Analysis of Indoor Thermal Comfort of Room Space in the International Standard Hotel Building

The objective of this study was to analyze the indoor thermal comfort of room space international standard hotel buildings. The sample of the study was guests staying at five international standard hotels. The total sample were 1,092 people from five international standard hotels then sampling through Slovin formula of 10% to determine the number of respondents as many as 92 respondents. Primary data was collected through survey and questionnaires. Data was analyzed with software regarding air temperature of international standard hotel rooms both indoor and outdoor has fulfilled the prerequisites of ASHRAE, Thermal Environmental Conditions for Human Occupancy (Standard 55-66).Indoor air temperature of the five hotels observed was between 28.85 °C to 29.54 °C, with the air temperature approaching the comfort zone ranging from 20.5 °C to 27.1 °C. The outdoor air temperature of international standard hotel room space observed is on average range between 28.42 °C to 40.52 °C, with a standard deviation ranging from 0.01 to 0.44. The maximum value is between 28.45 °C to 41.41 °C and a minimum value is 28.40 °C to 39.87 °C. Solar radiation on international standard hotel building observed is in an average range between 32.79 watts / m2 to 769.75 watts / m2, with a standard deviation ranging from 0.95 to 285.43 watts / m2. The maximum value is between 36.37 to 918.97 watts / m2 and a minimum value is between 30.08 to 715.63 watts / m2. Solar radiation has a major influence in changing the indoor thermal comfort temperature in hotel rooms.


INTRODUCTION
International standard hotel buildings are commercial buildings that must be equipped with various operational facilities which guarantee indoor thermal comfort (Bohdanowicz & Martinac, 2002). Thermal comfort according to the American Society of Heating, ASHRAE, Thermal Environmental Conditions for Human Occupancy (Standard 55-66) as "state of mind expressing satisfaction with the thermal environment" (ANSI/ASHRAE, 2017). Then it is defined by the International Standard Organization (ISO) in Standard 7730 (ISO, 2005). According to Gagge et al. (1967) feeling comfortable is difficult because it implements the Buildings must be designed based on indoor thermal comfort, especially considering the influence of air temperature, wind velocity, solar radiation as a matter of significant influence on the thermal comfort of the room (O'hegarty et al., 2015). There are a number of hotel designs less attention to the standard dimensions of space that meet the criteria of comfort requirements for customers. Many of them sacrifice the comfort of inner space for customers by reducing the dimensions of the room to increase the number of rooms and for other space functions (Hendrarto et al., 2012). The circulation zone contained in buildings is used to connect spaces and activity to another. A circulation zone is designed to facilitate the mobility of users in order to be able to use and enjoy part or all of the building facilities (Pynkiawati et al., 2009). This is intended to have an indication of the relationship between temperature climates with the sleep quality of hotel room users (Rupp et al., 2015).
The hotel as a guest rest place is designed to have rooms with suitable thermal comfort with comfortable air temperatures during the day and at night. The air temperature the building should be maintained in accordance with air velocity, radiation intensity and humidity level with the aim of obtaining thermal comfort (Tharziansyah & Rahman, 2008). Various air temperature differences effect on the various thermal effects air temperature, air velocity, and solar radiation which affect the condition of buildings (Gandhi et al., 2018). Thermal comfort standards such as ASHRAE standard 55 (ANSI/ASHRAE, 2013) have been widely used to design thermal comfort in various countries, including in determining the thermal comfort of international standard hotels. Thermal comfort standards are divided into 7 scales, namely: hot (+3), warm (+2), slightly warm (+1), neutral (0), slightly cold (-1), cool (-2) and cold (-3) (Fanger, 1970;Hamzah et al., 2018).
For the Government of Indonesia to provide comfort thermal guidance for buildings in general based on the Indonesian National Standard (SNI) 03-6572-200103-6572- (BSN, 2001 where buildings must provide a thermal environment: 1) cold comfort: 20.5 -22.8 °C (Te); 2) comfort: 22.8 -25.8 °C (Te); and warm comfort: 25.8 -27.1 °C (Te) (Hamzah et al., 2018). This guideline uses effective temperature (Te) which is defined as the stagnant and saturated atmosphere temperature, producing the same effect as the atmosphere in objective observations. Therefore, the combination effect of dry and humidity temperature is made (Auliciems & Szokolay, 2007), so thermal and energy management needs to be used in a variety of thermal management systems (Zhang et al., 2018).
One important problem in achieving indoor thermal comfort in buildings is the influence of different type of building functioning. Depends on the activity occurs in the hotel (Alwetaishi, 2016). Efforts to reduce high air temperatures can be done by green area to soothing the thermal atmosphere of the environment around the hotel building (Kosonen et al., 2010). The international standard used to determine indoor thermal comfort prerequisites for room utilities must have a comfortable temperature at 23.3 °C, so comfort quality is required according to the Percentage of Dissatisfaction Prediction index (PPD Index) (Jaffal et al., 2012). The number of star-rated hotels with international standards has sprung up in Indonesia affecting the thermal conditions of the air temperature in each room. Through observation, it was found a number of wasteful hotel rooms in the utilization of air conditioning (AC). To minimize energy use and realize indoor thermal comfort the room space of a hotel building, it is necessary to analyze indoor thermal comfort in the room. The objectives of this study are: 1. Reporting the indoor thermal environmental conditions the rooms in international standard hotel buildings. 2. Analyzing response of hotel guests staying toward the indoor thermal environment conditions in room space. 3. Finding operational temperatures in each hotel room based on the Indonesian climate.

