3x3x7 Custom insulated grow box to grow in a near freezing ambient environment

Hi guys, Id like to discuss some configuaration and details of a custom outdoor grow box I would like to design and build very shortly and will post the build pics here.

I am going to grow in my garage from now on, biggest challenege I can think I am going to face is the garage is not heated during the winter, living in Canada that means outdoor ambient temps of freezing and below.

Keeping the plants and there roots at a happy temperature is my goal with this discussion.

I have a metal garden trolley from a garden center on wheels, it has a 3x3 base and is seven feet tall, it comes with three metal shelves that I can change the height of. I would like to add inulated walls to the outside, likely sheets of rigid foam, aswell as seperate a veg and flower chamber, and be able to have it breathe this freezing air somehow.

This is a personal grow so I dont require huge yields, but I do need to keep temps in check to make sure I get any yeild at all.

My thought is that I should stack the two compartments on one another, likely keeping a veg compartment on the bottom, with the bloom chamber above so I can run the veg light 24/7 and use the heat from that light and compartment, to keep the flower chamber happy when those lights are off 12/12.

With a max height of 7', I think flowerring may be difficult if I try and grow as big of plants as Im used to.

I already own a 600 digital MH/HPS system with a cool hood and I also have 3 100W samsung led quantum boards that I believe are 3000k and could be used for either compartment.

Just looking for ideas and brainstorming materials and methods I should take into consideration, I am curious as to how thick of insulated walls is recomended for this temperature, I would love to line the unit with 3" thick rigid foam, but I fell the air intake sucking in the freezing cold air kind of kills the whole point of the insulation.

Im very handy when it comes to fabrication, so anything custom I will not shy from, just not sure how to configure this to work in my environment with such cold winters and regular 80 degree summers

Thanks and cheers

No cold climate growers ??

One little thought... If you setup two flowering chambers next to each other and ran them on a flip, the heat from the light thats on could keep the other tent warm provided you circulate the air back and forth between them while also ventilating them as required to CO2 / humidity.

The real problem is when you are trying to keep the RH% down and it requires so much ventilation that temps drop regardless of one light always being on.

Thats just something to consider when you are planning your setup.

Running autos in the winter and keep the light on 24/7 is the easiest option. Id go with ac infinity fan that way you have temp control built into it. The only real issue I see if do the way I said is that the intake air when fan does kick on gonna be super cold possibly make your pots cold if your intake is at bottom. I guess could put some insulation on the pots to keep em warm.

If you vent the boxes directly into the garage you will get ice on your walls, mold in the spring.

If you vent the air out of the garage, the pipe with act as a dehumidifier and collect a lot of condensation . You will need to insulate them , and make a water trap .
Like a dirt trap on the gas lines .

I like the idea of running autos so you can keep the lights on, this will make things easier.

Or you could go a little bigger n use the grow to heat the garage.
Have the spaces venting into the garage, with a big dehumidifier to remove the moisture , then have a ventilation setup to control the heat of the garage.
In the summer change the piping for the air to blow straight out.

Really slick when it’s dialled in.

Autos
Below info taken from elsewhere.

Foylon:
A more durable version of mylar, made of spun polyester fabric and reinforced with foil laminate. Foylon is resistant to most solutions, won't tear or fade, and can be wiped or washed clean.

A great solution for growers who are interested in long term use, and though it may be slightly more expensive than mylar, its durability will more than make up for its cost. It has the ability to reflect about 95% of the light and approximately 85% of the heat energy, so a good ventilation system should be used in conjunction with folyon.

A recommended method to attach Foylon to the walls would be using Velcro, as it makes taking it down for cleaning much easier nd reduces the risk of tearing, creasing or bending it. If this is used for your walls, making sure you get it flush with the wall with no pockets of air between it and the wall to prevent hotspots.

The problem I see on top of everything thats been mentioned is that you’re going to want to open the box pretty regularly for watering and plant maintenance. Not sure how to solve that without building in an insulated “lung” room to temper that air and allow access. Is it an attached garage? If so, you could duct the inlet air from the house and exhaust outside.