Winter growboxes

Hi there,

I was late in thinking of how to keep growing through the winter, and am now stuck on which system would fit our needs. They are:
* Maine zone 5a
* small scale, just for 2 people: lettuce, arugula, ta-tsoi?
* indoor growing: vertical three-tiers, each tier approx. 2'x4'
* desire to limit energy inputs

We have an unheated east-facing sunroom that gets about 5 hrs. of diffuse sunlight. Two possibilities?
A. build a polycarbonate box with 3 tiers and front door; reflective rear and side surfaces;
B. build a similar box, though install grow lights and use 1/2" reflective rigid foam insulation on interior surfaces. No polycarbonate.

I'm assuming the additional layer of polycarbonate (Plan A) will result in higher ambient growing temperatures, but I just don't know whether the seedlings would thrive with the generally cold temperatures. The lights would take care of that, but it seems overkill--and expensive--to have a light above the three growing tiers. (Perhaps one light and rotate the crops?)

Anyone with similar experience, or with some helpful perspective?

Thanks!

Craig

Mine is extremely low tech. I am using recycled plastic containers on the shelf of our skylight. So so results, but its partly my fault.  I have to keep switching the boxes between the windows on the two sides of the house for better sun and I tend to forget.

We have lettuce greens in one and planted some sad baby beets in the other.  Those are producing greens very well. First time I have tried anything like this and will try to do a better job in the future since I am getting some results.

Thanks! You've got some advantage with a more southern locale, at least.

Eliot Coleman's books are about growing things all year in Maine. They're a great read and I highly recommend them.

Thanks for the reference!