Solar cooling options for rabbit barn

We’re in the process of designing a 10 ft x 14 ft rabbit barn, using a carport A-frame structure as the genesis. We’ll secure it to the ground, add corrugated roofing, and, for predator barrier reasons, are looking at using lap siding. We have a LOT of skunks and raccoons here. Construction plans came together much more quickly after the spousal unit remembered we had this frame already and I found an Instructable for adding the roofing! The floor will remain dirt for urine absorption and vermicomposting.

What I’d really love some input on is cooling. Most of our summer is above the 85F degree mark during the day, which, as we know, is bad news bears for bunnies. We want to to this without running power. The oak and photinia are to the south of the barn, so that side is shaded starting at about 10am. I’m not a big fan of vinca, but it’s there and we can encourage it up the east side of the barn. I’ll plant something tall and sun-grabbing on the west side for shade. The doors will be to the north so they can be opened during the day for lots of air flow.  Considering a solar fan; anyone have a favorite model? Would love some input on what others have done or ideas to keep our rabbits cool.

I just watched a video with rabbits where they were in Texas and talked specifically about how they situated their hutches to keep the rabbits comfy.
(i'm sorry, I know the video is 15 min, I don't remember where exactly it was but he mentioned orienting it in a certain direction because of sun and wind.)

I like to use the 12" automotive 12v brushless fans. I have found them for about 30 bucks at our local automotive stores.  Sometimes you can get them real cheap in junkyards.  I got one last year for 5 bucks at the flee market.  Most will have an amp reading on them.  A 10 amp will need a 120 watt solar panel.  I hook them directly together with a switch to turn it off when not needed.  My rabbits don't ever like being in the sun and need to be well ventilated.  The ammonia smell will get extremely strong in a barn.  All of my rabbits are out side on the east side of the barn.  They get just a little sun in the morning right now and by 8 am they are in the shade.  Raccoons and skunks don't mess with them, but the neighborhood dogs have.  I made extra strong bottoms for the pens and keep them 30-36 inches off of the ground so the dogs can't get leverage on the pens.  I just had a litter of 12 this past weekend and all are doing good.

Helpful video; thank you! Shade, check. Orientation, check. Fan....that one I’m still puzzling over. Had a brain wave last night about making the north wall out of 2x3 goat wire and not putting any cages on that side (so the darn varmints can’t reach through to grab bunny parts) for maximum air flow. Has anyone found a solar-powered fan that’s powerful enough for a shed that size? Preferably under a hundred bucks, but it would be more expensive to lose rabbits than to pay for a fan that does the job.

Thanks, Christopher! I must have been watching the video and posting response while you were posting. I was wondering about how much power we’d need in a panel to run the fans, so this is super helpful.

This may not be practical for everyone and it could be labor intensive, but I always thought if I kept rabbits, I would make some sort of underground area for them to go into on hot days.  Mike Oehler talks about keeping rabbits in the cold sink in his underground greenhouse book.  If you could make sonething like a small root cellar with miniature bunny steps or just a slope to get down into it, the rabbits should be able to go up and down as they please.  For less labor, you could make a small dome structure on flat ground with a tunnel type entrance, and bury it in 4 or 5 feet of earth.  I'm still kicking around an idea like that for my dogs.  It would be climate controlled and impervious to storms.  It would be a really fun project for someone if they had the extra time.  Earth bags would probably be the fastest, strongest, cheapest solution.

Velecrations used to post here and they bred rabbits in the Mexican dessert.
As I recall,the rear of each cage had an "underground " lair as a cool place to retreat to.
Check their stuff out here:http://velacreations.com/blog/rabbit-dwellings/

It looks like Medford  might be to humid for swamp coolers or other evaporator cooling,  but if you have a pool or pond you could put a coil in front of your fan and run a loop to the  body of water.

I would consider a layer of foil faced insulation board as a ceiling ,creating an "attic" between the ceiling and corrugated roof.

We might work toward underground options in the future, but are a little time-limited right now for that.

Tell me more about creating an attic; I’m totally ignorant about how that affects cooling but would like to learn.

The solid roofing will heat up from the sun and then radiate heat into the space beneath it.
If that space includes your rabbits, they will get hot as well.
To build an "attic" lay 2x4's across the horizontal parts of the carport frame and screw them to the tubing with long self tapping screws.
Attach insulative board, foil side up to the top of the 2x4s, with screws and fender washers.
Close in the open ends of the frame that form triangles with mesh to keep out wildlife but allow air flow.
Cap your roof with a ridge vent and you should have decent convection air flow through the attic.
Add a solar powered fan if you want but that might be overkill.

If you want to use the attic for drying/storing hay,  screw your fan boards to the bottom of the 2x4s and plywood on the top and frame a hatch into the floor.

I would NOT put any of your own body weight into the attic  floor,  but it should hold hay just fine.

William Bronson wrote: The solid roofing will heat up from the sun and then radiate heat into the space beneath it.
If that space includes your rabbits, they will get hot as well.
To build an "attic" lay 2x4's across the horizontal parts of the carport frame and screw them to the tubing with long self tapping screws.
Attach insulative board, foil side up to the top of the 2x4s, with screws and fender washers.
Close in the open ends of the frame that form triangles with mesh to keep out wildlife but allow air flow.
Cap your roof with a ridge vent and you should have decent convection air flow through the attic.
Add a solar powered fan if you want but that might be overkill.

If you want to use the attic for drying/storing hay,  screw your fan boards to the bottom of the 2x4s and plywood on the top and frame a hatch into the floor.

I would NOT put any of your own body weight into the attic  floor,  but it should hold hay just fine.

Aha! I get it. Thanks for that detailed explanation. I was wondering about potentially using an "attic" space for hay storage so that I can keep things close and easy to access. Any fire concerns or nutrient loss concerns with keeping hay up there? I realize that hay barns have used the upper portion for...a long time...but I also have witnessed our neighbor's barn catch fire from spontaneous combustion of their hay attic. (Granted, they were not the most observant or careful of farmers, but still, would like to avoid that outcome.) Additional bonus of what you've laid out here is that that mesh is cheaper and will be easier to cut and install than shiplap. I'm going to have a fair bit of babysaver wire left on this roll after building my cages, so, hey, already available.

On a semi-related topic, has anyone used wool for insulation? I'm thinking that might be workable for the walls. I've seen some info on alpaca fiber used as insulation, but I've got a good and inexpensive source of wool here locally.

Here is one of the fan setups.  This uses 90 watts at 12v.  Moves quite a bit of air in full sun.

It took some time, but the barn is up, the insulation boards create a ceiling, and the bunnies are in! Took them a couple of days to settle in, but they are starting to be more comfortable and active now. Since it's been so warm here, I put a big box fan in the barn to help with air movement and cooling and stuck a mister that we already had a couple of feet in front of it. Ta da, sorta-kinda swamp cooler. The temps have been lower in the barn than outside, so it's a step in the right direction.