Research Samples and Respondents
This study was conducted at five hotels which were observed the room temperature conditions indoor hotel rooms based on indoor and outdoor temperatures. The observation treatment was conducted by assessing the temperature condition after all air condition (AC) is turned off. The treatment of the observed time range was determined based on the time of observation to measure air temperature and solar radiation by setting three times namely 9:00, 12:00. And 15:00. The research was conducted at international standard hotels by determining five hotels, namely: 1) Grand Clarion has 17 floors with 533 rooms; 2) Aryaduta has 10 floors with 224 rooms; 3) Sahid Jaya has 12 floors with 204 rooms; 4) Swiss-Belhotel has 22 floors with 296 rooms; and 5) Aston has 19 floors with 177 room spaces. More details are shown in the table below: Sampling of this study is guests staying at five international standard hotels before observations. As for the number of samples registered at the reception based on length of stay: Total sample of 1,092 people from five international standard hotels is then carried out by the sampling through Slovin formula to determine the number of respondents. The Slovin formula uses a confidence level of 0.05 or 5% with the following formulations: So the sample in this study was 92 respondents, distributed in each hotel using the formula below: N sample Distribution of Respondents = ---------x total Slovin respondents N total More details about distribution results of respondents are shown in the table below: Based on the table above, shows the distribution of respondents were distributed questionnaires for surveys of room temperature during their stay, namely Grand Clarion Hotel as many as 40 respondents, Aryaduta Hotel 16 respondents, Sahid Jaya Hotel 13 respondents, Swiss-Belhotel 13 respondents and Aston Hotels there are 10 respondent.

Research Instruments
There are several instruments used to observe the indoor thermal comfort the rooms in the hotel building. A set of tools of HOBO Temp / Relative Humidity (RH) Indoor (UX100-011) which is equipped with several sensors and data loggers (Hobo-1) of four units placed in each room which are oriented north, south, east and west at the same time in one hotel building. HOBO Temp / Humidity Outdoor (MX 2300) is to measure air temperature and outdoor air relative humidity (Hobo-2). Instruments used to measure the average temperature of solar radiation (MRT) in the form of HOBO Solar Radiation Sensors (S-LIB-M003) and HOBO H21 USB Micro Station Data Logger (Hobo-3). The specifications of the instruments used in data collection are shown in table 4 (Hamzah et al., 2018).

