Solar pool cover year round in hot climate?

12 years ago

IÂve researched solar pool covers here, and I thought most folks used them for the winter, to aid in heating. They usually seemed to be removed in spring, and replaced with a shadecloth.

I thought the purpose of a solar pool cover was to retain heat...a good thing in winter, but a bad thing in summer. However, solar gh (Ron) has been kind enough to mention in a recent thread that his pool cover stays on the outside of his greenhouse (with two layers of shadecloth) in the hot Arizona climate, year round.

After more reading, I found this quote from Stressbaby: "It seems to me that the only reasons for taking off the cover are 1) vents, 2) aesthetics, and 3) wind or wind damage. If the cover transmits 80% of the light, then it's a 20% shade cloth and that could even help with daytime summer cooling. Another thing the cover does is diffuse light... light diffusion prevents foliage burn, improves photosynthesis, and decreases internodal stretch and plant height."

This seems to support RonÂs practice of keeping his solar pool cover in place year round. (I know Gardenerwantabe keeps his pool cover in place year round, but I don't think he uses his greenhouse in the summer.)

In the same thread, karenrei makes this statement about how a pool cover works:

"The bubbles do what bubbles do: they make it harder to lose heat...In short, things full of tiny air spaces are the best insulators against conductive heat loss."

This is what confuses me. I thought insulating against heat loss on 100° degree summer days would make it hotter inside, and I thought I needed to allow the heat to escape as quickly as possible, to facilitate cooling. I thought my climate was too hot to use a solar pool cover...even on sunny winter days...and definitely during summer.

FYI, my 10x12 greenhouse is glazed with 4mm twinwall polycarbonate. I use my greenhouse year round, including summer days sometimes ranging a bit over 100°. My plants (cacti) are fine with occasional 110° days. I have an exhaust fan that capable of 2950 CFM, Aluminet shadecloth, screens on my south wall, and two HAF fans in opposite ends for air movement.

I'd love to know:

1) Can the insulation provided by a solar pool cover aid in cooling my greenhouse in summer, by acting like a 20% shadecloth?

2) If itÂs so good at retaining heat in the winter, why wouldnÂt it make my greenhouse hotter in the summer by doing the same thing (retaining heat?)

3) Why do you folks remove your pool covers in the summer...just for looks, and/or access to roof vents?

Thanks so much for any help on getting my brain around this issue...I don't want to close the door on any good option.


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