Çalışma Masalarında Kullanılan Aydınlatma Aygıtlarının Performanslarının Ölçme Yöntemi İle Değerlendirilmesi

Abstract

Bir iç çevrenin görsel açıdan konforlu olabilmesi için, görsel konfor durumunda süreklilik sağlanabilmesi, göz sağlığının korunması ; dolayısıyla insan performansının ve gerçekleştirilen eylemdeki verimin arttırılması yönünden görsel çevre etkenlerinin belirli değerlere ulaşması ve bu değerlerin belirli sınırlar içinde tutulması zorunludur. Görsel konforu sağlamak açısından bir çevrenin gösterdiği performans, görsel çevre etkenlerinin ( aydınlık düzeyi, parıltı ve renk ) aldığı değere göre veya bu üç etkenin kullanıcının görsel ihtiyaçları açısından kontrol altına alınmışlığı ile değerlendirilebilir. Böylesi bir yaklaşımla, çevrenin bir parçası olması nedeni ile aydınlatma sisteminin performansının değerlendirilmesi veya sistemin tek aydınlatma aracından oluştuğu ve ışık kaynağının gücünün sabit tutulduğu koşullarda aydınlatma aygıtlarının performanslarının değerlendirilmesi de yapılabilir. Bu amaçla, birinci bölümde ele alman çalışma düzleminde gerçekleştirilecek olan eyleme uygun nitelikleri sağlayabilecek aygıt + kaynak sistemlerinde, aygıtın sisteme olan katkısını değerlendirebilmemize yarayacak olan belirli özellikler açıklanmıştır. Bunlar, iç aydınlatma aygıtlarının işlevleri, nitelikleri, ışığı yansıtma - geçirme - yutma özellikleri, geometrik özellikleri, verimi ve sınıflandırılması olarak ele alınmıştır. ikinci bölümde ise, iç aydınlatma aygıtlarının performans karşılaştırılması için gerekli olan değerlendirme kriterleri ile bu kriterlerin eldesinde izlenen yöntemler ve değerlendirme süreci aşamaları ele alınmıştır. Üçüncü bölümde, değerlendirme koşullarının ve kriterlerinin örnek alınan aygıtlar için uygulanması, ve böylece aygıtların sağladığı değerlerin karşılaştırılması ile eyleme uygun aygıtın seçilmesi anlatılmaktadır. Sonuçlar ve öneriler bölümde ise, bu örnek tez çalışmasının yapılmasıyla varılan sonuçlar açıklanmıştır.