Data Collection
Primary data has been collected through survey methods and questionnaires. Data collection was obtained as follows: 1. An objective measurement survey was conducted to collect environmental data around hotel and thermal buildings. Data of indoor room space the hotel, surveyed for subjective measurements in measuring the indoor thermal comfort level of hotel guest respondents. The survey was conducted using questionnaire by asking questions, which captured Thermal Sensation Voice (TSV), Thermal Comfort Voice (TCV), thermal preferences and thermal receipts of respondents. In addition to air temperature, the questionnaire provided was intended to get respondents' responses to air velocity, preferences of air velocity and humidity indoor the hotel room. The TSV response was measured based on ASHRAE standard 55, which uses a seven-point scale to measure the respondent's thermal sensation. 2. Indoor thermal comfort can also be measured by asking for thermal preferences and recipients of occupants (in this case hotel guest respondent). Thermal preferences are related to the question of whether hotel guests prefer to be warmer or cooler or there are no changes. In addition, questions related to air velocity and humidity was also included in the questionnaire. At the top of the questionnaire, respondents wrote the name of the hotel, room number, respondent's name, gender, age, weather conditions and the position of the room occupied. Hotel guests fill out questionnaires for at least 25 to 30 minutes in each room the researcher will visit. To prevent mistakes in choosing relevant answers based on hotel guest preferences, an explanation of the indicators used in the questionnaire that have been carried out, for example, the difference between "Very cold", "cold", "neutral", warm "and" hot ".

Process and Data Analysis
Data analysis was performed with MS Excel spreadsheet software and SPSS statistical package. Excel is used to calculate the average value of thermal environment variables and to produce a table showing the condition of a hotel room. For statistical analysis, SPSS version 23 with regression analysis was used. Regression analysis checks the correlation and linearity of data between TSV and operating temperature (To), TVC and operating temperature (To), and between PMV and operating temperature (To), TSV and TCV are collected from respondents' answers written in the questionnaire, while PMV is calculated based on ASHRAE standards using Excel software (ANSI/ASHRAE, 2013). PMV values are calculated by Excel software with sample calculations provided in the ASHRAE standard. According to Nicol (2004), the problem of using PMV in predicting indoor thermal comfort in hot climates in tropical countries is because the air temperature and air velocity exceed the limits that can be handled by PMV. Although the air temperature exceeds the PMV model limit, it can be used as an indicator to evaluate the indoor thermal comfort of buildings in the tropics. TSV responses are grouped according to ASHRAE scale, while TCVs are grouped using the Bedford scale.
To calculate PMV for each respondent, there are four appropriate environmental variables and two personal variables for each respondent. However, not all variables are collected due to limited equipment. MRT is only measured in the central point of the hotel room, while the air velocity value is measured at two points, namely A and B. To simplify the calculation process, the MRT score is applied to all points. Regarding air velocity, the arrangement is the air velocity score collected in a divided by points C and E, while those collected at point B are divided by point D and F respectively. By applying this arrangement, all respondents who are near the measurement point should have all six variables needed. This makes it possible to calculate PMV score based on four environmental variables and two personal. PMV for 92 respondents has been calculated.
The results of the study were analyzed based on statistical analysis using SPSS version 23. The statistical analysis used was regression analysis, which was based on Pearson correlation. Acceptance of linear regression analysis is determined by two criteria: regression linearity test (F-test) and the significance of the equation coefficient (t-count). This equation is statistical linear if the absolute value of F-count > F-table and significant value <probability (0.05). Table  F for the case is 3,844. The equation coefficient is significant if the absolute value of t-count> ttable and the significance of the value <half of the probability (0.025 for two tail). The T-table for the infinity of degrees of freedom is 1960. The data used for statistical analysis has been verified by checking its normality and reliability.

Participants'
The Participants' identity in form of gender, age, education level and work period, is presented to find out the number of frequencies and the percentage of respondents who are representative in giving responses.

