Measured Thermal Comfort Conditions in Iranian Hospitals for Patients and Staff

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1 Measured Thermal Comfort Conditions in Iranian Hospitals for and Staff Jamal Khodakarami 1, Ian Knight 2 1 Cardiff University, Cardiff/ Ilam University, Iran 2 Cardiff University, Cardiff Corresponding KhodakaramiJ@cardiff.ac.uk SUMMARY The occupants of hospitals like other buildings have widely differing thermal comfort requirements due to their different levels of clothing and metabolism. The study indicated three main groups of occupants in Iranian hospitals as: patients that are able to be covered, patients that are not able to be covered regarding their medical conditions, and staff. This study investigated the thermal comfort calculated to have been achieved for different occupants in Iranian hospitals. The thermal comfort achieved findings have been derived from basic monitoring of those parameters which affect thermal comfort in 14 rooms in 4 separate Iranian hospitals. The thermal comfort results calculated for each room are compared with recommended Iranian and international standards for acceptable thermal comfort. The findings from this study showed a wide range of thermal comfort conditions were achieved in Iranian hospitals, and overall the thermal comfort conditions recorded during the measurement period were felt to be unacceptable. INTRODUCTION Thermal comfort can be expressed as that condition of mind which expresses satisfaction with the thermal environment [1]. A large volume of thermal comfort research over the last century has been distilled into international standards in terms of designing and maintaining comfortable thermal environments [2]. During this time two main approaches to thermal comfort research have been: the laboratorybased method, e.g. Fanger s PMV-PPD model [3] leading to EN ISO 7730 [1]; and the fieldbased method (e.g., the Adaptive Comfort Standard or ACS). Both of these methods are represented in the latest edition of ASHRAE s thermal comfort standard [4]. Air temperature, radiant temperature, humidity and air movement as the environmental variables combine with the metabolic heat generated by human activity and clothing worn by a person, to provide the six fundamental factors that define human thermal environments [5]. Hospitals occupants including and staff require different thermal comfort conditions due to their different levels of clothing and activity. Comparing the comfort levels of sedentary people at home, at work and in a climate chamber, shows that being at home, in a familiar and under control environment, leads to comfort and makes people less sensitive to temperature [6].

2 This paper presents the findings of an investigation undertaken to ascertain: Current thermal comfort conditions being achieved in Iranian hospitals. Potential solutions to improve thermal comfort achievement in these buildings. The thermal comfort conditions have been ascertained through a combination of monitoring those parameters which effect occupant thermal comfort along with occupant and site observations. The findings from the monitoring are compared with the Iranian Health Buildings Design standard [7] and international thermal comfort standards from ASHRAE, ISO7730 and CIBSE [8]. For the standards used, ASHRAE, CIBSE and Iranian standards indicate the indoor air temperature and relative humidity ranges for thermal comfort achievement. ISO7730 indicates a range for Predicted Mean Vote (PMV) or Predicted Percentage Dissatisfied (PPD) to achieve thermal comfort based on the six factors which define PMV or PPD: air temperature, relative humidity, radiant temperature, clothing and activity levels, and the air velocity [9]. Table 1 presents the relevant thermal comfort ranges from the standards. The thermal comfort of patients and hospital staff is affected by the thermal conditions provided including air temperature and relative humidity in hospital wards. [10] Due to different levels of clothing and activity in patients and hospital staff, these groups require different conditions to achieve thermal comfort. Table 1: Recommended conditions to achieve thermal comfort Standard Recommended thermal condition to achieve thermal comfort ASHRAE 23 ºC<Temp<26 ºC and 30%<Rh<60 ISO <PMV<+0.5, PPD<10% and 30%<Rh<60 CIBSE 22 ºC <Temp<24 ºC and 30%<Rh<60 Iranian Regulation 24 ºC <Temp<28 ºC and 30%<Rh<60 METHODS All the standards referred to for assessing thermal comfort require the measurement of relative humidity and air temperature. The calculation for ISO7730 also requires clothing and activity levels to be observed and radiant temperature and air velocity to be estimated [5]. Building monitoring with occupant and site observations were used as the method for data collection in this study. 14 patient rooms in 4 hospitals were selected as case studies. To cover the majority of conditions likely to be found in Iranian hospitals the selected healthcare buildings included four different types of activity. The selected rooms in each hospital were also different in other ways, including the orientation, type of patients, dimensions etc. The case studies consisted of: Two in-patient rooms in a small local clinic; three separate rooms in a private maternity hospital; four separate rooms in a new (prototype) hospital, and five separate rooms in a regional educational hospital. Table 2 presents the details of the monitored hospitals.

