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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 ba International Centre for Indoor Environment and Energy (ICIEE), Department of CivilEngineering , Technical University of Denmark (DTU) , Nils Koppels Allé, Building 402,DK-2800 , Kgs. Lyngby , Denmarkb Sustainable Use Consulting at DNV KEMA Energy & Sustainability , Oakland , CA , USAAccepted 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 incommercial kitchens (RP-1469): Procedure and physical measurements (Part 1), HVAC&R Research, 19:8, 1001-1015, DOI:10.1080/10789669.2013.840494

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HVAC&R Research (2013) 19, 1001–1015Copyright C© 2013 ASHRAE.ISSN: 1078-9669 print / 1938-5587 onlineDOI: 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 ofDenmark (DTU), Nils Koppels Alle, Building 402, DK-2800 Kgs. Lyngby, Denmark2Sustainable 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 thekitchens. Moreover, the size and arrangement of the kitchen zones, appliances, etc., further complicate an evaluation of the indoorthermal environment in commercial kitchens. In general, comfort criteria are stipulated in international standards (e.g., ASHRAE 55or ISO EN 7730), but are these standardized methods applicable to such environments as commercial kitchens? This article describesa data collection protocol based on measurements of physical and subjective parameters. The procedure was used to investigate morethan 100 commercial kitchens in the United States in both summer and winter. The physical measurements revealed that there is alarge range of kitchens environments and confirmed that employees are exposed to a warm-to-hot environment. The measured rangesof activities and temperatures in many cases were outside the range recommended by ASHRAE 55 and ISO EN 7730. The studyshowed that the predicted mean vote/percentage people dissatisfied (PMV/PPD) index is not directly appropriate for all thermalconditions in commercial kitchens.

Introduction

The restaurant industry in the United States is the nation’ssecond largest private sector employer, with its workforce of12.8 million projected to increase by 1.3 million positions in thenext decade (National Restaurant Association [NRA] 2012).As nearly one in ten of all employed Americans worked in arestaurant in 2011, the NRA expected restaurants to add jobsat a 2.3% rate in 2012, a full percentage above the projected1.3% 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 restaurantpositions compared to 1.4% for overall U.S. employment. Anadditional 2.4% increase in restaurant jobs is expected in theUnited States in 2013, which will result in 13.1 million ofrestaurants employees equal to 10% of the U.S. workforce(NRA 2013).

For countries such as the United States, where one of thelargest 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 manydifferent HVAC applications must operate within a sin-

Received February 4, 2013; accepted August 22, 2013Angela Simone, PhD, Associate Member ASHRAE, is Re-searcher. Bjarne W. Olesen, PhD, Fellow/Life MemberASHRAE, is Professor and Centre Director. John L. Stoops,PhD, Member ASHRAE, is Senior Principal Consultant. AmberW. Watkins is Consultant.∗Corresponding author e-mail: asi@byg.dtu.dk

gle space. Those different applications can be designedand determined by the appliance line and should followthe guidelines in the kitchen ventilation chapter of the2011 ASHRAE Handbook—HVAC Application (ASHRAE2011b), ASHRAE Standard 154 (ASHRAE 2011a), andin prEN16282 (ISO 2011). In the context of energy-savingstrategies, ASHRAE/IES Standard 90.1 (ASHRAE 2010b)contains more restrictive requirements for transfer air,demand-controlled ventilation (DCV), energy recoverydevices, and high performance hoods. Recent studies and de-velopments have attempted a total kitchen HVAC (TKHVAC)system approach and DCV for commercial kitchens, whichare expected to become a standard energy efficient prac-tice (Fisher et al. 2013). However, an acceptable thermalenvironment 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 ofthe indoor thermal environment in kitchens.

Previous studies in commercial kitchens have focusedmainly on air-conditioning and ventilation systems. Whenconsidering thermal comfort, such studies as Pekkinen andTakki-Halttunen (1992) and Livchak et al. (2005) dealt mainlywith the acceptable ranges of physical parameters reported instandards, 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) orISO Standard EN 7730 (ISO 2005), but it is questionablewhether these standardized methods are applicable to envi-ronments like commercial kitchens.

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Today there are no specific regulations or even parame-ters to determine whether thermal conditions in commercialkitchens are comfortable or cost effective. General evaluationcriteria for thermal comfort may be inadequate and unsuitablefor practical application.

Based on standardized methods (ASHRAE and ISO) andon pre-tested pilot measurements, Simone and Olesen (2012aand 2012b) introduced a procedure for collecting data on thephysical 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 UnitedStates in order to obtain enough of data to be able to evaluatethermal 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 climaticregion are analyzed in terms of the measurements using ex-isting comfort evaluation indices, such as the predicted meanvote/percentage people dissatisfied (PMV/PPD) index, andthe applicability in commercial kitchens is evaluated. The sub-jective evaluations were analyzed and used to define a thermalcomfort range in a warm environment in which the occupantshave high activity levels. These results are presented in Part 2of this series.

