Impacts of Window Form on Natural Light in Classroom in BWk Climate

The “window form” is a determining factor in the transmission of “daylight” into the interior of educational classrooms. Studies show that the use of daylight affects students' physical health and mental well-being. Therefore, in the design standards of educational spaces, the necessity of using daylight has been emphasized. On the other hand, increasing the brightness of the student's desk can cause glare. It is necessary for classroom to gain natural light and visual communication with outside as a matter of “visual comfort”. Literature review and recent major advances show that the most efficient window form in Khorramabad of classroom is “horizontal”. The current debates show that southern classroom needs a canopy to provide adequate daylight and to eliminate glare and reduce eyestrain. The significant gaps in the field might be the form of the window and the effect of daylight in the education classroom.The research hypothesis emphasize that horizontal-rectangular windows in classrooms do not satisfy “sense of beauty” of the students. It seems that the amount of light that enters the classroom through the horizontal-rectangular windows is suitable for the classroom. It is predicted that during the teaching hours, due to the high amount of light radiation and sometimes due to the lack of sufficient light in the classroom, students feel bored and drowsy.

The main purpose of this study is to evaluate the effect of window form on the quality of light absorption of educational spaces in BWk climate. A sample classroom in Semnan is selected as the case study of the research to examine the impacts of the window form. The research question is: What is the relationship between the window form (including shape and dimension) and the quality of natural daylight (the brightness of the daylight factor)?According to the research methodology, the independent variables are "dimensions" and "window form"; and “brightness” and “pleasant atmosphere inside the classroom” are dependent variables of the research which might be estimated based on 1- the daylight glare probability (DGP), 2- The Annual Sun Exposure (ASE), 3- the spatial daylight autonomy (sDA), 4- The daylight factor (DF) and 5- The Useful Daylight Illuminance (UDI). The research is to consider window materials, floor height, window OKB from floor, interior wall type and window glass type as controlled variables.The research enjoys qualitative-quantitative approach. The simulated environment in this study is a classroom with windows facing south in the city of Semnan. The dimensions of the examined classroom, in terms of length, width and height, have been selected according to the criteria of the Organization for Development, Renovation and Equipping of Schools (DRES). In the next step, students and professors use a questionnaire to express their opinion about the quality of daylight. For analytical simulation, a three-dimensional model of a “sample classroom” is simulated in commercially available software. Analyzes of daylight and well-being have been simulated in the Ladybug and Honeybee-Plus Tools, and the questionnaires have been analyzed by the means of SPSS Statistics.

It was DGP that shows challenging behavior in the case study of the research in spring, autumn, winter at 11 AM in the 15th day of each month. ASE examined in order to calculate how much of space gets direct sunlight more than standard levels which might be the case of glare (visual discomfort) or more energy consumption for cooling loads. ASE as a dynamic indicator shows risk of glare which is dependent on the window of the classroom dimensions directly. According to the dynamic indicator of sDA, the research is going to answer “is there enough daylight in the classroom and examines whether the classroom receives enough daylight during standard operating hours or not”? The results indicate that the model umber 4, is in the best condition and about 50% of the hypothetical points in the class absorb at least 300 Lux of sufficient natural light to provide light for other spaces. Those that absorb relatively less light require artificial light. DF analysis, which is a static indicator, according to the form of common windows in the country, the light absorption conditions in the cloudy sky are such that it has the desired light absorption in the middle part of the classroom and in the third part of the class. It has been concluded that the provision of lighting by artificial sources such as ceiling lamps, etc. is an integral element of the class, but it is recommended to provide energy for optimal use of artificial light. UDI is to be between 100 and 2000 Lux. The case study simulation shows that in the first, second and fourth samples of the space under the window, less than 10% of the daylight hours will receive useful daylight lighting.According to the results of the questionnaire provided to the students, 80% have felt drowsy because of the poor lighting conditions in the classroom. 66% of the pupils consider their priority to choose the light source and lighting to achieve a sense of comfort, the natural light entering the classroom through the windows along with the light supply through the lamp

The results concluded that the efficient height of the classroom window is 180 cm. Other dimensions might be result in glare and visual discomfort in BWk climate. Based on visual discomfort of direct sunlight, window overhangs might be great solution for the case as well as passive shading. The simulations endorse adoption of an awning or an overhang above the window of the classroom. The results emphasizes that the standard classroom which has been promoted by the Organization for Development, Renovation and Equipping of Schools (DRES) is not good enough to be used in BWk climate schools.