Indoor air quality in California homes with code‐required mechanical ventilation

Abstract

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.

Indoor air quality in new and renovated low‐income apartments with mechanical ventilation and natural gas cooking in California

“…Another four units were within 90% of the 2007 code requirements. Among the 63 houses in the HENGH study with measured whole‐dwelling mechanical ventilation airflow, all but two had ventilation equipment that was mostly or completely compliant with the 2007 code 17 . Four apartments of 22 with measurements (18%) had at least one bath fan that did not meet the requirement of 20 cfm continuous airflow for bathrooms.…”

“…16 The recently completed Healthy, Efficient New Gas Homes (HENGH) study of 70 California single, detached houses built since 2011 found that almost all had mechanical ventilation equipment with airflows that met the BEES requirements. [17][18][19] Measurements made in the homes while the dwelling unit MV systems were operating found that both formaldehyde and PM 2.5 were substantially lower than reported in the California New Homes Study (CNHS) conducted a decade earlier in homes constructed in 2002-2005. 20 The lower formaldehyde concentrations resulted both from the operation of dwelling unit MV systems reducing the number of homes with very low ventilation and also from state and federal regulations that limit formaldehyde emissions from manufactured wood materials.…”

“…The recently completed Healthy, Efficient New Gas Homes (HENGH) study of 70 California single, detached houses built since 2011 found that almost all had mechanical ventilation equipment with airflows that met the BEES requirements 17‐19 . Measurements made in the homes while the dwelling unit MV systems were operating found that both formaldehyde and PM 2.5 were substantially lower than reported in the California New Homes Study (CNHS) conducted a decade earlier in homes constructed in 2002‐2005 20 .…”

Automating the interpretation of PM 2.5 time‐resolved measurements using a data‐driven approach

“…These data are used to develop a source apportionment model and to test its performance. Dataset two was collected from 65 new California single‐family homes 20 and is used for the application. Table 1 describes the broad content of the two datasets.…”

“…MetOne ES-642 and BT-645 instruments (Met One Instruments Inc). 20 Both instruments are light-scattering monitors that work on a similar operating principle as the DustTrak. The indoor concentrations were measured centrally in a large open room (eg dining or living room).…”