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Occupant Feedback in Energy-Conscious
and ‘Business as Usual’ Buildings in India
Anoop Honnekeri Gail Brager, PhD* Sanyogita Manu
[CBE, UC Berkeley] [CBE, UC Berkeley] [CARBSE, CEPT University]
Rajan Rawal
[CARBSE, CEPT University]
* [email protected] (corresponding author)
ABSTRACT
Buildings account for 30% of energy consumption in India, and it is estimated that 70% of the
projected commercial building stock by 2030 is yet to be built. The recently established five-year US-India
Centre for Building Energy Research and Development (CBERD) project aims to address the barriers for
adopting low energy consuming strategies in buildings in India, while exploring the lessons that can also
be applied to the US context. This paper evaluates the performance of two energy-conscious (EC) and two
‘business as usual’ (BAU) buildings in Ahmedabad, India using a combination of physical measurements,
and a web-based occupant survey. The survey includes questions about Indoor Environmental Quality
(IEQ): thermal comfort, indoor air quality, air movement and acoustics; it also asked questions about
adaptive controls such as windows and fans.
The EC buildings performed well in many categories compared to the ‘business as usual buildings’.
One of the EC designed buildings in particular performed exceptionally well compared to the CBE
database which consists of over 600 buildings mainly from the US but also from 9 other countries. In the
other three buildings, dissatisfaction prevailed mainly with acoustic quality and office layout due to lack
of speech privacy and visual privacy, but this is common across the larger database. More than 70%
occupants were satisfied with thermal comfort in all except one of the BAU building and of the occupants
who were uncomfortable mostly cited air movement being too low as the reason for discomfort.
INTRODUCTION
Building construction is rapidly growing in India, primarily in the commercial sector with office type
work. The construction boom, along with the hot climate and increase in purchasing power in metropolitan
cities such as Mumbai and Chennai, has led to an unprecedented growth in air conditioner unit sales at
almost 20% per year (McNeil and Letschert 2008; Sivak 2009). Studies are being done with Governmental
support to evaluate energy efficient ways of providing comfort (Manu et.al. 2012). The Center for Building
Energy Research and Development (CBERD) project is a joint initiative of the US Department of Energy
and Indo-US Science and Technology Forum that aims to address the barriers for adopting low energy
consuming strategies in buildings in India, while exploring the lessons that can also be applied to the US
context. In order for low-energy space conditioning strategies to be widely adopted, it is crucial that
occupant comfort and well-being are simultaneously maintained or enhanced, and occupant feedback is
an invaluable source of information for investigating these impacts. Of particular interest is the use of
windows and fans, since air movement is a very cost efficient way of providing comfort.
Occupant feedback is also helpful in diagnosing prevailing issues in a building. For instance, it has
been found that in air-conditioned buildings, a large number of occupants are dissatisfied with the
temperature in their workspace during summer because it is too cold (Abbaszadeh et.al. 2006; de Dear
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
1
et.al. 1991). Appropriate action can be taken to address this issue by identifying if there are specific zones
in the building that have cold dissatisfaction complaints due to over-cooling. The energy savings accrued
by changing the air-conditioning unit setpoint even by few degrees could be significant, especially in warm
climates (Hoyt et.al. 2009).
In this paper, we present the results from a post occupancy evaluation of two energy conscious (EC)
and two ‘business as usual’ (BAU) offices using the Center for the Built Environment (CBE) online survey
tool and physical indoor temperature measurements. We evaluate the satisfaction in each category and
benchmark the performance to the CBE database of 600 buildings. This study is intended to be a pilot for
a larger study which will be scaled up to cover buildings with different passive systems in different
climates of India.
METHODOLOGY
Building selection
India has a varied range of office building types, starting from those that are purely naturally
ventilated to those that are highly energy intensive and use air conditioning throughout the year. This range
includes mixed mode buildings that use air conditioning during extreme condtions and operate in natural
ventilation mode for the rest of the year. Buildings that may be air conditioned for all twelve months but
have efficient system and operation or employ unconventional air conditioning systems also fall in this
varied mix of office building typologies. The buildings for this study were selected for the purpose of
covering this range as best as possible.
