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Perceptions in the U.S. building industry of the benefits and costs of improving Indoor Air Quality

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How building stakeholders (e.g. owners, tenants, operators, and designers) understand impacts of indoor air quality (IAQ) and associated energy costs is unknown. We surveyed 112 stakeholders across the United States to ascertain their perceptions of their current IAQ and estimates of benefits and costs of, as well as willingness to pay for, IAQ improvements. Respondents' perceived IAQ scores correlated with the use of high efficiency filters but not with any other IAQ-improving technologies. We elicited their estimates of the impacts of a ventilation-filtration upgrade (VFU), i.e., doubling the ventilation rate from 20 to 40 cfm/person (9.5 to 19 L/s/person) and upgrading from a MERV 6 to 11 filter, and compared responses to our estimates derived from IAQ literature and energy modeling. Minorities of respondents thought the VFU would positively impact productivity (45%), absenteeism (23%), or health (39%). Respondents' annual VFU cost estimates (mean = $257, SD = $496, median = $75 per person) were much higher than ours (always < $32 per person), and the only yearly cost a plurality of respondents said they would pay for the VFU was $15 per person. Respondents holding green building credentials were not more likely to affirm the IAQ benefits of the VFU, and were less likely to be willing to pay for it. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Perceptions in the U.S. building industry of the benefits and costs
of improving Indoor Air Quality
Abstract How building stakeholders (e.g. owners, tenants, operators, and
designers) understand impacts of Indoor Air Quality (IAQ) and associated
energy costs is unknown. We surveyed 112 stakeholders across the United
States to ascertain their perceptions of their current IAQ and estimates of
benefits and costs of, as well as willingness to pay for, IAQ improvements.
Respondents’ perceived IAQ scores correlated with the use of high-efficiency
filters but not with any other IAQ-improving technologies. We elicited their
estimates of the impacts of a ventilationfiltration upgrade (VFU), that is,
doubling the ventilation rate from 20 to 40 cfm/person (9.5 to 19 l/s/person)
and upgrading from a minimum efficiency reporting value 6 to 11 filter, and
compared responses to estimates derived from IAQ literature and energy
modeling. Minorities of respondents thought the VFU would positively impact
productivity (45%), absenteeism (23%), or health (39%). Respondents’ annual
VFU cost estimates (mean =$257, s.d. =$496, median =$75 per person) were
much higher than ours (always <$32 per person), and the only yearly cost a
plurality of respondents said they would pay for the VFU was $15 per person.
Respondents holding green building credentials were not more likely to affirm
the IAQ benefits of the VFU and were less likely to be willing to pay for it.
M. Hamilton, A. Rackes,
P. L. Gurian, M. S. Waring
Department of Civil, Architectural and Environmental
Engineering, Drexel University, Philadelphia, PA, USA
Key words: Building energy use; Ventilation; Filtration;
Stated preferences; Investment decision-making; IAQ
impacts.
M. S. Waring
Department of Civil, Architectural and Environmental
Engineering, Drexel University, 3141 Chestnut St.
Philadelphia, PA 19104, USA
Tel.: 011-215-895-1502
Fax: 011-215-895-1363
e-mail: msw59@drexel.edu
Received for review 24 September 2014. Accepted for
publication 31 January 2015.
Practical Implications
The survey elucidated the state of knowledge among U.S. building industry stakeholders on the costs and benefits of
Indoor Air Quality (IAQ), including showing that a majority doubt or are uncertain of the benefits of IAQ improve-
ments and also overestimate their costs. Educating stakeholders on the known benefits and relatively low cost of
improving IAQ could have the effect of increasing the number of IAQ-related upgrades in the building stock. Given
that green building professionals, who presumably have already received some IAQ-related education, were no more
likely to believe beneficial and were less likely to pay for ventilation and filtration upgrades than other respondents,
the indoor air community may need to reconsider and/or redesign existing education and outreach strategies.
Introduction
The benefits of improving Indoor Air Quality (IAQ)
for health, productivity, and other measures have been
documented in the technical literature by a number of
studies over the past few decades. For instance,
research suggests that measurable improvements in
overall building occupant welfare are associated with
several types of basic heating, ventilating, and air-con-
ditioning (HVAC) enhancements, including increased
ventilation rates (VRs) and greater filtration of particu-
late matter (PM).
Strong evidence for improved IAQ affecting occupant
welfare and productivity comes from VR studies (Clau-
sen et al., 2011). For instance, higher incidences of
airborne disease infections in commercial and institu-
tional buildings are associated directly with low VRs (Li
et al., 2007) and indirectly with high indoor carbon
dioxide (CO
2
) levels, which are a proxy for lower VRs
(Myatt et al., 2004). Also, increased VRs in offices (up
to 25 l/s/person) are associated with reduced Sick Build-
ing Syndrome (SBS) symptoms (Apte et al., 2000; Fisk
et al., 2009; Sundell et al., 2011), as well as with reduced
absenteeism in offices (Milton et al., 2000) and class-
rooms (Mendell et al., 2013; Sundell et al., 2011).
Higher VRs have also been linked to higher productivity
in offices (Sepp
anen et al., 2006) and better performance
on computerized testing of cognitive ability in English
primary schools (Bak
o-Bir
o et al., 2012), although the
generalizability of these findings is unclear.
1
Indoor Air 2015 ©2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
wileyonlinelibrary.com/journal/ina
Printed in Singapore. All rights reserved INDOOR AIR
doi:10.1111/ina.12192
Although it has been demonstrated that reduced
VOC source strength and increased VRs have similar
impacts on perceived air quality (Wargocki et al.,
2002), there remains some uncertainty regarding spe-
cific causal pathways. Moreover, increased VRs alone
may not be sufficient to improve IAQ. One study found
that increased ventilation in a call center with dirty fil-
ters led to increased complaints of SBS symptoms, but
that increased ventilation with a clean filter reduced
the number of reported symptoms (Wargocki et al.,
2004). Also, there is no available information on how
VRs impact long-term health outcomes, such as can-
cer, pulmonary disease, myocardial infarction, or
endocrine disruption.
Particles are another important determinant of IAQ
impacts, and most exposure to outdoor PM occurs
indoors (Jenkins et al., 1992; Klepeis et al., 2001; Lioy
et al., 1988; Wallace, 1993). Although the precise
mechanisms by which PM exposure affects human
health are unclear (Phalen and Wolff, 2000), exposure
to outdoor PM has established associations with acute
and chronic health endpoints. Increases in outdoor
PM
2.5
have been correlated with increased cardiovas-
cular and respiratory diseases (Dominici et al., 2006;
Pope et al., 2009), chronic bronchitis (Abbey et al.,
1994), and increased mortality (Dockery and Pope,
1994; Dockery et al., 1992; Pope, 2002; Pope et al.,
1995; Schwartz et al., 1996). Some studies have associ-
ated urban-level exposure impacts to predicted changes
in exposure inside buildings (Bek
o et al., 2008; H
anni-
nen et al., 2005), but others maintain that there is a
lack of understanding of the health effects of outdoor
PM once indoors (Clausen et al., 2011).
Modeling suggests that higher efficiency filtration in
the supply airstream reduces the level of outdoor PM
that enters indoor environments (Bek
o et al., 2008;
Fisk et al., 2002; H
anninen et al., 2005; Waring and
Siegel, 2008). Several case studies have shown that
increased filtration leads to reductions in PM, but none
have significantly linked improvements in health end-
points, even short-term and self-reported ones, directly
to the use of higher efficiency filtration (Skulberg et al.,
2005). Some evidence suggests that employing high-
efficiency particulate air (HEPA) filters in residential
buildings reduces markers used to predict future
adverse coronary events (Allen et al., 2011; Brauner
et al., 2008).
Not only is there evidence that improving IAQ
results in a measurable benefit in terms of health and
productivity, there is also an indication that these
improvements are cost-effective. In one study, Fisk
et al. (2011) modeled several IAQ improvements in the
U.S. office building stock, including increased VR, the
addition of airside economizers and controls, better
temperature control, and dampness and mold counter-
measures, and determined the potential annual net
benefit to be $20 billion. In a related effort, Fisk et al.
(2012) performed a benefitcost analysis of changes in
the amount of outdoor air supplied to U.S. office
buildings and estimated net annual economic benefits
of between $13 billion and $38 billion. It was further
noted that by using economizers and thus increasing
time-averaged VRs, it was possible to achieve well-
being benefits while saving energy at the same time, as
was also suggested by Rackes and Waring (2014) in a
proof-of-concept study of optimal VRs.
