ادراک حرارتی، روش های سازگاری عمومی و ایده مستاجر در مورد تجارت کردن بین آسایش حرارتی و صرفه جویی در انرژی در مناطق گرم و مرطوب
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|22953||2009||7 صفحه PDF||سفارش دهید||5056 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Building and Environment, Volume 44, Issue 6, June 2009, Pages 1128–1134
A field study conducted in workplaces and residences in Taiwan is carried out to clarify two questions in detail: (1) do people in the tropical climate regions demonstrate a correlation between thermal sensation and thermal dissatisfaction the same as the PMV–PPD formula in the ISO 7730; and (2) does the difference in opportunities to choose from a variety of methods to achieve thermal comfort affects thermal perceptions of occupants? A new predicted formula of percentage of dissatisfied (PD) relating to mean thermal sensation votes (TSVs) is proposed for hot and humid regions. Besides an increase in minimum rate of dissatisfied from 5% to 9%, a shift of the TSV with minimum PD to the cool side of sensation scale is suggested by the new proposed formula. It also reveals that the limits of TSV corresponding to 80% acceptability for hot and humid regions are −1.45 and +0.65 rather than −0.85 and +0.85 suggested by ISO 7730. It is revealed in the findings that the effectiveness, availability and cost of a thermal adaptation method can affect the interviewees' thermal adaptation behaviour. According to the discussion of interviewees' idea about the trade-off between thermal comfort and energy saving, it is found that an energy-saving approach at the cost of sacrificing occupant's thermal comfort is difficult to set into action, but those ensure the occupant's comfort are more acceptable and can be easily popularized.
After the adaptive model of thermal comfort became the spirit of changes to the current version of ASHRAE Standard 55  and , more and more researchers (e.g., Zhang et al. , Han et al. , Wong and Khoo , Henry and Wong , Yang and Zhang ; Cheng and Ng , Rangsiraksa , Kwok , de Dear and Fountain , Chan et al. , and Hwang et al. ) have paid attention to the study on thermally comfortable environment in the hot and humid climate, both in air-conditioned spaces and naturally ventilated spaces. According to PMV–PPD formula , the predicted mean vote between the limits of ±0.85 corresponds to the point where 80% of the residents feel satisfied. In line with this criterion, all the former studies determined the acceptable conditions for 80% acceptability from a linear regressive model of thermal sensation and air temperature without investigating the applicability of PMV–PPD formula to hot and humid region. Humphreys and Nicol  had suggested that people who live in the tropical climate regions would prefer a cooler-than-neutral thermal condition. The merit of the PMV–PPD formula, as shown in Eq. (1), is that it reveals a perfect symmetry with respect to thermal neutrality (PMV = 0). At PMV = 0, a minimum rate of dissatisfied of 5% exists. equation(1) PPD=100−95.0×exp[−0.03353×4PMV−0.2179×2PMV]PPD=100−95.0×exp[−0.03353×PMV4−0.2179×PMV2] Turn MathJax on As more and more field studies have found that thermal neutrality does not correspond to the optimal condition, the application of PMV–PPD curve in cold or hot climates is under suspicion. The point is when Fanger developed the PMV–PPD model, the correlated percentages of dissatisfied was not obtained by direct inquiry but by definition. Satisfaction is synonyms to the three categories (slightly cool; neutral; slightly warm) in the middle of the seven-point scale, while cold dissatisfaction is synonyms to “cool” and “cold” categories, and warm dissatisfaction to “warm” and “hot” categories. Some studies  and  tried to amend the correlation between dissatisfaction percentage and thermal sensation by redefining dissatisfaction. For example, Mayer  conducted a field study in Germany and gave a new definition of uncomfortable cold sensation by accessing the votes for cold, cool and slightly cool for cold climates. A new correlation between PMV and PPD for cold climate regions was also suggested in Mayer's article. As none of the amendments made for the correlation of PMV–PPD has been suggested for hot–humid climate, a question is very important and must be answered by thermal comfort researchers: do people in the tropical climate regions demonstrate a correlation between thermal sensation and thermal dissatisfaction the same as the PMV–PPD formula in the ISO 7730? This motivated us to conduct a comprehensive field survey on occupants' thermal sensation, preference and adaptation in workplaces and residences in Taiwan. Through comparisons on measured data of field survey and original data of Fanger's experiments , this study is expected to examine the applicability of PMV–PPD formula in hot and humid regions and further suggest a new correlation if the formula fails to apply. In addition to a variety of adaptation methods, occupants in residences have more opportunities to choose the methods of adaptation to achieve thermal comfort depending on their needs and their preferences. On the contrary, the methods and opportunities are limited to a certain degree in the workplaces. For example, usually in offices the control of air temperature for individuals and an electrical fan for increasing air velocity are not provided, even the clothing level is not as free for adjustment as in private spaces. Does the difference in opportunities to choose from a variety of methods to achieve thermal comfort affects thermal perceptions of occupants? It is worth to discuss in detail. Additionally, understanding occupants' most preferred method of adaptation may help to understand the implementation result of some low-cost or zero-cost methods, as advocated by the energy related department of Taiwan government in order to reduce energy consumption in the use of A/C systems. It is also hoped that the results of this study will contribute to this goal.