In India, a ‘business as usual’ office building is likely to have several climate-responsive strategies
such as external shading to reduce solar heat gain, interior blinds for controlling glare and visual comfort,
operable windows for natural ventilation, and some attention to daylighting. All four of the buildings
studied here have these features.
That said, not all Indian buildings have been designed to optimize the performance of these passive
features, or to make a conscious attempt with the active mechanical systems to reduce energy consumption.
The two buildings in our study that did at least one of these things are being characterized as energy-
conscious (EC) design. The other two buildings are being characterized as ‘business as usual’ BAU,
noting again that a BAU building in India will already have more climate-responsive features than its
counterpart in the U.S. The wall construction is similar in all four buildings, made predominantly of brick
masonry with cement plaster on both sides.
EC-1 is the office of an architecture firm. It takes the approach of relying on passive features to
maintain thermal comfort inside and is most likely the least energy intensive out of the four buildings. It
was designed to primarily operate in fully naturally ventilated mode, but was later retrofitted with air
conditioners following the installation of computers. The building has a high vaulted roof structure over
the studios that facilities better ventilation. It has large openings on the north set higher in the building,
while the lower openings on south are smaller to reduce direct radiation from entering the space. In the
low ceiling areas, clerestory windows provide diffuse daylight across the day. In other places, glass brick
is sometimes used to provide diffused daylight. Both the operable windows and pedestal fans are operated
by the occupants. The building mass is compact, and the building is partially underground, further reducing
the impact of direct radiation. Glazing is approximately 25% of the wall area. The vaulted roofs have an
air cavity filled with ceramic fuses (9” long conical pieces mixed with concrete) to provide thermal
insulation, and the entire roof is covered with high SRI tile. The immediate surrounding is heavily
landscaped with dense trees and water bodies, generating its own microclimate. The building has window
air conditioners and operates as a switch-over type mixed mode building where occupants turn off the air
conditioner and open the windows when the outdoor conditions are suitable for natural ventilation. The
total floor area is spread across four levels, including the mezzanine level. The lower and first floor is
occupied by the permanent staff while the mezzanine floor is occupied by temporary staff such as interns
and international scholars. 48 of the 54 permanent staff participated in survey, all of them located on lower
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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floor.
EC-2 is a building design and consulting firm. It is a LEED Platinum building, but took an entirely
different approach than EC-1 in their energy-conscious design. The firm we studied occupies the seventh
floor of a 11-story building that has the usual business-as-usual features described previously. Other than
installing double-glazed windows, EC-2 did not attempt to optimize the envelope, but instead reduced
their energy consumption by addressing the active systems that serves their air conditioned office space.
They have a very efficient HVAC system, demand controlled ventilation, energy-efficient lighting and
lighting controls, and occupancy sensors. Like all the buildings in our study, EC-2 has operable windows,
but they are not often used by the occupants as the air conditioning is used across the year. There are no
interior fans. The wall construction is much more heavily glazed than EC-1 (51-75% of the wall area). In
spite of the high WWR and lighting controls, the building seems to rely more on artificial lighting than
natural daylighting. The materials used in EC-2 conform to LEED 2.1 specifications such as low VOC
paints, coatings, adhesive, sealants and fabrics, green label carpets and cleaning materials. 31 out of the
91 occupants answered the survey.
Both of the following BAU buildings are similar in that they have not made any conscious attempt
in either the envelope, active system, or control strategies to reduce energy consumption. However, even
without explicit lighting controls, they both rely mostly on natural lighting for the majority of the occupied
hours. Both buildings also have ceiling fans (which are not being provided most of the time in newer,
sealed buildings in India).
BAU-1 is an office of a computer software developer firm in a heavily urbanized area, located on
eighth floor of an 11-story building (similar to EC-2 being on an intermediary floor of a taller building).
It is representative of the most energy intensive building with a business-as-usual envelope and air
conditioning system and operation. The office has a variable air volume (VAV) type central air
conditioning unit that is on throughout the year. The walls are heavily glazed, with the WWR being almost
identical to that in EC-2 (51-75% of the wall area). The windows are operable and have a reflecting glass.
