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Thermal comfort in commercial kitchens (RP-1469): Procedure and physical measurements (Part 1)

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The indoor climate in commercial kitchens is often unsatisfactory, and working conditions can have a significant effect on employees' comfort and productivity. The type of establishment (fast food, casual, etc.) and climatic zone can influence thermal conditions in the kitchens. Moreover, the size and arrangement of the kitchen zones, appliances, etc., further complicate an evaluation of the indoor thermal environment in commercial kitchens. In general, comfort criteria are stipulated in international standards (e.g., ASHRAE 55 or ISO EN 7730), but are these standardized methods applicable to such environments as commercial kitchens? This article describes a data collection protocol based on measurements of physical and subjective parameters. The procedure was used to investigate more than 100 commercial kitchens in the United States in both summer and winter. The physical measurements revealed that there is a large range of kitchens environments and confirmed that employees are exposed to a warm-to-hot environment. The measured ranges of activities and temperatures in many cases were outside the range recommended by ASHRAE 55 and ISO EN 7730. The study showed that the predicted mean vote/percentage people dissatisfied (PMV/PPD) index is not directly appropriate for all thermal conditions in commercial kitchens.
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Thermal comfort in commercial kitchens (RP-1469):
Procedure and physical measurements (Part 1)
Angela Simone a , Bjarne W. Olesen a , John L. Stoops b & Amber W. Watkins b
a International Centre for Indoor Environment and Energy (ICIEE), Department of Civil
Engineering , Technical University of Denmark (DTU) , Nils Koppels Allé, Building 402,
DK-2800 , Kgs. Lyngby , Denmark
b Sustainable Use Consulting at DNV KEMA Energy & Sustainability , Oakland , CA , USA
Accepted author version posted online: 10 Oct 2013.Published online: 27 Nov 2013.
To cite this article: Angela Simone , Bjarne W. Olesen , John L. Stoops & Amber W. Watkins (2013) Thermal comfort in
commercial kitchens (RP-1469): Procedure and physical measurements (Part 1), HVAC&R Research, 19:8, 1001-1015, DOI:
10.1080/10789669.2013.840494
To link to this article: http://dx.doi.org/10.1080/10789669.2013.840494
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HVAC&R Research (2013) 19, 1001–1015
Copyright C
2013 ASHRAE.
ISSN: 1078-9669 print / 1938-5587 online
DOI: 10.1080/10789669.2013.840494
Thermal comfort in commercial kitchens (RP-1469):
Procedure and physical measurements (Part 1)
ANGELA SIMONE1,, BJARNE W. OLESEN1, JOHN L. STOOPS2,and AMBER W. WATKINS2
1International Centre for Indoor Environment and Energy (ICIEE), Department of Civil Engineering, Technical University of
Denmark (DTU), Nils Koppels All´
e, Building 402, DK-2800 Kgs. Lyngby, Denmark
2Sustainable Use Consulting at DNV KEMA Energy & Sustainability, Oakland, CA, USA
The indoor climate in commercial kitchens is often unsatisfactory, and working conditions can have a significant effect on employees’
comfort and productivity. The type of establishment (fast food, casual, etc.) and climatic zone can influence thermal conditions in the
kitchens. Moreover, the size and arrangement of the kitchen zones, appliances, etc., further complicate an evaluation of the indoor
thermal environment in commercial kitchens. In general, comfort criteria are stipulated in international standards (e.g., ASHRAE 55
or ISO EN 7730), but are these standardized methods applicable to such environments as commercial kitchens? This article describes
a data collection protocol based on measurements of physical and subjective parameters. The procedure was used to investigate more
than 100 commercial kitchens in the United States in both summer and winter. The physical measurements revealed that there is a
large range of kitchens environments and confirmed that employees are exposed to a warm-to-hot environment. The measured ranges
of activities and temperatures in many cases were outside the range recommended by ASHRAE 55 and ISO EN 7730. The study
showed that the predicted mean vote/percentage people dissatisfied (PMV/PPD) index is not directly appropriate for all thermal
conditions in commercial kitchens.
Introduction
The restaurant industry in the United States is the nation’s
second largest private sector employer, with its workforce of
12.8 million projected to increase by 1.3 million positions in the
next decade (National Restaurant Association [NRA] 2012).
As nearly one in ten of all employed Americans worked in a
restaurant in 2011, the NRA expected restaurants to add jobs
at a 2.3% rate in 2012, a full percentage above the projected
1.3% gain in total U.S. employment.
In the last year, restaurant job creation continues to out-
pace that of other industries, resulting in 3% more restaurant
positions compared to 1.4% for overall U.S. employment. An
additional 2.4% increase in restaurant jobs is expected in the
United States in 2013, which will result in 13.1 million of
restaurants employees equal to 10% of the U.S. workforce
(NRA 2013).
For countries such as the United States, where one of the
largest employee sectors is in the restaurant industry, the well-
being of the employees is becoming one of the main issues.
The commercial kitchen is a unique space where many
different HVAC applications must operate within a sin-
Received February 4, 2013; accepted August 22, 2013
Angela Simone, PhD, Associate Member ASHRAE, is Re-
searcher. Bjarne W. Olesen, PhD, Fellow/Life Member
ASHRAE, is Professor and Centre Director. John L. Stoops,
PhD, Member ASHRAE, is Senior Principal Consultant. Amber
W. Watkins is Consultant.
Corresponding author e-mail: asi@byg.dtu.dk
gle space. Those different applications can be designed
and determined by the appliance line and should follow
the guidelines in the kitchen ventilation chapter of the
2011 ASHRAE Handbook—HVAC Application (ASHRAE
2011b), ASHRAE Standard 154 (ASHRAE 2011a), and
in prEN16282 (ISO 2011). In the context of energy-saving
strategies, ASHRAE/IES Standard 90.1 (ASHRAE 2010b)
contains more restrictive requirements for transfer air,
demand-controlled ventilation (DCV), energy recovery
devices, and high performance hoods. Recent studies and de-
velopments have attempted a total kitchen HVAC (TKHVAC)
system approach and DCV for commercial kitchens, which
are expected to become a standard energy efficient prac-
tice (Fisher et al. 2013). However, an acceptable thermal
environment must also be provided for kitchen occupants.
The appliances, size and arrangement of the kitchen zones,
number of employees, variable environmental conditions dur-
ing business hours, etc., further complicate an evaluation of
the indoor thermal environment in kitchens.
Previous studies in commercial kitchens have focused
mainly on air-conditioning and ventilation systems. When
considering thermal comfort, such studies as Pekkinen and
Takki-Halttunen (1992) and Livchak et al. (2005) dealt mainly
with the acceptable ranges of physical parameters reported in
standards, values that were established for indoor environ-
ments in which there was a low activity level.
Thermal comfort criteria are defined in international stan-
dards such as ASHRAE Standard 55 (ASHRAE 2010a) or
ISO Standard EN 7730 (ISO 2005), but it is questionable
whether these standardized methods are applicable to envi-
ronments like commercial kitchens.
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1002 HVAC & R Research
Today there are no specific regulations or even parame-
ters to determine whether thermal conditions in commercial
kitchens are comfortable or cost effective. General evaluation
criteria for thermal comfort may be inadequate and unsuitable
for practical application.
Based on standardized methods (ASHRAE and ISO) and
on pre-tested pilot measurements, Simone and Olesen (2012a
and 2012b) introduced a procedure for collecting data on the
physical environment and subjective perceptions in commer-
cial kitchens. The procedure was applied in a large study in-
volving more than 100 commercial kitchens in the United
States in order to obtain enough of data to be able to evaluate
thermal comfort. Different kitchens types (fast food, dining,
etc.) and different kitchens zones, in both summer and winter,
were investigated.
Part 1 of this series presents the results obtained from phys-
ical measurements. Differences between kitchen types (fast-
food, casual, and institutional kitchens), seasons, and climatic
region are analyzed in terms of the measurements using ex-
isting comfort evaluation indices, such as the predicted mean
vote/percentage people dissatisfied (PMV/PPD) index, and
the applicability in commercial kitchens is evaluated. The sub-
jective evaluations were analyzed and used to define a thermal
comfort range in a warm environment in which the occupants
have high activity levels. These results are presented in Part 2
of this series.
