Comparison of Thermal Sensations Under the Same Conditions in the Climatic Chamber and the Lecture Hall

. For many people, the feeling of thermal comfort becomes an important aspect of helping to increase concentration at work or study. Creating an appropriate indoor microclimate becomes a huge challenge for many designers of modern construction. The most important assumption of the work is to compare the thermal sensations of a group of four, aged 23 to 30, staying in the lecture class of an intelligent building and in a climatic chamber with the same internal parameters. For this purpose, the Testo 400 environmental meter was used, collecting the necessary parameters from the environment, and specially created surveys describing people's thermal feelings during the study. The air temperature and relative humidity were as follows: 21.7 o C and 30.80 %, while for the climatic chamber the same data was applied, but at the end of the study both parameters increased to 21.9 o C and 40.50 %. Moreover, it turned out that people in the lecture hall felt worse than in the climatic chamber with similar internal values. In addition, the average Thermal Sensation Vote (TSV) response showed that the perceived environment is comfortable for the study group staying in the climatic chamber, as opposed to the feeling of influenza in the room. Unfortunately, the Predicted Mean Vote (PMV) for the room and chamber exceeded the set value described in the ISO 7730 standard.


Introduction
The task of modern buildings is to provide the best possible conditions for the internal environment, as people work more and more and expand their knowledge. For that to be the case, they must feel comfortable indoors. The indicator that determines whether people feel comfortable in a given place is called Thermal Sensation Vote (TSV) and it is obtained by the answers of respondents completing the questionnaire specifying their thermal preferences. On the other hand, another Predicted Mean Vote (PMV) indicator, calculated from the data obtained from the environmental measurement, informs whether the prevailing conditions in the room are compliant with the ISO 7730 standard based on the Fanger model. The next Percentage of People Dissatified (PPD) indicator enables to know the percentage share of people who are dissatisfied with the prevailing conditions, similarly to the previous indicators, by means of questionnaires and the ISO 7730 standard [1,2].
One of the interesting research works on thermal comfort in a public building was proposed by Nakano & Tanabe [3], who examined the thermal sensations of passengers at four railway stations in Tokyo. The authors conducted surveys from 7:00 am to 8:00 pm. The results showed 80 % satisfaction in temperatures from 19 to 29 o C. A similar comparison was made by Krawczyk [4], but on two educational buildings -one intelligent and the other traditional. Moreover, Dębska & Krakowiak [5] analysed the thermal preferences of 83 people in three different educational buildings. The study was carried out using questionnaires and a microclimate device. It turned out that students preferred a temperature of 22.5 o C in an intelligent building than in traditional buildings. The authors of the works [6,7] primarily focused on thermal comfort by analysing the PMV and PPD indicators in the Energis intelligent building at Kielce University of Technology. In the first study, the Fanger model was modified, while the second study focused on the average thermal assessments of respondents and their dissatisfaction with internal conditions. However, studies in the climatic chamber were conducted by Kazanci et al. [8]. The chamber has been divided into two rooms in office conditions. 24 people, participated in the study. The temperature was kept constant at 26 o C. The results showed general satisfaction of the subjects. Another study by the authors of Solberg et. al. [9] focused on 21 people in a climate chamber. Efforts were made to recreate similar conditions to those in Norwegian offices, for 24 o C, 26 o C and 28 o C, respectively. Moreover, the authors of Białek & Dębska [10] conducted an analysis of the thermal sensations of 7 people in the classroom and one person in the climatic chamber. The same internal parameters in the chamber that had previously been saved in the classroom were recreated. The study showed that the values of PMV and TSV do not exceed the established range of thermal comfort, while a very high overshoot of the said range was obtained for PMV in the climatic chamber.
On the other hand, not only educational buildings are subject to study, but also nursing homes, hospitals and office buildings as in the authors' works [11][12][13]. The conclusions drawn by the researchers are the influence of external humidity in the preparation of the data, in the next paper on the inaccuracy of the PMV index, and in the third on the thermal differences of people in air-conditioned rooms with thermal sensations in people who do not have air conditioning in the office, becoming more susceptible to any temperature fluctuations. It needs to be remembered that thermal comfort is closely related to the issues of heat transfer [14][15][16][17][18][19][20][21] The research conducted so far does not provide any knowledge about people's thermal sensations by comparing ordinary classrooms with a climatic chamber. Therefore, the main goal of the work is to conduct research in the lecture hall and the climatic chamber with the same internal conditions, and then to compare TSV, PMV and PPD.