These benefits and costs associated with improving
IAQ have attained some consensus within the indoor
air research community. However, it is not clear
whether the likely magnitudes of these benefits and
costs are established in the perceptions of actual
building stakeholders, including tenants, owners,
operators, and designers/consultants. As such, we sur-
veyed 112 building stakeholders of their perceptions
of their IAQ and estimates of the benefits to occupant
well-being and energy-related costs of a specific IAQ
ventilationfiltration upgrade (VFU), and also of their
willingness to pay for the VFU. We also compared
their estimates to our own best estimates to identify
any discrepancies between these views, allowing one
to use these findings to increase awareness of the ben-
efits and costs of improved IAQ to shrink any knowl-
edge gaps between the research and stakeholder
communities.
Methodology
We conducted a survey to (i) characterize stakeholder
perceptions of their current IAQ state and importance
of IAQ in their commercial buildings; (ii) quantify dif-
ferences in their IAQ perceptions as they relate to
building characteristics, potential IAQ-improving tech-
nologies, and stakeholder groups; (iii) assess perceived
benefits and costs of a specific upgrade of building ven-
tilation and filtration that exceed current standards
and should, according to the literature, be expected to
improve IAQ; (iv) assess willingness to pay for the
upgrade for different types of stakeholders; and (v)
ascertain the extent to which IAQ is used in the mar-
keting of commercial space to be leased. Drexel Uni-
versity Institutional Review Board (IRB) approval was
obtained for all survey work in this article.
Survey instruments
A series of semi-structured interviews was completed
initially to ascertain whether our questions captured
information well and to make sure critical points were
not overlooked. The semi-structured interviews were
conducted on a convenience sample of 20 individuals
recruited by email or word of mouth. Each interview
was conducted by phone and lasted ~3545 min; upon
completion, participants were provided a $20 gift
card. With subjects’ permissions, interviews were
2
Hamilton et al.
recorded and were then coded by hand, compiled, and
used to develop the structured, online stated prefer-
ence survey.
For the structured survey instrument, four categories
of stakeholders were identified as critical to decision-
making in the market: (i) building owners; (ii) property
and facilities managers; (iii) tenants; and (iv) mechani-
cal system designers and consultants. Because respon-
dents were likely to have experience with multiple
buildings, they were asked to answer the survey ques-
tions based on ‘the last mechanically ventilated build-
ing [they] had worked with’, which was called their
‘reference building’ thereafter. Respondents were
recruited via trade shows, direct email invitations, pro-
fessional networks, and word of mouth. Respondents
were provided a $20 gift card for completing the online
survey. The online survey was administered between
late 2013 and early 2014, and it is reproduced in full in
the Appendix S1.
The survey had five sections. The first section con-
sisted of questions about basic demographic informa-
tion of each respondent and their reference building
(e.g. building type and IAQ-related technologies uti-
lized). In the second section, questions examined
respondents’ opinions about the definition, importance
of, and impacts of IAQ in general, as well as their per-
ceptions of their current state of IAQ, any actions that
had been taken to improve it, and maintenance fre-
quency in their reference building. Also, respondents
were asked to rate the IAQ in their reference building,
and this rating provided the basis for the metric ‘per-
ceived IAQ’ that was utilized as a dependent variable
in later analyses.
In the third section, respondents were presented
with an upgrade package and asked to estimate the
benefits and costs of implementing it in their reference
building. Respondents were first asked to consider the
‘current minimum standards’ for IAQ to be those
resulting from the American Society for Heating,
Refrigeration, and Air-conditioning Engineers (ASH-
RAE) Standard 62-2001 for offices and informed that
this specified a minimum VR of 20 cfm/person (9.5 l/
s/person) and a minimum efficiency reporting value
(MERV) 6 filter. They were then asked to consider
‘improved air quality’ to be that resulting from dou-
bling the VR to 40 cfm/person (19 l/s/person) and
installing a MERV 11 filter. These two improvements
define what we call the ‘ventilation-filtration upgrade’
(VFU).
The fourth section covered stated and perceived
organizational willingness to pay (WTP) for the speci-
fied VFU in terms of percent increase in energy costs
and added cost in US dollars (USD) per occupant per
year. Lastly, the fifth section queried respondents on
the extent and manner in which IAQ has been mar-
keted during the commercial building leasing and buy-
ing process.
Technical estimates for energy consumption
To compare our technical estimates to respondents’
estimates of the energy costs of improving IAQ with
the VFU, we estimated the operating cost impacts of
the VFU for a group of seven building energy use sim-
ulation models implemented in EnergyPlus software
(U.S. DOE, 2012). These models were based on U.S.
Department of Energy (DOE) Commercial Reference
Building models (Deru et al., 2011), modified to reflect
other HVAC system types and to match energy use
reported in the Commercial Buildings Energy Con-
sumption Survey (CBECS). The seven models spanned
from a small (3500 ft
2
or 325 m
2
) single-zone office
with a system equivalent to a residential furnace to a
medium-sized (53 600 ft
2
or 4982 m
2
) office with a cen-
tral boiler and chiller serving three variable air volume
(VAV) air handlers. All models had an occupant den-
sity of five occupants per 1000 ft
2
(~100 m
2
), similar to
the U.S. median in offices (Rackes and Waring, 2013).
For these building models, we developed a corre-
sponding pre- and a post-VFU version. In the pre-
VFU version, the VR was specified as 20 cfm/person
and the system static pressure was determined with
default EnergyPlus HVAC template objects, which was
600 Pa for single-zone unitary systems and 1000 Pa for
variable air volume (VAV) systems. In the post-VFU
version, the VR was 40 cfm/person, and the system sta-
tic pressure was increased by 100 Pa to account for the
difference between a MERV 6 and 11 filter. In practice,
pressure drop across filters varies greatly and depends
on fan type, system characteristics, and PM loading,
but 100 Pa is the difference between the minimum and
final resistances required for MERV 6 (150 Pa) and 11
(250 Pa) filters in ASHRAE Standard 52.2, which
defines MERV (ASHRAE, 2007).
Each of these before and after models was run in 15
cities representing 12 climate subzones (2A, 2B, 3A,
3B, 3C, 4A, 4B, 4C, 5A, 5B, 6A, and 6B), eight census
divisions, and 14 U.S. states. Results were annual
changes in electricity and natural gas consumption
resulting from the VFU in each location. These were
combined with estimates from the U.S. Energy Infor-
mation Administration (EIA) on electricity (U.S. EIA,
2014a) and natural gas (U.S. EIA, 2014b) prices by
state, as of February 2014, to estimate the changes in
energy operating costs in USD from implementing the
VFU. For our comparison to survey answers, we used
these to calculate both the energy cost change as a per-
cent of the building’s total energy expenditures, and
the real added annual cost per occupant in USD.
For the percent change in energy operating costs, we
wanted the denominator to reflect realistic energy
expenditures, which may not be captured by our ideal-
ized EnergyPlus reference models. Therefore, we
divided the cost increases derived from modeling the
VFU by the average commercial building energy
3
Building industry perceptions of IAQ impacts
expenditure reported to CBECS (U.S. EIA, 2006) for
each location’s census region and heating and cooling
degree day bin, all on an area-normalized basis.
(Because the change in expenditure from the VFU was
calculated with 2014 energy costs but the total energy
expenditure was in 2003 USD, the percent increase in
costs due to the VFU may be slightly overstated.) For
the added annual cost per occupant, the change in
energy operating costs was simply normalized by the
number of occupants.
Technical estimates for productivity, SBS impacts, absenteeism, and
PM changes
To compare our technical estimates to respondents’
estimates of the welfare benefits of improving IAQ with
the VFU, we estimated its associated productivity, SBS
impacts, and absenteeism changes. These estimates
were based solely on the change in VR due to the VFU
and did not include filtration effects. The productivity
estimate was from Sepp
anen et al. (2006), who used a
fractional polynomial model to account for the VR
productivity relations from seven field and three labo-
ratory studies, and our calculation used the functional
form for the response from Fisk et al. (2011). We note
that most of the field studies used by Sepp
anen et al.
(2006) were conducted in settings like call centers that
have higher occupant density and easily quantifiable
measures of performance such as call response time.
While they report that the relation of increased produc-
tivity and increased VR is statistically significant at a
95% confidence level up to ~32 cfm/person (~15 l/s/
person), the exact percent increase for other tasks per
added unit of ventilation is uncertain, especially for less
repetitive types of office work.
For changes in SBS prevalence rate with VR, the
Fisk et al. (2009) equation was employed. Those
authors screened and analyzed eight existing studies in
which questionnaires about SBS symptoms were
administered to occupants under different VRs. All of
the included studies were in office buildings, and all but
two included data from more than one site or trial. The
SBS symptoms varied by study, but in all cases, the
occupants did not know the true VR when they filled
out the questionnaire.
