Thanks for the replies. Due to the orientation of the house and the location of the back patio, I have no choice on the location. Did I mention it will also be right up under three 50' oaks? So clearly light is going to be somewhat of an issue. However i'm prepared for that since I'm already using them in the house. I grow orchids and they are mostly types that grow in fairly deep shade in Africa and Madagascar, so ironically, the north side light might just be perfect. Anyway, I'm really a lot more concerned about aspects of sunrooms having to do with temperature and humidity. I'm afraid that everything I do to both heat and cool it will eat up my humidity. This thing will be used essentially as a greenhouse. I call it a sunroom mainly because it will be attached to the house and (hopefully) very well insulated. I think the reality will end up being that I'll require some type of external humidifier year round in addition to misters/foggers. I may be able to design into it, an opening that can accomadate a small swamp cooler. That may just be an excellent idea? I guess my main confusion comes with what would be the best way to heat it? One or two small electric space heaters might be enough if it is insulated enough. Plus it should get some heat from the rest of the house. But I'm paranoid about losing power and i think i'd prefer something with natural gas. I think in an ideal world I would use a small gas powered hot water tank that feeds an under floor system. Anyway, any more thoughts? thanks!

No insulation in the roof makes changing out the windows a moot point in my opinion. All your heat is going out the top. If you plan on doing anything with the room, you better insulate the top. Closed cell spray foam is your only real solution here given the amount of space for insulation. Baseboard electric is horrid, very inefficient. I had bought one of those free standing baseboard type electric heaters once, I had the idea it would be good because its quiet. I used it for a month and saw a big difference in my electric bill, and stopped using it. What about the room underneath the sunroom? Isnt that cold also or is there insulation between the sunroom and the room below? How much sq ft is the sunroom and what is the current heating in the house?

Thanks, Matt, and maybe I should start another post, but does anyone have experience with swim spas? I have researched one out of Canada that looked really promising - Hydropool Hot Tubs and Swim Spas; self cleaning and looked great but then you dig deeper and check reviews on Facebook and either they are getting bashed or it's really junk. Endless pools don't look that great to me for the cost and all the chemicals. Then there is another one Aquafit Play and that one seems okay and has an ozone water cleaner but doesn't wow me. So, anyone out there with a swim spa to recommend? Now is the time to figure that out as the slab on the sun room would need to be 6 inches high to support a swim spa. Thanks everyone and Happy St. Patty's Day!

Another option is a ceiling hung, 220v circulating heater. Previously, I heated the 10x16 greenhouse with two 1,500 watt portable heaters - with radiant propane as backup. (Other than the south-facing glass roof, it's well insulated.) Northern Tool had several units: originally $249, marked down to $149 only to go on sale for $99 two years ago. I couldn't get to the store quick enough.... The have several 'sizes' or total watts. Each has three wattage settings in addition to a thermostat. Mine is a 7,500 watt unit, but I've only ever used the lowest 3,500 watt setting to maintain temps above 56F.... But yeah, heating the cats and not the space would be cheaper. If you have cats, keep the jugs the litter comes in. These can be filled with water (with a few drops of bleach) and placed in the sun for thermal mass.