Automating the Homestead

I think a lot of people over here listen to Jack's "The Survival Podcast", but in case someone missed it he had an excellent podcast about automation with Eric Escobar. Eric speaks about how you can automate several things on your homestead such as feeding animals and opening/closing the door to the chicken coop. This is done with these small $40 computers called Raspberry Pi's. Anyways, this was a podcast that I first thought that I would not find interesting at all but it was super interesting and beneficial.

Listen up!
http://www.thesurvivalpodcast.com/escobar-automation

I listened to that yesterday, it was a great podcast. My only issue with it was that it's not quite as simple as the guest made it out to be. It's not hard, per se, but it does require logical thought and the desire to tinker.
I've actually got a bit of experience with both the Arduino and Raspberry Pi. If anyone has any questions, I can definitely try to answer them/help. I am a computer guy by trade, but only dabble in embedded controls.

I agree with Derek, it's not as simple as you might think.

I'm also not sure that I would use the Raspberry Pi for such simple tasks, as Arduino's are probably a better fit, and much cheaper. (One can get Arduino Pro Minis on EBay for $2.50US, while Raspberry Pis are $25-$35 depending on the model.) I've been messing with Arduinos and Raspberry Pis with farm automation in mind for the last year-and-a-half, but haven't gotten to the point where I've got a working prototype. If there are any other folk interested in putting their heads together on this sort of thing, feel free to contact me. I'd love to be part of a project that develops, say, an intelligent solar powered water pump.

Well I'm new to all this. I have looked Into arduino before and it seemed much more complicated than what was explained.

I don't have any coding experience other than HTML in 1998. (Has anything changed? Lol ) my wife and have five chickens and I'm looking into aquaponics. This automation would really free is up. Especially since we have a three month old now.

My question to you guys with more experience is :
Where do I start ?

Do I need to Learn a programming language?
Which one?
How do I know which board to use?
Arduino?
Pico?
Raspberry?

Is there a web site where I can build and test projects and circuits before I start spending money on it? It may be cheap but new borns aren't.

It depends what you want to do.

The "brain" isn't the expensive part of most homestead projects, it is the sensors and actuators to actually do something useful--that usually takes more force than the silly little demo projects.

Don't spend $50 to program a thermostat when you can buy one for $10. Unless you add features like data logging or alarming that are worth the extra money to you.

I like to think of it this way:
Arduinos are less robust/powerful. They're typically targeted to perform a few simple tasks in one area. Not to say you couldn't make an arduino do more, it's just a lot more work.
A Raspberry Pi is a full on computer and has a lot more power as a result. I would use it more for a media center PC, or web gateway/central controller for multiple arduinos. You absolutely could use a Raspberry Pi for a point application like an arduino, but it almost seems a bit overkill to me.
If you were going to pick one platform only, I'd probably go with the Raspberry Pi since it's more powerful/featureful. However, I think they both have their places. If nothing else, it's a great place to start.

Regarding languages... They all do similar things in similar ways. For the most part, anyway. I would probably pick up Python and C/C++. Python is easy to learn, and there are dozens of tutorials. Take a look online for a site that teaches you basic programming concepts (like codeacademy) and then look for specific tutorials on your platform of choice. There are hundreds out there for the Pi and Arduino boards. Heck, with all the STEM stuff going on, you'll probably be able to find detailed courses on each.

The most important thing is to teach yourself to learn. Everything is available out there, and it's usually just a google search or two away.

I have a question about a power supply for my first automation project here on the farm.

I'm building an automatic chicken door and I believe that I have all the components but I'm not sure on the power supply.

Let me explain the system.

Light sensor turns ON when the sun sets. Closes a relay.
DPDT relay starts the motor to close the coop door.
Door is closed and trips limit switch opening circuit

Sun Rises light sensor turns OFF and relay opens
DPDT relay switches polarity and reverses motor. Opening the coop door.
Door opens and trips limit switch which opens circuit.

The window motor is out of a Mercedes.

I need to source a power supply. There are plenty of 12 volt DC power supplies that I have from old printers and computers.

Learning about how to answer this question is more important to me than actually finding the answer.
That way next time I won't have to ask and can improve on my next project.

Questions:
Does the amp supply need to be exactly what the window requires?
If it is lower, will it just run slowly?

It can't be too low compared to the motor rating or it will likely damage the power supply and the motor will likely stall.

