Evaluation of Thermal Comfort in an Iranian Educational Hospital Using PMV- PPD Model

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Javad Sajedifar: [PubMed] [Scholar]
Ramazan Mirzaei: [PubMed] [Scholar]
Gholam Heidar Teimori: [PubMed] [Scholar]
Ahmad Mehri: [PubMed] [Scholar]
Fatemeh Azadbakht: [PubMed] [Scholar]
Ali Choupani: [PubMed] [Scholar]
Mohammad Reza Taheri: [PubMed] [Scholar]

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Evaluation of Thermal Comfort in an Iranian Educational Hospital Using PMV- PPD Model

Javad Sajedifar ¹ , Ramazan Mirzaei ² , Gholam Heidar Teimori ³ , Ahmad Mehri ⁴ , Fatemeh Azadbakht ⁵ , Ali Choupani ⁶ and Mohammad Reza Taheri ^{7 , *}

Authors Information

¹ Department of Occupational Health Engineering, School of Public Health, Neyshabur University of Medical Sciences, Neyshabur, Iran

² Social Determinants of Health Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

³ School of Public Health, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh, Iran

⁴ Department of Occupational Health Engineering, Ilam University of Medical Sciences, Ilam, Iran

⁵ School of Public Health, Iran University of Medical Sciences, Tehran, Iran

⁶ Department of Occupational Health Engineering, School of Public Health, Mashhad University of Medical Sciences, Mashhad, Iran

⁷ Department of Occupational Health Engineering, Isfahan University of Medical Sciences, Isfahan, Iran

Article information

Biotechnology and Health Sciences: August 2017, 4 (2); e57653
Published Online: July 13, 2017
Article Type: Research Article
Received: September 18, 2016
Revised: April 8, 2017
Accepted: April 15, 2017
DOI: 10.5812/bhs.57653

To Cite: Sajedifar J, Mirzaei R, Teimori G H, Mehri A, Azadbakht F, et al. Evaluation of Thermal Comfort in an Iranian Educational Hospital Using PMV- PPD Model, Biotech Health Sci. 2017 ;4(2):e57653. doi: 10.5812/bhs.57653.

Abstract

Copyright: Copyright Â© 2017, Biotechnology and Health Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

1. Background

Working in indoor buildings for a long time, not controlling dangerous factors in the workplace, and the presence of unsuitable occupational conditions can cause different diseases and their complication among workers. One of these harmful factors is the lack of thermal comfort in the workplace (1, 2). Thermal comfort is defined as a condition in which the individual is mentally satisfied with the condition of his/her workplace (3). According to the definition of ASHRAE, thermal comfort is the temperature condition which 80% of people in a sitting position or those doing light activities find it acceptable (4). In fact, thermal comfort tremendously affects satisfaction, performance improvement, and productivity in occupational activities. Unsuitable conditions in the workplace can cause disturbance in physical and mental performances, and it eventually leads to an increase in the prevalence of human errors and accidents (5).

According to the report published by Bureau of labor statistics in 2004, around 14 million activities in different workplaces with complications of coldness and warmness have been reported by workers. One of these reported cases included the death of 18 workers due to unsuitable temperature condition (6). There are some evaluation criteria to determine thermal comfort, and 2 most important of which are PMV and PPD. PMV criterion is the result of measuring 6 factors including metabolism, cloth type, the speed of air flow, the temperature of the environment, relative humidity, and mean radiant temperature. This criterion is the best to diagnose thermal comfort, which has been provided by Fanger in 1970. PMV is more practical, particularly in the environment with an average level of temperature. PPD is suitable to predict the average thermal felt by a great number of people. This criterion ranges from 0 to 100. ISO (International standard organization) recommends this criterion to be less than 10% in the workplace (7). Recently, many studies have been conducted on thermal comfort, and they mostly have noted that the satisfaction of the staff in the workplace can be achieved by creating optimum thermal comfort, which is provided by an appropriate (8). In one study, thermal comfort in the university classes in Pakistans tropical regions was researched by Memon et al. The results revealed that 80% of the cases were satisfied with 32.5Â°C, which was 6.5 times more than ASHRAE Standard 55. This study also showed that by installing radiant cooling, instead of air conditioning, consumption of energy decreased down to 80%. It inhabited the risk of humidity compact as well (9). Another study done in china by Zhang et al., investigated the thermal comfort of students in semi-tropical regions and in classes equipped with a fan. The results of this project indicated that although the students reported the condition of thermal comfort as acceptable, PMV was higher than the standard value in these classes (10).

