It’s the efficiency at which the light source transfers electric energy into visible light. Unit: LM/W, namely the luminous flux that the light source gives out by consuming one watt of electrity. The higher the quantity is, the higher the efficiency. Luminous efficiency is an important parameter for assessing economic performance of the light source.
Luminous flux and light intensity represent the intensity of light sent from a light source or luminous element, while illuminance represents the intensity of the light received on an illuminated surface. Illuminance is the luminous flux received in a unit illuminated area; it’s usually shows as E, Lx or lm/m2. For example, the illuminance of a 40w incandescent lamp is 30Lx/1m. After a porcelain enamel shade is added, the illuminante increase to 73Lx. It’s 8000~20,000 outdoor at a cloudy noon but 80,000~120,000 Lx outdoor at a sunny noon.
Color Rendering Property
Color rendering property refer to the presented degree of the colors if an object when a light source illuminates it. The higher the color rendering property, the better the light source presents the colors and the more natural the colors we see. CIR defines the color rendering index of the sun as Ra=100. Different light sources have different color rendering indexes. Color Rendering property is also an important link in the design of illuminating decoration. It directly affects the effects of all decorative articles.
Color temperature is expressed as absolute temperature K. When a standard black object is heated to a certain degree, its color gradually changes from deep red to light red, orange red, white and finally to blue. When the color of a light source is the sames as that of the black object, we call the absolute temperature of ther black object the color temperature of the light source. When the color temperature is less than 3000k, the light is reddish, which gives a feel of warmness. When the color temperature is more than 6000k, the light is bluish, which gives a feel of coldness.