Lighting is a light application designed to make an environment and its objects suitable for visual perception in desired criteria. The lighting made in order to meet the demands within the scope of certain criteria in an entire volume is general lighting. Lighting of partial areas where various emphasis, orientation or different lighting levels are needed in addition to general lighting is defined as regional lighting. Regional lighting can be done to provide the required level of illumination at points where general lighting is insufficient. In addition, regional lighting is used to emphasize an object or to add aesthetic vision.
There are important criteria for the illumination of an environment. The most economical light sources should be used. Also, different solutions should be considered. In addition to operating-investment costs, the most suitable solution should be found to fulfill the desired visual comfort criteria.
Comfort criteria to be considered in lighting design; quality of illumination, quantity of illumination, luminance and surface properties.
The Quantity of Lighting : The quantity of lighting is a concept related to the level of illumination in the environment. The illuminance levels required for the volumes differ depending on the intended use of the volume.
The Quality of Illumination : The quality of illumination is a concept that includes the color of the light, its color rendering, the distribution of the luminance level and the shadow issues. It is not enough to have the desired level of illumination for the right illumination. In order for lighting to provide a complete solution, the environment must meet the color and visual criteria that serve the purpose of use.
Color Rendering: The closer the spectrum of an artificial light source to the spectrum of daylight, in other words, if all colors can be seen as perceived under daylight, the higher the color rendering of that source will be.
Light spectrum; It is a graph showing how much light contains in terms of which wavelength, energy or power units. While color rendering gains importance especially in spaces where soft color transformations and tones are important; It can be ignored in places where color perception is insignificant.
Color Temperature It is a qualitative approximation value specified in Kelvin (0 ° C = 273 ° Kelvin), with reference to which spectral properties a black mass, which does not reflect light, emits light at what temperature when heated.
Daylight equals 5000-5500 degrees Kelvin (color temperature). A low color temperature is perceived by the human eye as a color in the red direction and a high color temperature as a color in the blue direction. It is appropriate to use warm colors for low illuminance levels and cool colors for high illuminance levels. [video]
It is difficult to achieve the same level of illumination at every point of the illuminated space. Therefore, the fluctuation of the illuminance level must be within certain limits; There should not be a big difference between the minimum, average and maximum illuminance levels. The Sure / Emax ratio should be in the range of 0.4 to 0.6. To achieve this, light sources should be selected and positioned properly. If the light sources are not positioned correctly, negative situations such as glare, dim, dark parts, shadow formation will occur.
Shadow formation; We can eliminate it by transmitting the light coming from the light source to the object through indirect ways, by positioning the light sources to create minimum shadow or by directing the light from many points. Lighting intensity above the specified conditions causes physical problems such as fatigue and headache. Visual field of the eye; The object is looked at, the immediate environment, and the general environment. For optimal illumination, the luminous intensity ratios between these three sections should be within certain limits; Object looked at / Near surroundings 1/3 - 1/5 Looked object / General environment 1/5 - 1/10 Primary light sources / Near environment 1/20 Improper distribution of luminance, too high luminance or excessive variation of luminance in the space causes glare. In order to prevent this, measures such as increasing the angle between the light source and the direction of view, decreasing the flux of the light source, can be taken.
General and Regional (Local) Lighting General Lighting
It is the illumination of an entire volume with a light level intended for general use. Local lighting, on the other hand, is the illumination of a particular section in a volume for different purposes, differently and distinctly than the general lighting level. In order to provide the most suitable lighting solution in a volume, the placement and usage areas of the furniture should be determined well and solutions that meet all needs should be produced.
In order to meet general needs, regional lighting should be considered along with general lighting. For example, while the desired general light intensity in the kitchen is "300 lux"; On the bench, which is the working plane, the required illumination intensity is “500 lux” on average in order to minimize the possible accidents and to make the work more efficient.
Local lighting is important in terms of economy and comfort. Local lighting is a suitable solution for illuminating a painting, showcase, object exhibited in a museum, shelves and counters in stores. Spot halogen lamps, compact fluorescent lamps, metal halide lamps, fiber optic cables and LEDs are widely used in local lighting. While performing local lighting, the characteristics of the area to be illuminated should also be taken into consideration. For example, the illumination of an exhibited historical artifact with a lighting element that emits light while also emitting heat will damage the object and cause its property to deteriorate. Therefore, it would be more appropriate to use cold light sources that do not emit heat such as fiber optic cables and LEDs. Since striking is important for showcase lighting, we can use endless methods of lighting that are limited by our imagination, with alternative methods such as various light-shadow games and color filters.
The ratio of the light given by the lamps to the electrical energy they consume is the light efficiency, and the unit is lumen / Watt. Luminous efficiency in incandescent lamps 12 - 15 lm / WH 18 - 22 lm / W in halogen lamps 60 lm / W in compact fluorescent lamps 55 - 104 lm / W in fluorescent lamps The situation is slightly different, depending on the color of the LED, the light efficiency differs.
Red 45 Lm / W,
Green 67.2 Lm / W,
Blue 30.6 Lm / W,
Yellow is around 80 Lm / W.
Since white light is important in lighting, the efficiency for White Led is between 70- 161 Lm / W, although it varies according to the manufacturer.
Another issue that should be considered regarding LED light values is the light angles. Since LEDs are directed lights, light values are given in cd (candela) or mcd. By keeping the light angles low, high candela values are pronounced. This issue should be taken into account when making an assessment in the choice of LED.