I find the facts are not very clear on this article as previously mentioned by rpgeorge. I am a licensed electrical contractor have done so for over 25 years. When traditional LEDs came out they were touted to be everything but they lacked in light output ( I thought they were supposed to produce light but anyone who bought a traditional LED bulb found that while they may have lowered their hydro bill they also lowered their lighting levels ) Hi powered LEDs are coming to the market place now boasting 120 LM per watt and more, while this is not the light levels that PLANTS are craving it must be taken into consideration ( plants want PAR light for growth or cellular reproduction ). The growth rates that the newer style of hi powered LEDs are looking very promising according to several studies being done in the UK and at other greenhouses. I looked up the life expectancy of these HIDs that were being tested and noticed that they do not have an average or mean light ( when you installed the HID your light output was X...mean light output 6 months later your light output was 50% lower than X...average light output... this is why they must change the bulbs after 6 months or suffer the lower production levels ) output ratings they tout a 10000 hour life cycle while hi power LEDs are boasting 80000 hours or more. It also does not completely cover the cost of running air conditioning ( HIDs start at 450 degrees F and then warm up to 550 degree F while LEDs operate at 160 degrees F high power LEDs at 140 degrees F... I am sorry but I have to agree with the previous comment... please re validate your claims before you publish... I expected more accurate data... mm ratings aside please look at the plant growth they are experiencing ... that seems to tell the real story....