Root Cellar  

We built a root cellar under our front porch.  Typically, if you're building new your porch floor is formed out of a concrete slab, you need to put a foundation wall under it anyway, so why not put this area to good use?  Even if you can't deal with (or don’t want to deal with) traditional root cellaring (storing vegetables and fruit), you could use the space as a wine cellar, gun cabinet, place to brew beer, a battery shack for your PV/Wind system or simply more storage.

Locating the root cellar outside the footprint of the home permits the root cellar to maintain cooler temperatures more easily than a cellar located within the house, but even if you have a pre-existing home you may be able to section off a portion of your basement with good results.  Using an exterior grade door (preferably insulated) on your root cellar also helps to maintain proper temperature (both in the root cellar and in the house).  If you are building new, consider putting the root cellar door in the back of an unheated storage room so that the temperature difference is less.  You can use this room to store veggies that require somewhat warmer and drier storage than a root cellar provides, as well as canned goods and whatever else you may need to stash.

Root cellars must have ventilation!  This is one of most common mistakes that people make when designing/installing them.  Proper ventilation moves the ethylene gas that causes spoilage away from the produce, increasing your storage time and the quality of the items in storage.  It also slows down molds and mildews and other fuzzy things that thrive in dark, damp, still environments.  You need the equivalent of a low and high 2” PVC pipe, preferably placed so as to bring in fresh air low on one side and to vent stale air out high on the opposite side.    Don’t skip the vent pipes if you're building new, or at least their penetrations, even if you're not sure you want to use the space for a root cellar.  You can always cap them off and they're much more difficult to add later.

The root cellar should have no "standard" heating or cooling, other than a way to introduce outside air to cool the space. A "finished" floor is optional, and in fact a simple gravel floor is probably your best option for controlling humidity.  Root cellar produce keeps best with high humidity and cool temperatures.  A gravel floor introduces ground moisture and allows you to sprinkle the floor to add moisture when needed.  A single incandescent light (switched on exterior) should provide adequate lighting (unless your room is really huge) and, if for some reason your storage gets too cold, you can always use it to introduce a little heat.

The best resource we have found on root cellars is the book Root Cellaring: Natural Cold Storage of Fruits & Vegetables by Mike and Nancy Bubel.  No matter what your location or how much space you have, the Bubels are likely to have a root cellar option that will work for you.  It contains detailed explanations of how to store vegetables and fruits without electricity with specific temperature and humidity recommendations for each variety.  There are also good photos and diagrams, which I really like.

Links

Yakhchal - Ancient natural refrigerators - who knew?

Keep Your Ice Cream Cold Without Electricity - Nifty article on a home built refrigerator substitute that uses no electricity or fuel.

Build a Basement Root Cellar by Steve Maxwell - Article from Mother Earth News

A Root Cellar for Your Homestead  by Victoria Ries - Some basic information on the cellar, more information on the proper storage of the fruits and veggies themselves.