Im growing in an attic in an outdoor building at the moment and the night temps are getting dangerously close to freezing. At the moment i have one daylight bulb on 24/7 and a 600w HPS on 13/11.I had to drop the hours of the HPS because the power bill was too high. Less HPS means less heat and as a consequence the plants are suffering. What i want to know is instead of having one block of 13hours light, would it be ok to have 2 hours on, 1 hour off in intervals to space out the hours of the light so the temperature of the room doesnt drop too much. Also would the constant turning on and off of the light require more electricty and thus prove less efficient?