Evaluation of the thermal environment
in commercial kitchen
For many years the International Organization for Standard-
ization (ISO) and ASHRAE have been developing standards
for the indoor thermal environment. ASHRAE has mainly
developed standards for moderate thermal environments (e.g.,
ASHRAE 55/2010 [ASHRAE 2010a]), while ISO standards
cover the entire range from cold stress to comfort to heat stress
(e.g., ISO EN 7730/2005 [ISO 2005], ISO EN 7933/2004 [ISO
2004a], and ISO EN 11079/2007 [ISO 2007b]).
Thermal comfort is one of the four elements that influence
the indoor environmental air quality (IEQ) of a given space,
with the other three being lightining quality, acoustical qual-
ity, and air quality. It is defined as a “condition of mind which
expresses satisfaction with the thermal environment and is as-
sessed by subjective evaluation” (ASHRAE Standard 55/2010
[ASHRAE 2010a, p. 4]); this definition has been converted into
specifications in terms of physical parameters.
PMV is the most widely used index for evaluating indoor
thermal comfort, but it is recommended only for values
between ±2 on the 7-point PMV-scale (ISO EN 7730/2005
[ISO 2005]).
In commercial kitchens, it is also necessary to consider ther-
mal dissatisfaction that can be caused by an overall thermal
sensation that is too warm or too cold (i.e., the percentage dis-
satisfied, PPD) or the percentage dissatisfied by local thermal
discomfort (PD) due to draught, vertical temperature gra-
dient, radiant asymmetry, or warm or cold floors (ISO EN
7730/2005 [ISO 2005]).
The main activity in a commercial kitchen is the cook-
ing process, which generates heat and effluents that must be
captured and exhausted in order to control and guarantee
thermal comfort and good air quality for the employees. Pre-
vious studies in commercial kitchens have mainly focused on
air-conditioning and ventilation systems. They indicate that
kitchens are not typical of general spaces, and that thermal
comfort conditions in commercial kitchens are determined by
envelope heat gain and loss, people, lighting, and miscella-
neous equipment.
Thermal comfort in a commercial kitchen environment is
mainly driven by the radiant heat that directly impacts the
comfort of the workers, and by convective loads from both
hooded and un-hooded cooking appliances.
One published study of the commercial-kitchen environ-
ment indicates that the areas on the body that have the greatest
exposure to temperature differences are the chest and facial ar-
eas, situated between 1.5 and 1.8 m (59 and 71 in.) height above
the floor (Livchak et al. 2005). Additionally, it was found that
the greatest heat loads are encountered at the cooking line,
which produces the largest heat gains in the space, and where
the workers are exposed to the highest temperatures.
As described in many studies, thermal comfort has a large
impact on the performance and productivity of the employ-
ees. In particular, Wyon (1996) and later Livchak et al. (2005)
reported that an increase of temperature of 10F(5.5
C)
above the thermally neutral level may result in a 30% loss of
productivity.
In a commercial kitchen environment, there can be large
differences between the type of kitchen space (casual restau-
rant, institutional restaurant, or quick-service restaurant
[QSR]), kitchen activities (preparation, cooking, dish wash-
ing), building and type of HVAC system (insulation, windows,
air conditioning, natural ventilation), and kitchens that are
situated in many different climatic zones.
The kitchen environment presents a much broader range of
conditions than those that occur in offices, schools, and homes,
and the question is whether the methods described in exist-
ing thermal comfort standards are applicable. To determine
whether they do apply, ASHRAE Research Project RP-1469
was initiated. As part of the project, a measuring procedure
was established, focusing in particular on the processes char-
acterizing kitchen spaces and kitchen activities (ASHRAE
2012).
The procedure used to establish a database for the ther-
mal environment in commercial kitchens obtains both phys-
ical and subjective values. Two types of questionnaire based
on the ISO Standard 10551 (ISO 2001) were developed and
adapted to the kitchen environment and to kitchen workers
in order to achieve the highest possible participation by the
employees in the study. They were used in combination with
weekly recording of physical parameters supplemented by de-
tailed measurements on a particular day.
Method
As the commercial kitchen environment now includes con-
ditions that differ from those studied earlier, a measuring
procedure was established to focus on the different processes
that take place in a commercial kitchen. For example, em-
ployees facing high-energy appliances, such as an under-fired
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Fig. 1. Schema of procedure of data collection (color figure available online).
charbroiler, ovens, steamers, or deep-fat fryers, or subjected
to bursts of very humid hot air are subject to higher radiant
conditions than employees working on a preparation line with
their backs some distance from such appliances.
A general view of the procedure, from the recruitment of
kitchens to the data collection, is summarized in the flowchart
in Figure 1.
Recruitment of kitchens
Commercial kitchen spaces differ by type (casual, institu-
tional, or QSR), kitchen activities (preparation, cooking, dish
washing), building and HVAC system types (insulation, win-
dows, air-conditioning, natural ventilation), and locations in
different climatic zone. For this reason, measurements of ther-
mal parameters were recorded in different types of kitchens,
in different cities, and in different climatic zones throughout
the United States, as shown in Table 1. Site data were collected
in nine metropolitan areas located in different climatic zones,
according to ASHRAE Standard 169 (ASHRAE 2006) cli-
mate zone classifications. In all, 105 commercial kitchens in
summer and 104 in winter participated in the thermal comfort
evaluation of the kitchen environment, from which over 90%
participated in both seasonal study phases.
A “casual” dining restaurant is considered to be a
restaurant that provides table service, a franchise, chain, or
privately owned restaurant. A particular example of a kitchen
classified as “casual” is a small privately owned restaurant
with a single kitchen. The owner may often be the adminis-
trator or part of the kitchen staff. Restaurants grouped as
“institutional” are those typically located within a school,
an office, a government building cafeteria, or as part of a
Table 1. Number of measured kitchen types in United States.
Summer (Phase I) kitchen type
sample, August–October 2010
Winter (Phase II) kitchen type
sample, January–February 2011
Climate zone (ASHRAE
Standard 169 [ASHRAE 2006]) U.S. city QSR Institutional Casual Sum QSR Institutional Casual Sum
1—Moist Miami 9 3 0 12 9 3 0 12
2/3—Moist Atlanta 7 5 0 12 7 5 0 12
2/3—Dry Phoenix 6 4 2 12 6 4 2 12
4—Marine Seattle 5 9 0 14 5 9 0 14
4—Moist Nashville 2 3 4 9 2 3 3 8
4—Moist Washington DC 5 5 0 10 5 5 0 10
5/6—Moist New York 4 4 3 11 4 5 1 10
5/6—Dry Las Vegas 8 2 2 12 8 3 2 13
7—Moist Minneapolis 7 3 3 13 7 3 3 13
Sum by kitchen type 53 38 14 105 53 40 11 104
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1004 HVAC & R Research
hotel. Institutional restaurants in general had a more robust
ventilation system and a larger food-preparation area and
cooking line. Last, QSRs, such as those providing expedited
service or “fast food,” are typically owned and operated by
franchisees, corporations, or, in some instances, privately held
companies. The differentiation between kitchen types has
resulted in some overlapping, but the on-site visit during the
measurements improved the classification of the kitchen data.
Data collection
Data collection included several types of measurement: out-
door air temperature and humidity, HVAC system (supply and
make-up air temperature and relative humidity [RH]), indoor
(thermal) environment, physiological, and subjective evalua-
tion. The intention was to collect data describing the physical
environment and personal factors, such as clothing and activ-
ity, to be able to calculate existing indices of thermal comfort
and/or heat stress.
In order to be able to characterize adequately the HVAC
systems performance and to obtain some idea of the air quality
in each kitchen, the supply and exhaust airflows should have
been measured as well. However, supply and exhaust airflow
rates measurements were not technically feasible in most of
the kitchens. Carbon dioxide concentrations and indoor air
quality subjective evaluations were used as indicators instead.
