Point horizontal illumination level calculation: the horizontal illumination level (Ey) created by a light in the direction at a point M at distance r from the light source is calculated by the equation. Here,
I : light intensity in the direction (cd)
cos : angle between the ray reaching point M and the normal of the surface
r : Distance between light source and point M (m).
Point Vertical Illumination Level Calculation
Point vertical illumination level calculation: the vertical illumination level (Ed) created by a light in the y direction at point M is calculated by the equation. Here:
Bd: The angle between the vertical plane of the light reaching point M and the normal of the surface.
Lighting Quality Criteria According to TS EN 12464
The lighting quality criteria that must be provided in the lighting of interior spaces are specified in TS EN 12464. As an example, the lighting quality criteria that must be provided in office volumes are shown in the table below. Here Eo is the average illumination level, UGRL is the glare limitation coefficient, Ra is the color rendering index.
In the same standard, in addition to the quality criteria specified above, it is required that average uniformity values should also be provided depending on the lighting values in the working area and its surroundings within the volume. These values are shown in the table below.
Average Illumination Level in Interior Lighting
In interior lighting spaces, general lighting calculation is done using the utilization factor method. This method is also called "luminous flux or efficiency method". First, the average illumination level (Eo) value recommended in the standards (TS EN 12464) for the space where the lighting calculation will be made is determined from the relevant table. Then, the k room index is calculated depending on the geometric dimensions of the space.
k: room index
a: width of the room (m)
b: length of the room (m)
H: height of the room (m)
h: height of the fixture from the working plane (m)
hçd: height of the working plane from the floor (m)
la: suspension length (m)
h= H - hçd - la
The reflection factor values are determined depending on the surface colors of the ceiling, wall and working plane of the space.
Average Reflectance Factor of Ceiling (pt)
Average Reflectance Factor of Wall (pb)
Average Reflectance Factor of Working Plane (pçd)
%80
Very White
%70
Light Colored
%20
Dark Colored
%70
Light White
%50
Dark Colored
%50
Dirty White
%30
Very Dark Colored
The utilization factor value is read from the efficiency table of the fixture to be used in the lighting installation depending on the room index and the reflection factor of the ceiling, wall and working plane. The total luminous flux that the lamps to be used must give is calculated to provide the desired Eo average illumination level in the space.
m: maintenance factor
Eo: average illumination level (lux)
Φo: total luminous flux of lamps used in the volume (lm)
Φ1: luminous flux of lamp/lamps in the fixture used in the volume (lm)
Then, the total number of fixtures required for lighting the space is determined.
N: number of fixtures
Finally, it is checked by calculation whether the required average illumination level is achieved when N fixtures are used in the volume.
Calculation of Number of Fixtures
The determination of the number of fixtures required to achieve an average illumination level of 500 lx in the working plane at a height of 0.85 m when using 4x18W power 60 cm x 60 cm double parabolic louvered recessed office fixtures for a sample office volume of 6 m width, 10 m length, 2.75 m height, with reflection factors of 0.7, 0.5 and 0.2 for ceiling, wall and floor respectively is given in detail below (maintenance factor m=0.8 was taken).
Utilization factor table for Pelsan 4x18W tube fluorescent lamp fixture
Determining the Number of Fixtures with the Help of Lighting Calculation Chart
The lighting calculation chart provides information about the total number of fixtures according to the size of the volume in which the relevant fixture will be used and the desired illumination levels. With the help of these charts, the number of fixtures required for the desired illumination level can be easily determined. When creating the charts, the room height was accepted as 2.75 m considering general use. With the assumption that the room geometries are also rectangular, the charts were created for the case where the reflection factors are 0.7, 0.5 and 0.2 for ceiling, wall and floor respectively, which are frequently encountered in a classic office space, for values varying between 20 and 200 m2 total area. Maintenance factor 0.8 was taken in the calculations.
The chart below was created to determine the number of fixtures required to achieve 300 lx, 500 lx and 750 lx average illumination levels when using Pelsan 4x18W power 60 cm x 60 cm double parabolic louvered recessed office fixtures in a classic office space for areas varying between 20 and 200 m2. As can be seen from the chart, 12 pieces of 4x18W power tube fluorescent fixtures must be used to achieve 500 lx average illumination level in a 60 m2 volume.
Road lighting calculations are generally carried out according to the "point lighting calculation method".
Road Classes
The reflection properties of road surfaces are given by either the q (β,γ) luminance factor or the r (β,tgγ) reduced luminance factor. In reality, the luminance factor or reduced luminance factor depends on the directions of the point under consideration to the observer and light source. The road classes used in road lighting, average luminance factors and S1, S2 specular factors are given in the table below.
Road Class
qo
s1
s2
R1
0,10
0,25
1,53
R2
0,07
0,58
1,80
R3
0,07
1,11
2,38
R4
0,08
1,55
3,03
N1
0,10
0,18
1,30
N2
0,07
0,41
1,48
N3
0,07
0,88
1,98
N4
0,08
1,61
2,84
CI
0,10
0,24
-
CII
0,07
0,97
-
Table: Classification of road surfaces according to the material used
Road Class
Material Structure
R1 N1
Concrete road surfaces, asphalt road surfaces with artificial brightness of 15%, road surfaces consisting of 80% very bright crown particles.
R2 N2
Rough structured and normal fine gravel road surfaces, asphalt surfaces with artificial brightness of 10-15%, rough and coarse asphalt surfaces rich in gravel (60%) and with gravel size greater than 10 mm.
R3 N3
Dark colored coarse structured asphalt surfaces containing gravel with diameter of 10mm and smaller, rough but bright road surfaces
R4 N4
Mastic asphalt, bright and quite smooth structured road surfaces.
Turkey urban roads and lighting classes
Road Definition
Lighting Class
City connection and ring roads (single or double direction, including intersections and connection points with city passages)
-Speed ≥ 90 km/h
-Speed < 90 km/h
M1
M2
Urban main routes (boulevards and streets ring roads; distributor roads)
-≥50 km/h Speed
-≤50 km/h Speed
-Speed < 50 km/h
M1
M2
M3
City roads (main roads and connecting roads where entry and exit to residential areas is made)
-Speed ≥ 50 km/h; ≥3km intervals with intersections, cloverleaf separation available;
-Speed ≥ 50 km/h; ≥3km intervals with intersections, no cloverleaf separation;
-Speed < 50 km/h
-Other speed
M3
M4
M4
M5
Roads in residential areas
-≥30 Speed
-≤30 Speed
-Speed < 30
-Other speed
M4
M5
M5
M6
Lighting quality parameters required for different lighting classes
Determination of Points for Lighting Calculation on Road Surface
First, the calculation area must be determined. In road lighting calculations, the calculation area is the section between two poles. Observer positions are determined 60 m behind the first fixture in the calculation area and in the middle of each lane.
s: distance between poles (m)
wş: lane width (m)
N: number of calculation points in longitudinal direction
distance between poles; if s ≤ 30 m then N = 10
distance between poles; if s> 30 m then N is determined so that D ≤ 3 m.
Calculation of Illumination Level of a Point on Road Surface
The horizontal illumination level of a point is equal to the sum of the illumination levels created by all contributing fixtures at that point. The figure shows point P on the road surface where the illumination level will be calculated.
I(C,γ): light intensity value reaching point P from the i-th fixture (cd)
γ: angle that the light reaching point P makes with the vertical
a: number of fixtures contributing to point P
h: height of fixture photometric center from ground (m)
C: Plane angle.
Isolux Diagrams
Isolux diagrams are obtained by connecting points with equal illumination levels in lines on a plane. In these diagrams, the height of the light-emitting optical part of the fixture (approximately the mounting height of the fixture) is taken as a basis. In all diagrams, this value is taken as 10 meters for standardization. The diagram is built on a Cartesian grid system. The (0,0) point is determined as the center of the light-emitting surface of the fixture. The illumination level at the (0,0) point, in other words, directly below the fixture (Enadir) is given in the title of the diagram. The upper part of the (0,0) point is labeled as the sidewalk side, and the lower part is labeled as the road side. The positive and negative numbers on the X and Y axes (-7,-6,-5...0,1,2,3..) are used to determine the illumination levels at certain points in terms of fixture mounting height. For example, the road side (1,1) point indicates a point 10 meters to the right and 10 meters below relative to the fixture. To find the illumination level at this point, the isolux curve closest to that point is used. The values of the isolux curves are given at the bottom of the diagram. The conversion table on the right side of the diagram is used for fixtures at different heights. For example, for a fixture at 5 meters height, the found illumination level is multiplied by 4.
Cone Diagrams
Cone diagrams show the maximum and average illumination levels provided at certain distances from the fixture. The circles in the cone diagram represent the diameter of the illumination created by the light beam from the fixture at the mentioned distance; the numerical values next to these circles represent the maximum and average illumination levels provided within the circle.
Calculation of Luminance of a Point on Road Surface
The luminance of a point P on the road surface is equal to the sum of the luminances created by all fixtures at this point. The luminance of a point P,
is calculated by the equation. The luminance factor q is the ratio of the luminance value calculated for a specific observation direction and specific light direction to the horizontal illumination level. The representation of the quantities used is given in the figure. Here;
I(Ci,γi): light intensity value coming from the i-th source to point P (cd)
γi: angle between the ray coming from the i-th source to point P and the normal of the surface
h: height of fixture photometric center from ground (m)
q(βi,γi) : Luminance factor (cd/m /lx)
αq: Observation angle. Vertical angle between the light reflected from the road surface to the eye and the horizontal plane
β: Angle between the vertical plane of the light arrival direction and the observation direction
C: Plane angle
Industrial Area Lighting
*In industrial area lighting, vehicles with specific tasks require special lighting.
*Such lighting should primarily provide physical safety.
*The stroboscopic effect that causes misperception of object movements should be eliminated.
*Very high illumination levels should be avoided.
*In industrial area lighting, the comfort of people working in these areas should be considered.
*Care should be taken to prevent excessive reflection and shadows.
*Since such areas are constantly in operation, attention should be paid to energy saving in lighting.
*Since industrial facilities are generally high-ceiling spaces, light sources with long operating life should be preferred.
*Lamp replacement should be easy in fixtures used in these spaces.
*Explosion-proof fixtures should be used in places containing flammable explosive materials such as gas stations.
Fixture: 2X54W TL5 Karpat High Ceiling - 89W Karpat LED High Ceiling Space: Industrial Areas
Determining the Number of Fixtures with the Help of Lighting Calculation Chart The lighting calculation chart provides information about the total number of fixtures according to the size of the volume in which the relevant fixture will be used and the desired illumination levels. With the help of these charts, the number of fixtures required for the desired illumination level can be easily determined. When creating the charts, the ceiling height was accepted as 8 m considering general use. With the assumption that the room geometries are also rectangular, the charts were created for the case where the reflection factors are 0.3, 0.3 and 0.1 for ceiling, wall and floor respectively, which are frequently encountered in a classic office space, for values varying between 80 and 260 m2 total area. Maintenance factor 0.8 was taken in the calculations. The chart below was created to determine the number of fixtures required to achieve 200 lx, 300 lx and 500 lx average illumination levels when using Pelsan 89W Karpat LED and 2x54W Karpat TL5 high ceiling fixtures in a classic industrial area space for areas varying between 80 and 260 m2. As can be seen from the chart, 18 pieces of 89W Karpat LED or 19 pieces of 2x54W Karpat high ceiling fixtures must be used to achieve 300 lx average illumination level in a 240 m2 space.
Lighting Control
Energy savings can be achieved by using systems that ensure adequate lighting when needed. These systems automatically turn off lamps when there are no people based on signals from their sensors, and turn off or dim lamps when the amount of daylight entering the environment increases. Energy savings of up to 40% can be achieved with these systems that turn off during periods when lighting is not needed and dim to avoid excessive lighting.
Appropriate Lighting Design
In a design based on energy saving, first the surfaces in the relevant area (Wall, Ceiling, Floor) should be painted or covered with colors with high reflection factor. The required lighting should be considered for each relevant level. For example, if a lighting level of 1000 lux is required for the working plane in office lighting, the entire office should not be illuminated at 1000 lux level. Alternative Lighting Solutions * Lighting interior spaces that do not receive sufficient light from the outside environment during the day by carrying them through fiber optic cables or reflective pipes. * Use of solar energy systems that generate electrical energy from solar energy and store the electrical energy they obtain, and perform the lighting function during times when there is no solar radiation with the energy they store. * Since the goal in energy saving is to reduce energy input, this goal can be achieved by providing this energy from renewable sources. The need for emergency lighting can be met with small-sized wind-solar hybrid energy systems to be installed on the roofs of houses.
* Using High Efficiency Light Sources
Providing the light required for lighting from light sources with high efficiency factor is the first condition of energy saving in lighting. Light sources with high efficiency factor give more luminous flux per unit power. Therefore, in lighting made using sources with high efficiency factor, less luminous flux is given for the same illumination level. Therefore, in lighting made using sources with high efficiency factor, fewer light sources are needed for the same illumination level and less energy is consumed. For example, making factory interior lighting with fluorescent lamps instead of high-pressure mercury vapor lamps can provide savings up to 43%. Efficiency factors of light sources can be obtained from the comparative table of lamps.
* Using High Efficiency Fixtures
Fixtures cannot effectively distribute all the rays emitted by the light sources inside them to the area where they are used. Some of the rays are absorbed by the reflective surfaces or cannot be reflected to the intended area because these surfaces are not positioned correctly. To eliminate this situation, high-efficiency fixtures with quality and appropriately designed reflectors should be used.
* Using Components with Lower Losses
Discharge lamps, which are among the basic elements of efficient indoor and outdoor lighting today, generally require auxiliary components such as ballast, starter, igniter, etc. Among these elements, the active power loss of auxiliary components such as ballast, which are constantly in circuit, significantly affects the efficiency of the system. For example, system efficiency can be increased by using ballasts with less active power loss (low-loss magnetic or electronic ballasts) or busbar channels instead of classical installation.
Energy Saving in Lighting
Energy saving is achieved by increasing lighting efficiency and reducing energy input without compromising visual performance and comfort. This saving is not achieved by inadequate lighting as is wrongly believed. Because inadequate lighting, although it reduces energy consumption, negatively affects the productivity of people working in the relevant area, so ultimately it does not provide savings. It can also cause an increase in work accidents, which can produce results that are the exact opposite of what is expected. This saving can be possible by improving the following lighting components.
* Using high efficiency light sources
* Using high efficiency fixtures
* Using components with lower losses (For example: using ballast with lower losses)