The absenteeism impact was estimated with an expo-
nential response model (Fisk et al., 2011, 2012) that
extrapolated from the results of a study of VR and
short-term absence in 40 buildings (Milton et al.,
2000). Fisk et al. (2012) noted that the absenteeism
relation was formulated from results of only one study
(albeit including 40 buildings) and may be more uncer-
tain than those for productivity and SBS prevalence,
which were based on multiple studies.
Although we did not compare them to respondents’
estimates, we determined the PM-related impacts due
to the combined effects of the filtration upgrade and
the VR increase. Generally, the former tends to reduce
the indoor concentration of outdoor PM, while the lat-
ter has the opposite effect because it introduces more
outdoor PM. There is also a third, subtler effect on
PM: if the HVAC system total supply airflow rate is
constant, an increase in VR will reduce the air recircu-
lation rate and thus the total effective filtration (pre-
suming, as is common, that only the total supply air is
filtered and ventilation air is not also filtered). PM cal-
culations were time-averaged (El Orch et al., 2014;
Riley et al., 2002), with size-integrated removal rates
relying on specific assumptions and methods that have
been previously described (Rackes and Waring, 2013).
To estimate a reasonable range of PM percent reduc-
tions due to filtration, calculations were performed for
both urban and rural PM size distributions (Jaenicke,
1993) and for total supply airflows corresponding to
0.64 cfm/ft
2
(3.3 l/s/m
2
), which is the median from the
U.S. Environmental Protection Agency BASE study
for supply flows measured at the diffusers (Persily and
Gorfain, 2008), and 0.30 cfm/ft
2
(1.5 l/s/m
2
), which is a
typical lower limit for air distribution design. This cal-
culation ignored any indoor PM formation due to ter-
pene oxidation (Youssefi and Waring, 2012, 2014) by
ozone, hydroxyl radicals, or nitrate radicals (Waring,
2014; Waring and Wells, 2014).
Results and Discussion
Survey demographics
For the 112 respondents, demographics and reference
building categorizations are listed in Table 1. The most
common respondent role was consultant or designer
(38%), followed by property or facilities manager
(24%), building owner (21%), and tenant (18%).
Within the building owner category, about one-third
leased their building to other tenants, while two-thirds
occupied the building themselves. Approximately one-
third of respondents reported holding some kind of
green building certification, such as from the U.S.
Green Building Council’s Leadership in Energy and
Environmental Design (LEED) program. A majority
of respondents’ reference buildings were office build-
ings (60%), although other types were represented.
Most buildings were in an urban (54%) or suburban
(45%) environment.
Respondents were recruited via mailing lists from
trade shows and through personal and professional
networks. This process began in our location (Philadel-
phia, PA) and was later expanded geographically. All
respondents were from the U.S., and 77% were from
the Mid-Atlantic or northeastern U.S., including Penn-
sylvania (55%), New Jersey (10%), Delaware (5%),
Connecticut (3%), New York (3%), and Virginia
(1%). There was a substantial minority from Califor-
nia (10%), and one respondent each from Colorado,
4
Hamilton et al.
Florida, Illinois, and Texas. Eleven percent of respon-
dents did not indicate their location, and we note that
a respondents’ state was not necessarily the same one
where his or her reference building was located.
Because this work used a convenience sample, there is
no single sample frame and it is not possible to calcu-
late a non-response rate.
Perceptions of current IAQ and standard compliance
When asked to rate the IAQ in their reference building
with designations corresponding to a Likert scale from
1 to 5, with ‘poor IAQ’ corresponding to 1 and ‘excel-
lent IAQ’ to 5, most respondents rated their current
IAQ as ‘good’ (i.e. a rating of 3). The overall distribu-
tion was fairly normal, with a mean of 3.18 and a stan-
dard deviation (s.d.) of 0.98 (Figure 1a). This response
will be referred to as ‘perceived IAQ’ henceforth.
Most respondents reported that the IAQ in their
building met or exceeded ASHRAE’s minimum stan-
dards (Figure 1b). (For all relevant questions, a note at
the bottom of the prompt reminded, ‘For example, for
offices ASHRAE Standard 62-2001 specifies a mini-
mum ventilation rate of 20 cfm/occ and a MERV 6
filter’.) Only 9% thought their building did not comply
with the standard. A plurality believed that mainte-
nance was carried out strictly according to guidelines
(44%), and equal proportions believed that mainte-
nance was carried out less or more frequently than dic-
tated by guidelines, or did not know (19% each). For
this question, certain maintenance procedures (includ-
ing filter change, visual inspection of coil and cleaning,
and outdoor air damper check) were suggested to
respondents to clarify the scope of the question. For
answers to these questions, differences among stake-
holder groups (e.g. owners vs. tenants) were not signifi-
cant when a chi-squared test of independence was
performed on a cross-tabulation of the data.
When asked whether their reference building had
IAQ problems (Figure 2a), a large majority of respon-
dents (81%) reported that there were none. Of those
who did, different stakeholder groups were equally
likely to indicate that there were problems in their ref-
erence building. Among the 19% reporting problems,
the most commonly cited types (respondents could
indicate up to three) were ventilation-related issues
(57% of the 19% who had reported problems, or 11%
of all respondents), followed by outdoor air pollution
(24% of those reporting problems, or 4% of all respon-
dents). Those reporting problems cited temperature
and odor-related problems next most frequently (19%
each), followed by VOCs and humidity (14% each),
and dust and mold (10% each).
Reported use of IAQ technologies
Respondents were also given a list of specific IAQ-
related technologies or practices and asked to select all
that were present in their reference building (Fig-
ure 2b). Airside economizers were the most frequently
cited (62% of respondents), followed by high-efficiency
filters (51%) and demand control ventilation (45%).
Only 8% of respondents indicated that none of these
technologies were in their reference building; an addi-
tional 11% did not know. These self-reported values
are somewhat uncertain, as the majority of respondents
(at least the 62% who were not designers or consul-
tants) may not be familiar with all of the technologies
or whether they were actually present. Also, as these
values were not drawn from a representative sample,
caution should be used in their interpretation. That
being said, in the case of economizers, the reported per-
centage was reasonably close to 50%, the percentage of
commercial buildings with economizers according to
CBECS (Fisk et al., 2012; U.S. EIA, 2003).
Relating perceived IAQ to respondent and building characteristics and
use of technologies
To identify which factors may have some effect on the
perceived IAQ ratings, a number of contingency tables
were run between the dependent variable of perceived
Table 1 Respondent and reference building demographics (total n=112)
nPercent
Respondents role
Building owner 23 21
Property or facilities manager 27 24
Tenant 20 18
Consultant or designer 42 38
Holds any green building certification
Yes 36 32
No 74 66
Undisclosed 2 2
Building type
Office 67 60
Retail 9 8
Education 15 13
Other 21 19
Building location
Urban 60 54
Suburban 50 45
Rural 2 2
Approximate building age
05 years 20 18
615 years 21 19
1630 years 31 28
3150 years 20 18
51100 years 18 16
100200 years 2 2
(mean =31.3 years, s.d. =26.7 years)
Climate zone
244
3109
46962
52724
622
5
Building industry perceptions of IAQ impacts
Perceptions in the U.S. building industry of the benefits and costs
of improving Indoor Air Quality
Abstract How building stakeholders (e.g. owners, tenants, operators, and
designers) understand impacts of Indoor Air Quality (IAQ) and associated
energy costs is unknown. We surveyed 112 stakeholders across the United
States to ascertain their perceptions of their current IAQ and estimates of
benefits and costs of, as well as willingness to pay for, IAQ improvements.
Respondents’ perceived IAQ scores correlated with the use of high-efficiency
filters but not with any other IAQ-improving technologies. We elicited their
estimates of the impacts of a ventilationfiltration upgrade (VFU), that is,
doubling the ventilation rate from 20 to 40 cfm/person (9.5 to 19 l/s/person)
and upgrading from a minimum efficiency reporting value 6 to 11 filter, and
compared responses to estimates derived from IAQ literature and energy
modeling. Minorities of respondents thought the VFU would positively impact
productivity (45%), absenteeism (23%), or health (39%). Respondents’ annual
VFU cost estimates (mean =$257, s.d. =$496, median =$75 per person) were
much higher than ours (always <$32 per person), and the only yearly cost a
plurality of respondents said they would pay for the VFU was $15 per person.
Respondents holding green building credentials were not more likely to affirm
the IAQ benefits of the VFU and were less likely to be willing to pay for it.
M. Hamilton, A. Rackes,
P. L. Gurian, M. S. Waring
Department of Civil, Architectural and Environmental
Engineering, Drexel University, Philadelphia, PA, USA
Key words: Building energy use; Ventilation; Filtration;
Stated preferences; Investment decision-making; IAQ
impacts.
M. S. Waring
Department of Civil, Architectural and Environmental
Engineering, Drexel University, 3141 Chestnut St.