3 Table 2: Monitored hospitals Case study activity No of wards No of beds No of active beds Year of construction No of monitored rooms Building No1 TER1 TER2 Building No2 KR1 KR2 KR3 Building No3 TR1 TR2 TR3 TR4 Building No4 IKR1 IKR2 IKR3 IKR4 IKR5 General Maternity General General The temperature and relative humidity data was recorded by calibrated loggers at 10 minute intervals for around two weeks for each of the case studies. The globe temperature was also measured to allow calculation of mean radiant temperature. Site visits provided observations of clothing, activity and air velocity. No noticeable air movement was observed in any of the case studies, so a value of 0.1m/s was used to cover the air velocity in all monitored rooms. The clothing and activity levels observed during the study are recorded in Table 3 and Table4. Table 3: Clothing types for patients and staff in hospital wards* Clothing Clothing level (clo) without cover with cover Light-weight shirts with long sleeves Normal shirts with long sleeves Light-weight trousers Normal trousers Light summer jackets Socks Shoes (thin soled) Panties pants and bra Singlet Blanket ** Total clothing *** 0.49 clo 1.39 clo 0.88 clo *- ISO 7730: Moderate thermal environments- Determination of the PMV and PPD indices and specification of the conditions for thermal comfort ** - the clo for blankets assumed to be same as boiler suit in ISO 7730 *** - Total clothing =? clothing Table 4: Activity rates for patients and staff in hospital's wards **** activity Metabolic rate (met), % of time Staff, % of time Reclining % - Seated, relaxed % 5 % Sedentary activity % Standing, light activity % Standing, medium activity % Walking on the level % Total activity 0.82 met 1.50 met ****- 1 - ISO 7730: Moderate thermal environments- Determination of the PMV and PPD indices and specification of the conditions for thermal comfort Staff

4 From Table 3, this study assumes that the mixture of clothing types for patients without a blanket cover gives a 0.49 clo, for patients with cover 1.39 clo, and for staff 0.88 clo. From Table 4, this study assumes that the average activity rate for patients is 0.82 met, and for staff is 1.50 met. RESULTS Comparisons of recorded data with ASHRAE, CIBSE, and Iranian standard recommended ranges of air temperature and relative humidity have been completed. PMV and PPD values have also been calculated for each case study and compared with recommended ranges in ISO7730. Table 5 summarizes the findings in terms of the percentage of the time that the buildings achieved the recommended values for the standards. Table 5: Maximum radiant temperature ranges for hospital users in Iran (All users assumed to be in conditions of: air temperature from 20ºC to 28ºC, air velocity from 0.1 m/s to 0.5 m/s, and relative humidity from 30% to 60%) Users with blanket 12.3 ºC to 43.3 ºC without blanket 25.6 ºC to 50.5 ºC Staff -4.7 ºC to 35 ºC Maximum radiant temperature range Table 5 shows that overall the rooms monitored met ASHRAE recommended temperature and RH requirements 27% of the time; CIBSE recommended temperature and RH requirements 4% of the time; and Iranian regulations for recommended temperature and RH requirements 67 % of the time. Standarad acceptability for monitored buildings % Acceptability 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Building No 1 Building No 2 Building No 3 Building No 4 Ave. of all Buildings Monitored hospital ASHRAE acceptability CIBSE acceptability Iranian regulation acceptability Figure 1: ASHRAE, CIBSE, Iranian regulation acceptability in monitored buildings.

5 Referring to the more detailed ISO7730 requirements we found that only 1 % of the monitored time were the staff estimated to be in the comfort zone, though these same conditions meant that thermal comfort conditions were met 39 % of time for the patients with blankets and 17 % of time for the patients without blankets. Figure 1 and Figure 2 present these results in graphical format. ISO 7730 acceptability in monitored buildings for sevaral users % Acceptability 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Building No 1 Building No 2 Building No 3 Building No 4 Ave. of all Buildings Monitored hospital ISO 7730 for staffs ISO 7730 for patients with cover ISO 7730 for patients without cover Figure 2: ISO 7730 acceptability in monitored buildings for Staff, Patient with blanket and Patient without blanket in Iranian hospitals. Figure 3: Measured indoor conditions in monitored hospital rooms compared to the zones of acceptable conditions for each standard.