A hospital hosts 3 different categories of individuals: medical staff, patients, and visitors, all of whom having different expectations about the hospital building, For the staff, the hospital is their work place and permanent environment, but for patients, the hospital tends to be a temporary place to stay, while waiting to return home (11). In the light of discussion above, creating thermal comfort in workplaces is vital and further research should be conducted to solve thermal discomfort in hospitals and improve the optimum thermal condition for workers. In addition, thermal comfort has an important role in promotion of the managers productivity approach. This study seeks to address thermal comfort of the staff of Al Zahra hospital in Esfahan, a large city in Iran.

2. Methods

This was a cross-sectional and deceptive-analytical study conducted in official units (health, nutrition, public relations and evaluation management unit), educational groups office, kitchen, laundry, stock, pharmacy, and educational classes built in the underground floor of Al Zahra educational and treatment center in the summer of 2015. In this study, methods 7730 and 10,551 recommended by ISO were used to determine the subjective and objective rate of thermal comfort. Thermal comfort was measured objectively by determining the parameters including air temperature, relative humidity (RH), and the speed of air flow, the mean radiant temperature, metabolism rate, and the thermal resistance of clothing.

Air temperature, relative humidity, speed of air flow, and the mean radiant temperature were measured by WBGT (wet bulb globe temperature) meter; KIMO instrument: AMI 300 and other parameters (i.e., metabolism and thermal resistance of clothing) were estimated according to the standard (12). A checklist of activities and their metabolic rates was provided, therefore, in this study, as mentioned in the standard, the metabolic rate for sedentary works for office and non-office works was 1.2 and 2.5, respectively (13). In addition, to identify the resistance of clothing for light summer clothing (0.5 clo) and official clothing (1 clo) (14), the participants were asked what sort of clothing they wear in the workplace.

According to an initial assessment of the hospital wards and previous studies and placement of kitchen, self-service, and the laundry room in the basement of the hospital, the staff working in the underground were recruited for this study and those working in other floors and the wards with less than 2 staff were excluded from this research.

Moreover, PMV and PPD indices through ISO equation 7730 were estimated to finally determine thermal comfort (15). The measurement of the first 4 parameters was performed in 5 points in every room and 3 times in each point within 30 minutes. To determine the rate of thermal comfort subjectively, the feeling of 161 workers about the temperature condition of their workplace was asked using a questionnaire (Table 1). According to the options of this questionnaire, the workers selected one of the following items: hot, warm, a little warm, moderate, a little cool, cool, and cold. Next, PMV and PPD indices were calculated based on the workers assessment about the temperature in their workplaces. Finally, collected data were analyzed by SPSS 20, and statistical analyses were done using descriptive statistics and one-sample t test.

Table 1. The Averages of Age, Weight, Height and Body Mass Index (BMI) of the Participants at Al Zahra Education and Treatment Center in Summer of 2015^a

Ward	Age, y	Weight, kg	Height, cm	BMI, kg/m²
Pharmacy	35.5 Â± 5.3	68 Â± 7.8	166 Â± 12	25 Â± 1.1
Stock	35.1 Â± 3.2	72 Â± 6.3	172 Â± 9.4	24 Â± 0.8
The offices of educational sectors	32.7 Â± 4.8	62 Â± 9.8	162 Â± 7.6	23 Â± 0.9
Day clinic	40.2 Â± 7.8	67 Â± 10.1	166 Â± 8.6	24 Â± 1.2
Kitchen	35.5 Â± 2.1	79 Â± 6.5	171 Â± 5.5	27 Â± 0.5
Laundry	38.9 Â± 6.7	75 Â± 8.7	172 Â± 6.3	25 Â± 0.4
Sterilization	43.5 Â± 5.9	72 Â± 3.3	167 Â± 5.1	26 Â± 0.7
Educational classes	32.5 Â± 4.6	67 Â± 6.8	165 Â± 10.6	23 Â± 0.6
Official units	36.4 Â± 4.2	69 Â± 7.1	168 Â± 6.8	24 Â± 0.4

^aValues are expressed as mean Â± SD.

3. Results

Table 1 presents the demographic characteristics (ie, age, weight, height, and BMI) of the hospital staff in different wards. The results of measured environmental parameters in the studied units of the hospital are presented in Table 2. As demonstrated in this kitchen kitchen had the highest level of temperature due to its especial conditions. The highest level of wet temperature in the laundry room appeared to be due to the washing machines. Educational classes and their dependent sectors had the highest rate of air flow because of their natural ventilation, and laundry, sterilization, and kitchen units had the highest radiation temperature, respectively.