Evaluation of the thermal environmentin commercial kitchen

For many years the International Organization for Standard-ization (ISO) and ASHRAE have been developing standardsfor the indoor thermal environment. ASHRAE has mainlydeveloped standards for moderate thermal environments (e.g.,ASHRAE 55/2010 [ASHRAE 2010a]), while ISO standardscover the entire range from cold stress to comfort to heat stress(e.g., ISO EN 7730/2005 [ISO 2005], ISO EN 7933/2004 [ISO2004a], and ISO EN 11079/2007 [ISO 2007b]).

Thermal comfort is one of the four elements that influencethe 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 whichexpresses 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 intospecifications in terms of physical parameters.

PMV is the most widely used index for evaluating indoorthermal comfort, but it is recommended only for valuesbetween ±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 thermalsensation that is too warm or too cold (i.e., the percentage dis-satisfied, PPD) or the percentage dissatisfied by local thermaldiscomfort (PD) due to draught, vertical temperature gra-dient, radiant asymmetry, or warm or cold floors (ISO EN7730/2005 [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 guaranteethermal comfort and good air quality for the employees. Pre-vious studies in commercial kitchens have mainly focused onair-conditioning and ventilation systems. They indicate thatkitchens are not typical of general spaces, and that thermalcomfort conditions in commercial kitchens are determined byenvelope heat gain and loss, people, lighting, and miscella-neous equipment.

Thermal comfort in a commercial kitchen environment ismainly driven by the radiant heat that directly impacts thecomfort of the workers, and by convective loads from bothhooded and un-hooded cooking appliances.

One published study of the commercial-kitchen environ-ment indicates that the areas on the body that have the greatestexposure to temperature differences are the chest and facial ar-eas, situated between 1.5 and 1.8 m (59 and 71 in.) height abovethe floor (Livchak et al. 2005). Additionally, it was found thatthe greatest heat loads are encountered at the cooking line,which produces the largest heat gains in the space, and wherethe workers are exposed to the highest temperatures.

As described in many studies, thermal comfort has a largeimpact 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 10◦F (5.5◦C)above the thermally neutral level may result in a 30% loss ofproductivity.

In a commercial kitchen environment, there can be largedifferences 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 aresituated in many different climatic zones.

The kitchen environment presents a much broader range ofconditions 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 determinewhether they do apply, ASHRAE Research Project RP-1469was initiated. As part of the project, a measuring procedurewas established, focusing in particular on the processes char-acterizing kitchen spaces and kitchen activities (ASHRAE2012).

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 basedon the ISO Standard 10551 (ISO 2001) were developed andadapted to the kitchen environment and to kitchen workersin order to achieve the highest possible participation by theemployees in the study. They were used in combination withweekly 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 measuringprocedure was established to focus on the different processesthat 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 subjectedto bursts of very humid hot air are subject to higher radiantconditions than employees working on a preparation line withtheir backs some distance from such appliances.

A general view of the procedure, from the recruitment ofkitchens to the data collection, is summarized in the flowchartin Figure 1.

Recruitment of kitchens

Commercial kitchen spaces differ by type (casual, institu-tional, or QSR), kitchen activities (preparation, cooking, dishwashing), building and HVAC system types (insulation, win-dows, air-conditioning, natural ventilation), and locations indifferent 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 throughoutthe United States, as shown in Table 1. Site data were collectedin nine metropolitan areas located in different climatic zones,according to ASHRAE Standard 169 (ASHRAE 2006) cli-mate zone classifications. In all, 105 commercial kitchens insummer and 104 in winter participated in the thermal comfortevaluation of the kitchen environment, from which over 90%participated in both seasonal study phases.

A “casual” dining restaurant is considered to be arestaurant that provides table service, a franchise, chain, orprivately owned restaurant. A particular example of a kitchenclassified as “casual” is a small privately owned restaurantwith 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 typesample, August–October 2010

Winter (Phase II) kitchen typesample, January–February 2011

Climate zone (ASHRAEStandard 169 [ASHRAE 2006]) U.S. city QSR Institutional Casual Sum QSR Institutional Casual Sum

1—Moist Miami 9 3 0 12 9 3 0 122/3—Moist Atlanta 7 5 0 12 7 5 0 122/3—Dry Phoenix 6 4 2 12 6 4 2 124—Marine Seattle 5 9 0 14 5 9 0 144—Moist Nashville 2 3 4 9 2 3 3 84—Moist Washington DC 5 5 0 10 5 5 0 105/6—Moist New York 4 4 3 11 4 5 1 105/6—Dry Las Vegas 8 2 2 12 8 3 2 137—Moist Minneapolis 7 3 3 13 7 3 3 13Sum by kitchen type 53 38 14 105 53 40 11 104

