A Community and Forum For Aquaponic Gardeners

To insultate or not

I intend to raise channel catfish and bluegill which I believe will adapt to the 20F to 115F temperature range where I live. I'm planning to use IBCs for the tank, sump, and grow beds. The system will be outside, and my intention is to enclose them in plywood and insulate the tanks, and beds with 2" a rigid foam insulation in order to extend the growing season with an electric tank heater.

This will add about $6.50 per sq foot of grow bed plus the utility bill. Some considerations are that I may not get a significantly improved yield due to the daylight hours being shorter in the Winter, but I might get an early start in the spring and possibly better fish production. So maybe it would only be heated in the late winter early spring...???

As you can see, my head is filled with too many options each with pros and cons and I have my doubts about the cost defectiveness of this idea,

Any advise would be welcome.

0 members like this

Replies to This Discussion

Permalink Reply by Kellen Weissenbach on January 2, 2012 at 1:27pm

A properly designed earth sheltered greenhouse would allow you to grow all year long with extremely stable temps in your area.

Permalink Reply by Bob Campbell on January 2, 2012 at 1:58pm

I have a green house which I'll admit is not properly designed (a single layer of corrugated polycarbonate sheets) , but my experience with it was that temperature was very expensive to control. I don't want to throw a lot of cash at this to begin with, but maybe you could point me in the right direction for a good green house design. Earth sheltered is probably not an option since I'm on a residential lot.

Kellen Weissenbach said:

A properly designed earth sheltered greenhouse would allow you to grow all year long with extremely stable temps in your area.

Permalink Reply by Kellen Weissenbach on January 2, 2012 at 2:15pm

Hi Bob,

Even with a more traditional style greenhouse, there are some things that you can do to help keep temps more stable, relatively inexpensively. Thermal storage is a good technique to use. For instance, you could use some black barrels filled with water to help store heat produced during the daytime. Place them on the north side of your greenhouse where the sun from the south facing glazing will shine on them and warm them during the day. They will slowly release this warmth as air temperatures in the greenhouse go lower during the overnight hours.

Regarding the greenhouse, what kind of design are you working with? Is it a lean-to style or more shed style? Do you have glazing on all sides? On the Roof?

Permalink Reply by Bob Campbell on January 2, 2012 at 3:01pm

It's 10'x16'x10'eve with a 14' peak and glazed on all sides, I sealed all the corners with expanding foam. (I know... I should insulate the north wall and roof. 8-)

I built a solar collector that is capable of rising 55 gallons of water to 92 degrees during the winter days. But freezing still happened. I also placed a second barrel in the shed style green house for a bit more thermal mass. But the BTU's I was storing paled in comparison to the night time losses.

I ran a small electric heater for a while but this is not a commercial operation and I could not justify the expense.

So considering the failed attempt in the green house I would prefer now to work with the seasons and plant appropriate crops outside I now live in Northern California, but I came from Tucson where I had a lean to greenhouse build of the same materials. Winters were not as cold and the heat from the shared adobe wall of my house was enough to allow me to grow year round. In that green house I used 5- 55 gallon barrels as passive thermal mass which helped balance the temperature swings in both summer and winter.

.

Kellen Weissenbach said:

Hi Bob,

Even with a more traditional style greenhouse, there are some things that you can do to help keep temps more stable, relatively inexpensively. Thermal storage is a good technique to use. For instance, you could use some black barrels filled with water to help store heat produced during the daytime. Place them on the north side of your greenhouse where the sun from the south facing glazing will shine on them and warm them during the day. They will slowly release this warmth as air temperatures in the greenhouse go lower during the overnight hours.

Regarding the greenhouse, what kind of design are you working with? Is it a lean-to style or more shed style? Do you have glazing on all sides? On the Roof?

Permalink Reply by Bob Campbell on January 2, 2012 at 3:09pm

I'm still learning to use Google SketchUp but here's a plan I drew.

My earth bermed aquaponics skectch

Permalink Reply by Kellen Weissenbach on January 2, 2012 at 3:33pm

I would insulate the entire roof (both north AND south) and probably both the east and west side walls too because you are losing more btu's than you are gaining from them. The south wall should provide enough sunlight for growth. The sun is low in the winter, so you rarely get any good direct sunlight through the roof glazing, yet you lose the most heat from it.

With your Underground AP design, remember that most of the heat loss will be from the surface of the water in your fish tanks, sumps, etc. AND likely even more from the actual growbeds. Growbeds are very efficient heat exchangers. Insulated tanks and growbeds are very wise, but they have to be covered too. Growbeds could maybe be covered with some poly to help reduce the super cooling?

Permalink Reply by Bob Campbell on January 2, 2012 at 4:12pm

Thanks, those are some good ideas.

Permalink Reply by Kellen Weissenbach on January 2, 2012 at 4:19pm

No problem Bob. Good luck, and let me know if you have any other questions. I'm always happy to help!

Permalink Reply by Bob Campbell on January 2, 2012 at 8:16pm

The ideas you gave me were very good. So I'll do the energy calcs with the idea of enclosing the system in the green house. What you said makes a lot of sense. I like the idea of insulating the roof and walls.

The additional thermal mass of the fish tanks and gravel in the grow beds could make quite a difference to the energy calculations. My previous greenhouse setup had only a 5 gallon reservoir of hydroponic solution. So the extra thermal mass will help.

I'm also thinking an extra layer of polyethylene on the south wall may help insulate. But while building the green house I found it difficult to find specs on light transmission. The corrugated polycarbonate seems to work, but I sense that it blocks a fare amount of light. Do you think one more layer of polyethylene will reduce the available light by too much?.

Thanks for the advise, I'm feeling much more comfortable with this plan. I actually like the idea of keeping it all inside because it will allow me to provide additional light during those short winter days and I love to sit in my green house with the plants! It's one of the most relaxing places I can think of.

Kellen Weissenbach said:

No problem Bob. Good luck, and let me know if you have any other questions. I'm always happy to help!

Permalink Reply by Kellen Weissenbach on January 11, 2012 at 2:06pm

Hi Bob,

Sorry for the delayed response. I must have missed the notification of your reply.

An extra layer of polyethylene would do some good assuming you can make a couple things work correctly with it. The polycarb glazing needs to be made as air tight as possible. Hang the polyethylene so that you have at least an inch of air space between it and the polycarb. Assuming you framed out the greenhouse with 2x4's, this would make for a nice big air space as well. This dead air space makes pretty good insulation (relatively speaking) while still letting a very good amount of light in. It's a bit like making a double pane window.

Speaking of double pane windows... You might keep an eye out for some used UNCOATED (older) double pane windows. Coated ones (newer) will reflect a lot of the light (and heat), which you don't want to do. Anyway, these windows will give you far superior insulation as your glazing material. Plus, they just look pretty darned cool I think too. I like to keep an eye on craigslist for this type of stuff.