Data were recorded in summer and winter and in the three
identified kitchen zones (cooking, food preparation, and dish
washing) shown by the area inside the dashed line in Fig-
ure 2, these being considered likely to have different thermal
conditions in the commercial kitchen. During the visit to the
kitchens, a sketch of each kitchen and its different zones was
made (e.g., Figure 2), including the location of the measuring
devices that have been installed, the location of the supply
and exhaust of the HVAC system, the exhaust hood and other
details (e.g., type of supply device and exhaust grill, use of
free-standing fans, etc.), and other notes.
The data recorded during the measurements are listed be-
low according the grouped tasks listed in the schema of Fig-
ure 1. The following parameters were measured.
1. Long-term measurements (LM) (first to third walk-
through; during a typical week, normally Monday to Sat-
urday): air temperature (ta), operative temperature (to), and
RH for a whole week in time intervals of 15 min; examples
of the measured spots, representative of kitchens zone, are
shown in Figure 2 as a rectangular green spot.
2. Short-term (or spot) measurements (SM) (second walk-
through): subjective parameters, such as estimated activity
level (met) and clothing insulation (Icl), globe temperature
(tg)andtaat 0.1 m and 1.7 m (4 and 67 in.) height above
the floor, air (ta), operative (to), radiant temperature (tr),
air velocity (va), and RH at 1.1 m (43 in.) above the floor
and at 0.3 m (1 ft) distant at the workstation (where the
employees were working during the peak operating hours
of a working day [breakfast, lunch, and/or dinner time])
during on-site SM. All physical parameters were recorded
for 15–20 minutes, having 30–40 equally spaced points over
time (30-s time-interval), with an exception for air velocity
and directional operative temperature. The air velocity
was recorded for 15–20 min with a minimum interval
time of 1 s, while the directional operative temperature
was recorded in a time interval of 30 s for a minimum of
5 min for each direction (up–down, right–left, front–back).
Fig. 2. Cooking, food preparation, and dishwashing areas of a kitchen sample (color figure available online).
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Volume 19, Number 8, November 2013 1005
Physical parameters collected at each representative
worker location are shown in Figure 2 by a red arrow.
3. Short-term questionnaire (SQ) (second walk-through): on-
site survey of occupants’ subjective reaction to the indoor
environment obtained while recording the physical mea-
surements.
4. Long term questionnaire (LQ) (first to third walk-through):
general survey of background information on the employ-
ees and their overall evaluation of the working conditions.
From the average of the physical data recorded at 1.1 m
(43 in.) height and the estimated individual parameters (cloth-
ing and activity), individual PMV/PPD indices and weighted
averages for climate, kitchen type, and zone were calculated.
In particular, by using the ASHRAE thermal comfort tool
(Huizenga 2011) a PMV value was assigned to each of 364
employees encountered during the on-site SMs.
Instrumentation for physical measurements
The physical environmental parameters were measured with
the instruments shown in Figure 3. RH was measured and
recorded using a small data logger (Figure 3a) with an accu-
racy of ±2.5% (Hobo). The air, globe/operative, and flat ra-
diant temperature sensors were built based on ISO Standard
7726 (ISO 1998) descriptions and as described by Simone et al.
(2007). In the measurement range of 50F to 104F(10
Cto
40C), these temperature sensors have an accuracy of ±0.5F
(±0.3C). The air temperature sensors (Figure 3b) were built
by enclosing a temperature sensor within an open-ended ra-
diation shield (the cylinder) that enabled a free flow of air to
come in contact with the sensor.
A grayish globe sensor of 4 cm (1.6 in.) diameter was used
to measure the globe temperature (Figure 3c), which, at 1.1 m
(43 in.) height above the floor, is an estimate of the opera-
tive temperature (to) for a standing person and thus closely
related to the global thermal perception of the occupant and
to calculate the mean radiant temperature, from the difference
between air and operative temperature, in the minimum tem-
poral average of 12 min with 24 equally spaced points over
time.
A flat sensor, having two opposed faces with a matte gray
finish, each 7 cm (2.8 in.) in diameter (Figure 3d), was used
to measure the directional operative temperature (to,i )andto
evaluate the radiant asymmetry that occurred when an em-
ployee was facing a high-temperature radiant surface, such as
appliances in the cooking zone. The sensor records two values
of operative temperature at a time in the same point in space,
equal or different according to the direction of the plate that
faces the opposite hemisphere in the same room volume. The
average value of the temperature was taken as the temporal
average over at least 5 min with 10 measurements that were
equally spaced in time. The plane radiant temperature (tp,i )
in six directions and the mean radiant temperature (tr)were
calculated according to Equations 1 and 2:
tp,i=to,ia·ta
1a(1)
tr=0.08 ·(tp,up +tp,down)+0.23 ·(tp,right +tp,left)+0.35 ·(tp,front +tp,back )
2·(0.08 +0.23 +0.35)
(2)
with irepresentative of the direction 1, 2, 3, 4, 5, or 6 of the
sensor facing up, down, right, left, front, or back, relative to
the direction the employee was facing.
An omnidirectional anemometer was used for measuring
air velocity (Figure 3e). This sensor can measure in the range
of 0.005 to 5 m/s (9.8 to 984 ft/min) with an accuracy of
0.02 m/s (4 ft/min) ±1% of readings. The portable data logger
connected to the anemometer recorded air velocity with a
minimum interval time of 1 s (1-Hz frequency). The average
air velocity over 12–15 min was used in the analysis. The above
sensors yielded a voltage that was directly recorded by a small
logger (Figure 3a) and afterward converted to the relevant
units by the calibration equations. This way of storing data
was very convenient for measurements in kitchens, avoiding
any hindrance for the workers, and disturbing them and their
work as little as possible.
As shown in Figure 4a, the data loggers recorded kitchen
temperatures, humidity, and carbon dioxide (CO2) concentra-
tions. In addition to what was described above in the “Data
Collection” section, loggers to record LMs (Figure 4a) were
installed for the duration of one week, or slightly less. The
loggers referred to short-term recorded data (Figure 4b) only
during the peak operation time (or rush time) of the kitchen,
i.e., during the busiest working hour(s). Monitoring a period
of 15–20 min during that peak period was performed, as it may
be considered to provide the worst thermal environment for
the employees. Recording devices were used for more detailed
SMs of thermal parameters (air temperatures, humidity, air
velocity, and radiant temperatures) and, as earlier explained,
at different heights during the peak operating hours in one
working day (breakfast, lunch, and/or dinner time).
Fig. 3. Equipment of sensors for measuring thermal parameters (color figure available online).
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1006 HVAC & R Research
Fig. 4. a. LM devices. b. SM stand placement (color figure available online).
Evaluation of clothing and metabolism
During the SMs (second walk-through), the items of clothing
worn were noted, how often and how much the clothing insu-
lation was changed, and an evaluation of thermal resistance
and vapor diffusion resistance (when possible). Later, the ther-
mal insulation value of each worker’s clothing was estimated
as stipulated in ISO 9920 (ISO 2007a).
The activity level in a kitchen changes considerably during
a working day, so a time-weighted average over each 1-h period
was calculated. The employees’ activity level was estimated by
observation and by analyses, recording the heart rate of one
or more individuals within each kitchen, together with their
age, weight, and sex, as stipulated in ISO Standard 8996 (ISO
2004b).
Subjective evaluation measurements (SM and LT)
Subjective evaluation is a very important component of any
procedure for evaluating the thermal comfort condition of an
indoor space. The methods used for the collection of occu-
pants’ perception data are described in the present article, but
the results obtained and an analysis of the subjective mea-
surements will be reported in a second article (Part 2). Two
questionnaires, one on long-term general effects (LQ) and one
on occupants’ immediate reactions (SQ), each as described in
ASHRAE Report RP-1469 (ASHRAE 2012), were used to
evaluate thermal and working conditions, to support physical
data monitoring, and to analyze the relationship between the
physical parameters of the environment and subjective aspects
Fig. 5. Seven-point thermal sensation scale (color figure available
online).
of the occupants’ perception of thermal comfort in the kitchen
environment.
