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Jay Angler
Post     Subject: insulated concrete tarps/blankets for high tunnels?

James Whitelaw wrote:

This 2015 article from Low Tech Magazine gets into some of the details and sources of various designs and includes an image where inner and outer mats are deployed at night to minimize radiation loss of heat.

Great article, James! Picture "C" in the first group of 4 pictures, shows a doubled roof truss system where the insulation can be rolled down easily on the inside of the plastic film.

I understand the article's point about the cost/benefit of plastic film over glass, and I understand that special greenhouse plastics are being developed that last longer, but I still wonder about the "cradle to grave" costs of plastic when one adds the cost of disposal?  

The OP specifically is asking about insulated concrete curing tarps. This company - https://www.tarpsnow.com/concrete-curing-blankets.html - states that these tarps have water phobic insulation and use tough material for "extended longevity" - but what does that mean? Rolling them up during the day will protect them from solar UV which is hard on tarps. If they were on the inside of the greenhouse cover such as in picture "C" in  the article James linked to, damage from wind buffeting would be non-existent, but if it was rolled down on the outside, it might go through a lot of freeze/thaw cycles which could damage it. I find things don't like to flex as much the colder they are. They look like an interesting possibility, but I worry about what will happen when they get old and whether there will be any options for recycling.
James Black
Post     Subject: insulated concrete tarps/blankets for high tunnels?

Jay Angler wrote:I've seen pictures of thick straw covers on Chinese greenhouses, but I got the impression that they didn't roll them up every morning - it was an infuriatingly vague reference.

That said, #2 Son explained to me that due to the way heat moves through glass, if I wanted to insulate a small greenhouse, I would be much better to have insulation on the *inside* to stop the heat from getting through the glass. The danger of this would be the humidity freezing on the glass and then melting the next day which could result in water where one doesn't want it. So much depends on climate - when we lived in Ottawa, this would be a serious issue, but here on the Wet Coast, I can probably design things so the water drained to a suitable location. My sister has some outside metal roller blinds that she puts up and down with the turn of a handle. She can use them to stop sun in the summer as well, and she feels that even though they are by no means perfect, they were worth the cost.



This 2015 article from Low Tech Magazine gets into some of the details and sources of various designs and includes an image where inner and outer mats are deployed at night to minimize radiation loss of heat.
echo minarosa
Post     Subject: insulated concrete tarps/blankets for high tunnels?

I have seen some listed that were nearly the same weight as the plastic sheeting. I've seen references to double-walled plastic for high tunnels and that too would add weight. As for losing early light, that would also be a time of greatest heat loss (coldest part of the day). It takes a bit for sun to reach my yard as well. Not arguing, but bouncing thoughts off of y'all.
R Scott
Post     Subject: insulated concrete tarps/blankets for high tunnels?

Downsides I see are weight and cost.  Cost can be overcome if bought used.  But the weight issue will probably mean you will need a few extra heavy row hoops or more of them.  

One positive/negative is the total light occlusion if you don't pull it off at daybreak.  Could lose valuable light, could prevent baking as more people lose plants to overheating than freezing by getting busy/lazy and not pulling the covers quick enough in the morning.
Jay Angler
Post     Subject: insulated concrete tarps/blankets for high tunnels?

I've seen pictures of thick straw covers on Chinese greenhouses, but I got the impression that they didn't roll them up every morning - it was an infuriatingly vague reference.

That said, #2 Son explained to me that due to the way heat moves through glass, if I wanted to insulate a small greenhouse, I would be much better to have insulation on the *inside* to stop the heat from getting through the glass. The danger of this would be the humidity freezing on the glass and then melting the next day which could result in water where one doesn't want it. So much depends on climate - when we lived in Ottawa, this would be a serious issue, but here on the Wet Coast, I can probably design things so the water drained to a suitable location. My sister has some outside metal roller blinds that she puts up and down with the turn of a handle. She can use them to stop sun in the summer as well, and she feels that even though they are by no means perfect, they were worth the cost.
Trace Oswald
Post     Subject: insulated concrete tarps/blankets for high tunnels?

I would want some easy method to roll them up or fold them to save doing it manually each morning and evening, but I can't see why it wouldn't work.
echo minarosa
Post     Subject: insulated concrete tarps/blankets for high tunnels?

Has anyone used insulated concrete tarps/blankets for retaining heat at night in high tunnels? Thoughts?