Hotel Location and Sketch
Location of the study was conducted in Indonesia with observations of international standard hotels in the city of Makassar. The following is shown in the lay out of five international standard hotels observed. Location of the measurement point is marked with a description of the rooms R1, R2, R3, and R4.

Grand Clarion Hotel
Grand Clarion Hotel is located at AP. Pettarani 03 Makassar street, established in 2006, the hotel has been used for 11 years with 17 floors which have 533 rooms providing 17 types of rooms which having Air Condition system based on indoor and outdoor temperatures.

Aryaduta Hotel
Aryaduta hotel is located at Somba Opu 297 Makassar street, was established in 1996, the hotel has been used for 21 years with 10 floors that have 224 hotel rooms providing 13 types of rooms which having Air Condition systems based on indoor and outdoor temperatures.

Sahid Jaya Hotel
Sahid Jaya Hotel is located at DR. Ratulangi 33 Makassar street, was established in 1996, the hotel has been used 21 years with 12 floors which has 204 hotel rooms providing 4 types of rooms, which having Air Condition system based on indoor and outdoor temperatures.

Swiss-Belhotel
Swiss-Belhotel, located at Ujung Pandang No 8 Makassar street, was established in 2016, the hotel has been used for 1 year with 22 floors that have 296 hotel rooms providing 6 types of rooms, namely having an Air Condition system based on indoor and outdoor temperatures.  The survey was conducted on a clear day where the average outdoor temperature was 39.7 °C, with the minimum of 23.7 °C in the morning and a maximum of 33.4 °C during the day. The average relative humidity at that time was 69.2% with a minimum of 50.0% and a maximum of 85.8%. This external thermal environment is collected from the Meteorological Station located at Sultan Hasanuddin International Airport (5 ° 4S, 119 ° 33'E, 17 m above sea level) about 20 km away from the city center.

Indoor and Outdoor Room Temperature Conditions
Room temperature conditions in international standard hotel rooms based on observation time for Grand Clarion hotels, Aryaduta and Sahid Jaya, there are four observations object rooms, while Swiss-Belhotel and Aston hotels, and have three observation objects.

Solar Radiation Hotel Buildings
It is known that outdoor solar radiation conditions of international standard hotel rooms are based on observation times for Grand Clarion, Aryaduta, Sahid Jaya, Swiss-Belhotel and Aston hotels with 30 objective observations data according to average, standard deviation, maximum and minimum. More clearly the table shows the conditions of outdoor solar radiation in the international standard hotel rooms. Outdoor Solar radiation of Grand Clarion hotel room at 09.00 was in an average 29.07 with a standard deviation of 0.01 with a maximum of 29.10 and a minimum of 29.05, at 12.

Guests Responses toward Thermal Environment
Guest responses to the thermal environment of the five international standard hotels were observed based on the questionnaire questions corresponding to the ASHRAE standard 55 identifying hotel guests' responses to the thermal environment in the form of air temperature, comfort feeling, preference and level of reception with hotel room air temperature. The picture above shows that the respondent's response to the air temperature of the five international standard hotels observed showed that the most responds with the assumption that the hotel room is slightly cold (-1) as much as 31.5% and warm (2) as much as 6.5% . Means generally hotel guests want a hotel room that is slightly cold and not too warm (-1 to 2) (figure 13a). The feeling of being a guest of the five international standard hotels observed gave a response to feelings indicating a preference for cold comfort (-1) of 32.6% and very warm response (2) as much as 2.2% ( figure 13b). This means that respondents desire the cold comfort to very warm air temperature (-1 to2). The picture above shows that the respondent's response to the air temperature of the five international standard hotels observed showed that the most responds to feeling like the cooler in the hotel room (-1) as much as 62% and the least states there is no change (0) as much 17.4%. This means that generally hotel guests like coolers in hotel rooms that give a cold feeling ( figure 14a). Furthermore, the level of reception for air temperatures in hotel rooms generally provides an acceptable response (1). This means that hotel guests can accept the existence of hotel rooms with air conditioning (figure 14b).