Philadelphia, PA 19104, USA
Tel.: 011-215-895-1502
Fax: 011-215-895-1363
e-mail: msw59@drexel.edu
Received for review 24 September 2014. Accepted for
publication 31 January 2015.
Practical Implications
The survey elucidated the state of knowledge among U.S. building industry stakeholders on the costs and benefits of
Indoor Air Quality (IAQ), including showing that a majority doubt or are uncertain of the benefits of IAQ improve-
ments and also overestimate their costs. Educating stakeholders on the known benefits and relatively low cost of
improving IAQ could have the effect of increasing the number of IAQ-related upgrades in the building stock. Given
that green building professionals, who presumably have already received some IAQ-related education, were no more
likely to believe beneficial and were less likely to pay for ventilation and filtration upgrades than other respondents,
the indoor air community may need to reconsider and/or redesign existing education and outreach strategies.
Introduction
The benefits of improving Indoor Air Quality (IAQ)
for health, productivity, and other measures have been
documented in the technical literature by a number of
studies over the past few decades. For instance,
research suggests that measurable improvements in
overall building occupant welfare are associated with
several types of basic heating, ventilating, and air-con-
ditioning (HVAC) enhancements, including increased
ventilation rates (VRs) and greater filtration of particu-
late matter (PM).
Strong evidence for improved IAQ affecting occupant
welfare and productivity comes from VR studies (Clau-
sen et al., 2011). For instance, higher incidences of
airborne disease infections in commercial and institu-
tional buildings are associated directly with low VRs (Li
et al., 2007) and indirectly with high indoor carbon
dioxide (CO
2
) levels, which are a proxy for lower VRs
(Myatt et al., 2004). Also, increased VRs in offices (up
to 25 l/s/person) are associated with reduced Sick Build-
ing Syndrome (SBS) symptoms (Apte et al., 2000; Fisk
et al., 2009; Sundell et al., 2011), as well as with reduced
absenteeism in offices (Milton et al., 2000) and class-
rooms (Mendell et al., 2013; Sundell et al., 2011).
Higher VRs have also been linked to higher productivity
in offices (Sepp
anen et al., 2006) and better performance
on computerized testing of cognitive ability in English
primary schools (Bak
o-Bir
o et al., 2012), although the
generalizability of these findings is unclear.
1
Indoor Air 2015 ©2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
wileyonlinelibrary.com/journal/ina
Printed in Singapore. All rights reserved INDOOR AIR
doi:10.1111/ina.12192
result in health benefits (39%) and productivity
increases (45%), but a minority (23%) of respondents
thought there would be a decrease in absenteeism.
Therefore, for all three benefits, a majority of respon-
dents either thought the benefit would not result from
the VFU or were unsure.
In our respondent set, a majority of building mar-
ket stakeholders did not perceive a strong connection
between ventilation and filtration interventions to
improve IAQ and advance positive impacts. Given
the manner in which the question was posed, which
was improving IAQ ‘above the current minimum
standards’, along with the large fractions of respon-
dents that thought their reference building currently
met or exceeded minimum standards, the overall
response suggests a strong degree of deference in the
industry to the minima established by the standard.
Interestingly, this view was also reflected in our semi-
structured interviews, in which several subjects did
not recognize that standards were meant to establish
minimum acceptable operating levels and equated
‘good indoor air quality’ to operating conditions in
which ASHRAE standards were met (but not neces-
sarily exceeded).
Several observations may be made regarding these
data based on cross-tabulations with other categorical
variables:
Perceptions of whether the VFU would lead to
health, absenteeism, or productivity benefits in the
reference building were not significantly related to
perceived IAQ (chi-squared statistics for these tabu-
lations were not significant).
Respondents with older reference buildings were
more likely to believe there would be health benefits
associated with improving the IAQ above current
Table 2 Chi-square statistics computed for contingency tables for variable of perceived Indoor Air Quality (IAQ) and each other listed variable (n=112)
Pearson chi-square value df Asymp. sig. (2-sided) Association
Variable
Problems with current IAQ? 24.060 4 <0.010 Negative
Actions taken to improve IAQ? 5.491 4 0.241 Positive
Respondent owns building? 0.943 4 0.918 Positive
Green building certification 4.729 4 0.316 Positive
Urban? 13.365 4 0.010 Negative
Building age (binned) 25.483 12 0.013 Negative
Reported frequency of maintenance 13.284 12 0.349 Positive
Reported ASHRAE compliance 60.828 12 <0.010 Positive
Technologies Utilized
Economizers 4.902 4 0.298 Positive
Demand control ventilation (DCV) 8.613 4 0.072 Positive
Supply air temperature reset 4.669 4 0.323 Positive
High-efficiency (HE) filters 12.369 4 0.015 Positive
Low VOC furnishings 2.587 4 0.629 Positive
None (no technologies utilized) 5.431 4 0.246 Negative
Table 3 Results of forward stepwise regression on dependent variable of perceived Indoor Air Quality (IAQ)
Independent variable Unstandardized coefficients Standard error Standardized coefficients tSig.
(Constant) 3.509 0.289 12.145 0
Urban/non-urban 0.544 0.174 0.275 3.130 0.002
Building uses high-efficiency filters 0.424 0.168 0.216 2.519 0.013
Approximate building age (binned) 0.223 0.088 0.218 2.523 0.013
Maintenance frequency 0.208 0.085 0.211 2.459 0.016
39%
23%
45%
28%
37%
34%
33%
40%
21%
0% 10% 20% 30% 40% 50%
Health
Absenteeism
Productivity
Percent of respondents
Benefits of VFU
Don't know No Yes
Fig. 3 Respondent perceptions of whether three prompted ben-
efits would result from our specified ventilationfiltration
upgrade (VFU), which doubles ventilation from 20 to 40 cfm/
occ (9.5 to 19 l/s/occ) and increases filtration from a minimum
efficiency reporting value (MERV) 6 to 11 filter (n=112)
7
Building industry perceptions of IAQ impacts
minimum standards; v
2
(3, n= 112) = 7.862,
P= 0.049.
Respondents with urban reference buildings were
more likely to believe there would be productivity
benefits associated with improving IAQ above cur-
rent minimum standards; v
2
(1, n= 112) = 7.560,
P= 0.006.
Tenants and property and facilities managers were
more likely to believe there would be IAQ-related
productivity benefits than other stakeholder groups;
v
2
(3, n= 112) = 8.123, P= 0.044.
The affirmative perception of IAQ-related benefits
did not vary significantly by whether a respondent
possessed any type of green building certification
(again using a chi-squared test of independence).
However, specific types of green certifications were
not considered separately.
The minority of respondents who affirmed that there
would be a decrease in absenteeism or an increase in
productivity was asked to estimate percent changes for
the respective impact, and those were compared to our
technical estimates (Table 4). In general, these respon-
dents strongly overestimated the productivity benefits
of the VFU. The median building industry estimate
was a 10.0% increase, and responses skewed upward,
with a mean of 15.4%, s.d. of 11.7%, and a range from
0% to 60%. (One respondent said there would be a
productivity increase but then estimated its magnitude
to be 0%.) Our technical estimate was much smaller at
1.4%. However, directly comparing market responses
to the technical estimate may be misleading, as the sur-
vey question was general while the technical estimate
used quantitative relationships of task improvements
measured in particular settings. Conversely, respon-
dents who thought a decrease in absenteeism would
result from the VFU tended to underestimate its mag-
nitude. The median industry estimate of reduced rela-
tive absenteeism was a 10% decrement, with a mean of
15.8%, s.d. of 12.9%, and a range from 3% to 50%.
The technical estimate of 28% was thus a larger
decrease than most respondents estimated.
Perceptions of the cost of the VFU package
Survey subjects were next asked to estimate the costs
of VFU implementation. Subjects were asked to esti-
mate: (i) the percent increase in their reference build-
ing’s energy costs and (ii) the added annual cost per
occupant in USD. We did not ask the respondents
to limit their answers about cost per occupant to
energy use only, so it possible that some included
capital or maintenance costs in their estimates. How-
ever, we think it likely that most did base their esti-
mates only on added energy expenses given that the
cost question directly followed the energy increase
question.
A wide range of answers was given for both ques-
tions, indicating that respondents generally did not
have a good understanding of the costs associated with
the VFU in their reference building. For the percent
increase in energy costs, estimates for respondents in
all climate zones ranged from 0% to 75%, with a
mean of 15% (s.d. =14.3%) and a median of 15%
(Figure 4a). The median for respondents in each cli-
mate zone was approximately 24 times higher than
the median technical estimate in that climate zone
(Table 4). Indeed, for most climate zones, the range of
responses was above and barely overlapped the range
of technical estimates. For example, in climate zone 4,
the median technical estimate was a 4.0% increase in
energy costs, while the median increase given by
respondents in climate zone 4 was 15.0%.
