19085-1701857-UL_Prop_65_Test_Results_2019

Released by UL Environment
Date Prepared:
February 11, 2019
Report #:
1000339735-1162663EA
©2019 UL LLC
CA Prop 65 Exposure Assessment Page 7 | 15
office may not be fully representative due to its omission of common area, it nevertheless is
selected to represent the private office scenario in the model (Table 1) because of its more
conservative lower airflow rate.
School classroom scenario
The standard school classroom scenario defined in CDPH Standard Method V1.2 (Table 4-2) is
commonly used for assessing VOC emissions from building products and classroom furniture.
The CDPH standard classroom scenario is typical of re-locatable classrooms used widely in
California and is generally representative of site-built classrooms for K-12 schools (Jenkins et al.
2004). It is a 12.2-m (24-ft) wide by 7.32-m (40-ft) long classroom with a 2.59-m (8.5-ft) ceiling
height. The resulting floor area is 89.2 m
2
, and the volume is 231 m
3
. The assumed occupancy
is 27 pupils and one teacher. The 2007 version of ASHRAE Standard 62.1, Table 6-1, for
classrooms occupied by individuals, ages five and up, establishes the minimum ventilation
requirement at 5 L/s-person (10 cfm/person) and 0.6 L/s-m
2
floor area (0.12 cfm/ft
2
). Thus, the
minimum total flow rate of outdoor air for the standard classroom is 654 m
3
/h (182 L/s or 385
cfm). This produces a ventilation air change rate of 2.8 h
-1
for occupied hours. As documented
in various reports, classroom HVAC systems sometimes do not deliver the required amount of
outdoor air for a variety of reasons including poorly-designed or overridden controls and lack of
maintenance. In addition, HVAC systems may not be turned on sufficiently early in the school
day to achieve a fully ventilated condition prior to the start of class. Therefore, the CDPH
standard uses an average ventilation rate over a 168-h week assuming 40 hours of operation at
654 m
3
/h (2.8 h
-1
) and 128 hours of operation with ventilation of only 0.2 h
-1
due to infiltration.
This yields an average flow rate of 191 m
3
/h (53.1 L/s or 112 cfm).
Residential scenario
General housing characteristics in the U.S. and the ventilation rates for homes, mostly single
family, have been the subject of numerous field studies and simulation ventilation studies (e.g.,
Persily 2010). The CDPH Standard Method V1.2, Appendix B, includes an indoor air exposure
scenario for a new single-family detached (SFD) residence. New homes were selected as the
basis for the scenario as they tend to have considerably tighter envelopes than older homes and
can be expected to operate closer to minimum ventilation rate requirements. The size of the
SFD home in the CDPH standard is taken from statistics on new U.S. homes published by the
U.S. Census Bureau (2008). For 2008, the median size for new SFD homes was 206 m
2
(2,215 ft
2
); however, a floor surface area of 211 m
2
was included in the residential model due to
availability of data on a specific floor plan of this size. The minimum ventilation airflow rate
requirement for this home and configuration was calculated using the 2007 version of ASHRAE
Standard 62.2, Table 4-1a. From the table, the ventilation airflow rate requirement is 127 m
3
/h
(75 cfm). According to the National Association of Home Builders (NAHB) consumer preference
survey conducted in 2007, the 2.44 m and 2.7 m ceiling height are most preferred by consumers
(NAHB 2007). Therefore, the CDPH standard assumed a 2.59-m (8.5-ft) average height
yielding a home volume of 534 m
3
. The minimum airflow rate in this volume corresponds to a