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hotel. Institutional restaurants in general had a more robustventilation system and a larger food-preparation area andcooking line. Last, QSRs, such as those providing expeditedservice or “fast food,” are typically owned and operated byfranchisees, corporations, or, in some instances, privately heldcompanies. The differentiation between kitchen types hasresulted in some overlapping, but the on-site visit during themeasurements 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 andmake-up air temperature and relative humidity [RH]), indoor(thermal) environment, physiological, and subjective evalua-tion. The intention was to collect data describing the physicalenvironment and personal factors, such as clothing and activ-ity, to be able to calculate existing indices of thermal comfortand/or heat stress.

In order to be able to characterize adequately the HVACsystems performance and to obtain some idea of the air qualityin each kitchen, the supply and exhaust airflows should havebeen measured as well. However, supply and exhaust airflowrates measurements were not technically feasible in most ofthe kitchens. Carbon dioxide concentrations and indoor airquality subjective evaluations were used as indicators instead.

Data were recorded in summer and winter and in the threeidentified kitchen zones (cooking, food preparation, and dishwashing) shown by the area inside the dashed line in Fig-ure 2, these being considered likely to have different thermalconditions in the commercial kitchen. During the visit to thekitchens, a sketch of each kitchen and its different zones was

made (e.g., Figure 2), including the location of the measuringdevices that have been installed, the location of the supplyand exhaust of the HVAC system, the exhaust hood and otherdetails (e.g., type of supply device and exhaust grill, use offree-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), andRH for a whole week in time intervals of 15 min; examplesof the measured spots, representative of kitchens zone, areshown in Figure 2 as a rectangular green spot.

2. Short-term (or spot) measurements (SM) (second walk-through): subjective parameters, such as estimated activitylevel (met) and clothing insulation (Icl), globe temperature(tg) and ta at 0.1 m and 1.7 m (4 and 67 in.) height abovethe floor, air (ta), operative (to), radiant temperature (tr),air velocity (va), and RH at 1.1 m (43 in.) above the floorand at 0.3 m (1 ft) distant at the workstation (where theemployees were working during the peak operating hoursof a working day [breakfast, lunch, and/or dinner time])during on-site SM. All physical parameters were recordedfor 15–20 minutes, having 30–40 equally spaced points overtime (30-s time-interval), with an exception for air velocityand directional operative temperature. The air velocitywas recorded for 15–20 min with a minimum intervaltime of 1 s, while the directional operative temperaturewas recorded in a time interval of 30 s for a minimum of5 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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Physical parameters collected at each representativeworker 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 indoorenvironment 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 weightedaverages 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 364employees encountered during the on-site SMs.

Instrumentation for physical measurements

The physical environmental parameters were measured withthe instruments shown in Figure 3. RH was measured andrecorded 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 Standard7726 (ISO 1998) descriptions and as described by Simone et al.(2007). In the measurement range of 50◦F to 104◦F (10◦C to40◦C), these temperature sensors have an accuracy of ±0.5◦F(±0.3◦C). The air temperature sensors (Figure 3b) were builtby enclosing a temperature sensor within an open-ended ra-diation shield (the cylinder) that enabled a free flow of air tocome in contact with the sensor.

A grayish globe sensor of 4 cm (1.6 in.) diameter was usedto 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 closelyrelated to the global thermal perception of the occupant andto calculate the mean radiant temperature, from the differencebetween air and operative temperature, in the minimum tem-poral average of 12 min with 24 equally spaced points overtime.

A flat sensor, having two opposed faces with a matte grayfinish, each 7 cm (2.8 in.) in diameter (Figure 3d), was usedto measure the directional operative temperature (to,i) and toevaluate the radiant asymmetry that occurred when an em-ployee was facing a high-temperature radiant surface, such asappliances 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 thatfaces the opposite hemisphere in the same room volume. Theaverage value of the temperature was taken as the temporalaverage over at least 5 min with 10 measurements that wereequally spaced in time. The plane radiant temperature (tp,i)in six directions and the mean radiant temperature (tr) werecalculated according to Equations 1 and 2:

tp,i = to,i − a · ta1 − a

(1)

tr = 0.08 · (tp,up + tp,down) + 0.23 · (tp,right + tp,le f t) + 0.35 · (tp, f ront + tp,back)2 · (0.08 + 0.23 + 0.35)

(2)

with i representative of the direction 1, 2, 3, 4, 5, or 6 of thesensor facing up, down, right, left, front, or back, relative tothe direction the employee was facing.