Guest Response to Air Velocity
Guest responses to air velocity at the five international standard hotels observed based on appropriate questionnaire questions of ASHRAE standard 55 identified responses based on air velocity and preferences with air velocity. The picture above shows that the respondent's response to air velocity in the five international standard hotels observed showed that the most responding to air velocity in a hotel room stated slightly silent (-1) as much as 51.1% and the least stated was too breezy (2) as much as 2.2%. This means that generally hotel guests prefer the slightly silent to breezy air velocity in the hotel room ( Figure 15a). Furthermore, guests' responses to the preference for air velocity in the hotel rooms generally prefer a decreased air speed (1) as much as 55.4% and the least stated there are no changes (0). This means, guests want a decrease in air velocity in the room of the hotel room they occupy (figure 15b).

Respondent Response toward Solar Radiation
Guests' responses to indoor and outdoor solar radiation at the five international standard hotel rooms observed based on questionnaire questions that were in accordance with ASHRAE standard 55. The picture above shows that respondents responses to solar radiation for indoor the international standard hotel room observed showed that the ones that gave the least dry response (1) were 41.3% and the least were very humid (-2) which was 2.2% . Means generally the solar radiation indoor the hotel room started from a slightly humid to slightly dry (figure 16).

CONCLUSION AND DISCUSSION Conclusion
Measurement and calculation of objective observations based on the orientation of air temperature of international standard hotel rooms both analyzed from indoor and outdoor have fulfilled the prerequisites of ASHRAE, thermal environmental conditions for human occupancy (Standard 55-66).Indoor air temperature of the five hotels observed at temperatures between 28.85 °C to 29.54 °C, which indicated that the hotel management always pay attention to air temperature according to indoor thermal comfort, based on the response of hotel guests who expect comfort, feeling joy and accept with the air temperature approaching the comfort zone ranges from 20.5 °C to 27.1 °C.
The outdoor air temperature of international standard hotel room observed was in an averages ranging from 28.42 °C to 40.52 °C, with a standard deviation ranging from 0.01 to 0.44. The maximum value is between 28.45 °C to 41.41 °C and a minimum value of 28.40 °C to 39.87 °C. Indicating that the outdoor air temperature of the hotel room is high because the observations were carried out in the dry season at the three time observation treatments, namely 09.00, 12.00 and 15.00. Where the outdoor air temperature is affected by air velocity. The response of hotel guests generally comfort with silent air velocity and a decrease in air velocity that affects thermal conditions while inside the hotel room. Solar radiation in the building of international standard hotel room observed is in an average range between 32.79 watts/m 2 to 769.75 watts/m 2 , with a standard deviation ranging from 0.95 to 285.43. The maximum value is between 36.37 watts/m 2 to 918.97 watts/m 2 and the minimum value is between 30.08 watts/m 2 to 715.63 watts/m 2 . This means that solar radiation in hotel building space is extremely influences changes in indoor thermal comfort temperature in hotel rooms.
Recommendations for international standard hotel management to pay attention to the importance of indoor, outdoor, and solar radiation by considering green space, the utilization of heat-resistant materials, refusing heat absorption in buildings and reducing conventional energy use in a room treatment of hotel rooms.

