The luminous efficiency of fluorescent lamps is about 55-80lm/W (the luminous efficiency of Philips T8 tubes is 72lm/W). LED fluorescent tubes can have a luminous efficiency as high as 100lm/W. Cree has announced that the luminous efficiency of their recently promoted XLampXP-G series can reach up to 130lm/W, and expected to reach 150lm/W two years later.
Not all light emitted from LED chips/LED lighting boards can 100% reflected by reflectors / projectors. Fluorescent tubes can send out 360 degree light. In spite of using reflectors, some of opposite direction light will be inevitably wasted. Generally speaking, there will be about 30% light will be wasted for fluorescent tubes. The valid / lamp luminous efficiency of them is only 70% of the initial luminous efficiency. The general beam angle of LED fluorescent tubes is 120 degree. Almost all light is effective with the help of reflectors. In the view of many manufacturers and users, 120 degree is a narrow beam angle for fluorescent tubes. But this is enough in practical cases. As we mentioned before, the luminous efficiency of Philips T8 fluorescent tubes is 72lm/W, 36W fluorescent tubes can have an output luminance of 2592lm. Then the lamp efficiency of traditional fluorescent tubes is only 70%. Thus the valid luminous efficiency of the entire lamp is about 1814.4lm. Assumed that the luminous efficiency of LED fluorescent tubes is 100lm/W, a 18W LED tubes can have a output luminance of 1800lm. Sending out light with the same brightness, LED Tube Lights only consume half power than traditional fluorescent tubes do.
High power efficiency: All lights except for incandescent bulbs need special power supplies, including LED lighting products. Therefore, we need to take into account of power efficiency when we estimate the whole lamp efficiency. Take Philips 36W T8 fluorescent tubes for instance, the rated power of which is 36W. But as a result of accessing to magnetic ballasts, the actual measured power is 42.4W. The rest 6.4W is consumed by core inductors. Efficiency decreases to 85%. Most of domestic core inductors can consume more than 10W power due to their low quality, the power factor of them is lower than 0.512. Normally, the power efficiency of LED drivers / power supplies is as high as 90%. One 18W LED tubes only need a driver with output power of 20W. And the power factor is 0.9.