Root cellar question

Can you store your root vegetables in a miniature home-made root cellar?

The one we saw on a show was nothing more than a plastic box filled with builders sand. They filled it half way, dampened the sand and put the onions in this case in lines with about 4" between, covered with damp sand 4" and did another layer. They stored this plastic box in their garage.

Does this sound practical? Thanks for advice :)