Light color of the lamp itself: color temperature (unit: K Kelvin)

The light color of a lamp is related to the apparent color of the light emitted by the lamp (lamp chromaticity) and is expressed by correlated color temperature (TCP).
Light colors are usually classified into three groups according to their correlated color temperature (TCP), as shown in the table below.
The choice of light color is a matter of state of mind and aesthetics, and should be considered to look natural.

Color rendering (Ra)

The general color rendering index (Ra) according to JIS Z 8726 is an index that objectively indicates how well a light source reproduces colors when exposed to natural light.
The maximum color rendering index is 100, and this value decreases as the color rendering quality decreases.
In addition, safety colors according to JIS Z 9101 must always be recognizable and clearly identifiable.
Example) The color rendering index (Ra) of ShinyU LED is 80

Illuminance uniformity (Uo): minimum illuminance / average illuminance

An index that expresses the uniformity of the illuminance distribution within a specific range.
The closer to 1, the less unevenness in brightness.

[Calculation formula] Illuminance uniformity = minimum illuminance ÷ average illuminance

Luminance uniformity (Kidokinseido): minimum luminance / average luminance

An index that expresses the uniformity of luminance distribution within a specific range.
It is an important indicator in road lighting.
The closer to 1, the less unevenness in brightness.

[Calculation formula] Luminance uniformity = minimum luminance / average luminance

Maintenance rate

The luminous flux is reduced due to changes in the light source over time and contamination due to the accumulation of dust on the light source and equipment.

Indoor Unified Glare Rating (UGR)

This value is based on the discomfort glare evaluation method specified by the CIE for indoor lighting facilities in 1995. (hereinafter referred to as UGR)

Indoor Uniform Glare Limits (UGRL)

This is the upper limit of the UGR value that is acceptable for lighting installations. (hereinafter referred to as UGR limit value)

Indoor Discomfort Glare Calculation Method
The evaluation of discomfort glare for indoor lighting facilities is calculated using the following formula based on the unified indoor glare evaluation method.
It is desirable that the UGR of the lighting facility does not exceed the UGR limit value (UGRL) indicated in the JIS General Rules for Lighting Standards (JIS Z9110:2010).
Please refer to CIE 117 for details of indoor uniform glare evaluation method.

Lb	：	Background luminance (cd/m2)
L	：	Luminance (cd/m2) of the light-emitting part of each luminaire relative to the direction of the observer's eyes
ω	：	The solid angle (sr) of the emitter of each luminaire relative to the observer's eye direction
p	：	Guth's position index for each luminaire's distance from the line of sight

■ Relationship between UGR stage and degree of glare

UGR stage	degree of glare
28	start to feel too bad
25	uncomfortable
22	begin to feel uncomfortable
19	be on one's mind
16	start to feel anxious
13	felt
10	start to feel

Outdoor glare rating (GR)

Values based on the CIE 1994 method for evaluating discomfort glare for outdoor sports and plaza lighting facilities. (hereinafter referred to as GR)

Outdoor glare limit (GRL)

This is the upper limit of the GR value that is acceptable for outdoor lighting facilities. (hereinafter referred to as GR limit value)

Outdoor discomfort glare calculation method
The discomfort glare for outdoor lighting facilities is calculated using the following formula based on the outdoor glare evaluation method.
It is desirable that the GR of the lighting facility does not exceed the GR limit value (GRL) indicated in JIS General Rules for Lighting Standards (JIS Z9110:2010).
Please refer to CIE 112 for details on outdoor glare evaluation methods.

Lvl	：	sum of equivalent beam luminances (cd/m2) produced by individual luminaires
E eye	：	Illuminance in the plane perpendicular to the observer's line of sight (lx) (horizontal downward 2°)
θ	：	Angle (°) between the line of sight of the observer and each lighting fixture
Lve	：	Ambient Equivalent Light Curtain Luminance (cd/m2)
ρ	：	Average reflectance of an area (e.g. ground)
Ehav	：	Average illuminance (lx) of an area (e.g. ground)

■Relationship between GR stage and degree of glare

GR stage	degree of glare
90	Intolerable
70	get in the way
50	acceptable limit
30	don't really care
10	It does not bother me