An omnidirectional anemometer was used for measuringair velocity (Figure 3e). This sensor can measure in the rangeof 0.005 to 5 m/s (9.8 to 984 ft/min) with an accuracy of0.02 m/s (4 ft/min) ±1% of readings. The portable data loggerconnected to the anemometer recorded air velocity with aminimum interval time of 1 s (1-Hz frequency). The averageair velocity over 12–15 min was used in the analysis. The abovesensors yielded a voltage that was directly recorded by a smalllogger (Figure 3a) and afterward converted to the relevantunits by the calibration equations. This way of storing datawas very convenient for measurements in kitchens, avoidingany hindrance for the workers, and disturbing them and theirwork as little as possible.

As shown in Figure 4a, the data loggers recorded kitchentemperatures, humidity, and carbon dioxide (CO2) concentra-tions. In addition to what was described above in the “DataCollection” section, loggers to record LMs (Figure 4a) wereinstalled for the duration of one week, or slightly less. Theloggers referred to short-term recorded data (Figure 4b) onlyduring the peak operation time (or rush time) of the kitchen,i.e., during the busiest working hour(s). Monitoring a periodof 15–20 min during that peak period was performed, as it maybe considered to provide the worst thermal environment forthe employees. Recording devices were used for more detailedSMs of thermal parameters (air temperatures, humidity, airvelocity, and radiant temperatures) and, as earlier explained,at different heights during the peak operating hours in oneworking day (breakfast, lunch, and/or dinner time).

Fig. 3. Equipment of sensors for measuring thermal parameters (color figure available online).

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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 clothingworn were noted, how often and how much the clothing insu-lation was changed, and an evaluation of thermal resistanceand vapor diffusion resistance (when possible). Later, the ther-mal insulation value of each worker’s clothing was estimatedas stipulated in ISO 9920 (ISO 2007a).

The activity level in a kitchen changes considerably duringa working day, so a time-weighted average over each 1-h periodwas calculated. The employees’ activity level was estimated byobservation and by analyses, recording the heart rate of oneor more individuals within each kitchen, together with theirage, weight, and sex, as stipulated in ISO Standard 8996 (ISO2004b).

Subjective evaluation measurements (SM and LT)

Subjective evaluation is a very important component of anyprocedure for evaluating the thermal comfort condition of anindoor space. The methods used for the collection of occu-pants’ perception data are described in the present article, butthe results obtained and an analysis of the subjective mea-surements will be reported in a second article (Part 2). Twoquestionnaires, one on long-term general effects (LQ) and oneon occupants’ immediate reactions (SQ), each as described inASHRAE Report RP-1469 (ASHRAE 2012), were used toevaluate thermal and working conditions, to support physicaldata monitoring, and to analyze the relationship between thephysical parameters of the environment and subjective aspects

Fig. 5. Seven-point thermal sensation scale (color figure availableonline).

of the occupants’ perception of thermal comfort in the kitchenenvironment.

The subjective evaluation of the thermal conditions wasconducted using the standard ASHRAE 7-point thermal sen-sation scale (see Figure 5) during the physical SM. Severalother questions adapted to the kitchen environment, but basedon ISO 10551 (ISO 2001), were asked in the LQ and consistedof 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 rateof 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 MEANSprocedure in SAS. The effect due to different seasons, summerand 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 11Casual 6 6Institutional 22 18Sum 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 andin 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 thepsychometric diagram in Figure 6. The operative temperatureand air humidity data were estimated from all SMs at 1.1 m(43 in.) height. The highest temperature values were found inthe cooking zones (up to 41.2◦C (106◦F)) and the highest RHin the dish-washing area (up to 76%); in particular, 22 cookingzones had a measured to higher than 31◦C (88◦F), while sim-ilarly high humidity levels were recorded in food-preparationand cooking areas. Operative temperatures to lower than 20◦C(68◦F), and as low as 15.9◦C (61◦F) in winter, were recordedin a number of different kitchens zones. Those values showthat even if all kitchens were provided with AC systems, therecorded temperatures were widely spread over a range thatwas much larger than expected. The reason for such big differ-ences in temperatures is likely to be not only poor performanceof the AC systems but factors such as the big differences in

exposure (cooking, dish washing, and preparation), keepingfood warm, etc.

From the detailed SMs, the average values of the measuredthermal parameters by type and kitchen zones were calculatedfrom time-averages of the SMs and then from the averages overkitchen 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, kitchentype, 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 arevery small. This is due to the cooking zone and preparationareas being close to each other in these smaller kitchens andalso due to a presence of more appliances in the preparationzone 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 4.0Preparation 23.9 (74.9) 23.5 (74.4) 24.4 (75.9) 34 0.29 (57) 0.7 3.4Dish 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 3.9Preparation 23.6 (74.5) 23.2 (73.8) 24.0 (75.3) 36 0.27 (53) 0.7 2.9Dish 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 3.1Preparation 25.9 (78.6) 25.4 (77.7) 26.5 (79.6) 38 0.22 (43) 0.6 2.6Dish 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.) 4 –2.3 ± 1.5 19.4 ± 3.3 (67 ± 12)

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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 tobe representative of most kitchen environments. More detaileddata analyses are given in what follows.

