As I finish putting up my greenhouse I have began to worry about the costs of heating during the winter months. Does any one have a resourceful way to save energy and heat during the winter? i have heard of people using 55 Gallon drums full of water to help keep the heat in during the night, has any one had success with this method or has another method that works? I'm open for any suggestions.
Hi placenciarita! I use sturdy 30-gal black plastic garbage cans, filled with water. The passive heating from the water in the cans is supplemental to an electric heater that kicks in when the temperature drops to near freezing. I don't need a lot of heat, as the plants in the greenhouse can stand a short period below freezing, and the system worked well for me last winter.
Edited to add: My greenhouse is glass & aluminum. I stick bubblewrap to the inside of the glass, to help with insulation. There is also insulating material buried in the floor, and covering the north-facing end of the greenhouse. It gets pretty cold here in the winter!
This message was edited Sep 28, 2007 3:40 PM
Thanks June_Ontario,
Thanks for the info, what did you use in the floor for insulation? the coldest it gets down here is usually about 25 but thats only for a couple days... But I'm trying to keep my plants growing in the winter and to do that the temperature has to be around 65 at night, so needless to say i want to conserve as much heat as possible.
The floor is layered, a couple inches of gravel, then a sheet of polystyrene, then more gravel on top. The polystyrene board has some holes punched through it to allow for water drainage.
Rita how neat. You built your GH right over your flower bed. Very very neat idea.
Here are some facts which might help you with heating...
Studies of greenhouse heat loss show virtually no loss of heat through the floor. One study I have seen shows a loss of 2-3% through the perimeter, that's about it. Why? My guess is that your deeper ground temps are 55F and that there simply isn't much of a differential between ground and GH temps. Over 50% of the heat loss is through the roof.
Also...and I have no studies to back this up, this is just my opinion based on temp observations in my own GH...in the absence of some means of managing the heat collected in black water containers, they don't do a whole lot either. Here is the rationale...You collect heat during the middle of the day when it is hot. You need that heat to be released in the middle of the night...that is the only way you really save on propane or nat gas or electric. However, that heat is released as soon as it starts to cool off. So as soon as the temperature differential favors release of the heat from the drums, they start to cool. This is often long before you actually need the heat. Maybe the drums start to cool at 3:30 or 4:00 in January. This is might be long beofre your heaters kick on. By the time the heaters kick on, the amount of heat energy stored in the drums is far less than it was at its midafternoon peak.
My approach is to save that space for plants, improve the R-value with layers of glazing opaque to LIR, insulate the north wall and north roofs as much as possible (mine are R-6 or so) and go from there.
SB
Thank you,
for all the replies I will be sure to insulate my north wall and experiment with checking my floor temp. too.
