected changes in air leakage if aging were modeled. These results imply that we should examine the causes of increased leakage and methods to avoid them. This increase in leakage with time should be accounted for in long-term population-wide energy savings estimates, such as those used in ratings or energy savings programs
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