Table 4 and Figures 7 and 8 set out the calculated PMVindex and measured operative temperature averages for eachclimatic zone during the summer and winter. The values areaverages over the climatic zone and weighted by the num-bers of occupants that took part in the thermal comfortevaluation.

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 PMVindex is not really applicable; ISO Standard EN 7730 (ISO2005) recommends using the PMV-index only in the interval± 2, meaning that most of the measured conditions are outsidethe 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 aredisplayed, with dots representing the outliers. The figureshows that the PMV differences between climatic zonesduring summer or winter are not significant. Within eachclimatic zone, a high percentage of calculated variables fallinto the gray area, which was not studied in the thermal

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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 modelshould not be applied to commercial kitchens.

In Figures 7a and 7b, where the variability of PMV and toaround the means are reported, it is evident that the opera-tive temperatures show larger differences between the climaticzones during summer and winter.

Working conditions in climate zones 1—moist, 5/6—moist,and 7—moist were significantly warmer than in climate zones4—marine and 5/6—dry (p < 0.02). During winter, the PMVindex was significantly lower in kitchens in climate zone5/6—moist (p < 0.01), while the operative temperature wassignificantly lower for kitchens in climate zone 4—marine.

In all climatic zones, the PMV index was significantly lowerduring 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 differencesbetween winter and summer.

When comparing the differences in temperature andPMV, in particular between climate zones 4—marine and2/3—moist, it should be noted that in 4—marine, the tem-perature was much lower than in 2/3—moist, but the PMVwas much higher. This discrepancy was due to the effects thatthe other physical parameters (reported in Table 4), the cloth-ing insulation (Icl = 0.6–0.7 clo) and the activity level (onaverage equal to 3.2 met ± 0.9 of standard deviation), have onthe PMV index. In this study, the ANOVA analysis shows asignificant effect on the PMV of the combination of to, RH,Icl, and metabolic rate together (F = 8.3 and p = 0.004), withthe single highest effect being that of operative temperature (F= 7.4, p = 0.007, and R2 = 0.52) and the second highest thatof 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 andwinter. The unweighted values of the operative temperature in

each climatic zone were higher in summer and slightly lower inwinter than the values weighted for occupancy. However, theyare still representative of hot kitchen environments in summerand warm in winter with an exception for 4—marine climatezone, where commercial kitchens tended to provide the mostthermally comfortable environments.

In Table 6 and Figure 9, the PMV index and operativetemperatures for the three kitchen types and for three workingareas are reported as an average of all the values within eachkitchen type.

When looking at the results for summer and winter inTable 6, it is clear that the PMV index for the cooking zone insummer is well above the range where the index is applicable.For casual and institutional kitchens, the cooking zone had asignificantly higher PMV index and operative temperature (p< 0.01) than other work zones. The PMV index for winter waswithin the range of application of the index. For all kitchentypes and work zones, the winter kitchen temperatures werecolder 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. Inthe institutional and casual kitchens, there was no significantdifference between the preparation and dish-washing zones,while for QSR kitchens, there was no difference between thecooking and preparation zones. The dish-washing zone wascolder, but as very few data points were obtained, the confi-dence interval is very large.

The method applied showed that the procedure to be usedin 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 andwinter, are given in Tables 7 and 8 and in Figure 10. The

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Fig. 9. Average of PMV and operative temperature (to) for kitchen type and kitchen zones with 95% confidence interval (color figureavailable online).

Fig. 10. Vertical profiles of average temperature distribution at the cooking line in summer (left) and winter (right) (color figureavailable online).

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Tab

le7.

Ave

rage

ofte

mpe

ratu

res

byki

tche

nty

pean

dzo

nein

sum

mer

.

Glo

bete

mpe

ratu

reA

irte

mpe

ratu

re�

t o�

t a

Kit

chen

Kit

chen

0.1

m(4

in.)

,1.

1m

(43

in.)

,1.

7m

(67

in.)

,0.

1m

(4in

.),

1.1

m(4

3in

.),

1.7

m(6

7in

.),

(hea

d–fe

et(h

ead–

feet

type

zone

◦ C(◦ F

)◦ C

(◦ F)

◦ C(◦ F

)◦ C

(◦ F)

◦ C(◦ F

)◦ C

(◦ F)

leve

l),K

(◦ F)

leve

l),K

(◦ F)

Cas

ual

Coo

king

29.2

(85)

34.5

(94)

37.9

(100

)28

.1(8

3)32

.6(9

1)36

.3(9

7)8.

