Chrmann, I really don't see anything 'special' with a solar prism greenhouse.. dispite thier "spin" on the shape.. is just a fiberglass gothic arch greenhouse. I see no rason why you cannot place your greenhouse so as it gets shaded during hottest part of day by DECIDEUOS ( dang my poor spelling) trees. get shade in the summer and good sunlight for heat in the winter. So far as how and what to grow, I agree with Nathan. Hit the local library, research oin itnernet, buy books and STUDY

Mike, in my post I said I did not use my lights to 'grow' plants, I said I use them to provide 'short night' response in my photoperiodic plants to postpone their bloom times. For that, I don't need 2K foot candles, I need 20 foot candles. For the purposes of determining the quantity of light your plant is actually getting you can't just spit out the wattage or lumen rating output of a bulb as rated on its package. For instance, a hundred watt, unshielded incandescent bulb, ten foot away from an object will only provide about 1.5 foot candles as measured at that objects surface. That isn't much, is it? So, you can't just say a lamp has X lumens and have that mean much of anything. That's the potential output of the bulb. What you are interested in are the readings at leaf level, measured in lux or light density and that is going to vary greatly depending on how far away the light source is, what design the reflectors are, angles, intensity at various points of the cone of the beam. Yadayadayada. And if you think you are actually doing much trying to supplement the natural light by hanging a few shop lamps from an overhead beam in a greenhouse with a flourescent tube in them............well, it's not going to hurt anything, but it probably has negligible actual benefit to the plant. So, if you are really needing to provide lighting by which a plant will actually grow.........then your supplemental growing light has to be quite close to the plant, or the output has to be considerably higher than you think if mounted from overhead beams. The only way to really tell is to meter it out at various points in a greenhouse. That's why I suggested the poster find out what intensity of illumination leafy veggies really take. If she/he can make do with natural light, it would save a lot of money, and I suspect they'll grow just fine without supplementation. That's why in all but special circumstances where high light levels are absolutely necessary for producing certain plants in a winter setting, most growers do not go the expense of installing supplemental lighting. It's expensive to install and it's expensive to run, unless you are just interested in starting a few seedlings or a very limited collection of conservatory plants.

. sczcasa; Yes, and no. Sounds like a car salesman answer, huh ? . . . The spectrum that the sun puts out is FAR wider than just visible light / photons. This is the part of the spectrum that we see. And, these photons do bounce around; some will hit something AND get absorbed; some will not and will be reflected back out the window. A solar collector is optimized to capture a WIDE portion of the spectrum of the sun's energy . . . visible ( that's why they're usually black/matte finish ), infrared, UV; whatever. Therefore they are good black body absorbers . . and hence collect from a wide portion of the sun's spectrum. They simply re-radiate whatever they collect across the entire spectrum; as heat for the most part. That's why the window material and type can make a big difference in their operation . . . . a high efficiency glass may indeed block some of the spectrum that could be used to generate heat. Stick black and white ( otherwise identical ) buckets full of water out in the sun some day . . . . see which one gets hotter . . . they're both subject to the same type and amount of solar insolation; but ABSORB differing amounts. So, yes; you're right . . . the very same energy that could generate heat with one of these heaters is present in a room without one . . . . but much of it randomly is reflected and therefore ununsed . . . And no; you're wrong . . . by choosing the makeup of a collector instead of relying on random things in a room; allows you to optimize the capture of a wider range of the spectrum to re-radiate as heat. I'm not saying these things are great and work wonderfully . . . I haven't used one. But the principle of their operation is indeed sound; and not a hoax. Bob

Yes, we did it to our 1830s house. The primary reason was the same one you are considering. We went on a major conservation rampage, shortly before utility rates doubled since our home had some major heating issues. Our porch needed replaced and it seemed like the perfect time to install a greenhouse in its stead. Ours is 12 x 24, has a brick floor and is heated with a gas fireplace. We also have a quiet, commercial ventilation fan at its apex to exhaust hot air, and shade it in summertime. Inside the greenhouse are three (what used to be) exterior doors into the house, and a window. We leave them open to the greenhouse year round with no problem. Ours is not directly south facing, so we do not get the larger solar gain in winter, but do get it from the west wall in the afternoon. On cold sunny days, we also get it from overhead. The south and east exposures are against the house, as it sits in an ell shaped area. We get a lot more sun in spring and fall, of course, and it has to get pretty cold outside before the heat comes on. What it does for us, it to provide a windbreak and a dead air space in winter, and that in itself is an excellent insulator. The kitchen stays a lot warmer now because of it, and it's very pleasant in winter, to have a fountain running out there, and ferns hanging outside the kitchen window. Because we are constantly in and out in all seasons, tending the g'houses, gardens and poultry, it also makes a respectable mud room to drop the boots and coats. We sometimes sit out there in winter to read, or have our morning cuppa. When we were doing the energy conservation thing, we got central heat (hot water radiators), new windows and did a lot of caulking and such. It cut our energy consumption for heating almost in half. May I ask what zone you're in? It would make a difference in how practical using a g'house would be, and how you will need to outfit it. If ours isn't shaded in summer, it gets hotter than Hades in there. That is something to consider.