Discussion
Survey studies on international standard hotels based on the indoor thermal comfort analysis of hotel room are influenced by air orientation temperatures of the buildings. Survey of processed data, showed that from five hotels observed there were differences in the objective observations of hotel room air temperature based on the observation time at 09.00, 12.00 and 15.00. Judging from the three treatment times for Grand Clarion hotel room air temperature in the range of 29.46 °C, Aryaduta ranges from 29.54 °C, Sahid Jaya Hotel ranges from 28.85 °C, Swiss-Belhotel ranges from 32.56 °C and Aston ranges from 29.23 °C. This shows the difference in air temperature due to the layout of the hotel building, so the ideal temperature from the five hotels is Sahid Jaya hotel which has stability in air temperature which is between 28. The study of objective observation survey data for outdoor air temperature obtained the determinant coefficient ofR 2 from the regression analysis at each of the different hotels, namely for Grand Clarion R 2 = 0.620, Aryaduta R 2 = 0.734, Sahid Jaya R 2 = 0.286, Swiss-Belhotel R 2 = 718 and Aston R 2 = 0.428. These results indicate that the Aryaduta hotel spread distribution of outdoor air temperature has an effect of 73.4% compared to Swiss-Belhotel 71.8%, the Grand Clarion 62%, Aston 42.8% and Sahid Jaya is 28.6% in influencing the condition of indoor rooms. The greater the influence of outdoor air temperature that surrounds the hotel building, the greater the effect on the effect of temperature to decrease to low temperature (cold to hot). Compared with some research results in the tropics, outdoor temperatures play an important role in changing the temperature of the building's room. In general the outdoor temperature is in the range of 28.2 °C -33.6 °C, which is almost the same as the air temperature (Alwetaishi, 2016). It means determining the outdoor temperature to be the main comparison to find out how much effective influence in determining indoor temperature conditions in the room, especially in changing cold conditions to cool and cool conditions to heat.
Observation survey study to see solar radiation in international standard hotel rooms indoor the results of comparison of the five hotels is known to be an average according to objective observation time treatment, namely 09. Objective observational survey data for solar radiation in international standard hotel room spaces obtained determinant coefficient of R 2 from the regression analysis at each of the different hotels, namely for Grand Clarion R 2 = 0.332, Aryaduta R 2 = 0.329, Sahid Jaya R 2 = 0.750 , Swiss-Belhotel R 2 = 727 and Aston R 2 = 0.731.
Some research results can be compared, especially for tropics with high solar radiation during the dry season, where solar radiation that illuminates hotel buildings significantly affects the indoor air temperature of hotel buildings, especially inside rooms, showing solar radiation plays an important role in the occurrence changes in building room temperature [10,20]. It means that solar radiation greatly affects the orientation temperature according to the position of the solar radiation in the morning, afternoon and evening, so that the radiation effect is felt in the afternoon because the building material stores heat.
For the objective observations carried out on five international standard hotels of treatment, measurement and calculation of air temperature indoor rooms, and solar radiation, the respondents' responses generally showed that had the most responses to slightly cold air temperatures (-1) and the least stated warm (2) or in other words the respondent needs air from -1 to 2. The response to feeling comfortable with the air temperature that is felt most is cold comfort (-1) and the least stated very warm (2). Means the desired response to hotel room air temperature that fosters comfort feeling of that is cold comfort conditions to very warm (-1 towards 2).
The response of guests to feeling comfort of the temperature in an international standard hotel room provides the most response by expressing their love for the presence of air conditioners. Respondent responses stated comfort with the air temperature in the room. The most responses said very cool (-1), which responds to say there was little change (0). It means that the respondent desire the cold and stable (no change) or from cold to stable air temperature in the hotel room (-1 to 0). The response to the level of acceptance of air temperatures in hotels is generally acceptable (1) and unacceptable (0). Means the room temperature of all five international standard hotels is generally acceptable.
The air velocity in an international standard hotel room has the most response, the air velocity is slightly silent (-1) and the least is breezy (2). This shows the respondent desire the air velocity to be quiet until too breezy (-1 to] 2). The favorite response with the most air velocity is the decreased air velocity (1) and the least response is no change (0). Preference with the desired air velocity is that air decreases and does not change (1 towards 0).
The most response in indoor and outdoor solar radiation of hotel rooms was slightly dry (1) and the least response was very humid (-2). Means the response of hotel guests desire the condition of the rooms occupied is in very humid conditions to slightly dry, so that the room's thermal conditions are maintained (-2 towards 1).