Needs to be a higher amp rating than the motor, including the start surge or locked rotor amperage of the motor.

If the power supply can't supply enough amps, the motor may run slower or it may stall and burn out.

- O.K., So I didn't see it mentioned here, If you want too see a whole series of simple tutorials on what is possible with Arduinos and Raspberry Pi(s)
Then take a quick tour over at Instructables.com

Also there is a link to a kickstarter thing here in the Alternate energy forums " One Less Refrigerator '' That will ether list the parts needed to automate
and power existing Tools/ Appliances Or sell you the completed devices !

The Control circuit does not need to run at the same volts or amps as the circuit being actuated/controlled, The Thermostat in virtually everyones home
is a 12 -24 volt circuit, That opens/closes a relay to supply electricity to its controlled circuit, usually 110 volts


Many of us have a 13 year old in the immediate family or living next door who understands and PLAYS with these gadgets !

Or you could find out where your Nearest Makerspace is and as them about an Arduino Raspberry Pi Group or check a couple of local event calendars

Where there is a will there is a way ! A rising time floats all boats ! Big AL

We mess with all of the above here. (audrino, raspberry pi, python and C++, even I the brute-force programmer have learned some C++)

It's our dream to have sensors and be able to run some stuff off our phones on our own. We just wired a netbook to be the controller brain (and my better half knows those details. I solder, he programs). We have two acres on two sides of the county road (a paved street in town) and need to be able to deal without having to run all the way over there....

Any updates on what someone else has managed? Mostly here we about gave his computer a nervous breakdown.....

Check out www.ebook777.com....lot of free downloadable ebooks.......several on Arduino and Raspberry Pi in the "hardware" category.
Books on Python and C++ languages are in the :software" category.

Most are in .PDF format, but a few are .EPUB

R Jay wrote:
Check out www.ebook777.com....lot of free downloadable ebooks.......several on Arduino and Raspberry Pi in the "hardware" category.
Books on Python and C++ languages are in the :software" category.
Most are in .PDF format, but a few are .EPUB

Thank you for the link! My better half is good at coding, it is his forte. My geekness runs more to hands-on. I should have been a machinist, born a generation too late, and still, am a much better bench-woman with fab and solder than he will ever be. (proven by employment and projects)

Again, thank you for the link.

This probably is far from the best solution, I admit, but since we already had a Smart Things security system set up, and I am not a programmer, I just got an extra Smart Things outlet and an electric pulley (like they have for automatic blinds), picked up some free wood at home depot to make a sliding upwards door, and set the Smart Things program to open and close the chicken coop door at sunrise and sunset. I also linked Smart Things through Alexa so if I need to override the program, I say, "Alexa, turn on chicken coop door." And the door will voice command open (or closed depending on which state it was in when I make the command, or control with thr Smart Things app if im away from home. Next step is to plug it into a solar panel on the roof of the coop. I've also got a hose hooked up to their drinking water when I go on vacation. I was working on an egg alert motion sensor, but that's not working correctly yet. Automated feeder would be easy to add if I had a good food holding option which i would hook up to the sunset switch to ensure all my chickens and ducks were safely inside. All of this just to not have to get up early, or to not have to rush home to close their door manually... and to take a periodic vacation from the homestead. (I have a chicken cam to check in.) If this is too on the grid, you could just get a separate sunrise and sunset timer to open/close the door.)

Deb Rebel wrote:

R Jay wrote:
Check out www.ebook777.com....lot of free downloadable ebooks.......several on Arduino and Raspberry Pi in the "hardware" category.
Books on Python and C++ languages are in the :software" category.
Most are in .PDF format, but a few are .EPUB

Thank you for the link! My better half is good at coding, it is his forte. My geekness runs more to hands-on. I should have been a machinist, born a generation too late, and still, am a much better bench-woman with fab and solder than he will ever be. (proven by employment and projects)

Again, thank you for the link.

