its winter my grow room is cold do I need heat or will my HID keep it warm

Im growing in a dormer which is an upstairs that is unrenivated. No insulation so its freezing in the winter how cold you ask I dont know it is the first snow this winter tonight. I plan on checkin on them periodically and seeng the temp. So far I have about 1/4 of the room inclosed in plastic in places as thick as four sheets inside where the op is it is split in two one side for veg one for flower. As of now it stays 74-77 degrees through all light cycle by the way the veg side is only up and running so far. I am using 30600 lumens of CFL half red half blue 4 65w 2 85w and 2 23w. I plan on switching to flower in a month. For flowering I am going to use 1000w HID I havnt decided HPS or MH. But the question I have is, Will the HID heat the room enough to keep it warm throught the winter? if not will I have to heat it durng the dark cycle? If so HOW?
-DocOc

With no insulation it is going to be tough brother , but I could be overestimating the amount of heat loss. Take temp readings through out the night and see what you get down to , might want to do one test night of 12/12 to see what its going to look like down the road. Is the room exposed rafters and beams like an attic or is it some what put together?

line your walls with foil bubble wrap, rather than multiple sheets of plastic.

you will probably still need to heat it. I would start with some some heat mats and a dehumidifier that generates some heat.

yeah its rafters and boards as a matter of fact I can see the roofing nails comin through the wood heres some pics

its probably like a 24 sq foot area split in two surrounded in plastic And mylar

Last night was the first night I opened the door and cranked up the heat but thats not gonna wrl for much longer it gut down as low as 50 degrees F so not crtical but its still early in winter and my gas bill is gonna be rediculous if I have to keep turning it to 71 all night

Yeah man you said it, it is still really early winter. Its not critical yet but it will be critical in the not to distant future when its 5 below zero. Get yourself a small digital space heater, nothing to big just one that you can adjust the temperature where it turn on periodically and that will keep your temps perfect with the light. Even if you run space heater for 24 hours a day everyday your electricity bill will only go up about 20 or 30 dollars., which is much cheaper than gas/oil. And try to keep it as airtight as possible. Your gonna need ventilation too so that's another thing your gonna need to consider. Also as far as the flowering phase goes, HPS would be the best choice as it has ideal light spectrums that the plant needs in that phase of its growth. MH is primarily used in the Vegging phase. Good luck my friend.

Try using a heat mat too keep the soil and roots warm. If u have too. Make a plastic tent. The heat mat should help keeping them warm.