616

8.1

15P

repa

rati

on26

.8(8

0)27

.8(8

2)28

.4(8

3)26

.5(8

0)27

.4(8

1)28

.1(8

3)1.

63

1.6

3D

ish

was

hing

26.8

(80)

27.9

(82)

28.8

(84)

26.6

(80)

27.9

(82)

28.9

(84)

2.1

42.

34

Inst

itut

iona

lC

ooki

ng26

.6(8

0)30

.6(8

7)33

.3(9

2)24

.9(7

7)28

.4(8

3)29

.3(8

5)6.

712

4.4

8P

repa

rati

on24

.2(7

6)24

.6(7

6)24

.9(7

7)23

.4(7

4)24

.2(7

6)24

.5(7

6)0.

71

1.1

2D

ish

was

hing

24.6

(76)

25.2

(77)

25.6

(78)

23.9

(75)

24.8

(77)

25.5

(78)

1.0

21.

63

QSR

Coo

king

25.4

(78)

28.6

(83)

30.4

(87)

24.2

(76)

27.3

(81)

29.0

(84)

5.0

94.

79

Pre

para

tion

24.5

(76)

26.1

(79)

27.1

(81)

23.7

(75)

25.9

(79)

26.8

(80)

2.6

53.

16

Dis

hw

ashi

ng23

.497

4)24

.2(7

6)24

.9(7

7)22

.5(7

2)23

.9(7

5)24

.8(7

7)1.

53

2.3

4

Bol

din

dica

tes

high

vert

ical

tem

pera

ture

diff

eren

ces

inth

eco

okin

glin

e.

Tab

le8.

Ave

rage

ofte

mpe

ratu

res

byki

tche

nty

pean

dzo

nein

win

ter.

Glo

bete

mpe

ratu

reA

irte

mpe

ratu

re�

t o�

t a

Kit

chen

Kit

chen

0.1

m(4

in.)

,1.

1m

(43

in.)

,1.

7m

(67

in.)

,0.

1m

(4in

.),

1.1

m(4

3in

.),

1.7

m(6

7in

.),

(hea

d–fe

et(h

ead–

feet

type

zone

◦ C(◦ F

)◦ C

(◦ F)

◦ C(◦ F

)◦ C

(◦ F)

◦ C(◦ F

)◦ C

(◦ F)

leve

l),K

(◦ F)

leve

l),K

(◦ F)

Cas

ual

Coo

king

23.7

(75)

26.4

(79)

30.5

(87)

22.4

(72)

24.6

(76)

27.7

(82)

6.8

(12)

5.3

(10)

Pre

para

tion

20.8

(69)

22.1

(72)

22.6

(73)

20.5

(69)

21.7

(71)

22.4

(72)

1.9

(3)

1.9

(3)

Dis

hw

ashi

ng19

.1(6

6)20

.3(6

8)20

.7(6

9)18

.9(6

6)20

.1(6

8)20

.3(6

8)1.

6(3

)1.

4(2

)In

stit

utio

nal

Coo

king

26.1

(79)

29.6

(85)

33.0

(91)

24.9

(77)

27.0

(81)

28.8

(84)

6.9

(12)

3.9

(7)

Pre

para

tion

22.5

(73)

23.6

(75)

24.5

(76)

21.9

(71)

23.1

(74)

24.4

(76)

2.0

(4)

2.5

(4)

Dis

hw

ashi

ng22

.9(7

3)24

.3(7

6)25

.0(7

7)22

.1(7

2)23

.5(7

4)24

.9(7

7)2.

1(4

)2.

7(5

)Q

SRC

ooki

ng20

.8(6

9)23

.9(7

5)27

.2(8

1)20

.1(6

8)23

.1(7

4)26

.5(8

0)6.

4(1

2)6.

4(1

2)P

repa

rati

on21

.5(7

1)23

.7(7

5)24

.8(7

7)20

.9(7

0)23

.2(7

4)24

.3(7

6)3.

3(6

)3.

4(6

)D

ish

was

hing

19.2

(67)

20.9

(70)

22.1

(72)

18.4

(65)

20.4

(69)

21.9

(71)

2.9

(5)

3.5

(6)

Bol

din

dica

tes

high

vert

ical

tem

pera

ture

diff

eren

ces

inth

eco

okin

glin

e.

1012

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Volume 19, Number 8, November 2013 1013

Fig. 11. Air and operative temperature (ta and to) variations in the three kitchens zones in summer and winter; shaded area indicatestime of occupancy (color figure available online).