The subjective evaluation of the thermal conditions was
conducted using the standard ASHRAE 7-point thermal sen-
sation scale (see Figure 5) during the physical SM. Several
other questions adapted to the kitchen environment, but based
on ISO 10551 (ISO 2001), were asked in the LQ and consisted
of eight parts: background characteristics, personal comfort,
personal control, work conditions, work area satisfaction,
health characteristics, environmental sensitivity, and clothing
(ASHRAE Report RP-1469 report [ASHRAE 2012]).
Statistical analyses
All statistical analyses were conducted with SAS software
(SAS Institute Inc., Cary, NC, USA) with a type I error rate
of α=0.05. In addition to the descriptive statistical analyses,
comparisons between kitchen types, climatic zones, and work-
ing areas were analyzed using a one-way ANOVA MEANS
procedure in SAS. The effect due to different seasons, summer
and winter, on the thermal environment was also evaluated.
Results and discussion
SMs were performed in a total of 74 commercial kitchens.
Table 2 shows the numbers of kitchens where the detailed
Table 2. Number of detailed measured kitchen.
Kitchen type Summer Winter
QSR 11 11
Casual 6 6
Institutional 22 18
Sum 39 35
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Fig. 6. Operative temperature data from all kitchen zone SMs in summer and winter (color figure available online).
SMs were carried out in the summer monitoring phase I and
in the winter phase II for each kitchen type.
An overview of the measured physical parameters in com-
mercial kitchens, in summer and in winter, is shown in the
psychometric diagram in Figure 6. The operative temperature
and air humidity data were estimated from all SMs at 1.1 m
(43 in.) height. The highest temperature values were found in
the cooking zones (up to 41.2C (106F)) and the highest RH
in the dish-washing area (up to 76%); in particular, 22 cooking
zones had a measured tohigher than 31C(88
F), while sim-
ilarly high humidity levels were recorded in food-preparation
and cooking areas. Operative temperatures tolower than 20C
(68F), and as low as 15.9C(61
F) in winter, were recorded
in a number of different kitchens zones. Those values show
that even if all kitchens were provided with AC systems, the
recorded temperatures were widely spread over a range that
was much larger than expected. The reason for such big differ-
ences in temperatures is likely to be not only poor performance
of the AC systems but factors such as the big differences in
exposure (cooking, dish washing, and preparation), keeping
food warm, etc.
From the detailed SMs, the average values of the measured
thermal parameters by type and kitchen zones were calculated
from time-averages of the SMs and then from the averages over
kitchen types or work place, and are shown in Tables 3 to 6.
Table 3 shows the yearly averages of all thermal environ-
mental parameters measured/estimated obtained from the av-
erage of SMs as a function of the number of occupants, kitchen
type, and working areas. The data show that for casual and in-
stitutional kitchens the cooking zone is the warmest; however,
for QSRs, the differences between cooking and preparation are
very small. This is due to the cooking zone and preparation
areas being close to each other in these smaller kitchens and
also due to a presence of more appliances in the preparation
zone for keeping the cooked food warm.
Commercial kitchens have air-conditioned indoor environ-
ments that are often isolated from the outdoor environment.
This is not always true for dish-washing areas, where a door or
Table 3. Average of measured physical parameters by kitchen type and zone.
Kitchen type Kitchen zone to,C(
F) ta,C(
F) tmr,C(
F) RH, % va, m/s (ft/min) Icl, clo Activity, met
Casual Cooking 31.3 (88.3) 29.2 (84.5) 35.2 (95.4) 36 0.41 (81) 0.7 4.0
Preparation 23.9 (74.9) 23.5 (74.4) 24.4 (75.9) 34 0.29 (57) 0.7 3.4
Dish washing 21.8 (71.3) 21.8 (71.3) 21.9 (71.4) 42 0.25 (49) 0.7 3.5
Institutional Cooking 30.9 (87.6) 28.5 (83.4) 34.6 (94.2) 30 0.39 (77) 0.7 3.9
Preparation 23.6 (74.5) 23.2 (73.8) 24.0 (75.3) 36 0.27 (53) 0.7 2.9
Dish washing 24.8 (76.6) 24.2 (75.6) 25.4 (77.8) 44 0.26 (51) 0.6 3.2
QSR Cooking 26.3 (79.4) 25.3 (77.6) 27.8 (82.1) 39 0.28 (55) 0.6 3.1
Preparation 25.9 (78.6) 25.4 (77.7) 26.5 (79.6) 38 0.22 (43) 0.6 2.6
Dish washing 19.8 (67.6) 19.1 (66.5) 20.4 (68.7) 42 0.14 (28) 0.6 2.4
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Table 4. Representative values of physical measurements by climatic zone and season.
Climate Number of to(±SD), va(±SD),
zone employees PMV (±SD) C(
F) RH (±SD), % m/s (ft/min)
Summer 1—Moist 32 2.7±0.9 29.0±2.8(84±5) 50 ±9 0.26 ±0.16 (52 ±31)
2/3—Moist 36 2 ±0.7 27.1±4.2(81±8) 44 ±8 0.25 ±0.08 (49 ±15)
2/3—Dry 14 2.1±2 28.3±6.2(83±11) 37 ±4 0.40 ±0.23 (79 ±45)
4—Marine 15 2.5±0.7 23.9±1.5(75±4) 51 ±5 0.31 ±0.20 (61 ±40)
4—Moist 45 2.9±1.9 26.6±5.3(80±10) 45 ±15 0.28 ±0.21 (54 ±42)
5/6—Moist 24 2.9±1.1 30.3±5.3(87±10) 52 ±12 0.49 ±0.19 (96 ±38)
5/6—Dry 15 2.1±1.7 24.9±6.1(77±11) 30 ±12 0.46 ±0.24 (90 ±47)
7—Moist 13 2.7±0.9 29.7±3.9(85±7) 31 ±4 0.29 ±0.12 (58 ±24)
Winter 1—Moist 25 0.4±1 25.4±3.3(78±6) 49 ±10 0.34 ±0.16 (67 ±32)
2/3—Moist 22 0.3±1.4 26.8±5.2(80±10) 20 ±6 0.25 ±0.09 (50 ±17)
2/3—Dry 21 0.8±0.9 26.3±4.2(79±8) 24 ±8 0.16 ±0.10 (32 ±19)
4—Marine 13 0 ±0.6 20.5±2.7(69±5) 38 ±4 0.19 ±0.13 (36 ±25)
4—Moist 47 0.7±1.1 25.8±5.1(78±9) 29 ±9 0.20 ±0.10 (40 ±19)
5/6—Moist 22 –0.8±1.3 23.1±4.5(74±8) 26 ±10 0.26 ±0.11 (52 ±22)
5/6—Dry 12 0 ±1.2 24.0±4.2(75±8) 22 ±8 0.40 ±0.31 (79 ±61)
7—Moist 8 –0.2±0.9 24.3±2.5(76±5) 18 ±2 0.41 ±0.20 (80 ±39)
Table 5. Representative values of physical measurements by climatic zone and season.
Summer Winter
Climate Number To (±SD), Number To (±SD),
zone of SMs C(
F) of SMs C(
F)
1—Moist 12 29.8±4.0(86±7) 11 25.4±3.3(78±6)
2/3—Moist 13 27.6±4.9(82±9) 9 25.7±5.5(78±10)
2/3—Dry 7 27.1±5.8(81±10) 11 25.6±4.7(78±8)
4—Marine 8 24.0±1.7(75±3) 5 21.3±2.6(70±5)
4—Moist 22 26.5±4.7(80±8) 20 24.5±4.8(76±9)
5/6—Moist 5 30.8±5.5(87±10) 7 23.7±5.6(74±10)
5/6—Dry 9 28.8±5.8(84±10) 11 23.3±3.8(74±7)
7—Moist 8 29.0±4.0(84±7) 5 24.1±3.1(75±6)
Table 6. Representative values of physical measurements by kitchen type and zone.