Methods
The research was carried out at the Kielce University of Technology, in one of the educational buildings called Energis, and in a climatic chamber. The Energis building was designed with sustainable construction in mind a decade ago. It has been equipped with Building Manager System (BMS) control systems, mechanical ventilation and underfloor heating. The climatic chamber, on the other hand, has two small rooms with dimensions of 2.70x1.80x2.30 [m 3 ] with the possibility of setting the temperature from -25 o C to +80 o C and 2.25x1.8x2.30 [m 3 ] for setting the temperature from +5 o C to +50 o C [10]. Both tested objects are shown in Figure 1. A microclimate meter and questionnaires were used to carry out the research. The first method allows you to get information from the environment about changes in internal parameters second by second. The Testo meter was used for the test, it has probes that collect data on air temperature, air velocity, carbon dioxide content and relative humidity. The meter was located in the central part of the lecture hall and worked for 15 minutes so that the parameters were as stable as possible. The second method is for students to complete the survey. It includes questions about current thermal sensations, willingness to change a given temperature and humidity, acceptability to internal parameters, well-being, productivity and clothing (to calculate the insulation performance of clothing) and data needed to calculate the Biomass Body Index (BMI), such as height and weight. The Testo 400 measuring device and the tested lecture hall are shown in Figure 2

Results and discussion
The study, which was carried out in the climatic chamber and in the classroom, involved 4 women in each, ranging in age from 23 to 30 years. First, a room test was performed to determine the microclimate parameters, which were later recreated in the climatic chamber. The parameters obtained are shown in Table 1 below. The air temperature in the climatic chamber slightly increased by 0.2 o C, compared to the lecture hall. Despite the fact that the relative humidity was applied as obtained in the lecture hall, it still significantly increased to 40.50 %. This may be due to the size of the chamber and the fact that the chamber was closed during the test, and people who sat in it increased the humidity by breathing up to about 40 %. Additionally, what you can pay attention to is the fact that the content of carbon dioxide was higher in the lecture hall than in the climatic chamber. This is an interesting phenomenon, all the more that it is in a smaller room that the increase in this value should occur, and not in a room with a much larger area.
In the further part of the work, indicators describing students' feelings about temperature and humidity as well as their dissatisfaction with the prevailing conditions will be discussed. First, attention will be focused on people's thermal sensation at a given moment, known as Thermal Sensation Vote (TSV). It is a question that determines whether the examined person is "too cold (-3)", "too cool (-2)", "pleasantly cool (-1)", "comfortable (0)", "pleasantly warm (+ 1) "," too warm (+2) ", and" too hot (+3) ". Figure 3 shows the obtained results of the conducted research. The set temperature for three people in the chamber was within the generally recognized comfort range from -1 to +1. Only one person felt that the room was too cool. 75 % of people in the lecture hall had similar feelings. Only one person said it was "pleasantly warm". The author's [10] research, which was also carried out in the room and in the climatic chamber, showed that despite 25 o C, almost 71 % of people described the temperature as "comfortable", and about 29 % of the wasps were too warm. Interpreting the obtained research analysis and comparing it to other studies by the author [10], it should be stated that 21.7 o C is definitely too low air temperature, which may contribute to deterioration of concentration or feeling shivering afterwards. By knowing people's thermal sensations, one can also know their thermal evaluation. The Thermal Assessment Vote (TAV) is responsible for this. It provides information on whether the air temperature according to the participants is "comfortable (2)", "acceptable (1)", "unpleasant (-1)" and "definitely unpleasant (-2)". Therefore, the obtained data is shown in Figure 4. People who were tested in the climatic chamber rated the temperature as comfortable with a value of 75 %, but one person (who probably marked "too cool" in Figure 3) rated it as unpleasant. On the other hand, people studying in the room assessed the temperature as comfortable -25 % and acceptable for 75 %. The research [10] shows that people in the room positively assessed the temperature, similar to Figure 4. Another indicator that helps to understand people's thermals is the determination of their thermal preferences. Thermal Preferences Vote (TPV) ranges from -2 to +2. Students answer the question whether they would prefer it to be "definitely cooler", "cooler", "no change", "warmer" and "definitely warmer". The results are presented in Figure 5 below. Based on Figures 3 and 5, it can be seen that people who were in the room and indicated that they were "too cool" in response to TSV, similarly their preferences were directed with the same percentage (75 %) towards warmer temperatures. One person showed no desire to change the temperature to a cooler or higher temperature. On the other hand, in the climatic chamber, a person who is too cold in the chamber would like it to be much warmer. Another person would like it to be warmer, and 50 % would like nothing to change. Relative humidity is also an important aspect influencing the comfort of people. The room should not be too dry or too humid, because you may feel dry throat or excessive sweating. Therefore, students rated the humidity as "too dry (-2)", "quite dry (-1)", "pleasantly (0)", "quite humid (+1)" and "too humid (+2)" as shown in Figure 6. It turns out that in both tested rooms, people rate the relative humidity as "quite dry" and "pleasantly". Only the difference appears in the percentage share. 