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1014 HVAC & R Research

conditions in the food-preparation and dish-washing zoneswere uniform and within normal comfort criteria, providing avertical 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 ofthermal radiation falling on a worker’s upper body and head,the vertical temperature differences in the cooking line werevery high, as shown by the bold numbers in Tables 7 and 8, upto 16◦F (8.6 K) for the casual kitchen type in summer and upto 12◦F (6.9 K) for institutional kitchen in winter.

The warm/hot environment in the cooking area exposedthe workers to temperatures higher than the 88◦F (31◦C), lim-iting exposure temperature as suggested by Weihe (1987). Thismay have negative health consequences (ASHRAE 2009).

As the food-preparation and dish-washing zones would notbe expected to cause any thermal discomfort for the kitchenstaff, the vertical temperature profiles shown in Figure 10 areonly the actual average values for the cooking zones in summerand 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 thermalenvironment at both times of year, most probably due to thedifferent type and use pattern of the HVAC systems installedin them. However, the cooking line in the institutional kitchensseems to be the environment where the occupants may com-plain more of radiant asymmetry (as indicated by the largerdifference between globe/operative and air temperature).

The large difference in the thermal environment betweensummer and winter in casual kitchen types was probably dueto more frequent use of natural ventilation for cooling. Thepresent results indicate that casual kitchens provide the worstenvironment for kitchen staff, although this remains to becorroborated by the forthcoming analysis of their subjectiveevaluations.

LMs

An example of the LMs that were obtained is shown in Fig-ure 11 for a QSR kitchen located in Miami, FL. Figure 11shows the air and operative temperatures recorded, as brokenand solid lines, respectively. During the 24-h data-recordingperiod, the temperature variation that directly influenced em-ployees’ thermal comfort occurred during assumed operatinghours from 10:00 a.m.to 10:00 p.m., represented by the shadedareas.

During the summer, considerable diurnal temperature vari-ations in the cooking line occurred, rising from 79◦F to 98◦F(26.1◦C to 36.7◦C), and detailed measurements were recorded(Figure 11a) during peak operating periods. The tempera-ture in the food-preparation line and dish-washing area hada daily temperature variation in the range of 72◦F to 92◦F(22.2◦C to 33.3◦C) and 75◦F to 90◦F (23.9◦C to 32.2◦C), re-spectively during working hours. Thermal radiation from thehot appliances raised the operative temperature by an ad-ditional 10◦F (5.8◦C). At night, the temperatures decreasedbut were still high; the air and operative temperatures inthe food-preparation and dish-washing areas were similar. Asshown in Figure 11b, the temperature increase in winter wasthe same in all kitchens zones: 9◦F (4.9◦C) during operatinghours.

Conclusions

A method and procedure for evaluating the indoor ther-mal environment in commercial kitchens was developed. Thismethod consisted of:

• LMs of radiant temperature, air temperature, and humidityover 1 week in three kitchen workspaces: cooking, dishwashing, and food preparation.

• on-site SMs of air temperature and operative (radiant) tem-perature at different heights, along with air velocity andhumidity in three work areas: the cooking, dish-washing,and food-preparation zones;

• an on-site survey of occupants’ subjective evaluation of theindoor environment, performed at the same time as the SMsare made;

• a general survey of background information about the oc-cupants and of their general evaluation of the workingconditions.

The proposed procedure was validated during on-site mea-surements performed in more than 100 kitchens located in9 states of the United States during the summer and winterseasons. 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 establisha benchmark database for the thermal environment in com-mercial kitchens. Differences due to climatic zone, summerand winter, and type of kitchen were found. The most criti-cal environment for kitchen staff is the cooking zone, wheretemperatures and vertical temperature differences that weretoo high for comfort and health were measured. The calcu-lated PMV index values did not differ between climatic zonesin either summer or winter, while the operative temperaturesdiffered greatly. The thermal environment in casual kitchensvaried seasonally, and kitchen staff in such kitchens are verylikely to be exposed to uncomfortable thermal environments.

Only the physical measurements are reported in the presentarticle, so these conclusions are restricted to them. They mustbe 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 evaluationcriteria for thermal comfort often used in office environmentscannot be applied in commercial kitchens. The PMV indexvalues obtained were often above +3 and significantly outsidethe upper limit reccommended in international standards forthe 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 ofhigh 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 acceptabilityof 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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Centre for Indoor Environment and Energy at the Techni-cal University of Denmark (DTU). The Culinary Institute ofAmerica (CIA) provided additional and substantial support.

References

ASHRAE. 2006. ANSI/ASHRAE Standard 169-2006, Weather Data forBuilding Design Standards. Atlanta, GA: ASHRAE.

ASHRAE. 2009. ASHRAE Fundamentals Handbook—Heating, Ventilat-ing, and Air-Conditioning Applications, SI Ed. Chapter 10, Indoorenvironmental health. Atlanta, GA: ASHRAE.