The science of artificial lighting is essentially that of providing facilities for vision, and much of its difficulty lies in the fact that it is not an exact science. It does not deal only or mainly with measurable physical quantities, but far more with sensations and reactions both physiological and psychological. Good lighting will make the scene appear "right" to the observer, with proper emphasis on important objects, with the essential details easy to see, and with due regard to the atmosphere created. The final judge of the lighting is not the photometer, but the eye. The physics of light and the science of light control are exact sciences, but there are three equal partners to vision, the light source, the eye and the object lit, of which only the first can be scientifically controlled. An essential preliminary, therefore, to the design of lighting installations is an understanding of the inter - relationship between these three partners. In order to have visual comfort in an artificial environment ; visual comfort durability conditions have to be provided ; the human eye health has to be protected ; consequently respect to the increase in human performance and the efficiency of a specific task, visual environmental factors must reach certain values and these values have to be kept in certain limits. The performance of an artificial environment in means of obtaining visual comfort is evaluated by the values that visual environment factors (illumination level, luminance and color ) could reach or by under takening control of these three factors in means of visual needs of the users. In such an approach, the performance of the lighting system can also be evaluated. XI This study consists of four main parts : Part 1 Indoor lighting fittings Part 2 The introduction of performance evaluation approach of the indoor lighting fittings which consists of the measurement method and the determination of proper lighting fitting Part 3 The performance evaluation of the lighting fittings that are used on study desks by using the measurement method and the determination of proper lighing fitting Part 4 The conclusion In the first part, the indoor lighting fittings are basicly defined. The light source + lighting fitting systems have to provide proper qualities for the specific task that will be realized on the study plane. For the evaluation of the contribution of the lighting fitting to the system, some properties of the fitting have to be known. These are : - the characteristics of the lighting fittings, - reflection - refraction - diffusion properties of the lighting fittings, - the geometrical properties of the lighting fittings - the efficiency of the lighting fittings. The lighting fittings can be classified according to the materials used in the production and the character that is provided by the fitting to illumination. Artificial light costs money, and the forms of the lighting fittings in which it is available are limited even though far more varied than they were a few years ago. For both these reasons it is desirable to use the light from any source to the best possible advantage, both from the point of view of providing the maximum illumination levels in the places where it is most needed and from that of achieving such distribution of light which will give the best " seeing " in any given circumstances with minumum number of light sources. Most primary light sources tend to distribute their light more or less impartially in all directions. This means that much of it will go where it will do little good and may, in some cases, even do harm. Many sources, otherwise very convenient, are also excessively bright, so that either directly or when the light produced by them is reflected off objects they may cause glare. Xll The purpose of light control is to redirect the light by the help of lighting fittings in such a way that wastage and troubles due to excessive brightness or bad distribution will be avoided. In the second part, the evaluation criteria that are necessary for the performance evaluation of the lighting fittings, the methods that are followed for the attaintment of these criteria and the evaluation process stages are explained. The evaluation criteria for the indoor lighting fittings can be defined as "illumination level ", " luminance " and " color ". These are the environmental factors that take the main role for obtaining a healty indoor enviroment which provides visual comfort. Therefore, respect to the increase in human performance and the efficiency of the specific task, these factors must reach certain values that are determined by the authorities and these attainable values have to be kept in certain limits. In determination of the level of illumination, measurement method can be applied. In the measurement method, the levels of illumination are measured by the luxmeter on various points chosen on a grid on the study plane. By the help of the illumination values obtained at the end of measurements, the matching illuminance level curves has to be arranged on a graphical system. By depending on these illumination level values, luminance of the same points on the study plane can also be calculated. In calculation of the luminance ratios, center of the central field ( an A - 4 form sheet ) is taken as a referance point on the study plane, and the luminance at this point is proportioned to the luminances of the other points under considerations. This helps us to compare the realized luminance ratios with the permitted luminance ratios for the specified task. In the third part the specific task is determined as reading and writing on a study desk, and according to this task the evaluation conditions and criteria are being introduced as well as the properties of the sample lighting fittings, that are used for the application and evaluation processes. The sample lighting fittings are used on a 70 x 100 cm study plane, and 77 points are determined for the measurement of illuminance.A 100 W bulb is used with both fittings at the same heights from the study plane.An A - 4 size white sheet is used as a visual target ( central field ) for the calculation of luminance ratios. X1II By using the measurement method, the illumination levels on the determined points on the study plane are measured by the help of a lux meter for each of the lighting fittings. By the help of the illumination values obtained at the end of measurements, the illuminance level curves are arranged as a graphical system and the variation of the illumination values on the study plane is determined. By obtaining these illumination values, luminances of all points under consideration on the study plane are calculated. In calculation of the luminance ratios, central point of an A - 4 size sheet placed on the study plane, is taken as a referance point ( visual target ), and the luminance at this point is proportioned to the luminances of the other points in the same plane. In the subsequent step, the realized luminance ratios with the permitted luminance ratios for the specified task can be compared with eachother. The evaluation method and criteria that are determined in part two, are being applied to the chosen lighting fittings in the same order. Therefore firstly the illumination levels provided by two different lighting fittings are compared to differentiate the performance levels of the lighting fittings. And secondly, luminance ratios that were reached on the certain points taken into consideration on the study plane are compared with eachother. In addition to these, the illumination levels and luminance ratios that are realized by the chosen lighting fittings are compared with the given permitted values of illumination levels and luminance ratios. As a result, the lighting fitting with better performance is determined among the chosen ones. In the final and recommendations part, outcomes of the thesis are briefly summerized. In the illuminance industry, the production of the lighting fittings are mostly realized only by aesthetic designs. A lighting fitting design has to have theoretical and technical bases, in addition to aesthetic bases. The evaluation processes should be considered as the main part of design process for the lighting fittings. It is a real mistake to permit those who are deprived of technical data to design lighting fittings ; and in addition to these the designs that does not have proper qualities for the specific task cannot provide visual comfort and health in an artificial environment. This thesis is a sample study. By comparision of the appropriateness of the different sort of lighting fittings with eachother for the specific task, the levels of realization of the visual comfort conditions that are provided by the lighting fittings are determined. As a result of these evaluation and application steps of the thesis, the proper lighting fitting have to be chosen for the specific task that will be realized on the study plane.