As in the other buildings, BAU-1 has interior blinds and exterior shading. 27 out of the 140 occupants
answered the survey.
BAU-2 is an office of a building construction and MEP consulting firm in a less dense and more
vegetated area, located on ground and first floor of an 8-story building. It has a variable refrigerant flow
(VRF) type central air conditioning unit, operable windows and ceiling fans. The glazing area is in between
the other examples (30-50% of the wall area). The windows have a clear glass, compared to the reflective
glazing of BAU-1. While the air-conditioning in BAU-1 operates almost continuously throughout the year,
in BAU-2 occupants have a choice to operate it when indoor becomes uncomfortable. 40 out of the 46
occupants answered the survey.
CBE web-based survey tool
The CBE web-based survey tool is an efficient way of remotely getting occupant feedback on indoor
environmental quality (IEQ) and various other aspects of the building. Participation in the survey is
voluntary and occupants can choose not to answer any question. The questions in the survey were designed
after extensive inputs from facility managers and designers so as to report the most useful feedback
(Eisenhower 2000). The survey consists of a core module with eight IEQ categories and additional
modules such as window and fan usage. Since the surveys were being admisistered in India, the phrasing
of the questions and options were tailored to suit the local culture and parlance. The survey asked
occupants to rate their satisfaction during summer with these different aspects on a 7-point scale that
ranged from -3 (Very dissatisfied) to 0 (Neutral) to +3 (Very satisfied). The tool also has a unique feature
that is helpful for diagnostic purposes; when an occupant votes to be dissatisfied in any category, the tool
automatically follows up with branching questions that ask about the reasons for dissatisfaction. Details
about the building features such as floor area, number of occupants, LEED compliance and type of HVAC
system, envelope and glazing are filled out by the building manager separately. More details about the
CBE survey tool can be found in (Zagreus 2004). A list of the most relevant survey questions is illustrated
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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in Table 1.
Table 1. Important Categories Included in the CBE survey
Variable Questions asked
Thermal comfort Satisfaction with temperature, ability to control temperature, thermal comfort
during summer
Indoor air quality Satisfaction with air quality (i.e. stuffy/stale, cleanliness, odors)
Air movement Satisfaction with amount of air movement, ability to control amount of air
movement
Window usage
Satisfaction with operable windows (summer and winter and monsoon)
Importance of having an operable window to the user
Times adjusted (daily, weekly, monthly)
Time of adjustment
Reasons to ‘open’ or ‘close’ a window
Fan usage Satisfaction with ceiling fans, Times adjusted during summer(daily, weekly,
monthly), Time of adjustment, Reasons to turn ‘on’ or ‘off ’ a fan
Acoustics Satisfaction with noise level and sound privacy
RESULTS
Weather
Figure 1 shows the boxplot of outdoor dry bulb temperature
(DBT) based on the ISHRAE weather file (EnergyPlus
webpage). Ahmedabad experiences a semi arid climate with
predominantly three seasons: summer, monsoon and winter.
April to June is the summer season where the mean DBT is
above 30 ˚C with a highest recorded value of 44 ˚C. Summers
are dry with a mean relative humidity (RH) of 53%. July to
October is the monsoon season where the mean monthly DBT
is 28 ˚C and mean RH is 70%. November and March are the
two transition months with mean DBT of 26 ˚C and mean RH
of 47%. December, January and February are the winter
months where the mean DBT is comparatively lower at 21 ˚C and mean RH is 52%.
Summary of occupant feedback in all the four buildings
Figure 2 shows the percentile scores compared to the overall CBE dataset, and Figure 3 shows the
mean percentage satisfied per survey category in each building (Occupants voting +1 and above were
counted as satisfied). In both, green colors designate better performance and orange designates low
performance. Figure 2 illustrates that EC-1 (which uses more passive strategies to achieve its energy
efficiency) is the best performer of the four buildings, and compared to the CBE database ranked fairly
well in most of the survey categories except for ‘office layout’ and ‘air movement’ satisfaction. EC-2
(using improved active systems to achieve low energy consumption) did relatively well in thermal comfort,
acoustics, and lighting performance, but ranked low in office layout, air quality and workspace satisfaction.