Rebecca Sheldon wrote:This probably is far from the best solution, I admit, but since we already had a Smart Things security system set up, and I am not a programmer, I just got an extra Smart Things outlet and an electric pulley (like they have for automatic blinds), picked up some free wood at home depot to make a sliding upwards door, and set the Smart Things program to open and close the chicken coop door at sunrise and sunset. I also linked Smart Things through Alexa so if I need to override the program, I say, "Alexa, turn on chicken coop door." And the door will voice command open (or closed depending on which state it was in when I make the command, or control with thr Smart Things app if im away from home. Next step is to plug it into a solar panel on the roof of the coop. I've also got a hose hooked up to their drinking water when I go on vacation. I was working on an egg alert motion sensor, but that's not working correctly yet. Automated feeder would be easy to add if I had a good food holding option which i would hook up to the sunset switch to ensure all my chickens and ducks were safely inside. All of this just to not have to get up early, or to not have to rush home to close their door manually... and to take a periodic vacation from the homestead. (I have a chicken cam to check in.) If this is too on the grid, you could just get a separate sunrise and sunset timer to open/close the door.)

Deb Rebel wrote:

R Jay wrote:
Check out www.ebook777.com....lot of free downloadable ebooks.......several on Arduino and Raspberry Pi in the "hardware" category.
Books on Python and C++ languages are in the :software" category.
Most are in .PDF format, but a few are .EPUB

Thank you for the link! My better half is good at coding, it is his forte. My geekness runs more to hands-on. I should have been a machinist, born a generation too late, and still, am a much better bench-woman with fab and solder than he will ever be. (proven by employment and projects)

Again, thank you for the link.

I do farmsit for a friend that keeps about 20 hens, in the middle of a month off, and from that, plus at home as I grew up (we ran about 30 layers, and every third year, about 200-300  pulllets for the family-round-robin) about 10-15 minutes after sundown, you should have every hen in. If it couldn't figure it out in a year, it went in the noodle/soup pot, and there were a few every brooder year....

I guess there are two ways to look at efficiency;

Automation
Technique

I am firmly encamped in the latter category as I am a minimalist by nature. In Industry they call it Lean Manufacturing, or Just-In-Time-Inventory, but basically it is a simple concept; eliminate as many steps as possible to get the same result. This takes thinking things through and getting multiple uses from one product: versatility in other words. Another key ingredient is in tracking things, I I propose that if everything is calculated out, automation is far more inefficient then first considered. Kind of like financial costs, its the hidden ones that make or break an operation.

In the case of a chicken door, I propose that automation is far more inefficient. When calculating the time to design the opener, order the parts, build them, iron out the details, then keep the item operating satisfactory, more time would be invested then simply walking out to the coop and opening and closing the door as I do. How much time does that take...honestly not much, especially since I am typically out in the yard about dusk anyway do other things. At first it seems great, "I don't have to go out and open or close the chicken door", but hidden time-suck comes in by all the tasks to keep that simple function going.

One has to remember in all this that the Mayans were reported to have met their demise from having too complicated a society. I am old school I know; I don't even have a cell phone, but after watching my co-workers get irrate because their spouse would not answer their texts, I realized just how much simpler my life was. I also realized how inexpensive it was to avoid being irritated as much...an electronic leash I call them. My farm might not be cool and snazzy, but sheep farming is low-tech, low-cash flow farming that humans have been doing for 9000 years. Keeping it simple keeps it profitable.

There are many solutions.  There are very few "wrong" answers.   I'm pretty old school, so I get that for sure.  Sometimes the simple solution really is the best solution.

Certainly, there are examples of automation that is more work, more money and less effective in the end.  For some harmless entertainment, go look up the youtube channel Shitty Robots

to watch automation run horribly amok.


On the other hand, it's hard to find people who know anything about animals to fill in if you're on vacation, or in the hospital for a week.

On the third hand, reasonable estimates suggest that 1/4 of all the jobs in north america might be replaced by automation in next decade or two.

It might be an important skill to develop to understand microprocessors and automation....

And if you enjoy it and you're learning something, good on you.



Good luck and have fun along the way.

Chicken door technology is out there and reliable. I use pullet shut. No issues at all.

It's amazing what has happened over the last few years. Game cameras are now texting pics vs pulling the chip out of the camera.

Using an app, I can change my thermostat settings st the house, turn lights on and off.

It's gonna be amazing what we see in the next few years.