Summer Winter
Kitchen Kitchen Number of To (±SD), Number of PMV To (±SD),
type zone employees PMV (±SD) C(
F) employees (±SD) C(
F)
Casual Cooking 15 4.9±0.8 34.9±1.7(95±6) 14 1.0±1.2 27.4±3.5(81±13)
Preparation 5 2.4±0.8 28.7±1.6(84±6) 10 –0.2±1.1 21.4±2.8(71±10)
Dish washing 2 2.0±0.4 28.7±0.1(84±0) 6 –0.2±0.7 19.5±3.1(67±11)
Institutional Cooking 38 3.7±1.4 30.9±5.3(88±19) 30 1.6±0.9 30.4±4.8(87±17)
Preparation 59 1.7±0.9 24.0±3.7(75±13) 46 0.2±0.7 23.1±3.1(74±11)
Dish washing 25 2.1±1.1 24.7±2.6(76±9) 23 0.3±0.8 24.9±2.8(77±10)
QSR Cooking 12 2.8±0.6 29.1±2.8(84±10) 12 –0.2±1.0 23.6±3(74±11)
Preparation 37 1.8±0.5 26.6±2.6(80±9) 25 –0.4±0.9 24.8±2.9(77±10)
Dish washing 1 1.2±n.a.21.4±n.a.(71 ±n.a.)42.3±1.5 19.4±3.3(67±12)
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Volume 19, Number 8, November 2013 1009
Fig. 7. Average of PMV and operative temperature (to) for climate zones with 95% confidence interval (color figure available online).
a window to the outside can be opened for by the employees.
Regardless of the season, the average data in Table 3 is likely to
be representative of most kitchen environments. More detailed
data analyses are given in what follows.
Table 4 and Figures 7 and 8 set out the calculated PMV
index and measured operative temperature averages for each
climatic zone during the summer and winter. The values are
averages over the climatic zone and weighted by the num-
bers of occupants that took part in the thermal comfort
evaluation.
Even if the average PMV values are within the PMV range
±3 (see Table 4 and Figure 7a), several individual values are
outside this range (see Figure 8), indicating that the PMV
index is not really applicable; ISO Standard EN 7730 (ISO
2005) recommends using the PMV-index only in the interval
±2, meaning that most of the measured conditions are outside
the range, indicating a high percentage of dissatisfaction.
In Figure 8, from the lower line up, the 10th, 25th, 50th
(the median), 75th, and 90th percentiles of PMV values are
displayed, with dots representing the outliers. The figure
shows that the PMV differences between climatic zones
during summer or winter are not significant. Within each
climatic zone, a high percentage of calculated variables fall
into the gray area, which was not studied in the thermal
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1010 HVAC & R Research
Fig. 8. Median of PMV with percentile variables for climate zones in summer and winter (color figure available online).
comfort model, indicating once more that the PMV model
should not be applied to commercial kitchens.
In Figures 7a and 7b, where the variability of PMV and to
around the means are reported, it is evident that the opera-
tive temperatures show larger differences between the climatic
zones during summer and winter.
Working conditions in climate zones 1—moist, 5/6—moist,
and 7—moist were significantly warmer than in climate zones
4—marine and 5/6—dry (p<0.02). During winter, the PMV
index was significantly lower in kitchens in climate zone
5/6—moist (p<0.01), while the operative temperature was
significantly lower for kitchens in climate zone 4—marine.
In all climatic zones, the PMV index was significantly lower
during winter than during summer. This is not the same for op-
erative temperature. For climate zones 2/3—dry, 2/3—moist,
4—moist, and 5/6—dry, there were no significant differences
between winter and summer.
When comparing the differences in temperature and
PMV, in particular between climate zones 4—marine and
2/3—moist, it should be noted that in 4—marine, the tem-
perature was much lower than in 2/3—moist, but the PMV
was much higher. This discrepancy was due to the effects that
the other physical parameters (reported in Table 4), the cloth-
ing insulation (Icl =0.6–0.7 clo) and the activity level (on
average equal to 3.2 met ±0.9 of standard deviation), have on
the PMV index. In this study, the ANOVA analysis shows a
significant effect on the PMV of the combination of to,RH,
Icl, and metabolic rate together (F=8.3 and p=0.004), with
the single highest effect being that of operative temperature (F
=7.4, p=0.007, and R2=0.52) and the second highest that
of the activity level (F=6.6, p=0.01, and R2=0.21).
The actual average values of operative temperature (SM)
are shown in Table 5 for each climatic zone during summer and
winter. The unweighted values of the operative temperature in
each climatic zone were higher in summer and slightly lower in
winter than the values weighted for occupancy. However, they
are still representative of hot kitchen environments in summer
and warm in winter with an exception for 4—marine climate
zone, where commercial kitchens tended to provide the most
thermally comfortable environments.
In Table 6 and Figure 9, the PMV index and operative
temperatures for the three kitchen types and for three working
areas are reported as an average of all the values within each
kitchen type.
When looking at the results for summer and winter in
Table 6, it is clear that the PMV index for the cooking zone in
summer is well above the range where the index is applicable.
For casual and institutional kitchens, the cooking zone had a
significantly higher PMV index and operative temperature (p
<0.01) than other work zones. The PMV index for winter was
within the range of application of the index. For all kitchen
types and work zones, the winter kitchen temperatures were
colder than the summer.
As may be seen in Figure 9, the PMV of QSRs was signif-
icantly different from that of the other types of kitchens. In
the institutional and casual kitchens, there was no significant
difference between the preparation and dish-washing zones,
while for QSR kitchens, there was no difference between the
cooking and preparation zones. The dish-washing zone was
colder, but as very few data points were obtained, the confi-
dence interval is very large.
The method applied showed that the procedure to be used
in commercial kitchens must differ from what is used in offices,
as more detailed measurements (different zones and more ver-
tical points) are required.
The measured vertical air temperatures, globe tempera-
tures, and vertical air temperature profiles, for summer and
winter,aregiveninTables7and8andinFigure10.The
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Volume 19, Number 8, November 2013 1011
Fig. 9. Average of PMV and operative temperature (to) for kitchen type and kitchen zones with 95% confidence interval (color figure
available online).
Fig. 10. Vertical profiles of average temperature distribution at the cooking line in summer (left) and winter (right) (color figure
available online).
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Table 7. Average of temperatures by kitchen type and zone in summer.
Globe temperature Air temperature tota
Kitchen Kitchen 0.1 m (4 in.), 1.1 m (43 in.), 1.7 m (67 in.), 0.1 m (4 in.), 1.1 m (43 in.), 1.7 m (67 in.), (head–feet (head–feet
type zone C(
F) C(
F) C(
F) C(
F) C(
F) C(
F) level), K (F) level), K (F)
Casual Cooking 29.2 (85) 34.5 (94) 37.9 (100) 28.1 (83) 32.6 (91) 36.3 (97) 8.6168.115
Preparation 26.8 (80) 27.8 (82) 28.4 (83) 26.5 (80) 27.4 (81) 28.1 (83) 1.6 3 1.6 3
Dish washing 26.8(80) 27.9 (82) 28.8 (84) 26.6 (80) 27.9 (82) 28.9 (84) 2.1 4 2.3 4
Institutional Cooking 26.6 (80) 30.6 (87) 33.3 (92) 24.9 (77) 28.4 (83) 29.3 (85) 6.7124.4 8
Preparation 24.2 (76) 24.6 (76) 24.9 (77) 23.4 (74) 24.2 (76) 24.5 (76) 0.7 1 1.1 2
Dish washing 24.6 (76) 25.2 (77) 25.6 (78) 23.9 (75) 24.8 (77) 25.5 (78) 1.0 2 1.6 3
QSR Cooking 25.4 (78) 28.6 (83) 30.4 (87) 24.2 (76) 27.3 (81) 29.0 (84) 5.094.79
Preparation 24.5 (76) 26.1 (79) 27.1 (81) 23.7 (75) 25.9 (79) 26.8 (80) 2.6 5 3.1 6
Dish washing 23.4 974) 24.2 (76) 24.9 (77) 22.5 (72) 23.9 (75) 24.8 (77) 1.5 3 2.3 4
Bold indicates high vertical temperature differences in the cooking line.
