نوع مقاله : مقاله پژوهشی

نویسندگان

• مریم فخاری ¹
• ریما فیاض ²
• مریم مهرآور ³

¹ دانشجوی دکتری معماری، دانشکده معماری و شهرسازی، دانشگاه هنر. تهران. ایران

² دانشیار دانشکده معماری و شهرسازی، دانشگاه هنر.تهران.ایران

³ دانشجوی کارشناسی ارشد معماری و انرژی، دانشکده معماری و شهرسازی، دانشگاه هنر. تهران. ایران

چکیده

آسایش بصری  در فضاهای اداری به ویژه در مناطق شهری پر تراکم و سایه اندازی بناهای مجاور اهمیت زیاد دارد. برای طراحی مناسب روشنایی آگاهی از سطح روشنایی مطلوب ضروری است. در حال حاضر در ایران، این محدوده برای فضاهای اداری تعریف نشده است و متخصصین برای جبران این نقیصه به یافته‌های دیگر کشورها رجوع می‌کنند. به دلیل تفاوت‌های اقلیمی و تفاوت فرهنگ استفاده از روشنایی، ممکن است یافته‌های دیگر کشورها برای ایران مناسب نباشد. از این رو پژوهش پیش‌رو به دنبال تعریف محدوده رضایت‌مندی از شدت روشنایی در ساختمان‌های اداری شهر تهران است. روش استفاده شده پیمایش و مطالعات میدانی است. به همین منظور تعداد ۵۰۹ پرسشنامه در دو فصل تابستان و زمستان، در ۱۴۶ اتاق در تابستان و ۱۰۹ اتاق در زمستان توسط کاربران در شش ساختمان اداری با ویژگی‌های مختلف از جمله یک طبقه تا سیزده طبقه، پلان باز و با اتاق‌های خصوصی، نوساز و قدیمی، به منظور ارزیابی شرایط روشنایی محیط تکمیل شدند. هم‌زمان با تکمیل پرسشنامه توسط کاربران، پارامتر فیزیکی شدت روشنایی در سطح میز کار کاربران، اندازه‌گیری شدند. از روش‌های آماری مرتبط در نرم افزار SPSS برای تحلیل داده‌ها و یافتن ارتباط بین متغیرهای تحقیق، استفاده شد. نتایج نشان می‌دهد که شدت روشنایی مطلوب در این فضاها ۶۰۰ تا ۶۵۰ لوکس است و شدت روشنایی بین ۵۵۰ تا ۶۰۰ لوکس نیز شرایط آسایش را فراهم می‌کند. شدت روشنایی کمتر از ۵۵۰ لوکس برای کاربران مطلوب نیست.

کلیدواژه‌ها

• ترجیحات روشنایی
• آسایش بصری
• طراحی روشنایی
• شدت روشنایی
• روشنایی طبیعی

عنوان مقاله [English]

Acceptable illuminance level for office occupants in Tehran

نویسندگان [English]

• Matryam Fakhari ¹
• Rima Fayaz ²
• Maryam Mehravar ³

¹ Ph.D. Candidate in Architecture, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran

² Associate Professor, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran

³ MSc of Energy &Architecture, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran

چکیده [English]

Extended Abstract
The accurate prediction of the visual comfort zone in an indoor environment is a difficult task as it depends on a large number of parameters such as individual and environmental variables. This is especially the case for large compact urban areas in which the density and shadow from neighboring buildings can limit the accessible daylighting in indoor spaces. In-office spaces where employees spend many hours of the day, lighting is one of the most important environmental parameters as most of the activities are based on receiving visual information from the surroundings. Besides, satisfaction with lighting conditions is one of the main elements which significantly affect the overall comfort levels of the environment.
Currently, in Iran, the visual comfort zone and preferred illuminance level are not defined for office spaces, and experts refer to the findings of other countries. To assess the lighting in architectural spaces and define the conditions for conformity in many standards, metrics are used as a physical measure. Generally, there are static and dynamic metrics to evaluate various aspects of daylight. Static metrics such as illuminance-based daylighting metrics and Daylight Factor (DF) are typically evaluated based on illuminance and have been used in building regulations for a long time. In most standards and codes, the minimum recommended illuminance level on work planes for regular office work is 500 lx.
Because of the differences in climate and culture, the findings of other countries may not be appropriate for Iran. On the other hand, many studies have been conducted to find an acceptable lighting level in offices in which the results show the acceptable range for illuminance in different countries are not the same. So, this paper investigates the satisfaction range for illuminance in the office spaces which could be used by architects and researchers. Therefore, a field study was conducted to evaluate the illumination levels, to examine the effect of lighting conditions on employee satisfaction and employees’ perception of lighting level with actual illuminance levels in office spaces in Tehran using both questionnaire and physical illuminance measurements.
The focus is on six office buildings in the megacity of Tehran, Iran. The buildings were selected to consider different spaces in old and new ones, one-story and high-rise buildings, open plan, and cubicle offices with different window orientations. The selected rooms were one, two- or multi-person offices, located on different floors, with various window orientations, having optionally atrium/outside window. Interior artificial lighting in all buildings is fluorescent with a color temperature between 4000K and 5000K.
The survey involved 509 questionnaires (280 were filled in summer and 229 in winter). Most of the participants have spent at least three months in their rooms, and have been adapted to the environment and all of them were Iranians (to avoid the impact of occupants’ culture on lighting perception). Most of them reported that they spend more than 8 hours or between 6 to 8 hours in their offices during the day. Field measurement includes illuminance, temperature, and relative humidity. The questionnaires were filled out in 146 and 109 rooms in summer and winter respectively. At the same time as users completed the questionnaire, the physical parameters were measured.
The Spearman rank correlation coefficient was applied for quantitative variables. By using a monotonic function, the Spearman rank correlation coefficient is a non-parametric measure that assesses statistical dependence between two variables to describe the relationship between them. The results revealed that occupants were more satisfied with higher illuminance levels. To investigate the acceptable range for the lighting level, the measured illuminance is categorized into certain levels. For this purpose, the measured lighting level was classified into 14 ranges. The values of less than 300 lx are in the first category, higher than 900 lx are in the last category and the values between these are classified into 50 lx intervals. The highest satisfaction from the environmental lighting level is provided in the illuminance range of 600 to 649 lx. The illumination more than this range results in more satisfaction compared to illuminance lower than 550 lx. Thus, there is an optimal range of satisfaction with lighting level and the most preferred lighting comfort range for these office spaces is 600 to 649 lx. While the illuminance greater than 550 lx is acceptable for most of the occupants.

کلیدواژه‌ها [English]

• Lighting preferences
• Daylighting
• artificial lighting
• illumination comfort