Everybody wants to use
led for lower energy costs, but the reality is it generally takes 5-10 years to save enough money in energy bills to make back the difference from the high up front costs. Essentially your just paying 5-10 years worth of savings up front. So your not actually saving anything for the first 5-10 years tell after you break even. When you pack plants in closely together, you just get over crowded plants. If your just growing seedlings it's fine to pack them in close, but if you expect them to reach full size they need room to grow. Spacing would be determined by the size of the full grown plant. LED'S do run cooler than HID, but if the plants your growing will do fine under florescent lighting, florescent
lights aren't much different than LED''s in that respect.