Table 8. Average of temperatures by kitchen type and zone in winter.
Globe temperature Air temperature tota
Kitchen Kitchen 0.1 m (4 in.), 1.1 m (43 in.), 1.7 m (67 in.), 0.1 m (4 in.), 1.1 m (43 in.), 1.7 m (67 in.), (head–feet (head–feet
type zone C(
F) C(
F) C(
F) C(
F) C(
F) C(
F) level), K (F) level), K (F)
Casual Cooking 23.7 (75) 26.4 (79) 30.5 (87) 22.4 (72) 24.6(76)27.7(82)6.8(12)5.3(10)
Preparation 20.8 (69) 22.1 (72) 22.6 (73) 20.5 (69) 21.7(71)22.4(72)1.9(3) 1.9(3)
Dish washing 19.1 (66) 20.3 (68) 20.7 (69) 18.9 (66) 20.1(68)20.3(68)1.6(3) 1.4(2)
Institutional Cooking 26.1 (79) 29.6 (85) 33.0 (91) 24.9 (77) 27.0(81)28.8(84)6.9(12)3.9(7)
Preparation 22.5 (73) 23.6 (75) 24.5 (76) 21.9 (71) 23.1(74)24.4(76)2.0(4) 2.5(4)
Dish washing 22.9 (73) 24.3 (76) 25.0 (77) 22.1 (72) 23.5(74)24.9(77)2.1(4) 2.7(5)
QSR Cooking 20.8 (69) 23.9 (75) 27.2 (81) 20.1 (68) 23.1(74)26.5(80)6.4(12)6.4(12)
Preparation 21.5 (71) 23.7 (75) 24.8 (77) 20.9 (70) 23.2(74)24.3(76)3.3(6) 3.4(6)
Dish washing 19.2 (67) 20.9 (70) 22.1 (72) 18.4 (65) 20.4(69)21.9(71)2.9(5) 3.5(6)
Bold indicates high vertical temperature differences in the cooking line.
1012
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Volume 19, Number 8, November 2013 1013
Fig. 11. Air and operative temperature (taand to) variations in the three kitchens zones in summer and winter; shaded area indicates
time of occupancy (color figure available online).
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1014 HVAC & R Research
conditions in the food-preparation and dish-washing zones
were uniform and within normal comfort criteria, providing a
vertical temperature difference between head (1.7 m (67 in.))
and feet (0.1 m (4 in.)) of 3–4 K. Due to the high level of
thermal radiation falling on a worker’s upper body and head,
the vertical temperature differences in the cooking line were
very high, as shown by the bold numbers in Tables 7 and 8, up
to 16F (8.6 K) for the casual kitchen type in summer and up
to 12F (6.9 K) for institutional kitchen in winter.
The warm/hot environment in the cooking area exposed
the workers to temperatures higher than the 88F(31
C), lim-
iting exposure temperature as suggested by Weihe (1987). This
may have negative health consequences (ASHRAE 2009).
As the food-preparation and dish-washing zones would not
be expected to cause any thermal discomfort for the kitchen
staff, the vertical temperature profiles shown in Figure 10 are
only the actual average values for the cooking zones in summer
and winter. The casual and QSR kitchens show different tem-
perature distributions in summer and winter, unlike the insti-
tutional kitchens, which were found to have a similar thermal
environment at both times of year, most probably due to the
different type and use pattern of the HVAC systems installed
in them. However, the cooking line in the institutional kitchens
seems to be the environment where the occupants may com-
plain more of radiant asymmetry (as indicated by the larger
difference between globe/operative and air temperature).
The large difference in the thermal environment between
summer and winter in casual kitchen types was probably due
to more frequent use of natural ventilation for cooling. The
present results indicate that casual kitchens provide the worst
environment for kitchen staff, although this remains to be
corroborated by the forthcoming analysis of their subjective
evaluations.
LMs
An example of the LMs that were obtained is shown in Fig-
ure 11 for a QSR kitchen located in Miami, FL. Figure 11
shows the air and operative temperatures recorded, as broken
and solid lines, respectively. During the 24-h data-recording
period, the temperature variation that directly influenced em-
ployees’ thermal comfort occurred during assumed operating
hours from 10:00 a.m.to 10:00 p.m., represented by the shaded
areas.
During the summer, considerable diurnal temperature vari-
ations in the cooking line occurred, rising from 79Fto98
F
(26.1C to 36.7C), and detailed measurements were recorded
(Figure 11a) during peak operating periods. The tempera-
ture in the food-preparation line and dish-washing area had
a daily temperature variation in the range of 72Fto92
F
(22.2C to 33.3C) and 75Fto90
F (23.9C to 32.2C), re-
spectively during working hours. Thermal radiation from the
hot appliances raised the operative temperature by an ad-
ditional 10F(5.8
C). At night, the temperatures decreased
but were still high; the air and operative temperatures in
the food-preparation and dish-washing areas were similar. As
shown in Figure 11b, the temperature increase in winter was
the same in all kitchens zones: 9F(4.9
C) during operating
hours.
Conclusions
A method and procedure for evaluating the indoor ther-
mal environment in commercial kitchens was developed. This
method consisted of:
LMs of radiant temperature, air temperature, and humidity
over 1 week in three kitchen workspaces: cooking, dish
washing, and food preparation.
on-site SMs of air temperature and operative (radiant) tem-
perature at different heights, along with air velocity and
humidity in three work areas: the cooking, dish-washing,
and food-preparation zones;
an on-site survey of occupants’ subjective evaluation of the
indoor environment, performed at the same time as the SMs
are made;
a general survey of background information about the oc-
cupants and of their general evaluation of the working
conditions.
The proposed procedure was validated during on-site mea-
surements performed in more than 100 kitchens located in
9 states of the United States during the summer and winter
seasons. The procedure can be recommended for data collec-
tion in future studies and for evaluating future kitchen appli-
ances. The results obtained in the validation study establish
a benchmark database for the thermal environment in com-
mercial kitchens. Differences due to climatic zone, summer
and winter, and type of kitchen were found. The most criti-
cal environment for kitchen staff is the cooking zone, where
temperatures and vertical temperature differences that were
too high for comfort and health were measured. The calcu-
lated PMV index values did not differ between climatic zones
in either summer or winter, while the operative temperatures
differed greatly. The thermal environment in casual kitchens
varied seasonally, and kitchen staff in such kitchens are very
likely to be exposed to uncomfortable thermal environments.
Only the physical measurements are reported in the present
article, so these conclusions are restricted to them. They must
be corroborated by the subjective evaluations that were ob-
tained at the same time, and this will be reported in a subse-
quent article.
It is the view of the authors that the general evaluation
criteria for thermal comfort often used in office environments
cannot be applied in commercial kitchens. The PMV index
values obtained were often above +3 and significantly outside
the upper limit reccommended in international standards for
the applicability of the PMV index (+2).
The standard PMV-PPD index is thus not suitable for ap-
plication in commercial kitchens, due to the combination of
high activity levels and high air and radiant temperatures.
The present study indicates that it will be necessary to estab-
lish a method (and a standard) for assessing the acceptability
of working environments providing conditions that range be-
tween thermal comfort and heat stress.
Acknowledgments
This project was supported by ASHRAE RP-1469 “Ther-
mal Comfort in Commercial Kitchens” and the International
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Volume 19, Number 8, November 2013 1015
Centre for Indoor Environment and Energy at the Techni-
cal University of Denmark (DTU). The Culinary Institute of
America (CIA) provided additional and substantial support.
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... Simone et al. [38] directed a study on commercial kitchens in the United States using PMV and PPD indices based on physical measurements. The consequence of this indicated that the most suitable thermal comfort index PMV is not directly applicable to kitchens due to high temperature and high metabolic rate. ...