Table 2. Measured Thermal Parameters According to Wards at Al Zahra Educational and Treatment Center in Summer of 2015^a

Ward	Tw, Â°C	Td, Â°C	Tg, Â°C	Va, m.s^-1	RH, %
Pharmacy	17 Â± 2.1	28 Â± 1.8	28 Â± 0.5	0.1 Â± 0.04	35.6 Â± 1.1
Stack	16 Â± 1.2	27 Â± 0.8	27 Â± 0.3	0.1 Â± 0.09	33 Â± 1.8
Official units
Health unit	16 Â± 1.3	28 Â± 1.1	27 Â± 0.4	0.1 Â± 0.07	31 Â± 2.3
Nutrient unit	16 Â± 1.1	27 Â± 0.7	28 Â± 0.5	0.1 Â± 0.11	34.4 Â± 3.4
Assessment unit	16 Â± 1.7	27 Â± 1.5	27 Â± 0.7	0.1 Â± 0.05	36.2 Â± 2.8
Public affair	15 Â± 0.8	25 Â± 0.6	26 Â± 0.4	0.1 Â± 0.13	36.8 Â± 1.4
The offices of educational sectors	14 Â± 1.4	24 Â± 1.2	26 Â± 0.3	1 Â± 0.35	45.5 Â± 2.6
Educational classes	21 Â± 0.6	26 Â± 0.4	27 Â± 0.4	1 Â± 0.27	66 Â± 6.8
Kitchen	22 Â± 2.3	32 Â± 1.8	33 Â± 0.2	0.2 Â± 0.14	46.4 Â± 3.1
Laundry	24 Â± 1.8	30 Â± 1.4	35 Â± 0.2	0.2 Â± 0.16	62.7 Â± 5.8
Day clinic	16 Â± 1.5	27 Â± 1.2	27 Â± 0.8	0.3 Â± 0.18	34.4 Â± 2.4
Sterilization	18 Â± 0.5	30 Â± 0.2	35 Â± 0.6	0.2 Â± 0.13	36.5 Â± 3.1

Abbreviations: d, Dry; g, Glob; Tw, Wet Temperature; Va, Air Velocity.

^aValues are expressed as mean Â± SD.

The results of the subjective assessment of warmness felt by the studied cases are presented in Table 3. As demonstrated in this in in general, 117 out of 116 staffs felt their workplaces as slightly warm to hot, indicating a high dissatisfaction with their workplace.

Table 3. The Subjective Assessment of Warmness Felt by the Studied Cases at Al Zahra Educational and Treatment Center in Summer of 2015

Warmness Scale	The Frequency of Vote	Credible Percentage	The Scale of Degree
Hot	40	25	3
Warm	52	32.5	2
Slightly warm	25	15.6	1
Normal	27	16.9	0
Slightly cool	8	5	-1
Cool	5	3.1	-2
Cold	3	1.9	-3
Total	160	100	–

Table 4 demonstrates PPD and PMV according to physical measurement in every studied unit. As presented in this the the most and least rates of these indices were found in the kitchen and the places of educational groups, respectively. Table 5 demonstrates the average of individual units. This reveals reveals that the rate of physical PMV was drastically higher than the subjective one.

Table 4. Measured PMV and PPD According to Each Unit at Al Zahra Education and Treatment Center in Summer of 2015^a

Ward	PMV	PPD
Pharmacy	1.4 Â± 0.2	46 Â± 3.5
Stack	1.2 Â± 0.2	35 Â± 2.2
Official units
Health unit	1.2 Â± 0.4	35 Â± 2.1
Nutrient unit	1 Â± 0.3	26 Â± 1.8
Assessment unit	1 Â± 0.1	26 Â± 1.6
Public affair	10.9 Â± 2.6	22 Â± 1.5
The offices of educational sectors	0.7 Â± 0.09	15 Â± 1.1
Educational classes	0.7 Â± 0.1	18 Â± 1
Kitchen	2.5 Â± 0.3	93 Â± 5.6
Laundry	2.5 Â± 0.5	93 Â± 8.7
Day clinic	1.1 Â± 0.2	30 Â± 3.5
Sterilization	2.2 Â± 0.6	85 Â± 7.6
Total	1.8 Â± 0.4	62.7 Â± 4.8

^aValues are expressed as mean Â± SD.

Table 5. The Subjective and Predicted Mean Vote According to Each Ward at Al Zahra Education and Treatment Center in Summer of 2015^a

Ward	Predicted Mean Vote	Subjectively Predicted Mean Vote
Pharmacy	1.4 Â± 0.2	1.82 Â± 0.5
Stack	1.2 Â± 0.3	-0.5 Â± 0.05
Official units
Health unit	1.2 Â± 0.4	1 Â± 0.06
Nutrient unit	1 Â± 0.1	0.86 Â± 0.04
Assessment unit	1 Â± 0.2	0.86 Â± 0.03
Public affair	10.9 Â± 0.9	0.86 Â± 0.07
The offices of educational sectors	0.7 Â± 0.08	-0.5 Â± 0.03
Educational classes	0.7 Â± 0.07	0.37 Â± 0.01
Kitchen	2.5 Â± 1.2	2.3 Â± 0.6
Laundry	2.5 Â± 1.5	1.5 Â± 0.5
Day clinic	1.1 Â± 0.1	0.6 Â± 0.09
Sterilization	2.2 Â± 0.3	2.6 Â± 0.4
Total	1.8 Â± 0.4	1.39 Â± 0.3

^aValues are expressed as mean Â± SD.