The estimates for the added cost of the VFU in dol-
lars per person per year ranged from $0 to $2500 with
a mean of $257 (s.d. =$496) and a median of $75
(Figure 4b). For a few climate zones, survey participants
reported median values that were reasonably close to
the median technical estimate (e.g. $25.00 vs. $15.50,
respectively, for climate zone 5), but in others, they
were much larger (e.g. $275.00 vs. $10.48, respectively,
for climate zone 3). Overall, respondents greatly over-
estimated the cost per person, with approximately 65%
saying it would be over $30, which was the maximum
of the range of our technical estimates in any climate
or office type. In addition, the distributions were quite
skewed, with about 17% saying the cost would be
more than $300 a person, or more than ten times the
maximum technical estimate. There was a correlation
between estimates of percent increase in energy costs
and added cost per person (Spearman’s rho =0.348,
P<0.001). That is, respondents who answered high to
one question generally answered high to the other,
although not necessarily by a ratio that represented the
particular energy costs and occupant densities in the
reference buildings (as these values are unknown).
Individual stakeholder groups had different esti-
mates of the costs associated with employing the VFU
(Figure 5a). Tenants in particular often most overesti-
mated the costs associated with making technological
IAQ improvements, but their estimates varied widely
and were sometimes lower than other groups. Building
owners and property and facility managers had reason-
ably similar estimates from the standpoint of their cen-
tral tendencies, although each group had quite
different ranges of dispersion. While designers and con-
sultants’ median estimates were the lowest of the four
groups, their estimates were still higher than most of
our best estimate models.
Interestingly, there were not significant relationships
between perceptions of IAQ-related benefits and
perceptions of associated costs for the VFU among all
respondents. Respondents’ estimates of energy costs
and estimates of added cost per occupant were
8
Hamilton et al.
cross-referenced with the affirmative perception of que-
ried benefits (health, absenteeism, or productivity). No
results were significant (when utilizing a chi-squared
test), nor were they significant for the cross-tabulation
of cost estimates with the use of specific IAQ-related
technologies (e.g. economizers) or with generic green
building certification.
Willingness to pay for improved IAQ
In this section, respondents were queried about their
organization’s willingness to pay (WTP) for the
VFU. To assess WTP, respondents were randomly
presented with one of five annual USD costs per
person ($15, $50, $150, $500, or $1500) and asked
whether their organization would likely be willing to
pay this cost (Figure 5b). Across all cost categories,
525% of respondents indicated they did not know
whether their organization would pay or not. For a
cost of $15 per person, a plurality of respondents (a
majority, excluding the unsure) thought their organi-
zation would be willing to pay for IAQ improve-
ments. However, for all cost categories greater than
$15, a majority of respondents indicated their orga-
nization would not be likely to pay for such an
upgrade.
Table 4 Comparison of technical estimates and industry responses of benefits and costs of our specified ventilation-filtration upgrade (VFU), which doubles ventilation from 20 to 40 cfm/
occupant (9.5 to 19 L/s/occupant) and increases filtration from a minimum efficiency reporting value (MERV) 6 to 11 filter. SD =standard deviation.
Technical Estimate
a
Industry Response
b
Benefits
Productivity
c
Absenteeism
c
SBS symptoms
c
Indoor PM
2.5d
Indoor PM
10d
Values or range
1.4%
28%
24%
52% to 37%
55% to 39%
Median (min to max)
10.0% (0% to 60%)
10.0% (3% to 50%)
Mean (SD)
15.4% (11.7%)
15.8% (12.9%)
n
49
25
Energy increase
e
Climate zone 2
Climate zone 3
Climate zone 4
Climate zone 5
Climate zone 6
Median (min to max)
4.1% (2.7% to 7.7%)
2.3% (1.6% to 8.4%)
4.0% (2.4% to 9.1%)
5.5% (0.2% to 9.9%)
8.1% (2.1% to 11.6%)
Mean (SD)
4.7% (1.6%)
2.7% (2.6%)
4.1% (3.0%)
5.4% (3.0%)
6.8% (4.2%)
Median (min to max)
17.5% (10% to 30%)
8.5% (0% to 30%)
15.0% (0% to 75%)
10.0% (3% to 25%)
15.0% (10% to 15%)
Mean (SD)
18.8% (8.5%)
9.7% (8.9%)
16.4% (17.4%)
13.2% (6.7%)
15.0% (7.1%)
n
4
10
69
27
2
Cost increase
f
Climate zone 2
Climate zone 3
Climate zone 4
Climate zone 5
Climate zone 6
Median (min to max)
$16.08 ($11.74 to $20.51)
$10.48 ($5.36 to $21.38)
$14.09 ($8.85 to $30.98)
$15.50 ($0.55 to $30.59)
$20.98 ($5.54 to $28.21)
Mean (SD)
$16.40 ($2.24)
$8.96 ($7.09)
$14.19 ($10.25)
$15.61 ($8.96)
$16.91 ($10.53)
Median (min to max)
$100 ($80 to $200)
$275 ($0 to $2500)
$100 ($0 to $2000)
$25 ($2 to $2000)
$90 ($80 to $100)
Mean (SD)
$126.67 ($64.29)
$572.70 ($799.53)
$265.95 ($472.33)
$133.83 ($402.74)
$90.00 ($14.14)
n
3
10
58
24
2
a
Based on 14 simulations each in climate zones 2 and 6, 28 simulations each in zones 3 and 4, and 21 simulations in zone 5
b
Benefit market estimates based only on respondents who believed the benefit existed
c
Based on ventilation rate change alone
d
Based on ventilation rate and filtration efficiency changes
e
Percent increase in energy operating costs; increases due to VFU normalized by average commercial building energy expenditure from CBECS (U.S. EIA, 2006)
f
Added annual cost per occupant; USD/occupant-yr
24%
21%
21%
18%
4%
5%
1%
1%
0%
2%
3%
0% 5% 10% 15% 20% 25%
0—5%
6—10%
11—15%
16—20%
21—25%
26—30%
31—35%
36—40%
41—45%
46—50%
>50%
Percent of respondents
Energy change due to VFU
43%
24%
5%
5%
3%
2%
0%
1%
0%
7%
9%
0% 10% 20% 30% 40% 50%
$0—50
$51—100
$101—150
$151—200
$201—250
$251—300
$301—350
$351—400
$401—450
$451—500
>$500
Percent of respondents
Annual cost per occupant due to VFU
(a) (b)
Fig. 4 Respondents’ estimate required (a) percent energy change and (b) added annual cost per occupant (in USD) to improve Indoor
Air Quality with our specified ventilationfiltration upgrade (VFU), which doubles ventilation from 20 to 40 cfm/occ (9.5 to 19 l/s/
occ) and increases filtration from a minimum efficiency reporting value (MERV) 6 to 11 filter (n=97)
9
Building industry perceptions of IAQ impacts
To identify factors that may affect WTP, responses
across all cost categories were pooled and recoded into
a dichotomous variable ‘Likely to pay,’ which was
coded positively only if a respondent had answered
‘Yes’ to the prompted WTP question. A forward bin-
ary logistic regression (using the likelihood ratio
method) was run on the ‘Likely to pay’ variable using
different predictors. The resulting regression model
was significant (omnibus v
2
=41.698, df =5,
P<0.001) and explained approximately 41% of the
variance in ‘Likely to pay’ (Cox and Snell R
2
=0.410).
Respondents were more likely to pay if they owned
their building, thought there would be productivity
benefits, or thought the added cost per person would
be high. Of course, the higher the USD of the prompt,
the less likely respondents were to say they would pay.
Interestingly, those with some type of green building
certifications were also significantly less likely to pay.
In theory, these respondents should be familiar with
the research findings about IAQ impacts, and their
skepticism suggests that green building certification
programs may need to better convey the benefits of
better filtration and increased ventilation.
The meaning of ‘would the organization managing
the building be likely to pay’ depends on whether the
respondent is a representative of the reference building.
Owners likely responded based on what they them-
selves would pay, while other stakeholders presumably
responded with what they thought owners were likely
to pay. To further isolate the impact that ownership
has on stated likelihood to pay, a binary logistic regres-
sion was run on ‘Likely to pay’ with ownership as the
only predictor variable. The regression model was sig-
nificant (omnibus v
2
=10.615, df =1, P=0.001) and
was able to explain ~11% of the variance in stated like-
lihood to pay for improved IAQ (Cox and Snell
R
2
=0.109). Thus, owners indicated a significantly
greater willingness to invest in the VFU than tenants
believed they would beby about a factor of five,
according to the odds ratio given by the model. Of
course, this is only a stated WTP. Perhaps owners were
overly generous in their self-estimation, but it may also
be the case that tenants would be surprised by their
building owners’ receptiveness to implementing IAQ
improvement measures.