... (1.1 m) above the workstation floor" as per the recommended by ASHRAE standard [5]. The chest and facial area are a significant body part that is affected due to temperature variation inside the commercial kitchen environment [35,38]. Hence the temperature difference of medium and standing activity level of work condition inside the kitchen like pantry car should be recorded as per the recommendation. ...
... The measuring distance and height of the MRT are assumed to be similar to the "air temperature" in commercial kitchen environments [5,38,41]. Air movement has an essential impact on the variation of "MRT and air temperature". The comfortable range of MRT for official occupants 18°C-27°C, which varies on the person's clothing and activity level. ...
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Railway transportation plays a significant contribution to carrying passengers in India. In which during the journey, pantry cars are involved to serves the food to all onboard passengers. The kitchen atmosphere of the pantry car gets very hot and humid during cooking which could affect occupants’ thermal comfort. Therefore, the current research article describes a review of the factors affecting human thermal comfort inside the kitchen of the railway pantry car. The factors influencing of human thermal comfort inside pantry car kitchens are classified into two categories viz; environmental factors that include “air temperature, mean radiant temperature, relative humidity, air velocity” and personal or individual factors including “metabolic rate and clothing insulation”. All these factors need to be considered in order to achieve the optimum level of thermal comfort inside the kitchen environment of the pantry car. With the assistance of all these factors, we can estimate the thermal comfort indices such as; SET “standard effective temperature,” PMV “predicted mean vote,” PPD “predicted the percentage of dissatisfied,” thereby recognizing the acceptable thermal sensation range for occupants’ (chefs) in the pantry car kitchens during the work period. These kinds of parametric studies can cover a wide group of all pantry car chefs in evaluating thermal comfort. Furthermore, there is a need to apply all the consequences of this research to increase the chef’s thermal comfort inside the pantry car kitchen while working.
... Rahmillah [5] conducted thermal comfort research on residential kitchen in Indonesia and found that the Predicted Percentage Dissatisfied (PPD) among cooking workers were as high as 90%. Simone [6] tested the physical measurements of the cooking zone, preparation zone, and dish-washing zone of more than 100 commercial kitchens in the United States in both summer and winter and collected the subjective parameters of the kitchen staff. They revealed that there was a highly uneven in the kitchen environment and pointed out that staff was exposed to a warm to hot environment. ...
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This study investigated the annual variation of the indoor thermal environment in a typical canteen kitchen and tried to evaluate the actual working status of the exhaust fume system. Parameters were measured in the canteen kitchen, including indoor environment (temperature, humidity, air velocity); outdoor environment (temperature; humidity); exhaust fume system (temperature, airflow rate, oil fume concentration, energy consumption), and makeup air system (temperature, humidity, air velocity) from April 2019 to January 2020. In addition, we also interviewed the chef’s thermal comfort in this kitchen. From the data available, we could find that 82.92% of the working hours in summer were above the acceptable range. Only 17.08% of the working hours were within the tolerance range (26–32 °C). The questionnaire results showed that 83.33% of chefs felt hot in summer. Most chefs’ wet sensations in the four seasons were neutral, and 91.6% of the chefs felt dissatisfied with the draft sensation. In addition, 88.33% of the chefs felt the fume overflowing from the exhaust hood. This may be because the exhaust fume system of the canteen kitchen was operated under the air velocity of 9.18 ± 1.6 m/s, and its exhaust airflow rate was 10,634.80 ± 189.30 m3/h, which is lower than the minimum exhaust airflow rate (12,312 m3/h). The measurement results indicated that the exhaust fume system could not remove the waste heat and fume pollutants effectively.
... Hourly vehicle traffic count by vehicle type on Des Voeux RoadWest, July 14-16, 2014 The peak kitchen temperature was estimated to be 41.2 °C based on a summer time field study conducted in Miami, USA under similar subtropical climates(Simone et al., 2013). Such a high temperature is reasonable for Hong Kong, given that cooking with open fire is commonly practiced in local cuisine. ...
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How much can greenery cool a city remains inconclusive in literature, especially in a high-density city where plants interact with anthropogenic heat from surrounding buildings and traffic. A novel simulation model, the Urban Greenery and Built Environment, was developed to assess the time-varying interactions between plants and anthropogenic heat at street scale. The model has been evaluated using field studies in two parks in Hong Kong. A reasonably good agreement was observed between measured and predicted temperature and humidity. Sensitivity studies were then conducted to compare the cooling performances of greenery in five scenarios under various coverage ratio and climates. By covering 40% of site with greenery, a practical limit, the expected air temperature and UTCI reductions were 0.3 °C, lower than previous estimates due to limited sunlight and ground-level surfaces for planting; the cooling benefits of greenery were predicted to be higher in dry climates and lower in humid ones. In a high-density city, plants converted sensible heat into latent gains at a slower rate than the anthropogenic exhaust heat. Alternative strategies, such as breeze enhancement, water-spray and management of anthropogenic heat discharges were predicted to further help to cool the city by 3.1 °C, 6.8 °C, and 1.8 °C, respectively.
... Continuous operation of and proximity to high heat-generating ovens and food warmers, inadequate or insufficient ventilation, a high worker density compared with the physical size of the kitchen space and a lack of adherence to a proper work/rest schedule because of constant meal demand are all factors that may contribute to levels of excessive heat stress in this setting. Simone et al. (2013) found that the interior temperature in restaurant kitchens is unacceptable and climate zone influences thermal conditions in the kitchens. Where temperatures can be raised by machines, cooking equipment and inadequate ventilation, the kitchen staff is most at risk, with dry temperatures in the kitchen exceeding 30 °C (Heinonen 1997). ...
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The article examines the gender disparities as women are at a greater risk to exertional heat illness that may go unreported in the industry, according to several reports. It is important to study the behavioural heat adaptations and prevalent behaviours for workers in order to understand the magnitude of the danger they face. Cooking is considered a safe occupation, but hazards certainly do exist and can represent a risk to the health and safety of the workers. Controls can be established to reduce the risk of illness. To attract and retain workers, the food service business must provide a good quality of life. Contribution: The study suggests how female workers in the catering establishments can adjust their behaviour to improve their experience at work. Are women more vulnerable to environmental parameters? Christian theology provides women equal status with men (Kategile 2020), however there are traces of androcentric aspects within the Bible. Women’s involvement in development is based on the theological premise that true development must have a holistic approach towards human development (Onwunta 2009). However, Sibani (2017) stated that the role of God or a creator of a religion, is always taken by a male and a woman’s place is in the household. The article conducts a comprehensive analysis of the literature on the various behavioural adaptation mechanisms used by kitchen staff to cope with heat exposure at work. Thermal tolerance variations are becoming more pronounced because of ethnicity and cultural differences. Health interventions and enhanced work performance are important objectives of workplace safety. Regulated heat in the workplace can be factored into the theory concerning the relationship between gender differences and contextual components. This would increase female food service workers’ understanding of thermal comfort, which is beneficial to productivity efficiency, worker satisfaction and well-being of workers.
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Indian Railways is one of the largest passenger transport networks in the “world” covering almost all parts of the subcontinent. Pantry car is an integral part of the railway, which provides food to the passengers during the journey. This study aims to evaluate the “indoor and outdoor thermal comfort parameters” and working conditions in the kitchen of the Indian “railway pantry car”. The field measurement was carried out during the summer season on six “Indian Railway Pantry Car Coaches (IRPCs)”. The “indoor and outdoor environmental parameters” were recorded during different cooking periods; “breakfast, lunch, snacks, and dinner” inside the pantry car. The consequence of this study revealed that the “indoor thermal comfort parameters” like; “wet-bulb temperature, mean radiant temperature, air temperature, relative humidity” were higher as compared to outdoor parameters except for air velocity. Most of the time, indoor parameters were higher during the lunch and snacks periods while lower at the breakfast period. Similarly, indoor Heat Index (HI) value was recorded higher than the outdoor. The indoor HI values range were found to be (40–58 °C), which indicated “danger to extreme danger” work condition. These outcomes will help to understand the “working environment of the railway pantry car kitchen”. Further, data measurements during winter and other seasons could be used to predict the thermal environment of the “pantry car”.