6 Figure 3 presents graphically the spread of the monitored indoor thermal conditions across all the monitored buildings. This figure shows that nearly half of all the measured data fell inside the values recommended by the different CIBSE, ASHRAE and Iranian regulations. When the data fell outside these acceptable ranges it is seen that the rooms were then generally too hot and dry. This graph also shows building No1 had the most data outside the recommended ranges PMV Recommended PMV in ISO 7730 PMV for with cover PMV for without cover PMV for Staffs Min recommended PMV in ISO 7730 Max recommended PMV in ISO :00 02:00 04:00 06:00 08:00 10:00 12:00 Time 14:00 16:00 18:00 20:00 22:00 Figure 4: Average PMV achieved in Iranian hospitals for patients and staff Figure 4 presents the comparison between the recorded data and the ISO7730 recommended ranges. On average, Figure 4 shows that while the hospital staff generally experience uncomfortably hot thermal conditions, patients with blankets are generally the most thermally comfortable group in the hospital, though with a tendency towards overly warm conditions in the afternoons. For patients without a blanket for any reason the thermal conditions will generally be too cool. Table 6 presents this data as the percentage of acceptable PMV and PPD for patients and staff by each of the monitored hospitals. Table 6: PMV and PPD acceptability for three main user groups in case studies % PMV acceptability ( -0.5<PMV<0.5) for % PPD acceptability (PPD<10%) for Case study Staff With cover without cover Staff With cover without cover Bu. No1 0 % 9 % 80 % 0 % 9 % 79 % Bu. No2 1 % 68 % 12 % 1 % 67 % 12 % Bu. No3 0 % 32 % 39 % 0 % 32 % 38 % Bu. No4 3 % 65 % 10 % 3 % 64 % 10 % Ave. All 1 % 44 % 35 % 1 % 43 % 35 % On average the patients were more comfortable than the staff during the monitoring period. This table shows while 1 % of monitored time the hospital staffs were placed in comfort thermal conditions, 44 % of monitored time the patients with blanket and 35 % of monitored

7 time the patients without blanket were placed in comfort thermal conditions. The table also shows that there were significant variations in the comfort conditions achieved in the different hospitals, though the staff were universally uncomfortable for all hospitals. DISCUSSION The different user groups of the hospital had thermal comfort requirements that were difficult to accommodate in one space. Therefore the best solution would appear to be to provide different thermal zones for different user groups in hospitals. In particular, it appears that staff should be provided with work areas in the wards that are controlled to very different conditions to the general wards. Although, the monitored indoor thermal conditions in Iranian hospitals were generally within the recommended range of the Iranian thermal regulation, they were generally out of the thermal comfort zones recommended by ISO7730, ASHRAE and CIBSE. The next stage of the study will try to answer some key questions including: is there any possibility for reconciling the thermal conditions required by different groups of occupants in Iranian hospitals? How much can modifying existing designs improve thermal comfort? How much more comfort could be achieved through a new vernacular for the design and operation of Iranian hospitals? REFERENCES 1. ISO "International standard 7730: Moderate thermal environments- Determination of PMV and PPD indices and specification of the conditions of thermal comfort", Geneva: International standards organization. 2. R. de Dear "Thermal comfort in practice", Indoor Air 14: Fanger, P.O "Thermal Comfort", Copenhagen: Danish Technical Press. 4. ASHRAE "ANSI/ASHRAE Standard 55R Thermal environmental conditions for human occupancy", Atlanta: American Society of Heating, Refrigerating and Air- Conditioning Engineers, Inc. 5. K.C. Parsons "Human thermal environments: The effects of hot, moderate, and cold environments on human health, Comfort and Performance", Taylor & Francis, ISBN: Oseland, N "Predicted and reported thermal sensation in climate chambers, offices and homes", Energy and Buildings 23(2): Management and planning Organization (M.P.O.) "Health Building design1/design guide for mechanical services of medical surgical care unites", Islamic republic of Iran. 8. CIBSE "Environmental design, CIBSE Guide A", the chartered Institution of Building Services Engineers, London. 9. B.W. Olesen, K.C. Parsons "Introduction to thermal comfort standards and to the proposed new version of EN ISO 7730", Energy & Buildings 34, J. Skoog, N. Fransson, et al "Thermal environment in Swedish hospitals summer and winter measurements", Energy and Buildings 37: