Lighting terminology - lighting calculations

3.2.1 Light intensity distribution; Distribution of light intensity
The curve or table indicates that the light source or lamp has a luminous intensity value in each direction of the space.

3.2.2 symmetrical light intensity distribution
The intensity distribution when there is an axis of symmetry or at least one plane of symmetry.

3.2.3 rotationally symmetrical light intensity distribution
The light intensity distribution curve of the polar coordinate in the plane is the light intensity distribution obtained by rotating around the axis.

3.2.4 total flux
The sum of the luminous flux of the light source in the 4p spherical solid angle.

3.2.5 luminous flux in the lower hemisphere
The total luminous flux of a light source or luminaire within 2p solid angle below the horizontal plane.

3.2.6 upper hemisphere luminous flux
The total luminous flux within the 2p solid angle of a light source or luminaire on a horizontal surface.

3.2.7 direct flux
Luminous flux from the lighting device is directly obtained on the surface.

3.2.8 Indirect flux
The luminous flux obtained after reflection on the surface from other surfaces.

3.2.9 Reference plane reference surface
Measure or specify the plane of illumination.

3.2.10 Working plane working plane
A reference plane that works on its surface.

3.2.11 Luminaire calculation height calculating height of luminaire
The distance from the light center of the lamp to the work surface.

3.2.12 utilization factor utilization factor
The ratio of the luminous flux projected onto the reference plane to the nominal luminous flux of the light source in the lighting device.

3.2.13 Room space ratio
Characterize the value of the room geometry. Its calculation formula is:

(3.2.13)
Where RCR - room space ratio;

a - room width;
B—the depth of the room;
c - lamp height calculation.

3.2.14 room index
Characterize the value of the room geometry. Its calculation formula is:

(3.2.14)
Where K - the ventricular index;

a - room width;
B—the depth of the room;
h - lamp height calculation.

3.2.15 Average illuminance average illuminance
Specifies the average illuminance on the surface.

3.2.16 average brightness average luminance
Specifies the average value of brightness on the surface.

3.2.17 Minimum illuminance minimum illuminance
Specifies the minimum illuminance on the surface.

3.2.18 Maximum illuminance
Specifies the maximum illuminance on the surface.

3.2.19 normal illuminance
The flat illuminance value perpendicular to the incident direction of light.

3.2.20 Horizontal illuminance horizontal illuminance
The illuminance at a point on the horizontal plane.

3.2.21 vertical illuminance
The illuminance value that is accepted at a point on the vertical plane.

3.2.22 Maintenance factor maintenance factor
The ratio of the average illuminance or the average illuminance on a specified surface of a lighting device to the average illuminance or average luminance obtained on a prescribed surface when the device is newly installed under the same conditions after a certain period of use.

3.2.23 Maintaining Average Illumination maintaineded average illuminance
The average illuminance on the surface should not be less than this value. It is the average illuminance on the specified surface at the time when the lighting device must be maintained.

3.2.24 Initial average illuminance
The average illuminance on a given surface when the lighting device is newly installed. The initial average illuminance is obtained by dividing the predetermined maintenance average illuminance value by the maintenance coefficient value at the time of maintenance.

3.2.25 Uniformity uniformity ratio of illuminance
Specifies the ratio of the minimum illuminance to the average illuminance on the surface.

3.2.26 Average cylinder illumination average cylinderical illuminance
At a given point, the average illuminance on a very small cylindrical surface. The axis of the cylinder is usually erect.

3.2.27 mean spherical illumination; scalar illumination average spherical illuminance, scalar illuminance
At a given point, the average illuminance over the entire surface of a very small ball.

3.2.28 Illuminance Vector Illuminance Vector
It is used to describe the directional characteristics of light at a point in space. Its magnitude is the maximum illuminance difference across the two sides of the surface passing through the point, and the direction from the higher illuminance to the low illuminance vector is the eye.

3.2.29 point light source
When the size of the light source is very small compared to its distance from the illuminated surface, the size of the source is negligible at the time of computer and measurement.

3.2.30 line light source light sourec
For a continuous lamp or luminaire, the total length of the luminescent band is much greater than the distance between it and the illuminance calculation point and can be regarded as a line light source.

3.2.31 Area light source area(surface) light source
The whole piece of luminous surface or luminous ceiling composed of luminaires, whose width and length is greater than the distance between the luminous surface and the illuminated surface, can be regarded as surface light sources.

3.2.32 (light source or luminaire) light center (of a light source or luminaire)
The light spot used as the origin at the time of measurement and calculation.

3.2.33 Lamp spacing spacing of luminaire
The distance between the center lines of adjacent fixtures.

3.2.34 Mounting height of luminaire
The distance from the bottom of the lamp to the ground.

3.2.35 Luminaire distance ratio spacing height ratio of luminaire
The ratio of the distance between the fixture and the calculated height of the fixture.

3.2.36 Luminaire maximum permissible ratio of height to maximum ratio
The ratio of the maximum fixture spacing to the fixture's calculated height to ensure the required uniformity of illuminance.

3.2.37 use coefficient method; lumen method of utilization factor, lumen method
Calculate the average illuminance of the work surface based on the geometry of the room, the number and type of luminaires. The lumen method considers both the direct light flux and the reflected light flux.

3.2.38 point method
Using the luminosity data of the luminaire, calculate the illuminance of each point on the surface.

3.2.39 power per unit area
The installed power of the lamp on the illuminated area.

3.2.40 Illuminance ratio
The ratio of the illuminance on a certain surface of a room to the general lighting illuminance on the work surface.

3.2.41 mixed light source luminous flux ratio luminous flux ratio of combined light source
When using two kinds of light sources for mixed lighting, the ratio of the luminous flux of the former light source to the sum of the luminous flux of the two light sources.

3.2.42 iso-intensity curve
In the imaginary sphere with the center of light of the light source as the center of the sphere, the curve corresponding to the points corresponding to the directions of the light emission intensity is connected, or the plane of the curve is projected.

3.2.43 iso-illuminance curve
The curve or curve group that connects the points of equal illumination on the surface.

3.2.44 Spatial iso-intensity curve spacing ISO-illuminance curve
In the center of a light source or a luminaire, the line connecting the points with the same illuminance on a section in space is called an illuminance curve such as space. The curve is represented by Cartesian coordinates.

3.2.45 iso-luminance curve ISO-luminance curve
The curve or curve group of the point of equal brightness on the connecting surface.

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