I am amazed at all of the wonderful technologies out there being discussed. You guys that come up with stuff rock!
But I can't help but wonder if this is just another example of how we are being sucked into a lull of complacency with automation. What I mean to say is that while I love things that run on autopilot, I still really feel the need to connect with nature.
I have no judgement for those who use these automated convienences. But I work in healthcare and see the best equipment fail all the time. Life-saving equipment that fails without the help of human intervention, so I am very biased. I just don't trust the equipment over my oversite.
I never want to get up at 4:00 am to go outside in the freezing cold to water and feed an animal, but it's what I signed up for. I knew that going in, so I do it with love. Love because I chose this lifestyle.
I want to see me animals everyday. I want that fresh air in my face, even if it's frigid. I need to be part of my land, and learn how to be responsible for it's productivity.
I know technology could free up some of my time, but then it would only be benefiting myself. My animals benefit from human interaction, and so do I.
I  fully support those who can use automation to take a break, or simply have more time with the family.
But I feel, there will always be those of us who opt for the old fashioned way of life, I just happen to be one of them.

Well, my wishes for 'automation' is to be able to check if the irrigation is doing what it should, is there a dog out there ripping up things, etc; and temperature/precipitation/wind warnings. Especially in spring and fall here we can get early am snapfreezes and something to warn me that the temperature is dropping at this rate, and/or has hit a certain temperature, means I can sleep until summoned. If I was out of town, whoever I have around that agreed to keep an eye on it... if I get the 'line pressure drop' warning I can tell them or they can get the warning themselves to stop over and see what popped off or broke on the irrigation system. I do want the house and shop lights turned into smartlights so I can turn off everything my spouse leaves on all night without having to run around and do it manually, and he would have no excuse to leave the shop lights on. He could turn them on at the door, at least, and at 3 am when I see them still on and can hear him snoring, turn them off without going over there.

Automation for greenhouse heating, cooling, and venting is where I think the 'automation' is at.  Mostly, I want monitors and feedback so I have to worry less.  I can check on things easier. I can use my time more efficiently that way. And yes, it costs in time and money to install and keep it running. Being able to sleep at 3 am is worth it.

To me the main question is why?
If you rig up something to let the chickens out, won't you still have to walk there anyway to gather the eggs?
And likewise, if the door closing is automated at night, who will check if everybody's in? If any chickens are hurt? Have decided to roost in a tree?

Don't get me wrong, I love the idea of making things easier. That's why dogs are wonderful on the homestead. They know what they have to do, and they do it well. That's why we have mulch instead of timed watering systems. Gravity-based feeders and waterers instead of tossing feed by hand and carrying water in bucket, and goodness knows what other labor-saving devices.

But when you take the human factor out of things, and have automation for the sake of automation, other areas get passed over. Everything needs to be thought of thoroughly, rather than just being attracted to the shiny new stuff.

Automation for greenhouse heating, cooling, and venting is where I think the 'automation' is at.  Mostly, I want monitors and feedback so I have to worry less.  I can check on things easier. I can use my time more efficiently that way. And yes, it costs in time and money to install and keep it running. Being able to sleep at 3 am is worth it.

I think, for the most part, that automation of many farm tasks is unnecessary.....personal attention to details is more important....you can't expect what you don't inspect....

However, in my opinion, automating a greenhouse or a aquaponics system would be a good idea, though:

https://sonyarouje.com/2016/02/17/farm-automation-system-based-on-arduino-and-raspberrypi/

http://www.cnx-software.com/2014/02/27/diy-farm-garden-automation-with-arduino-and-apduino-project/

...and concerning those disappearing Mayans...the newest theory....

http://www.smithsonianmag.com/science-nature/why-did-the-mayan-civilization-collapse-a-new-study-points-to-deforestation-and-climate-change-30863026/

Then there is computer numerical control......

Here is some one doing it.
[youtube]https://www.youtube.com/channel/UCd8t8Dq8oZeAjGDx_87azBw[/youtube]
[youtube]https://www.youtube.com/watch?v=Lfv4eYJkL_Q[/youtube]

Guerric Kendall wrote:To me the main question is why?
If you rig up something to let the chickens out, won't you still have to walk there anyway to gather the eggs?
And likewise, if the door closing is automated at night, who will check if everybody's in? If any chickens are hurt? Have decided to roost in a tree?

Don't get me wrong, I love the idea of making things easier. That's why dogs are wonderful on the homestead. They know what they have to do, and they do it well. That's why we have mulch instead of timed watering systems. Gravity-based feeders and waterers instead of tossing feed by hand and carrying water in bucket, and goodness knows what other labor-saving devices.

