Prof. Dr. Meltem YILMAZIntroductionDaylight While light is a creative medium, its most basic function is to enable us to see. ur visual acuity relies on the !uantity of light and its s"ectral distribution. #eeing is therefore not only about distinguishing light and shade, but also color. $he movement of light is a linear "rocess %here time and s"ace meet. Any moment reveals fro&en movement in time. We have evolved to res"ond to daily and seasonal change brought about by the movement of the sun, the moon and the stars. $hrough the "assage of light %e trac' the change of day into night as %ell as form and surfaces moving in light.In the ()th century, the electric light has radically changed our %ay of life. $he rhythm of life %as for the centuries determined by the cyclical succession of day and night. It %as only the emergence of electric lighting that enabled man to brea' a%ay from this im"erative rhythm. All at once, technology gave man the "ossibility of %arding off dar'ness and imagining a different %orld.ur modern society is e!ually de"endent on abundantly available artificial light in any "lace and at any time. It is not only necessary to guarantee the continuity of our activities, but also to give sha"e and atmos"here to our visual "erce"tion of the environment, inde"endent of the availability of daylight .*or all architectural s"aces %hose envelo"es are "enetrated by any o"ening to the e+terior environment, lighting design begins %ith recognition of the entry of daylight. It is a first consideration because the "resence of daylight in an interior strongly influences s"atial "erce"tion and also changes the color of surfacing materials in terms of ho% they a""ear else%here in the room under a number of different 'inds of electric illumination. $he amount of sunlight reflected about an interior is determined by the si&e and sha"e of a"ertures in the s"atial envelo"e , as they relate to the "ro"ortions of a room. Direct daylight %ill "enetrate dee"er into a room the higher the to" of the %indo% is above the floor. Windo%s can reduce de"endence on electric lighting and lo%er energy costs. Passive solar design calls for south-facing %indo%s, but it is im"ortant not to neglect daylighting in other "arts of the building.. When "lanning for good daylighting, %e have to consider the illumination "rovided by the s'y rather than direct sunlight, %hich is often undesirable.ood daylighting is not sim"ly a function of the !uantity of light. In fact, some techni!ues that increase the !uantity of daylight can actually decrease its !uality. $he t%o main !uality issues are glare and light distribution. .lare can be either disabling or discomforting. It is disabling %hen it interferes %ith the ability to see. It is discomforting %hen there is e+cessive contrast bet%een light and dar' surfaces in a room. .lare does not nesessarily increase %ith increasing %indo% si&e./oom *inishes0 *or ma+imum daylight levels,uniformity and the least glare, room surfaces should have matte finishes. #hiny finishes create reflections that result in glare..lass $y"e0 .la&ing that allo%s the highest transmission of the visible "ortion of the solar s"ectrum "rovies the highest daylight levels.Windo% Position0 $he higher the %indo%, the greater the Daylight *actor and the dee"er the "enetration of daylight into the s"ace. 1+tending the %indo% to the floor does little to increase daylight levels. 2lerestory %indo%s that allo% dee" "enetration of daylight %hile avoiding normal vie%ing angles are a good daylighting strategy.While u" to the mid-()th century almost all schools and %or'"laces used daylight as their "rimary source of lighting, the advent of ine+"ensive energy and the "roliferation of fluorescent lights in the 345)s and 346)s made daylight as an illumination source almost irrelevant. When energy costs began soaring in the 347)s the 8gla&ed s'in9 loo' of many buildings became an e+"ensive, though "o"ular and attractive, liability that often increased the costs of both heating and cooling. 2ooling, in "articular, %as a ma:or cost, leading to the elimination of solar gain-the heat generated by direct natural sunlight through %indo%s. ;e% construction deem"hasi&ed direct sunlight and brought forth lo%er ceilings and lo%er building s'in-to-volume ratios. Dro""ed ceilings, heavily tinted glass, and insulating "anels, designed to reduce heat from %indo%s, gained %ides"read acce"tance. $he net result of this change in architectural and design "riorities