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In the contemporary research work, the Response Surface Methodology (RSM) is used to simultaneously maximize compressive strength and minimize the absorption of water in the cement mortar (nano materials blended). Three important process parameters including nano silica (0–3wt%), w/c ratio (0.48–0.52wt%), and Plasticizers (0–1wt%) were augmented to acquire the best values of response using the numerical box-behnken design with desirability analysis. The nano silica was replaced by cement in 0%, 1%, 2%, and 3% and water–cement ratios of 0.48, 0.50, and 0.52 with the addition of 1% of polycarboxylate admixture in the cement mortar separately. The research work aims to increase the mechanical properties of cement mortar using nano silica and mineral admixtures. The compression test was carried out using ASTM standard mortar cube to investigate their mechanical properties. The optimal results showed that the nano mortar with 2% nano silica, 0.5 water cement ratio (w/c), and 1% plasticizers, attaining high compressive strength and effectively increasing the mechanical properties of cement mortar.
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In normal cooking system in which we used to place cooking utensil directly on open flame, the thermal efficiency of the cooking utensils is ranging in between 25 and 40%. There are some mechanisms and day to day practices through which we can increase this efficiency value up to above 65%. For this one effective method is to enhance or modify the shape and size of cooking utensils we are using in our kitchens. This cooking utensils can be of various sizes depending on BIS standards mentioned time to time. Open utensil cooking is generally widely used method for cooking at different strata of society. LPG consumption for such different strata of society should be analyzed, and efforts should be done to minimize the overall energy consumption value. This can be achieved by enhancing geometry of utensil and checking effect of different parameters on their efficiency. Here a systematic work has been carried out in which parameters like utensil shape and size, its different aspect ratio, its volume has been considered, and results are drawn showing effect of varying aspect ratio on thermal efficiency of utensil as well as on overall gas consumption in cooking process. Finally, most efficient modified utensil has been deduced out of selected ones.KeywordsEfficient cooking potsThermal efficiencyOptimum shape
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Background: The hot and humid environment inside the kitchen is a cumulative sign of health impact that deteriorates the well-being and productivity of cooking workers, which could be a barrier to thermal comfort. As the cooking task progresses throughout the day, uncomfortable thermal conditions inside a kitchen work environment may diminish the work quality of the kitchen workers. Objective: The objectives of the study were to evaluate the measured environmental factors of thermal comfort during various cooking periods [morning, day, evening, night] and examine the occupant's perception votes followed by further investigating the worker's thermal comfort conditions using PMV, PPD, SET, WBGT, and TSI indices. Methods: The study was carried out inside the kitchen of the university canteen at IIT Guwahati, India. The objective and subjective measurements were accomplished during the summer season, while CBE thermal comfort software was employed for calculating the thermal comfort indices like PMV, PPD, and SET. Results: The results of this study revealed that during entire cooking time, the recorded environmental factors of thermal comfort were found outside the recommended limits as per ASHRAE-55 standard, which indicates very hot prevalent conditions. Also, cook's perception vote (TSV, TCV) for the existing environment did not follow the central three categories of votes (+1, 0, -1), even the cooking workers were also not satisfied with the prevailing environmental conditions, as 88% subjects responded dissatisfaction with the thermal environment. While, estimated values of thermal comfort indices (PMV, PPD, and SET) designated morning time cooking period slightly comfortable than the other cooking periods, but still not accordance with the ASHRAE-2017 standard. The WBGT index designated day cooking period as hazardous, with rest of cooking periods under severe risk level. In contrast, the TSI index indicated entire cooking periods under "slightly warm" thermal sensation. Conclusion: The assessment of this study showed that the existing kitchen environment of the university canteen is not conducive for workers. Improper ventilation design may cause the overheating inside the kitchen, which may increase the dissatisfaction rate of the employed workers and also affects the energy savings in the kitchen environment, which helps maintain thermal comfort. Further studies are required to improve the thermal comfort of the kitchen occupants by providing proper design interventions based on heating and cooling air ventilation systems.
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The present study investigates the type of temperature sensor that best represents the operative temperature, i.e., the type of sensor that will integrate the influence of air and mean radiant temperature in the same way as a person. Size, shape and colour of the sensor will have an impact on the relative influence of air and mean radiant temperature in a space. In an experimental chamber different combinations of air temperature and radiant heated or cooled surfaces were tested. Several types of sensor (flat, sphere, ellipsoid, half-sphere, grey, black, white) were used to measure the operative temperature. Besides comparing the type of sensor, the influence of the sensor position in the room was experimentally investigated. The results show that a grey sensor of 3-5 cm diameter is the best size. The best shape, however, depends on the position of the sensor in the space.
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A commercial kitchen is a complicated environment where multiple components of a ventilation system including hood exhaust, conditioned air supply, and makeup air systems work together but not always in unison. That is why many kitchens are hot. A hot and uncomfortable kitchen contributes to productivity loss, employee turnover, and eventually profit loss for the restaurant operator. Using thermal displacement venti- lation in kitchen environment allows for a reduction in space temperature without increasing the air-conditioning system capacity. Application of two systems (traditional mixing venti- lation system and thermal displacement ventilation system) is compared in a typical kitchen environment using computa- tional fluid dynamics (CFD) modeling. Often kitchen exhaust hoods are provided with untempered makeup air. It is not uncommon to hear the claim that this makeup air is exhausted through the hood without having any effect on kitchen space temperature. The validity of this claim is analyzed in this paper for two makeup air configurations using a combination of measured data and results from CFD models. Kitchen space temperature increase is calculated as a result of supplying unconditioned makeup air during the summer.
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In a country such as the United States, the largest employee sector is in the restaurant industry. This makes the commercial kitchens an important space that needs to be evaluated and consequently improved in terms of thermal comfort and indoor air quality conditions, for the wellbeing of the employees. It is relevant to know how the employees assess the thermal conditions and what their subjective reactions in commercial kitchens are. The subjective feedback is the effective way, together with the physical measurements, of defining the values of thermal comfort parameters in commercial kitchens. Today, no study on subjective feedback from kitchen employees has been reported. In the present paper, two types of survey were developed and tested in the field. The questions are based on the ISO 10551 standard and adapted to the kitchen environment. Answers dealing with the working conditions and the environment in general, including some facts about the person (age, weight, height, etc.), and SBS symptoms, were recorded.
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Conditioning the outdoor air to replace air exhausted from a commercial kitchen imposes a significant energy burden. A primary component of all DCV systems is the variable frequency drives (VFD) on both the exhaust and makeup air fans. Integrated with a strategy to monitor appliance activity under the hood, the DCV system will modulate the exhaust and makeup air fans in concert with appliance use. The need for an easy-to-use tool that would accurately determine the heating and cooling load for a given amount of outdoor air led to the development of a no-cost, publicly available software tool, the Outdoor Air Load Calculator (OALC). The cornerstone of a DCV system is the complement of VFDs that allow the DCV microprocessor to modulate the exhaust and make-up air fan speed in response to cooking appliance activity. It also provides speed adjustment necessary if a direct-drive fan is to be used. Without a VFD, usually the speed of a direct-drive fan cannot be field adjusted, and the ability to balance airflow on a CKV system is virtually impossible.
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This article describes kitchen air supply methods for increased thermal comfort, ventilation effectiveness and worker productivity. The design of ventilation systems for commercial kitchens is one of the most demanding tasks facing the professional engineering community today. The large amounts of effluent released during the cooking process, combined with excess convective and radiant heat, create hostile environments for kitchen personnel. The challenge is enormous for design engineers, as well as for the manufacturers of kitchen ventilation products, to provide comfortable working conditions in kitchens utilizing today's diverse cooking equipment.
ANSI/ASHRAE Standard 169-2006, Weather Data for Building Design Standards
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