75 % of people in the climatic chamber and 50 % of people in the room said "pleasantly", and 25 % of people in the chamber and 50 % of people in the room "quite dry". A difference can be noticed in the assessment of humidity at work [10], where approximately 43 % of people additionally thought that it was quite humid. Figure 7 will discuss Humidity Preferences Vote (HPV). Mainly, the respondents answer whether they would like "more dry (-1)", "no change (0)", "more humid (+1)". Taking into account Figure 6 and based on the data in Figure 7, a full analogy can be seen in the respondents' answers and their feelings. There is no percentage change with the "no change" answer (same as in Figure 6). However, you can see that people who indicated in Figure 6 that it is "quite dry" in the rooms under study, in Figure 7, their preference is that the room is "more humid". In general, humidity was felt better in the set conditions than in the lecture hall.
Thermal Sensation Vote and Predicted Mean Vote are no less important indicators. In addition to providing information on the current feelings of people, TSV also enables the average response of the respondents to be found on the basis of surveys, which is then compared with the PMV. It primarily determines whether the prevailing temperature has met the thermal expectations of the respondents. The PMV is calculated on the basis of ISO 7730 [1]. To do this, use the Fanger model [2], which needs parameters such as air temperature, relative humidity, air velocity, clothing insulation, etc. On this basis, it is assessed whether these attractions meet the standard or exceed the established comfort ranges . The comfort range for both is -0.5 to +0.5. Each time it is exceeded, it informs about the feeling of thermal discomfort. Figure 8 shows the calculated TSV from the questionnaires and the PMV from the standard for both test sites. For the lecture hall, TSV from the polls was higher than the PMV. The difference was 0.15. Both indicators were exceeded, which means that the prevailing conditions did not meet the thermal expectations of people and we can say about the feeling of discomfort. Taking into account the climatic chamber, the TSV from the surveys was within the comfort range and was -0.50, but the PMV was already exceeded three tons compared to the TSV. The conclusion that comes to mind is that the temperature in the form set in the climatic chamber was felt much better than in the lecture hall itself. In the study [10] PMV for the climatic chamber was 0.15 and for the room 0.08. Compared to the latest research, you can see the discrepancy in the results. PMV was very low, almost zero. On the other hand, with TSV in the chamber, the mean of respondents' responses was 2, and in room 0.43. Additionally, with the help of questionnaires, we can find out the percentage of people who feel discomfort and are dissatisfied with the prevailing markets (Predicted Percentage of Dissatisfied -PPD). The ISO 7730 standard also makes it possible to find out the value of PPD in line with modern guidelines. It is recognized that 10 % of people may be dissatisfied with the microclimate. Figure 9 shows a comparison of the received values for PPD from the questionnaires and from the standard for the tested rooms. For people in the room during the study, the survey showed 75 % dissatisfaction with the indoor climate, while for the chamber it was 25 %. On the other hand, the standardized PPD showed 31 % discomfort for the room, and almost twice as much for the chamber, amounting to about 55 %. This means that none of the examined places can be said to feel thermal comfort.

Conclusions
The first of the main conclusions is the fact that, despite similar parameters, the chamber made people feel comfortable in it for 75 % of respondents, while in the lecture room 75% of people marked the answer "acceptable". Moreover, the same percentage of people are satisfied with the relative humidity. The second important finding is that none of the obtained results of PMV and TSV fell within the thermal comfort sensation, except for the TSV for the chamber of 0.50. In the case of PPD, the percentage of dissatisfied people was high especially in the lecture room. This is probably due to the size of the room and the small number of people during the examination. In this case, for the set parameters in the climatic chamber, they turned out to be crucial, because 3 out of 4 people were satisfied with the climatic conditions. This information and data from the tests may have a significant impact in the future on the design of rooms and their size, as well as the possibility of setting specific temperatures for given needs, because it may increase the efficiency at work or the concentration of people in class. Nevertheless, in order to reach an unambiguous conclusion, the research should be continued.