Marketing of IAQ
In the final portion of the survey, respondents were
asked about the marketing of IAQ during the leasing
and buying of commercial space. Building owners and
property and facilities managers were asked about their
own marketing practices, while tenants and consultants
were asked to reflect on their experiences when others
were doing the marketing to them. Most owners or
owner representatives did not report marketing IAQ
(34% claimed to), and most tenants reported not hav-
ing seen owners attempting to command higher rents
as a result of better IAQ (21% of tenants and consul-
tants said they have seen this, 48% said they have not,
and 31% had no knowledge of this). Figure 6 shows
that nearly four in ten owners and facilities and prop-
erty managers believe that 10% or fewer of all tenants
consider IAQ during the buying or leasing process.
In contrast with owners’ perceptions of tenants’ con-
siderations of IAQ, nearly half of tenants (48%) claim
to consider IAQ ‘indirectly’ during the buying or leas-
ing process, either via building location, age, or green
building certifications. Additionally, 26% claimed to
consider it ‘directly’, while the remaining 26% reported
‘no consideration’. Despite this, only 21% of the 62
tenants and consultants indicated they had seen owners
asking for higher rents for better IAQ. Of these 13
respondents, most indicated that they trusted claims
from owners that a building had ‘better IAQ’; 54%
were either ‘confident’ or ‘very confident’, while 38%
were ‘neutral’. In short, although reports of using
improved IAQ as a real estate selling point are rela-
tively rare, when they are made, a slim majority here
found them credible.
$1 $10 $100 $1,000
Owner
PM/FM
Tenant
Consultant
Annual cost per occ due to VFU
9
3
5
5
3
7
15
12
19
14
6
5
5
1
3
0% 25% 50% 75% 100%
$15
$50
$150
$500
$1500
Percent of repondents WTP for VFU
Most likely yes Most likely no Don't know
(a) (b)
Full range of technical estimates
Fig. 5 (a) Stakeholder group differences in estimated added annual cost per occupant to improve Indoor Air Quality with, as well as
in the shaded region the range of our technical best estimates (x-axis on log scale) and (b) perceived organizational willingness to pay
(WTP) by prompted cost for our specified ventilationfiltration upgrade (VFU), which doubles ventilation from 20 to 40 cfm/occ (9.5
to 19 l/s/occ) and increases filtration from a minimum efficiency reporting value (MERV) 6 to 11 filter (n=112). PM/FM =property
or facilities managers
10
Hamilton et al.
Study design and limitations
Our study was not designed to test specific hypotheses,
but rather to assess the perceptions of building indus-
try respondents, which we recorded regardless of their
basis or accuracy. In our view, the fact that all
responses are self-reported is appropriate for a study
on perceptions. However, it imposes limits on the abil-
ity to identify associations between IAQ perceptions
and other factors, like whether a building is old or
compliant with ASHRAE 62-2001, because these are
also self-reported. Some factors (building age) are
probably reasonably reliable when self-reported,
whereas others (standard compliance) may not be. In
particular, real VRs in buildings are difficult to assess
accurately, so it is unlikely that people had any basis to
truly evaluate their own perceptions for this question.
Our results should thus be interpreted with these
nuances in mind, recognizing that the conclusions
herein apply to the self-reported, perceived state of the
world of our respondents. For example, the self-
reported use of high-efficiency filters and frequent
HVAC maintenance were both associated with better
perceived air quality. We do not know whether these
practices were really in place in the reference buildings
where people said they were, or if better perceived IAQ
was due to verifiably better IAQ, so we cannot con-
clude from our study that high-efficiency filters and
frequent maintenance are associated with better air
quality. However, we do not need a survey to make
that conclusion; the benefits of filtration and mainte-
nance are already established. The conclusion from this
work is that those benefits appear to be appropriately
reflected in the perceptions of market actorsregardless
of the mechanism.
Readers may still question whether different stake-
holders have different types of knowledge and
whether many lack sufficient IAQ-related knowledge
to respond in an informed manner. The answers to
these questions are certainly ‘yes’, and in a sense
these levels of knowledge are part of what we were
trying to evaluate in this study. However, where we
thought respondents’ lack of knowledge would be a
limitation, we tried to construct the survey to mini-
mize the impact, for example, by asking all respon-
dents to keep in mind a reference building they knew
well, and repeatedly supplying the definition of rele-
vant ASHRAE standards. Furthermore, the particu-
lar knowledge of different stakeholder groups
confounds expectations about their responses. For
instance, designers and consultants are more likely to
understand the meaning of and compliance with
ASHRAE standards but may have less knowledge
about the state of IAQ or actual technologies
employed, having spent less time in their reference
buildings than members of other groups. As another
example, owners or tenants who deal with energy
billing should have better context with which to eval-
uate energy-related financial impacts.
Moreover, in some of the central findings of the sur-
vey, variations among stakeholder groups were differ-
ent than one might expect based on prior assumptions
about their level of knowledge; that is, those expected
to be more knowledgeable about technologies, stan-
dards, or building science did not express opinions
more similar to the technical IAQ consensus. For
example, while designers and consultants were gener-
ally closer to the technical estimates on cost, tenants
and property and facility managers were more likely to
believe that the VFU would increase productivity. Sim-
ilarly, those with green building certificates were not
more likely to see any benefits of the VFU, despite the
emphasis in many certification programs on improving
indoor environments by increasing the VR above the
standard minimum.
One final caveat is important. Because the survey
respondents were drawn using convenience sam-
pling, there may be sources of bias that are impos-
sible to quantify, and results might not be entirely
representative of the stakeholder population at
large. Also, as about three quarters of responses
were from the Mid-Atlantic and Northeastern U.S.,
the perceptions of stakeholders in other parts of
the country may be underrepresented, if regional
differences exist.
Conclusions
The findings of this study suggest that a very substan-
tial portion of commercial building stakeholders do
not recognize the benefits of good IAQ or the efficacy
of ventilation and filtration in achieving it. Majorities
of respondents either did not think or know that that
these measures could lead to increased productivity
(55%), absenteeism (77%), and any health benefits
38%
20%
9%
7%
9%
1%
5%
3%
3%
5%
0% 10% 20% 30% 40%
0—10%
11—20%
21—30%
31—40%
41—50%
51—60%
61—70%
71—80%
81—90%
91—100%
Percent of owners and PM/FM
Percent of tenants perceived to
consider IAQ when leasing space
Fig. 6 Binned percentage of tenants considering Indoor Air
Quality (IAQ) when leasing space, as estimated by building
owners and property and facilities managers (PM/FM) (n=50)
11
Building industry perceptions of IAQ impacts
(61%). Our results also suggest an abiding faith in min-
imum requirements set by standards. To the extent that
benefits of exceeding the current standards were recog-
nized, an association with productivity outcomes
appeared more firmly established than associations
with absenteeism or any health outcome. Perhaps most
strikingly, those with green building certifications were
less likely than the surveyed population at large to rec-
ognize a connection between productivity, absentee-
ism, or health benefits and increased ventilation or
filtration. Even among respondents that did recognize
a benefit, quantitative estimates of the benefit varied
widely and often showed little agreement with our tech-
nical best estimates based on the IAQ literature.
Respondents were not much better at estimating the
costs of the proposed VFU, and energy cost percent
increase estimates were a factor of ~24 times higher
than our modeling estimates. Cost increases expressed
in annual USD per person overlapped the range of
technical estimates but were in many cases higher by
orders of magnitude. When asked about willingness to
pay for the VFU, the only cost for which a plurality of
respondents said they would pay was quite low ($15
per person), but encouragingly within the range of our
best estimate of cost. Taken together, these results sug-
gest that better information about the benefits (greater
than people think) and costs (less than people think) of
IAQ improvements could induce building stakeholders
to adopt them. In some cases, inclusion of additional
technology in buildings to sense and report risks
related to IAQ might be warranted, as even with edu-
cation, stakeholders and occupants may not recognize
impacts of IAQ components that they cannot physi-
cally perceive. Thus, encouraging greater investment in
improving IAQ in the workplace likely requires bridg-
ing the gap of understanding of stakeholders about the
real benefits and costs of improved IAQ.
Acknowledgements
This work was partially funded by the U.S. Depart-
ment of Energy (DOE) through the Consortium for
Building Energy Innovation (CBEI).
Supporting Information
Additional Supporting Information may be found in
the online version of this article:
Appendix S1. Indoor air quality survey.
References
Abbey, D.E., Ostro, B.E., Petersen, F. and
Burchette, R.J. (1994) Chronic respira-
tory symptoms associated with estimated
long-term ambient concentrations of fine
particulates less than 2.5 microns in aero-
dynamic diameter (PM2. 5) and other air
pollutants, J. Expo. Anal. Environ. Epi-
demiol.,5, 137159.
