Many gardeners discover online resources about the walipini, or pit greenhouse, with hopes of year-round food production, only to learn that they are made for equatorial regions. If, like me, this doesn't put a damper on your romantic notions of year-round fresh greens, you'll probably keep looking and find other solutions, such as gardening indoors or in geodesic domes or heated hoop houses to combat winter chills.
Of course, each option has advantages and disadvantages, including large carbon footprints, inconsistent warmth, weather-dependent energy costs, and initial outlay.
A winter growing space that is all of these things (and more) is what I propose as a solution. Traditional greenhouse with a retractable top for growing in the summer. I should also mention that it's simple to construct, easy to use, and reasonably priced.