But when you take the human factor out of things, and have automation for the sake of automation, other areas get passed over. Everything needs to be thought of thoroughly, rather than just being attracted to the shiny new stuff.

Well said, and this echos much of what went through my head when I saw the farm bot video months ago.

Here is my main issue with automation for living things. Life does not conform to automation well. You wouldn't automate the care of your infant, a lot of people take serious issue with the automation of livestock care (even omnivores), and pets while automated toys give them a short term benefit it does not replace the hands on play with a human or another animal. Life is complex and complicated. Sure you can program in what you think are the requirements for life, but are you sure that is all life needs? Personally I feel plants do better with interaction from the gardener.

The old woo woo of plants liking classical music wasn't that the plants liked classical music, they liked the music that the experimenter liked. Again the woo woo of the polygraph scientist who did all the studies with plants hooked up to polygraphs demonstrated a bonding between plants and their caregivers. Now plenty of people will dismiss this as woo woo, and that is fine that is why I even included the term woo woo so we can just get it out there these things are not mainstream science, though it also does not mean they are wrong either. I accept plants are alive and they are a lot more complex than we likely realize. The sharing of nutrients between relative plants, or same species plants for example. The combat between opposed species, and communication to warn of attacks. The main stream science is showing more and more how complex and interconnected the plant world is. If I am going to utilize those plants in some way, I prefer treating them well and investing my time in their care. I will talk to them and touch them with affection. I will be happy and smile when they do something like produce a seed or fruit. I will laugh if I find something a plant has done that seems silly, like a vine that grew in a weird pattern. Me personally I find this sort of personal engagement with plants in the end produces much better crops. This might be wishful thinking woo woo, but to me I don't care if it is in my mind or real. For me I enjoy spending time with the plants. If nothing else, it makes me feel better just being among the plants.

I noticed that there seems to be an emphasis on "data collection." This is only one side of automation.  Sure....the graphs displayed on the screen are "pretty"....there might even be an alarm generated if something becomes "abnormal."  This situation could be described as being a  "supervisory" level of control.

Management by exception....hmmm....

True automation involves an instrumentation "loop", where sensors take a measurement, an input/output device compares the measurement with what is within a "normal" range, and if it "deviates"....either higher or lower....then the control side of the loop is activated to take corrective action. This continues until the measurement no longer "deviates".

Greenhouses....aquaponics....probably the only places where instrumentation control loops can be fully effective.

R Jay wrote:
Then there is computer numerical control....

This is an awesome device. I would never use it in a million years though. Why?
By the time you finished setting it up, programming parameters, troubleshooting, etc, you would have missed the entire growing season.
How cost feasible are these devices on a larger scale? Who fixes them when they break? How sturdy and weatherproof are they? Can they withstand mother nature?
I think it's great techie innovation at work here, just not a practical solution, when all it really takes is putting your own hands in the dirt and adding some water.
Now, saying that, these ideas are probably great for "big ag". It would make sense for them, but let's remember why we have so many issues with "big ag".
Isn't this how our food system began it's downward spiral? I firmly believe that while many agriculture advances have benefitted the entire world, we managed to screw it up for money.
Agriculture started as a perfect system using nature's cycles. Now, it's a machine with formulas and bottom lines. What happened to the 💓?
I do support permaculture in any way, so if this is part of it, then I guess I should be more supportive. This device would be great work a handicapped person. Or someone who has lost their mobility.
There can always be a benefit from this technology, the problem seems to be when humans get greedy because of the technology.

They key here is "anything that is tedious can and should be automated."  Using automation to take the decision out of the hands of the human is probably unwise.  But using machines to do something that the human might procrastinate because it's a "chore' is probably a good use.

Automation doesn't just mean using computers or electronics, either.  Self-medicating goats can be a form or automation.  Or having a feeder that dispenses food when a heavy enough animal steps on a plate, but not when critters try to get at it.  Or putting your rabbit hutch over your worm bins.  A lot of the permaculture ideas of stacking functions is automation in a way, as in, it automatically happens.

Also, using automation as a backup plan for when you're away or injured seems to make a lot of sense.

My strategy for automating my farm has been to get up in the morning, and automatically do the morning chores. About sunset, I automatically do the evening chores.

I like a thermostatically controlled heater in the greenhouse, and I love the non-electrical window openers.