Of the BAU buildings, BAU-1 is the lowest performer of the four buildings across most of the categories,
while BAU-2 ranked relatively well in thermal comfort and lighting, but low in air movement satisfaction.
For illustrative purposes in Figure 3, a satisfaction percentage below 70% is assumed to be the
threshold for concern. This is more flexible that the conventional 80% satisfaction threshold used in
thermal comfort standards, for example. Figure 3 shows that 70% or more occupants were satisfied in
EC-1 in all survey categories except for office layout and air movement. It’s interesting to note that even
though acoustic satisfaction was in the 95th percentile in Figure 2, this is based on only 78% of the
occupants being satisfied, as shown in Figure 3. That is because acoustics generally receives the lowest
satisfaction scores in the database, so even 78% is considered quite good, and was also unusually high
Figure 1. Ahmedabad weather
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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compared to the other four buildings. The reasons for that are not entirely clear, although the high valuted
roof could possibly be a factor. The dissatisfaction with office layout was related mainly with visual
privacy (too many people walking around in the work area) and the amount of workspace available for
work (this may be due to this being a traditional architecture firm that requires a lot of workspace for paper
drawings). The dissatisfaction with air movement prevailed mainly because of the lack of sufficient air
movement (rather than air movement being too high), and the inability to control it. However, these
complaints were limited to only two zones, D and E. This was surprising since these zones have pedestal
or bracket fans, both of which should be adequate to increase air movement close to the person, even more
effectively than stratification created by the vaulted roof. This may suggest that even though these fans
are available, there are reasons that people are not using them or they are not located properly.
In EC-2, although the building was in the 90th percentile of the CBE database for thermal comfort,
this is associated with only 71% of the occupants being satisfactied. This is because this is a pervasive
problem in buildings, and thermal issues are usually the #2 complaint (following acoustics). Of the IEQ
categories, occupants were most satisfied with lighting, but the highest satisfaction ratings had nothing to
do with IEQ (i.e., office furnishings, general building satisfaction, and cleanliness/maintenance). The
satisfaction percentage in EC-2 was lowest with acoustics, air quality, office layout and air movement.
Lack of sound privacy was the main reason for acoustic dissatisfaction while it was the lack of visual
privacy for the dissatisfaction with office layout. A few occupants from EC-2 opined that the air was
stuffy/stale, not clean and had a bad odor; the source for bad odor was mainly from the toilets. However,
the complaints were limited to one particular zone. With regards to air movement satisfaction, occupants
were mainly dissatisfied with amount of air movement (saying they preferred to have more air movement)
and the ability to control the amount of air movement. This is not surprising given that this building does
not have fans.
BAU-1 is having the biggest challenges with their workplace conditions; less than 70% of the
occupants were satisfied in all the categories except for workspace satisfaction, where it was 77% (Figure
3). Higher satisfaction may, in part, be due to this office having relatively low occupant density (10 sq.m.
per person, compared to a more typical 6.5 sq.m. per person for India). Amongst the dissatisfied categories,
acoustic quality, office layout and thermal comfort were the categories in the lowest satisfaction range;
around 50% or less. Similar to EC-2, lack of sound and visual privacy were the main reasons for
dissatisfaction with acoustics and office layout respectively. Overall thermal comfort satisfaction was very
low in BAU-1 compared to the other three buildings. Those who were dissatisfied cited multiple reasons
of discomfort such as incoming sun, air movement being too low and the heating/cooling system not
responding quickly to the thermostat.
Occupant response in BAU-2 was in sharp contrast to BAU-1; 70% or more occupants were satisfied
with all categories except acoustics (Figure 3). Sound privacy was once again the main source of
dissatisfaction. An important point to note with regards to acoustics dissatisfaction in EC-2, BAU-1 and
BAU-2 is that occupants were less dissatisfied with noise levels as compared to sound privacy (both of
these questions make up the combined metric for acoustic quality); this pattern is common across the CBE
database.
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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Figure 2. Percentile ranking of the case study
buildings compared to the CBE database.
