Here’s an interesting project by Chris Magwood and crew. They used a steel quonset hut to build a large earth sheltered root cellar in Canada.
“Our 2013 project at Circle Organic farm involved constructing a large, root cellar-style vegetable storage facility attached to the vegetable processing barn. Our research showed us that small subterranean root cellars have a long history, but that the principle has not been applied on a larger scale. Julie and Andrew at Circle Organic want to be able to store a number of different root crops on a scale that would allow them to run their CSA (community shared agriculture) program year-round.
More at Endeavour Centre.org