Yararlanma katsayılarının ingiliz normlarına göre hesaplanması ve kullanımı

Abstract

Bir hacim için aydınlatma planlaması yapılırken, ilk önce o hacmin ne amaçla kullanılacağı tespit edilir Daha sonra armatür seçimi yapılır ve istenen aydınlık düzeyini elde etmek için seçilen armatürden kaç adet kullanılacağı hesaplanır. Bunların yanında hacimlere ait olan ve o hacmin verimini belirten yararlanma katsayıları da önem taşır. Çünkü bu yararlanma katsayıları, armatür adedinin belirlenmesinde kullanılan formül içerisinde bir yere sahiptirler. Bu çalışmada yararlanma katsayılarının, noktasal ve doğrusal iki tip armatür için nasıl elde edileceği anlatılmıştır. Bunun için bir bilgisayar programı yazılmış, böylece istenilen yararlanma katsayıları çok daha çabuk bir şekilde elde edilmiştir. Daha açıklayıcı olması açısından laboratuvarda deneyi yapılan bir armatürün ölçüm değerleri verilmiş, bunun sonucu olarak elde edilen sonuçlar gösterilmiştir.There are several limits which have been taken under consideration to form basis of an effective illumination. Not only economical and decorative aspects of illumination, but also purpose of illumination and use of rooms should be carefully taken into account during projecting phase[l]. All calculations should be performed under the consideration of above conditions. Before going into details about the topics mentioned above, a pre-project should be done. This pre-project should give results which are as close as possible to the final states. The most effective way to achieve this is using the utilisation factors. At the same time, these factors are the efficiency of rooms. As can be seen in this study, these factors are related to various factors. Distribution factors and reflectances of three surfaces (floor, walls, ceiling), dimensions of the room, spacing of luminaires, height of luminaires above the working plane, etc can be given as examples for these factors. The purpose of this study is calculating of utilisation factors with the aid of a computer program. This calculation is done according to the British standarts. The results are presented in a standart utilisation factor table. If it is needed, only three utilisation factor values of a special room can be calculated and presented. Easy to follow the calculation in computer, to provide visual comfort and visual adaptation, the program is written in "Visual Basic". In the first step of this study, tables used in the program and application of these tables are explained. Later, some facts about calculation of utilisation factors in various other countries' codes are given. The BZ ( British Zonal ) Classification and CIE ( Comission Internationale de L'Eclairage ) flux codes of a luminaire are explained. In the second step, only utilisation factors are examined. The calculation of the recommended illuminance or the necessary number of luminaires needed to accomplish this illuminance with the aid of the utilisation factors is explained in this step. For taking form of the utilisation factor tables, photometric data of the luminaire, shape of the room, positions and reflectances of the surfaces should be given. Avarage reflectances of the surfaces and related to these values, effective reflectances of the cavities and the calculation of room index are explained. For linear Xlll luminaires, the axial and transverse spacings between luminaires in relation to maximum spacing to height ratio are examined. In addition, in relation to these spacings the equations used for getting utilisation factors in relation to distribution factors. In chapter 2, the necessary way for getting utilisation factors are explained by aid of some tables. This way can be explained as follow. The first table is used to enter the measured values. These values are light intensity values. These values are entered into suitable row and column. Avarage of each rows are calculated. The avarage intensity values of light are multiplied by zone factors. Thus, zonal flux values can easily be calculated. Total of the values from 0° to 90° is the zonal flux in the sub-half globe. Total of the values from 0° to 180° is also the total flux in arbitrary units. By using the equations given below, the values needed can be determined. By multiplying zonal flux values by scale factor, zonal flux from lamps can be calculated. Afterwords, for determining avarage intensity according to 1000 total lm from lamps, column J ( or column J and column K for linear luminaires ) are completed[3]. ICO = M / Total bare lamp flux in arbitrary units (1) OF = ICO x 1000/ M (2) AICO = Lx(ÖF/1000) (3) YICO = ICO - AICO (4) For spacing to height ratio value ( AYO ), which is equal to 0.5, the avarage intensity values of angle of elevations are entered into the table. These values are written on the next column by multiplying zonal multipliers. Later, maximum illuminance and minimum illuminance are determined. Thus, the mid point ratio (ONO) can be calculated by using equation below. E(l) ONO = (5) E(2) This operation must be continued until finding a value less than 0,7. The highest value of spacing to height ratio that produces a mid point ratio greater than 0,7 is nominal spacing to height ratio ( AYO NOM). A different table is used to get distribution factors. Avarage intensities, according to 1000 total lm from lamps are written into suitable column in the table. For each room index, zonal multiplier values ( BÇ ) are taken into its column for XIV nominal spacing to height ratio of the Uuminaire. The values located in these columns are multiplied each other. Later, the distribution factors can be determined. The last step of getting utilisation factor tables is to use the transfer factors and to take into account inter-reflections. In this way, the utilisation factors can be calculated by the equations below. YK(Z) = DK(Z)xTK(Z,Z) + DK(D)xTK(D,Z) + DK(T)xTK(T,Z) (6) YK(D) = DK(Z)xTK(Z,D) + DK(D)xTK(D,D) + DK(T)xTK(T,D) (7) YK(T) = DK(Z)xTK(Z,T) + DK(D)xTK(D,T) + DK(T)xTK(T,T) (8) After getting utilisation factors, for the desirable illuminance level, necessary hminaire number can be found out using following equation. (9) Where, E is the avarage illuminance needed, S is the area of the working surface, YK(S) is the utilisation factor coefficient of the surface S, (j> is the bare lamp flux of a luminaire. In the last chapter, an explanation is given for the computer program software written. Thus, when the user runs the program, he can easily learn the functions of the buttons on the forms, follow each steps and get his results needed quickly. In the program, thirteen differen forms are used. These are: "The Selection of Luminaire Type", "Intensity Values for Symmetric Luminaires", "Intensity Values for Linear Luminaires", "Entering the Total Flux and the Selection of Table", "Standart Floor Utilisation Factors Table for Symmetric Luminaire", "Standart Walls Utilisation Factors Table for Symmetric Luminaire", "Standart Ceiling Utilisation Factors Table for Symmetric Luminaire", "Utilisation Factor Values for Symmetric Luminaires", "Standart Floor Utilisation Factors Table for Linear Luminaire", "Standart Walls Utilisation Factors Table for Linear Luminaire", "Standart Ceiling Utilisation Factors Table for Linear Luminaire", "Utilisation Factor Values for Linear Luminaires" and "Entering the Total Flux and the Selection of Table for Linear Luminaires". Firstly, "The Selection of Luminaire Type" form İs seen on the screen. According to selection "Intensity Values for Symmetric Luminaires" or "Intensity Values for Linear Luminaires" is seen on the screen. Later, "Entering the Total Flux and the Selection of Table" is also seen. The flux value is entered and the table needed is selected. In this way, one of the standart tables is formed or for different XV reflectances and different room index, three utilisation factor values are determined. The standart presentation of utilisation factor values for floor is like as can be seen in Table 1. Table 1. "Standart Floor Utilisation Factors Table for Symmetric Luminaire" XVI The values, which have to be entered in the main form of the program, are measured before the beginning of forming the tables. The measured result values for the linear luminaire are given in this study. By aid of these values, the utilisation factors can be found using the computer program. And necessary luminance number is find out using equation (9).