Allen, R.W., Carlsten, C., Karlen, B., Lec-
kie, S., Eeden, S.V., Vedal, S., Wong, I.
and Brauer, M. (2011) An air filter inter-
vention study of endothelial function
among healthy adults in a woodsmoke-
impacted community, Am. J. Respir. Crit.
Care Med.,183, 12221230.
Apte, M.G., Fisk, W.J. and Daisey, J.M.
(2000) Associations between indoor
CO
2
concentrations and sick building
syndrome symptoms in U.S. office
buildings: an analysis of the 1994-1996
BASE study data, Indoor Air,10, 246
257.
ASHRAE (2007) Method of Testing General
Ventilation Air-Cleaning Devices for
Removal Efficiency by Particle Size
(ASHRAE Standard 52.2-2007).
Bak
o-Bir
o, Z., Clements-Croome, D.J.,
Kochhar, N., Awbi, H.B. and Williams,
M.J. (2012) Ventilation rates in schools
and pupils’ performance, Build. Environ.,
48, 215223.
Bek
o, G., Clausen, G. and Weschler, C.J.
(2008) Is the use of particle air filtration
justified? Costs and benefits of filtration
with regard to health effects, building
cleaning and occupant productivity,
Build. Environ.,43, 16471657.
Brauner, E.V., Forchhammer, L., Møller,
P., Barregard, L., Gunnarsen, L., Afs-
hari, A., W
ahlin, P., Glasius, M.,
Dragsted, L.O., Basu, S., Raaschou-
Nielsen, O. and Loft, S. (2008) Indoor
particles affect vascular function in the
aged: an air filtration-based interven-
tion study, Am. J. Respir. Crit. Care
Med.,177, 419425.
Clausen, G., Bek
o, G., Corsi, R.L., Gunnar-
sen, L., Nazaroff, W.W., Olesen, B.W.,
Sigsgaard, T., Sundell, J., Toftum, J. and
Weschler, C.J. (2011) Reflections on the
state of research: indoor environmental
quality, Indoor Air,21, 219230.
Deru, M., Field, K., Studer, D., Benne, K.,
Griffith, B., Torcellini, P., Liu, B., Halv-
erson, M., Winiarski, D., Rosenberg, M.,
Yazdanian, M., Huang, J. and Crawley,
D. (2011) U.S. Department of Energy
Commercial Reference Building Models of
the National Building Stock. Golden, CO,
National Renewable Energy Laboratory.
Dockery, D.W. and Pope, C.A. (1994) Acute
respiratory effects of particulate air pollu-
tion, Annu. Rev. Public Health,15, 107
132.
Dockery, D.W., Schwartz, J. and Spengler,
J.D. (1992) Air pollution and daily mor-
tality: associations with particulates and
acid aerosols, Environ. Res.,59, 362373.
Dominici, F., Peng, R.D., Bell, M.L., Pham,
L., McDermott, A., Zeger, S.L. and Sa-
met, J.M. (2006) Fine particulate air pol-
lution and hospital admission for
cardiovascular and respiratory diseases,
JAMA,295, 11271134.
El Orch, Z., Stephens, B. and Waring, M.S.
(2014) Predictions and determinants of
size-resolved particle infiltration factors
in single-family homes in the US, Build.
Environ.,74, 106118.
Fisk, W.J., Faulkner, D., Palonen, J. and
Seppanen, O. (2002) Performance and
costs of particle air filtration technolo-
gies, Indoor Air,12, 223234.
Fisk, W.J., Mirer, A.G. and Mendell, M.J.
(2009) Quantitative relationship of sick
building syndrome symptoms with
ventilation rates, Indoor Air,19,
159165.
Fisk, W.J., Black, D. and Brunner, G. (2011)
Benefits and costs of improved IEQ in
U.S. offices, Indoor Air,21, 357367.
Fisk, W.J., Black, D. and Brunner, G. (2012)
Changing ventilation rates in U.S. offices:
implications for health, work perfor-
mance, energy, and associated economics,
Build. Environ.,47, 368372.
H
anninen, O.O., Palonen, J., Tuomisto, J.T.,
Yli-Tuomi, T., Sepp
anen, O. and Jantun-
en, M.J. (2005) Reduction potential of
urban PM2.5 mortality risk using modern
ventilation systems in buildings, Indoor
Air,15, 246256.
12
Hamilton et al.
Jaenicke, R. (1993) Tropospheric aerosols,
In: Hobbs, P.V. (ed) Aerosol–Cloud–Cli-
mate Interactions, San Diego, Academic
Press, 1–31.
Jenkins, P.L., Phillips, T.J., Mulberg, E.J.
and Hui, S.P. (1992) Activity patterns of
Californians: use of and proximity to
indoor pollutant sources, Atmos. Environ.
A. Gen. Top.,26, 21412148.
Klepeis, N.E., Nelson, W.C., Ott, W.R.,
Robinson, J.P., Tsang, A.M., Switzer, P.,
Behar, J., Hern, S.C. and Engelmann,
W.H. (2001) The National Human Activ-
ity Pattern Survey (NHAPS): a resource
for assessing exposure to environmental
pollutants, J. Expo. Anal. Environ. Epi-
demiol.,11, 231252.
Li, Y., Leung, G.M., Tang, J.W., Yang, X.,
Chao, C.Y.H., Lin, J.Z., Lu, J.W., Niel-
sen, P.V., Niu, J., Qian, H., Sleigh, A.C.,
Su, H.J., Sundell, J., Wong, T.W. and
Yuen, P.L. (2007) Role of ventilation in
airborne transmission of infectious agents
in the built environment A multidisci-
plinary systematic review, Indoor Air,17,
218.
Lioy, P.L., Waldman, J.M., Greenberg,
A., Harkov, R. and Pietarinen, C.
(1988) The total human environmental
exposure study (THEES) to benzo(a)
pyrene comparison of the inhalation
and food pathways, Arch. Environ.
Health,43, 304312.
Mendell, M.J., Eliseeva, E.A., Davies,
M.M., Spears, M., Lobscheid, A., Fisk,
W.J. and Apte, M.G. (2013) Association
of classroom ventilation with reduced ill-
ness absence: a prospective study in Cali-
fornia elementary schools, Indoor Air,23,
515528.
Milton, D.K., Glencross, P.M. and Walt-
ers, M.D. (2000) Risk of sick leave
associated with outdoor air supply
rate, humidification, and occupant
complaints, Indoor Air,10, 212221.
Myatt, T.A., Johnston, S.L., Zuo, Z., Wand,
M., Kebadze, T., Rudnick, S. and
Milton, D.K. (2004) Detection of air-
borne rhinovirus and its relation to out-
door air supply in office environments,
Am. J. Respir. Crit. Care Med.,169,
11871190.
Persily, A. and Gorfain, J. (2008) Analysis of
Ventilation Data from the U.S. Environ-
mental Protection Agency Building Assess-
ment Survey and Evaluation (BASE)
Study. Washington, DC, National Insti-
tute of Standards and Technology.
Phalen, R.F. and Wolff, R.K. (2000) Special
issue: part I current issues in health
related particulate matter research,
Aerosol Sci. Technol.,32,13.
Pope, C.A. (2002) Lung cancer, cardiopul-
monary mortality, and long-term expo-
sure to fine particulate air pollution,
JAMA,287, 11321141.
Pope, C.A., Dockery, D.W. and Schwartz, J.
(1995) Review of epidemiological evi-
dence of health effects of particulate air
pollution, Inhalation Toxicol.,7,118.
Pope, C.A., Burnett, R.T., Krewski, D., Jer-
rett, M., Shi, Y., Calle, E.E. and Thun,
M.J. (2009) Cardiovascular mortality and
exposure to airborne fine particulate mat-
ter and cigarette smoke shape of the
exposure-response relationship, Circula-
tion,120, 941948.
Rackes, A. and Waring, M.S. (2013)
Modeling impacts of dynamic ventila-
tion strategies on indoor air quality of
offices in six US cities, Build. Environ.,
60, 243253.
Rackes, A. and Waring, M.S. (2014)
Improving indoor air quality and reduc-
ing energy use through multi-objective
optimization of building operations,
Energy Building,75, 272280.
Riley, W.J., McKone, T.E., Lai, A.C. and
Nazaroff, W.W. (2002) Indoor particu-
late matter of outdoor origin: importance
of size-dependent removal mechanisms,
Environ. Sci. Technol.,36, 200207.
Schwartz, J., Dockery, D.W. and Neas,
L.M. (1996) Is daily mortality associated
specifically with fine particles?, J. Air
Waste Manag. Assoc.,46, 927939.
Sepp
anen, O., Fisk, W.J. and Lei, Q.H.