Figure 3. Percentage of occupants satisfied in
each case study building
Thermal comfort during summer
Ahmedabad experiences hot summers. Occupants were asked about their thermal comfort opinion
‘in general’ and specifically during summer. However, to understand thermal comfort during the extreme
climate, evaluating thermal comfort satisfaction in summer is more crucial than in general. Using the 7-
point satisfaction scale described earlier, Figure 4 (a) – (e) shows the mean thermal comfort response in
each zone (labeled alphabetically) of EC-1, EC-2, BAU-1 and BAU-2 respectively (note that BAU-2 has
two floors). The color corresponds to the mean value and the numeric is the number of votes in each zone.
Figure 5 (a) – (e) shows the distribution of indoor temperature during occupied hours monitored from
February – April 2014 in each building. The color and numeric both represent the mean value of indoor
temperature while the green dot represents the sensor location.
Figure 4. Satisfaction with thermal comfort during summer.
The scale ranged from -3 (Very dissatisfied) to 0 (Neutral) to +3 (Very satisfied)
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
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Figure 5. Indoor temperature (°C) between February to April.
More than 70% of the occupants were satisfied with thermal comfort during summer in 3 of the
buildings - EC-1 (N=46), EC-2 (N=31) and BAU-2 (N=37) - while only 50% were satisfied in BAU-1.
The most cited reason for thermal discomfort in all the four buildings was air movement being too low.
The mapping in Figure 4 helps in identifying the zones where the mean satisfaction vote is less than zero.
For example, lowest satisfaction occurred in zone B in EC-1, zone B in EC-2 and zone D and G in BAU-
1. However, these zones had two or less number of responses and thus these findings are only illustrative,
and nothing conclusive can be said.
The mean value of indoor temperature during occupied hours monitored from Februry – March was
between 26 – 29 ˚C. The distribution was mostly uniform across all the zones in the building except for
EC-2 where the core zones were cooler than the perimeter zones. This could be very likely because EC-2
had the widest floor plate compared to the other three buildings.
In all four of the buildings, occupants voted that room air conditioners and window blinds/shades
were the controls that thay were most frequently adjusted. During summer, the majority of the occupants
said they either drank something cool or covered the window to keep themselves comfortable.
Window and fan usage
Windows and fans are two cost efficient ways of
providing comfort in warm climates, and are common in
buildings in India. Occupant satisfaction feedback
regarding both these adaptive actions is of interest mainly
during the summer. Figure 6 shows the percentage satisfied
with operable windows and ceiling fans in all four
buildings during summer. Looking first at windows,
overall, greater than 70% satisfaction with operable
windows was only achived in BAU-2. A few occupants
from EC-1 said the windows were inaccessible and there
were things blocking the window. This was surprising
since EC-1 is the building that paid particular attention to using passive, architectural strategies to achieve
low energy use. In EC-2, the LEED Platinum building where the focus was more on efficienct active
systems, occupants said most of the windows were fixed and in BAU-1 some of the reasons which made
it difficult to use windows were the inability to open windows fully and complaints from co-workers. The
most frequently cited reasons for opening a window in all the four buildings were, ‘to feel cooler’, ‘to
increase air movement’ and ‘to let in fresh air’. Interestingly, the prevailing reasons to close a window
were ‘to feel cooler’, ‘outdoor temperature getting warmer than indoors’ (both of these related to having
air-conditioning on during a hot day), and ‘to reduce outdoor noise.’ These reasons show that window
interaction is driven predominantely by outdoor temperature, air quality and noise levels.
Looking now at fan usage, overall, more than 70% were satisfied with fans during summer in three
Figure 6. Satisfaction with windows
and fans.
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
7
of the buildings - EC-1, BAU-1 and BAU-2 (the satisfaction with fans was low in EC-2 because the
building did not have any). The most cited reasons to turn on a fan in EC-1, BAU-1 and BAU-2 were ‘to
feel cooler’ and to ‘increase air movement’ while the reason to turn off a fan was to ‘reduce air movement’
and because ‘a co-worker requested it.’ These are all as one might expect, and the majority of the occupants
in EC-1, BAU-1 and BAU-2 said they were very sure of having the desired effect when they interacted
with fans.