One of these decades, perhaps I'll finally make a robot that can weed for me!!!

Joseph Lofthouse wrote:
My strategy for automating my farm has been to get up in the morning, and automatically do the morning chores. About sunset, I automatically do the evening chores.

I like a thermostatically controlled heater in the greenhouse, and I love the non-electrical window openers.

One of these decades, perhaps I'll finally make a robot that can weed for me!!!

I have been called roboweeder, by others that watch me bend over and get to business.

Sorry, my production factory was closed down decades ago and I doubt I could have successfully propagated more little roboweeders.

The only real automation I want is monitors to give me feedback (is the irrigation system okay and running or is there a fault, what is the temperature, windspeed, etc, and if there is a cold snap in progress, warning me of the temperature drop). Some stuff to control heating, cooling, and opening and closing vents on the spring propagation greenhouse. The only other one I want is smartlights so I don't have to run across the place turning off what my (suffering) better half leaves on. We are currently having a discussion/war again about Strawberry PI or Audrino, I think the greenhouse deserves Strawberry PI... as it's much more complicated.

The only real automation I want is monitors to give me feedback (is the irrigation system okay and running or is there a fault, what is the temperature, windspeed, etc, and if there is a cold snap in progress, warning me of the temperature drop). Some stuff to control heating, cooling, and opening and closing vents on the spring propagation greenhouse. The only other one I want is smartlights so I don't have to run across the place turning off what my (suffering) better half leaves on. We are currently having a discussion/war again about Strawberry PI or Audrino, I think the greenhouse deserves Strawberry PI... as it's much more complicated...

Unless you need to record data to review for a later date, sudden changes in weather can be forecast by watching a barometer.  For wind direction, a windsock or weather vane can be used.  A weather vane, with the various motifs that it can be cast into, is more desirable {I'm partial to the one that looks like a sailing ship}.

A distributed control system could be set up using a "Pi" as the central controller and Audrino units used as input/output devices at the sensor/control points---should be able to control the irrigation AND the greenhouse systems with a single system on WiFi....something to look into, maybe....

After just writing that, I got to thinking that this is may be the problem with the concept of automation....it is the not the use of computer components; that maybe it is the mindset that the use of instrumentation cultivates.  The change in thinking that it is no longer a greenhouse or irrigation or aquaponics....that it becomes a "system"....that maybe the system can be optimized....parameters for best performance "set in stone",.....or....constant tweaking to push the system into better performance.....

That is OK for a running...say...a 1000-ton per day kraft pulp mill.  Not so great for raising living things.  I do think that as long as that type of thinking is acknowledged and consciously avoided , then this type of automation has a place on the homestead.  

Totally agree. I need the weather info as I chart my seasons so I can roughly predict what will happen every year. Plus some crops I have grown have needed extra protection or more inspection/care if the wind gets to a certain point or comes from a certain direction... temperature, again, is if the temperatures drop to a worrying point or the one night at 2:30 am the temperature started dropping a degree a minute and I did have a warning system set up and it yelled. I was out there yanking steel fenceposts out of the ground and taking cages off and wrapping tomato plants with blankets, towels, and old teeshirts. Out of 35 I lost 2 and 6 more got 'scalded' on the wind side and sort of recovered. That is what I need, the forecast said nothing about the snap being possible and suddenly it hit. The rearing greenhouse it would be nice if the vents opened and closed by themselves in early morning and late evening... water levels in the RGGS system and the limited aquaponics I run, are monitored... is the irrigation system functioning or did I lose line pressure because something popped apart or broke? I might want a small webcam or two, also. Then when the dog goes off I can look and know if it's an arf for the sake of arf, or there's a reason for trying to bark up a lung. We answer our dog, that's their job and that's what we are supposed to do, but it's still nice to know if it's a raccoon first... on what to bring to the party.

I still have plenty to do, take care of, put my hand to. I just want the help to stay on top of it all. In that I think there is a place for 'automation'. I will never be finetuning like a machine; but keeping things together and not leave a big trail ...

It would be valuable to me to know the temperature of the greenhouse without having to walk out and check. Wireless thermometers aren't very expensive, but when I have money, there seems to be something that's higher priority, so I don't get them. I'd want two... One for inside, and one for outside. If I ever get around to burying earth-tubes under the greenhouse, I'd want them to be automated for storing/removing heat at optimal conditions.