Solar Greenhouse Design and Construction for Low Energy Use - Heating & Cooling

[Brad Howard]

I have been trying to educate myself on Solar Greenhouse design that would allow me to grow year round with little additional cost for cooling or heating. I live just outside Nashville, TN.  I thought I would share one of the most comprehensive sites I have found on this subject on the internet.  See the links below:

Subterranean Heating & Cooling for Greenhouses: http://www.roperld.com/science/solargreenhouses.htm#SHCSAmerican

 

A very interesting design in two sizes is located here: 

32' X 18' Neighborhood Solar Greenhouse size: http://www.roperld.com/science/solargreenhouses.htm#SHCSN

20' X 10' Backyard Solar Greenhouse size: http://www.roperld.com/science/solargreenhouses.htm#SHCSBY

Backyard Solar Greenhouse
Using Subterranean Heating and Cooling System built in Madison County Kentucky  http://www.roperld.com/science/SGHBackyardSHCS.htm

I think this information has been recently posted to the internet and it looks very well thought out and from the on-line picture the Backyard Greenhouse in Madison County Kentucky looks like it will both heat and cool itself year-round.

 

Has anyone else built a Solar Greenhouse using these ideas?  Do these designs efficiently heat and cool? Can you really grow year-round without huge energy bills? Opinions? I am just learning all I can before I build mine.

 

Thanks,

 

Brad Howard

 

[TCLynx]

I know I've seen some greenhouse designs on permacutlure sites that will work fairly well for growing year round as long as you are still growing seasonally appropriate plants.  This doesn't mean that you can get away with growing tilapia in a snow covered landscape with no additional heating.  If you can keep the greenhouse warm enough to keep water from freezing in the system, you can grow climate appropriate fish in a greenhouse aquaponics system.

[Vlad Jovanovic]

Hi TC, say we have the plants worked out, your typical winter stuff, spinach, cabbages, iceburg type lettuces etc, and we have an appropriate cold hardy fish, trout, carp, lake erie perch, whatever...and the water isn't freezing in the pipes...what about the bacteria?

I remembered seeing a chart ( I think that Rupert may have posted it, not sure) a while back that showed the biological activity of nitrifying bacteria at various temperatures. It pretty much monkey-wrenched my dream of getting away with 'just keeping the pipes from freezing' :(  I'll try to dig it up somewhere, but basically according to that chart, (and others that I've had the misfortune of looking at since then) the bacteria at below 10 or 12 (even 15) degrees Celsius were working at a drastically reduced rate. (Again this is according to the charts).

I am assuming that if your water is colder than is optimal for your particular type of fish, that the fish slow down as well, and that this sort of parallels with what the bacteria are doing? But what do you suppose happens if you have trout feeding full throttle (and higher protein food at that) at temps in the 7-10 degree range (45-50 Fahrenheit)? Is the bacteria really as sensitive to temps as the internet and books tells us?

[TCLynx]

When the water is cold, the fish won't be eating as much so the bacteria being slower usually isn't such a problem.  The system won't be churning the way it is in full summer but you should be able to keep it alive and still grow the cold weather crops.

 

If you are growing trout, you need more filtration to keep up with the reduce bio-filter rate at colder temperatures.  Just like if you are running much lower pH you may need more filtration to keep up with the less efficient bacteria function. 

 

Understand these issues exist so you are prepared for them but don't get too bound up with the numbers since there are people out there who grow trout in aquaponics and it works.  There are people out there who manage to overwinter systems at a slow tick in a minimally heated greenhouse.  You will just have to find the balance that works out in your situation. 

[Rob Nash]

 "Is the bacteria really as sensitive to temps as the internet and books tells us?" ...yes! but there is hope!

look up BioZome. this product contains "Archaea" wich can convert amonia to nitrate in freezing temps. this stuff rocks!     http://www.maximumyield.com/article_sh_db.php?articleID=504&yea...

[Vlad Jovanovic]

The article was certainly enlightening, and Biozome does seem promising...Rob, have you actually used the stuff in your AP system? Do you have any info on Archea behaves towards petroleum based plastics? (Liners, containers ect)...

[TCLynx]

Keep in mind in most of our natural systems, we have a variety of strains of bacteria that work at different temps and pH conditions.  If the lab tests dictated exactly how our outdoor natural system worked, then I doubt Aquaponics would be nearly so functional as it actually is.

Also keep in mind that most Fish slow down at lower temps as do most of the plants so it isn't necessary to have the bio-filter functioning full tilt when the fish aren't eating and the plants are not growing much.

[Debbie Buonomo]

Hi Brad,

I'm reading through some old posts with regards to building a solar greenhouse and stumbled upon yours.  Have you had any success with building a solar greenhouse without any need for electricity to heat?  I live south of Nashville just west of Columbia.  I'm curious to find out what others in middle TN have used for their, year round, AP systems.

I've read through some of the links you provided but need to take more time to study the ideas and concepts.  We're hoping to start building a greenhouse within the next month or so.  It depends on how quickly I can digest information. We had an AP system set up in our basement for a while and decided we need to get it outside.  

Look forward to hearing from you.

Debbie

[World traveler]

Yes.  Check out Lee Porter Butler's book. If you get one let me know. He's dead now....100% energy efficiency all over the USA.  add me as a friend. World Traveler in Bali