Hi All,
I am planning on building a lean-to greenhouse in Ohio zone 6a to house some citrus, figs and maybe some other semitropical stuff. There are several types of panes available - single glass 6mm, double glass, and low-E (blocks 30% of light)… Which of these would be ideal for my situation? I will have floor heating. The primary goal would be to maximize plant health, and secondary goal is energy efficiency, so insulating and warming in the winter, but not frying in the summer. Thanks.
Well, multi pane for energy efficiency of course. Not Low-e or other energy saving or UV blocking coatings, you want all the light getting through as much as possible (low-e may be ok, and it is somewhat harder to find uncoated these days). It is also somewhat harder to get as much sun as most plants need in the winter as well as keep the excess out during summer; shade cloth and/or good ventilation is often needed. Depending on the size/shape you are thinking of, some roof glazing will likely be needed to get light into the back/N side, especially for citrus and other light-loving plants.
You might also consider greenhouse plastic glazing, such as multi-pane polycarbonates. Easy to install, good insulation and does not break like glass. And offers more privacy than glass (which may be a plus or minus). But the plastic needs to be replaced every 10-20 years.
The best covering I’ve found is Palring 175. It lasts 3x as long as 6mil, 4 year greenhouse poly. But if you are set on glass that’s no help. Glass was never an option for me.
I use glass. I picked it up use from window replacement company. Optimum air space for holding heat is 5/8 inches.
Cool, but violates the laws of thermodynamics 
Can’t be invisible (no photon absorption) and generate energy.
You think it’s a bunch of BS?
Im really not sure why they still refer to the 6mil polly such as Klerks as 4 year?
For good reason this is still the standard of the industry and lasts way longer than 4 years.
Average life around here is 13 - 15 years.
Although in full disclosure i did have to replace one early after a Bobcat tryed to climb over the greenhouse.
Maybe because out here it lasts 3 years if you are lucky. Most climates are more demanding than the PNW.
I imagine so! All i have to do is watch the national weather forecast and count my blessings.
Have you considered using twin-wall poly instead of glass? That’s what I would do. It’s lighter and easier to work with, it doesn’t shatter, it has a much higher (but still bad) r value, etc.