ASHRAE. 2010a. ANSI/ASHRAE Standard 55-2010, Thermal Environ-mental Conditions for Human Occupancy. Atlanta, GA: ASHRAE.

ASHRAE. 2010b. ANSI/ASHRAE Standard 90.1-2010, Energy Stan-dard for Buildings Except Low-Rise Residential Buildings. Atlanta,GA: ASHRAE.

ASHRAE. 2011a. ANSI/ASHRAE Standard 154-2011, Ventilation forCommercial Cooking Operations. Atlanta, GA: ASHRAE.

ASHRAE. 2011b. ASHRAE Applications Handbook—Heating, Ventilat-ing, and Air-Conditioning Applications, SI Ed. Chapter 33, Kitchenventilation. Atlanta, GA: ASHRAE.

ASHRAE. 2012. Thermal comfort in commercial kitchens. ReportRP1469, ASHRAE, Atlanta, GA.

Fisher, D., R. Swierczyna, and A. Karas. 2013. Future of DCV forcommercial kitchens. ASHRAE Journal 55(2):48–54.

Huizenga, C. 2011. ASHRAE thermal comfort tool. CD, version 2. At-lanta, GA: ASHRAE.

ISO. 1998. ISO Standard 7726:1998, Ergonomics of the ThermalEnvironment—Instruments for Measuring Physical Quantities.Geneva, Switzerland: International Organization for Standardiza-tion.

ISO. 2001. ISO Standard 10551:2001, Ergonomics of the Thermal En-vironment. Assessment of the Influence of the Thermal EnvironmentUsing Subjective Judgment Scales. Geneva, Switzerland: Interna-tional Organization for Standardization.

ISO. 2004a. ISO Standard 7933:2004, Hot Environments—Analytical De-termination and Interpretation of Thermal Stress Using Calculationof Required Sweat Rate. Geneva, Switzerland: International Orga-nization for Standardization.

ISO. 2004b. ISO Standard 8996:2004, Ergonomics of the ThermalEnvironment—Determination of the Metabolic Rate. Geneva,Switzerland: International Organization for Standardization.

ISO. 2005. ISO Standard 7730:2005, Moderate Thermal Environments—Determination of the PMV and PPD Indices and Specification ofthe Conditions for Thermal Comfort. Geneva, Switzerland: Interna-tional Organization for Standardization.

ISO. 2007a. ISO Standard 9920:2007, Ergonomics of the ThermalEnvironment—Estimation of the Thermal Insulation and Water VaporResistance of a Clothing Ensemble. Geneva, Switzerland: Interna-tional Organization for Standardization.

ISO. 2007b. ISO EN Standard 11079:2007, Ergonomics of the Ther-mal Environment—Determination and Interpretation of Cold StressWhen Using Required Clothing Insulation (IREQ) and Local Cool-ing Effects. Geneva, Switzerland: International Organization forStandardization.

ISO. 2011. ISO Standard prEN16282—part 1-8:2011. Kitchen ventilation.Geneva, Switzerland: International Organization for Standardiza-tion.

Livchak, A., D. Schrock, and Z. Sun. 2005. The effect of supply airsystems on kitchen thermal environment. ASHRAE Transactions111(1):748–54.

National Restaurant Association (NRA). 2012. Restaurant industry fore-cast, 2011. www.restaurants.org.

National Restaurant Association (NRA). 2013. Restaurant industry fore-cast, 2012. www.restaurants.org.

Pekkinen, J.S., and T.H. Takki-Halttunen. 1992. Ventilation efficiencyand thermal comfort in commercial kitchens. ASHRAE Transac-tions 98(1):1214–8.

Simone, A., and B.W. Olesen. 2012a. Investigation of subject perceptionsof the environment in commercial kitchens. Proceedings of HealthyBuildings 2012, July 8–12, Brisbane, Australia.

Simone, A., and B.W. Olesen. 2012b. Thermal environment eval-uation in commercial kitchens: Procedure of data collection.Proceedings of Healthy Buildings 2012, July 8–12, Brisbane,Australia.

Simone, A., B.W. Olesen, J. Babiak, M. Bullo, and G. Langkilde. 2007.Operative temperature control of radiant surface heating and cool-ing systems. Proceedings of Clima 2007, June 10–14, Helsinki,Finland.

Weihe, W.H. 1987. Social and economic values of applied human clima-tology. Proceedings WMO/WHO/UNEP Symposium Climate andHuman Health, September 22–26, 1986, Geneva, WMO-WCAP No.1, pp. 233–50.

Wyon, D.P. 1996. Individual microclimate control: Required range, prob-able benefits and current feasibility. Proceedings of Indoor Air ’96,Tokyo, 1:1067–72.D

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