With winter upon us we spent the yesterday preparing the greenhouse for cold weather. The greenhouse that houses the aquaponic system is not heated, the only heat we provide is heaters in the water that help maintain the water between sixty-five and seventy-two degrees. By heating only the water we are able to lower the cost of operating the greenhouse. We have found that our cost for electricity stays about the same throughout the year, running the fans during the summer uses about the same electricity as the water heaters do during the winter .
One important thing we do that does help control heat loss is to keep as much cold air out of the greenhouse as we can. We do this by making sure we have as much of the openings in the greenhouse closed as possible. Yesterday we spent a good portion of the day covering all of the air vents and exhaust fans with half inch foam insulation. We screwed down the insulation and then taped the edges with aluminum foil tape to help prevent the cold wind from coming in or the warm air escaping. Only the front of the greenhouse has polycarbonate covering it, the back of the greenhouse is a metal building that contains the fish tanks. The rest of the greenhouse has clear six mil. plastic covering it. I would love to replace the plastic and single polycarbonate with double polycarbonate. That would definitely increase heat efficiency. (Future Plans)
This morning the air temperature outside was forty-two degrees but the greenhouse air temperature was fifty-four degrees. The water temperature was a nice sixty-eight degrees. In the event that we have extremely cold days where the greenhouse temperature drops below forty degrees I will use row covers. Row covers placed directly over the beds gives us four to six degrees for every row cover we place over our beds. For example if its twenty degrees outside the greenhouse will be around thirty degrees but if you add a double row cover over each grow bed you will have a bed temperature of around forty degrees. forty degrees is fine for cool weather crops. Sometimes it will be even wormer under the row covers because of the water temperature being maintained at sixty-five degrees. Maintaining the root temperature at sixty-five degrees helps keep the plants in good health and growing at a steady rate.