concept

Utilization factor (U) is the ratio of the luminous flux directly illuminating the road surface to the luminous flux emitted by all light sources, and is related to the height, elevation angle, arrangement method, and road width of the street lamp.

Luminous flux (Φ) is the sum of the energy emitted by the light source and received by human eyes. Indicates how much light energy is radiated per unit time, and the unit is lumens lm. Other representation methods: cd.sr (cd is the unit of luminous intensity: candela. Sr is the unit of solid angle steradian.

Illuminance (E) is the proportional coefficient between the luminous flux and the illuminated area, the unit is lux lx. 1lx refers to the energy that the luminous flux of 1lm is evenly distributed in an area of 1 square meter, that is, lm/m2.

The average illuminance of the road surface (Eav) is the average value of the illuminance of each point measured or calculated at a predetermined point on the road surface in accordance with relevant regulations.

The maintenance factor (k) is the ratio of the average illuminance or average brightness of the lighting device on the specified surface after a certain period of use and the average illuminance or average brightness obtained on the same surface when the device is newly installed under the same conditions.

The installation height (H) of the luminaire is the vertical distance from the light center of the luminaire to the road surface.

The installation distance (S) of the luminaires is the distance between two adjacent luminaires measured along the centerline of the road.

Overhang length (XL) is the horizontal distance from the light center of the lamp to the adjacent side edge stone, that is, the horizontal distance of the lamp extending or retracting into the edge stone.

Effective pavement width (Weff) is the theoretical pavement width used for road lighting design. It is related to the actual width of the road, the overhang length of the lamps and the arrangement of the lamps.