For replacement products, under the same luminous flux, the luminous efficiency can be used to estimate the energy saving ratio. For example, the luminous efficiency of a 40-watt incandescent lamp is about 13 lumens/watt, and the luminous flux is 520 lumens; the luminous efficiency of a replacement 10 watt fluorescent lamp is about 50 lumens/watt, and the luminous flux is about 500 lumens, which is 80% energy-saving than incandescent lamps; replacement is 5 A watt LED bulb has a luminous efficiency of about 100 lumens per watt and a luminous flux of about 500 lumens, which is 95% energy-efficient than incandescent lamps and 50% energy-saving than fluorescent lamps.
If it is calculated that the lighting time per day is 4 hours, then 1460 hours of lighting are required a year. Based on the comparison between the 5W LED bulb lamp and the fluorescent lamp tested by this publication, the efficiency of the 5W LED bulb lamp is equivalent to the efficiency of a 10W fluorescent lamp and a 40W incandescent lamp. In one year, the power consumption of incandescent lamps is 58,400 watt-hours, fluorescent lamps are 14,600 watt-hours, and LED bulbs are 7,300 watt-hours. Then converted to degrees (1 degree = 1 kWh), incandescent lamps need to use 58.4 kWh a year, fluorescent lamps 14.6 kWh, and LED bulb lamps 7.3 kWh.
