So, let’s talk about one of our insulation experiments we’re conducting for this season. The hyper observant among you might have noticed some slight differences in our greenhouse this year.
We decided to fill the cavities on the lower part of our greenhouse with insulative closed cell foam. We’ve been operating our greenhouse without this for years now. Honestly, we had some serious doubts whether insulating the lower part of our greenhouse would be beneficial.
In our greenhouse, almost all of the heavy lifting for insulation is performed by the UV rated plastic we discussed previously, installed across the upper part of our gambrel style roof. Heat rises and thus it’s going to escape from the top of the greenhouse, not the bottom. If there’s a potential benefit of insulating lower parts, it’s with reducing any potential for air exchange.
Honestly, for what closed cell foam costs these days, it’s unlikely we’ll ever see a return on investment from this. Just this tiny project was like $240! We’ve been observing and monitoring this secondary insulation effort for a few weeks now and it’s barely made a dent in the insulative performance. We do maybe see slightly faster warm up and slower cool down, but that’s just as likely variability in outdoor temperatures.
But, we had to know. We don’t really see people talking about insulating their greenhouses, so I guess it’s a “subarctic thing” that others just don’t understand. At least we now have cool Pink Panthers in our greenhouse, so that’s kind of rad.
We are making some concerted efforts to finish the insulation projects on our greenhouse this year. Our last task is weather sealing our door, which we’ll do once the snow is thawed and things are less of a soupy mess. This is also an area of questionable benefit, but it’s at least a whole lot cheaper to do!
So, if you’re pursuing a greenhouse insulation project, the lesson here is to focus your insulative efforts entirely on the upper parts of your greenhouse. This is where the magic happens. Everything towards the ground is a diminishing return. Even if it’s just thin sheet metal.
If anything changes our opinion, we’ll be sure to let you know. But, we figured some of you all might wonder about this and we’re here to try it out and let you know what we think!