نتیجه گیری انگلیسی
This study investigates the thermal perceptions and general adaptation methods in hot and humid regions by carrying out a field survey in workplaces and residences in Taiwan. The primary aim is to examine how the correlation between thermal sensation and thermal dissatisfaction has changed. Changes may result from the subjects' accommodation to hot and humid climate. The secondary aim is to understand the difference between occupants in workplaces and residences in the most preferred thermal adaptation method to achieve thermal comfort, as well as how such difference has affected the occupants' thermal perception. The third goal is to discuss interviewees' idea about the trade-off between thermal comfort and energy saving. The following conclusions have been reached. It has been confirmed by data gathered in this study that in hot and humid regions the desired optimal sensation on the ASHRAE scale is not ‘neutral’ but shifts to a position between ‘slightly cool’ and ‘neutral’. In other words, individual difference lies in the correlation between thermal sensation and percentage of dissatisfied, which is not as illustrated in the PMV–PPD formula that is in line with thermal neutrality. Based on our findings, a new correlation in accordance with TSV = −0.45 is developed for hot and humid regions. In comparison with the PMV–PPD curve, the proposed curve features higher values of PD for the warm side of TSV and lower values of PD for the cool side, as well as an increase in the minimum rate of dissatisfaction from 5% to 9%. According to the proposed TSV–PD formula, the limits of TSV that corresponds to 80% acceptability for hot and humid regions are −1.45 and +0.65 rather than −0.85 and +0.85 suggested by the ISO 7730. This corresponds with the shift of comfort zone to cooler conditions in hot and humid regions. In light of this, the acceptable range of air temperature for Taiwan is shifted from 22.6–29.2 °C to 20.4–28.4 °C, with a decrease of 2.2 °C in the lower limit and 0.8 °C in the upper limit. The investigation on thermal adaptation methods reveals that the effectiveness on relieving thermal discomfort, convenience in use and cost can affect occupant's habitual method of adaptation to achieve thermal comfort in different places. In the workplaces, occupants tend to achieve thermal comfort by lowering the air temperature; 57% of the interviews favored using A/C system. In residences, the occupants' favorite method is to increase air velocity by using the electrical fans (33%) or opening the windows (33%). It is found that the opportunities to choose adaptation method with regard to individual needs and preference contribute to the increase in satisfaction under moderated thermal conditions. Regulating the room temperature at 28 °C or above and using electrical fan in company with A/C system are highlighted in the Government's energy-saving campaign. A closer look into the implementation of these two methods sheds a light into the occupants' idea about the trade-off between thermal comfort and energy saving. It can be concluded that approaches without sacrificing occupant's comfort are more acceptable while those cost thermal comfort are hard to promote. Therefore, the Government should make more efforts to encourage workplaces to be equipped with electrical fans or ceiling fans instead of regulating the room temperature. It is believed that energy consumption can be further reduced if the fans are as commonly installed in workplaces as in private residences. It is hoped that findings of this study can be of some value to the establishment of guidelines to achieve optimal thermal comfort and reasonable energy use in buildings of the hot and humid regions.