4. Discussion

In the present study, the thermal comfort of the staff in one of the hospitals in Esfahan was investigated. The results of this study revealed that the kitchen, laundry, and sterilization areas had higher temperature than other units. Moreover, based on Table 4, the results of physical measurements in 9 units, placed in the underground floor of the studied hospital, showed that around 62.7% of the participants were dissatisfied with the thermal conditions of their workplace, which was about 50% more than the international standards of ASHRAE-55. The percentage of PPD in educational classes and the places related to educational sectors was 18% and 15%, respectively, which was close to ASHRAE standard. The reason for this finding was natural ventilation in these 2 units. In contrast, other units did not have any access to natural ventilation due to the improper design of the building. The air condition in workplaces, especially from thermal comfort aspect, is one of the most concerns of the managers in hospitals, governmental, and non-governmental organizations. Because various factors including sort of climate, job, and cultural conditions of the community, personal factors, and ventilation type affect the thermal comfort felt by individuals (16–19). The percentages of PPD were 93%, 93%, and 85% in the kitchen, laundry, and sterilization units, respectively. These high levels of PPD may be due to the type of occupation in the workplace. Moreover, the presence of these units in the basement makes the thermal condition to be difficult in other units as well. This shows that improper organization of the units and unsuitable design of the departments for providing natural ventilation could decrease their efficiency and the productivity of the organization. Omidvari et al. investigated the condition of thermal comfort in Taleghani hospital in Kermanshah. They found that the rate of PPD index in both male and female staff working in this hospital was higher than the recommended limits. Therefore, it was recommended to the officials of the hospital to reconstruct the ventilation system and the structure of the hospital (20). The achieved results of Najafis project revealed that the rate of thermal comfort in one of Shiraz shopping centers (Vakil Bazar) was suitable in the winter with respect to the physiological tension and thermal sensitivity due to its sufficient design (21). The investigation of the mean rates of physical and mental PMV according to every unit revealed that the total rate of physical and natural PMV was 1.8 and 1.39, proving this fact that the temperature of the staffs workplace from thermal comfort aspect was not acceptable and it was much higher than ASHRAE Standard 55. Aliabadi et al. reported in their study that the rate of PMV among the staff of studied industrial workshop increased after turning on the heating and radiant system installed on the roof (22). The results of Moman et al. demonstrated that creating suitable condition having thermal comfort cause to improve staffs PMV in their workplace (9). Azizpour et al. studied PMV and PPD in one Malaysian hospital. They found that the temperature in wards in which the patients were admitted, were slightly cold in day and cold at night (23). They reported in another project that the rate of PMV in nursing station and admission ward were less than 1 (24). In their study, Pourshaghaghy et al. found that the amount of PMV in some parts of the studied hospital in Kermanshah was not acceptable according to ISO defined standards for both sexes (25). On the other side, the study of Rav and Chov showed the satisfaction of 49% of the hospital staff about the thermal condition of their workplace (17). According to physical measurements conducted in different parts of the hospital, the rate of relative humidity (except for laundry and educational classes which this variation was 60%), was in standard spectrum in most sectors (30% – 60%). The measured temperature of thermal comfort in most units (except for educational sectors, public rations, and educational classes) was higher than ASHRAE Standard 55 temperature of thermal comfort. Therefore, the results of this investigation showed that most units, particularly laundry and kitchen, had insufficient rate of thermal comfort. It is necessary to remove physically harmful agents, which are found in the workplaces by engineering evaluation so that the health promotion, occupational satisfaction, and productivity improvement of staff can be achieved. Since the international standard organization determines suggests 10% for PPD as the recommended standard and this index was found to be higher than the recommended standard, it indicated that suitable thermal comfort was not found in the studied places. Thus, improving the condition of thermal comfort for the hospitals staff depends on removing the physically harmful agents by engineering evaluations and on proper design of the building to use natural ventilation for exchanging the air flow in the workplace. The current study was limited due to lack of resources and scarcity of employee participation. It is recommended that similar studies be conducted in other hospitals.

Acknowledgements

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Biotechnology and Health Sciences

Evaluation of Thermal Comfort in an Iranian Educational Hospital Using PMV- PPD Model

Article information

Abstract

1. Background

2. Methods

3. Results

4. Discussion

Acknowledgements

References

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