DISCUSSION
The occupant feedback surveys revealed that one of the energy conscious buildings (EC-1) was
performing well (i.e., it had a satisfaction percentage of above 70% in 8 out of ten categories.) Overall, in
all of the buildings occupants were primarily dissatisfied with the acoustics and office layout, which is
common across the entire CBE database. Acoustic dissatisfaction is an important area that needs to be
carefully evaluated since it is often seen as a potential barrier for natural ventilation. One of the arguments
against having natural ventilation in a city like Ahmedabad is that operable windows would bring in
outdoor noise. However, the survey results show that occupants were more dissatisfied with sound privacy
than noise levels, which has more to do with the open plan layout. In terms of the sources of noise that
bothered workers, people talking on phone and overhearing private conversations were the most frequently
cited sources of acoustic dissatisfaction, rather than outdoor noise.
Another result worth noting is that all the buildings ranked low in the air movement satisfaction
category compared to the CBE database, and the lack of air movement was repeatedly cited as the reason
for thermal discomfort. Occupants were also dissatisfied with the ability to control air movement and
opined that they needed more of it. This dissatisfaction prevailed mainly in zones that did not have fans,
which means more attention needs to be given to providing sources of air movement in these buildings.
Amongst those who had fans, the main reasons to turn on a fan were to feel cooler and increase air
movement. Moreover, when asked about the confidence of having the desired effect on turning on a fan,
the majority of the occupants voted that they were confident about this effect. This shows that occupants
perceive fans as fast-acting and they rely on it for achieving comfort in a short span of time. Windows on
the other hand were opened to let in fresh air in addition to feel cooler and increase air movement. There
was a consistent opinion about the reasons to close a window, i.e. when the outdoor got warmer than the
indoors. The key take-away from this result is that the occupants prefered to have air movement and when
there was a combination of windows and fans in use, they worked well in providing it.
The results also revealed an interesting aspect of occupant satisfaction in EC and BAU buildings.
Given that BAU-2 performed better than EC-2, this indicates that one cannot necessarily conclude that a
building designed for better energy efficiency will result in better occupant satisfaction as well. In addition
to needing to pay more attention to air movement and other indoor environmental factors, there could
possibly be latent factors such as interior layout, work culture, and connection to the outdoor views that
are important (all of these were better in BAU-2).
This study is a pilot for further research where surveys will be conducted across buildings in different
climates of India. Although spatial mapping of thermal comfort and temperature is a powerful method of
diagnostics, we were not yet able to generalize about the impact of relevant building design issues due to
the uneven distribution of the number of responses (i.e., zones where occupants voted to be dissatisfied
with thermal comfort had very few votes.) The scaled up study will consider ways by which we will ensure
a minimum number of responses from each zone.
CONCLUSIONS
Indoor Environmental Quality (IEQ) parameters were evaluated in two energy-conscious (EC) and
two ‘business-as-usual’ (BAU) buildings in Ahmedabad. The EC building that utilized more passive
architectural approaches performed well in most of the categories compared to the buildings in the CBE
database, the other three buildings had multiple categories of concern. Overall, the occupants expressed
maximum dissatisfaction with sound and visual privacy. They were mostly satisfied with thermal comfort
30th INTERNATIONAL PLEA CONFERENCE 16-18 December 2014, CEPT University, Ahmedabad
8
except in one BAU building. Those who were dissatisfied most frequently cited ‘air movement being too
low’ as the reason for dissatisfaction. In buildings that had fans, it was perceived to be a fast acting way
of providing comfort. Fans were operated mostly due to thermal and air movement needs while windows
were operated due to indoor air quality and acoustic reasons in addition to the two former reasons.
ACKNOWLEDGEMENTS
This study was funded by the US – India Joint Clean Energy Research and Development Center
(JCERDC) under the framework of the Center for Building Energy Research and Development (CBERD)
project supported by the US – India Science and Technology Forum and the U.S. Department of Energy.
We thank Margaret Pigman, Caroline Karmann and David Lehrer from CBE for their feedback on this
paper, Joan Tionko from CBE for her help with administering the surveys and Krishna Shah from CEPT
for her help with physical data monitoring.
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