I live in Minnesota. I want to build an indoor root cellar in the basement. I will insulate and vapor barrier a small room in the northeast corner of a walkout basement. My initial plan was to put a wire-mesh covered PVC pipe straight out the side of the house with a mechanical valve to pipe in free cold air throughout late fall, winter, and early spring. All the advice I have been given is to automate this and use a heat pump instead to maintain the approximately 40 degrees required. The other issue is how to keep the humidity at 85-90%. The commercial humidifiers I have found have a maximum of about 45%. Has anyone built indoor root cellars like this and what advice do you have?