Re: Walk in cooler in school bus build
Its possible, but not a home project at least for the reefer units. We've done small type walk in space and used commercial truck refrigeration source. This unit has a plug in system that runs off an on board electric motor driven compressor, and also has an onboard engine compressor unit with electronics to switch and control both compressor units. This is standard on reefer trucks, at least in this part of the world. As these units are exposed to a lot of direct sunlight with no other walls or ceilings to protect them, unlike a walkin in a building where the ambient temp is closer to room temp. So we install 5-6 inch insulation minimum here is 4.
Do a lot of research on this as its not a home type diy project for most just starting out. We don't install the refrigeration but do the insulated portion of the unit.
Our units can hold up in summer tropical heat and still maintain sub zero temps suitable for frozen foods and ice cream, so you may be able to get by with less depending on where you're located.