(2006) Ventilation and performance in
office work, Indoor Air,16,2836.
Skulberg, K.R., Skyberg, K., Kruse, K.,
Eduard, W., Levy, F., Kongerud, J. and
Djupesland, P. (2005) The effects of inter-
vention with local electrostatic air clean-
ers on airborne dust and the health of
office employees, Indoor Air,15, 152159.
Sundell, J., Levin, H., Nazaroff, W.W., Cain,
W.S., Fisk, W.J., Grimsrud, D.T., Gyn-
telberg, F., Li, Y., Persily, A.K., Picker-
ing, A.C., Samet, J.M., Spengler, J.D.,
Taylor, S.T. and Weschler, C.J. (2011)
Ventilation rates and health: multidisci-
plinary review of the scientific literature,
Indoor Air,21, 191204.
U.S. EIA (2003) Commercial Buildings
Energy Consumption Survey (CBECS).
United States Energy Information
Agency (EIA).
U.S. DOE (2012) EnergyPlus Energy Simu-
lation Software. Available at: http://
www.eere.energy.gov/buildings/energy-
plus/.
U.S. EIA. (2006) Commercial Buildings
Energy Consumption Survey, Table C6.
Expenditures by Census Region for Sum
of Major Fuels for Non-Mall Buildings,
2003.
U.S. EIA. (2014a) Electric Power Monthly.
Table 5.6.A. Average Retail Price of Elec-
tricity to Ultimate Customers by End-
Use Sector: by state, February 2014 and
2013. April 22, 2014. http://www.eia.gov/
electricity/monthly/epm_table_gra-
pher.cfm?t=epmt_5_6_a (accessed 1
May 2014).
U.S. EIA. (2014b) Natural Gas Prices. Com-
mercial Price, by state. April 30, 2014.
http://www.eia.gov/dnav/ng/NG_PRI_-
SUM_A_EPG0_PCS_DMCF_M.htm
(accessed 1 May 2014).
Wallace, L. (1993) A decade of studies of
human exposure what have we learned,
Risk Anal.,13, 135139.
Wargocki, P., Sundell, J., Bischof, W.,
Brundrett, G., Fanger, P.O., Gyntelberg,
F., Hanssen, S.O., Harrison, P., Picker-
ing, A., Sepp
anen, O. and Wouters, P.
(2002) Ventilation and health in non-
industrial indoor environments: report
from a European multidisciplinary scien-
tific consensus meeting (EUROVEN),
Indoor Air,12, 113128.
Wargocki, P., Wyon, D.P. and Fanger, P.O.
(2004) The performance and subjective
responses of call-center operators with
new and used supply air filters at two out-
door air supply rates, Indoor Air,14,716.
Waring, M.S. (2014) Secondary organic aero-
sol in residences: predicting its fraction of
fine particle mass and determinants of for-
mation strength, Indoor Air,24,376389.
Waring, M.S. and Siegel, J.A. (2008) Particle
loading rates for HVAC filters, heat
exchangers, and ducts, Indoor Air,18,
209224.
Waring, M.S. and Wells, J.R. (2014) Volatile
organic compound conversion by ozone,
hydroxyl radicals, and nitrate radicals in
residential indoor air: magnitudes and
impacts of oxidant sources, Atmos. Envi-
ron., published early online, doi:10.1016/
j.atmosenv.2014.06.062.
Youssefi, S. and Waring, M.S. (2012) Pre-
dicting secondary organic aerosol forma-
tion from terpenoid ozonolysis with
varying yields in indoor environments,
Indoor Air,22, 415426.
Youssefi, S. and Waring, M.S. (2014)
Transient secondary organic aerosol
formation from limonene ozonolysis in
indoor environments: impacts of air
exchange rates and initial concentration
ratios, Environ. Sci. Technol.,48,
78997908.
13
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... (60) Unfortunately, commercial building owners, managers, and operators often do not recognize the benefits of good IAQ. (61) Hamilton et al. (61) surveyed U.S. building industry stakeholders on the costs and benefits of IAQ, and showed that a majority of respondents either did not think, or did not know, that good IAQ measures could lead to increased productivity, reduced absenteeism, and improved health benefits. In fact, those stakeholders with green building certifications were less likely than the surveyed population at large to recognize a connection between productivity, absenteeism, or health benefits, and increased ventilation or filtration. ...
... (60) Unfortunately, commercial building owners, managers, and operators often do not recognize the benefits of good IAQ. (61) Hamilton et al. (61) surveyed U.S. building industry stakeholders on the costs and benefits of IAQ, and showed that a majority of respondents either did not think, or did not know, that good IAQ measures could lead to increased productivity, reduced absenteeism, and improved health benefits. In fact, those stakeholders with green building certifications were less likely than the surveyed population at large to recognize a connection between productivity, absenteeism, or health benefits, and increased ventilation or filtration. ...
... In fact, those stakeholders with green building certifications were less likely than the surveyed population at large to recognize a connection between productivity, absenteeism, or health benefits, and increased ventilation or filtration. (61) Even among respondents that did recognize a benefit, quantitative estimates of the benefit varied widely, and differed from scientific technical best estimates based on the IAQ literature. (61) Productivity gains from IAQ improvements are difficult to quantify. ...
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... Only 34 percent of owners claim to market IAQ in spaces, and only 21 percent of tenants say they have observed this despite 74 percent of tenants reporting that they consider IAQ either directly or indirectly when buying or leasing a space. Of the 21 percent of tenants who saw owners marketing IAQ, only 54 percent were confident that the claims were valid (Hamilton et al ., 2016). Clearly owners' perceptions of tenant expectations are misaligned with reality, and tenants are lacking trust in owners' decision-making around IAQ. Furthermore, this ignores the 26 percent of tenants who do not consider IAQ when leasing, which indicates that the benefits of improved IAQ are not universally accepted. ...
... The perceived benefit of improved IAQ needs to exceed these perceptions, rather than the actual costs, in order for a decision about ventilation changes to be made. The perceived benefits are similarly underestimated: only 41 percent of these stakeholders were willing to pay $15 per occupant per year for the same improvement in IAQ (Hamilton et al ., 2016). ...
... In actuality, the benefits of improved IAQ are several orders of magnitude larger than stakeholders realize. A follow-up paper on the CogFx study compared the benefits of increased ventilation in terms of increased productivity against the associated energy costs and environmental impacts. In agreement with Hamilton et al . (2016), energy costs were less than $40 per person per year to double ventilation rates from 9.4 l/s/person to 18.9 l/s/person in all the climate zones investigated. When the increased ventilation rate was coupled with an energy recovery ventilator (ERV), which captures some of the latent heat exhausted from the building, the costs were reduce ...
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... One reason could be inadequate communication and lack of confidence regarding the benefits of improving air quality, as well as low willingness to pay for these improvements. This is nicely demonstrated by Hamilton et al. (2016), who documented opinions of the US building industry. Their analysis showed that less than half of respondents expected that improving ventilation and filtration of buildings would improve productivity and even less associated these interventions with lower absence rates and health risks. ...
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... Some nascent research links one or a few specific features of IEQ to higher rental or asset price premiums and higher willingness to pay (Pivo and Fisher 2011;Simons and Throupe 2005;Benson et al. 1998;Hardin and Cheng 2003;Benjamin et al. 2001;Lee and Yoo 2020;Szczepańska et al. 2020Hamilton et al. 2016Kuehnel and Moeckel 2020;Kim et al. 2007). However, those empirical studies only focus on one specific IEQ feature at a specific time and in a specific setting, such as indoor air quality, acoustics, light quality, view or safety. ...
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Secondary organic aerosol (SOA) results from the oxidation of reactive organic gases (ROGs) and is an indoor particle source. The aerosol mass fraction (AMF), a.k.a. SOA yield, quantifies the SOA forming potential of ROGs and is the ratio of generated SOA to oxidized ROG. The AMF depends on the organic aerosol concentration, as well as the prevalence of later generation reactions. AMFs have been measured in unventilated chambers or steady-state flow through chambers. However, indoor settings have outdoor air exchange, and indoor SOA formation often occurs when ROGs are transiently emitted, for instance from emissions of cleaning products. Herein, we quantify 'transient AMFs' from ozonolysis of pulse-emitted limonene in a ventilated chamber, for 18 experiments at low (0.28 h-1), moderate (0.53 h-1), and high (0.96 h-1) air exchange rates (AER) with varying initial ozone-limonene ratios. Transient AMFs increased with the amount of ROG reacted; AMFs also increased with decreasing AERs and increasing initial ozone-limonene ratios, which together likely promoted more ozone reactions with the remaining exocyclic bond of oxidized limonene products in the SOA phase. Knowing the AER and initial ozone- limonene ratio is crucial to predict indoor transient SOA behavior accurately.
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