Volume 4, Issue 2 (2014)                   BSNT 2014, 4(2): 11-21 | Back to browse issues page

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ansari manesh M, nasrolahi N. Determination of occupant's thermal comfort zone to maximize the quality of indoor environment in office buildings of Kermanshah. BSNT. 2014; 4 (2) :11-21
URL: http://journals.modares.ac.ir/article-2-29326-en.html
1- PhD candidate in architecture, Islamic Azad University, Science and Research Branch, Tehran
2- Assistant Professor, faculty of Engineering, Ilam University, Ilam, Iran
Abstract:   (113 Views)
The increase in energy consumption within modern societies in addition to expiration of fossil resources are two vital factors which compel the world to alter dangerously, while construction industry around the world consumes 25%-40% of energy in different countries. Above all postindustrial era causes the increase in number of employees as well as bureaus. As a result, the amount of energy consumption and also the quality of indoor offices has always been one of the main concerns of architects. Several studies represent that the thermal discomfort is the most common complaint in offices. The thermal aspect of indoor buildings, not only provides comfort for the residents, but also brings saving in energy, health, productivity, and also a significant morale improvement of the staff. Since most complaints of indoor environment are caused by failure in providing the adequate thermal comfort, researches concentrated on several offices around the world suggest that indoor quality of such buildings is about average; in which many are dissatisfied about their workplace and while many are suffering from building-related illnesses that negatively affect the productivity, duration of working and having economic consequences for those countries. The requisite of thermal comfort within the indoor environment is the existence of thermal comfort standards. These standards define indoor thermal comfort zone according to the physical and personal indexes. The most important international standards are ISO7730 and ASHRAE 55. Nowadays, various models are introduced for appraising thermal comfort within different standards of thermal comfort. According to ASHRAE Standard 55 (2010) thermal comfort is defined as "condition of mind that expresses satisfaction with the thermal environment". Therefore thermal comfort contains different physical and psychological aspects, which means several factors are in effect for this purpose. Thermal comfort is related to four controllable factors namely air temperature, radiant temperature, air speed and as well as humidity. thermal comfort also is influenced by three additional factors: activity, clothing and personal expectations. As mentioned above, there are several standards for thermal comfort in the world. The most important ones are international standards ASHRAE 55 (North America) and ISO 7730 (Europe). These standards congruous the theoretical analysis of heat exchange of the human body and gathering information regarding the climate chamber. These standards are appropriate for stationary and homogeneous conditions which are not suitable and hence not much used in the real world. This fact is evident by the disparity between the predicted thermal comfort by these standards and the real sense of human comfort in different places. These standards specify comfort zones in which a large percentage of people perceive the environment thermally acceptable by certain personal criteria. According to these standards, acceptable thermal zone is defined based on satisfaction of at least 80% of the occupants. In other words, performing within the provided criterion of this standard does not mean the 100% satisfaction, as if it is difficult to satisfy everybody due to personal differences. It is to be mentioned that personal control of thermal environment or personal compatibility (by clothing or activity) also increases the satisfaction level. Considering the complexities of defining thermal comfort, several models are represented which are allied to the physical and psychological parameters as the physiological ones. Two forthcoming models are available for appraisal of thermal comfort: PMV model; which explains individuals' response to the thermal comfort in the physiology of the heat transfer. This model evaluates the indoor environments and constitutes the current thermal comfort standards. According to the aforementioned standards, environmental thermal conditions must be maintained homogeneously. Therefore, PMV model is not appropriate for appraising inert thermal sense in places like residential buildings which are not thermally homogeneous and have different thermal zones. However regarding several capacities of this model, many studies have been accomplished in order to adjust this model for such buildings by implementing some changes. The other model named 'adaptive' explains individuals' response to the thermal comfort considering behavioral, psychological and physiological aspects. The thermal comfort standards define the thermal environment conditions of residents based on data obtained by climate chamber experiments. Therefore, consequently, there are problems for using these standards and also thermal comfort models for those who are living in different climates. That is to say regions with different climatic conditions may need different levels of satisfaction parameters through these standards. In other words, due to different climates, cultures, and etc.,the thermal satisfaction conditions differ in different places. Hence, many countries all over the world have conducted field studies to introduce the most favorable thermal conditions that fit their location best. The lack of essential standards for determination of thermal satisfaction limits in office buildings in Iran, results in employees’ thermal dissatisfaction and overall performance reduction. This study uses field methods for measuring environmental variables (temperature and humidity) and also leading inventory (n=328). Kermanshah city is chosen as a case study. Since this city lacks a dominant type of office buildings and the only common aspect of such buildings is indoor offices, thus this feature is considered to choose the samples. To develop the questionnaire, that of ASHRAE 55 (2010) is used, however according to type of the research and the questions cover, some related questions are added. Moreover, answers are adjusted in seven scales in order to be analyzable using available scales of thermal comfort standards such as 7-point scale of ASHRAE. According to results, 81.7% of whole 328 respondents and 65.5% are satisfiedwithtemperature and humidity respectively. Adapting these results to ASHRAE 55, it is concluded that most staff are satisfied in their work place however the results are the opposite about the humidity. To determine suitable range of temperature and relative humidity in order to define comfort zone in offices in Kermanshah, measured data using FLUKE AIR METER are opposed to the results about temperature and humidity (questionnaire). Data analysis using SPSS represents that neutral temperature range through offices in this city is 20-26 centigrade and low relative humidity is about 19%.
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Received: 2019/01/12 | Accepted: 2019/01/12 | Published: 2019/01/12

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