Patti: You are a long ways north so in summer will get a good morning and afternoon sun thru the east and west walls. At most I'd insulate the north wall. If it is insulated and reflective then it will add more light than it loses. I like the corrugated polycarbonate but if you plan to heat in winter consider the twin wall polycarbonate. Both come in types that diffuse the light, a plus IMO. Something like Solar Soft 85, or maybe 90, would be my first choice if building another greenhouse in an area with low heating cost. If heating costs are high the same type material in twin wall. Here is a link that might be useful: Solarsoft 90

It can get real involved, and like yourself, we are looking for answers. Some kinda design where the glazing can be moved according to the seasons, or the glazing being able to be blocked more in the warm months and opened more to the sun in the winter. I can see getting a greenhouse independent of mechanical heating/cooling being more of a design challenge than home builds and pretty involved. Keep in mind in the mining days, air shafts were desinged in below ground mining not only to keep fresh air in, but to help keep the inside temperature between 68-72 degrees. This was done on a local gold mine here where we currently live in the mojave desert by miners in the late 1800's. Non computer aided, uneducated miners who came up with ways of working with the earth without electricity or fossil fuels who lived in cabins built into the earth where they stayed quite comfortable all year round. Plants need light though and that's the difference. We are planning on the greenhouse for use when we move up to the sierra nevadas @ 4500 ft elevation. Gets pretty warm in the summer months, but keeping the greenhouse warm will be the challenge opposite of your concern. I guess we need to keep a researchin' and doing our homework. My wife and I can't get too crazy financially with the project,( I can see where it could), so hopefully some old fashioned, low cost ingenuity will kick in, like the old miners days,( except we have the internet with these cool people/forums)! I'll post some more references as we find them, books, websites, etc.

I put a link below that should help you do calculations. You'll need the surface area of each wall and the roof, then plug in the R-value of each wall's insulation. Estimate the outside temperature, and the calculator will tell you the BTUs required to keep the structure at whatever temperature you choose. Be prepared to be let down :( Any clear building material that makes a good greenhouse will also have a low r-value. The most expensive double-pane glass is only R2, and I think all the poly coverings come in less than that. BUT if you had shutters with R12 fiberglass in them that you could open and close, and a small electric heater, I think you'd do fine. Part of the problem with passive ideas is the weather, especially in the winter the sun likes to not come out for a week or two at a time, and some of those days the high is below freezing. With no sun, the water barrels don't heat up like they should. When they turn into chunks of ice, they become a cool sink, and not a hot sink. If it gets cold enough, mass can work against you, instead of for you. Here is a link that might be useful: heat loss calculator

Morgan, I do not mind hopping over to this one to give you additional advice. : ) I am going to give you a heads-up: the further back you go in time, the more difficult it will be to build an exact replica. But, based on experience, I will not tell you that it is impossible because it truly is not. It will just require time, work, and money. Whenever I speak of my project, I like to provide a disclaimer about my involvement. We sought an architect after I researched (extensively), brainstormed, and created schematics for our project. My partner was okay with me taking the reins because of the wealth of knowledge (from design to code) that I had accumulated in regards to the project. Due to our lack of professional experience, I was adamant about getting an architect on board once I knew exactly what it was that we were wanting to create. We sought out architects classical backgrounds--one with notoriety and the other, less renown. The first offered to take my work and create plans. . .the second was willing to jump in and work off of what I had created. We choose the second one for the collaborative experience, and he still has an active role in our project. Anyway, I would recommend that you and your partner sit down and try to come up with a budget, the degree in which you want to replicate a historical home, and how much input you want to contribute to its design. You will need to decide if you want to give the architect or designer unlimited creative freedom, which could be fun to see what they come up with on their own. Or, you can decide if there are any non-negotiable design elements that must be present in your project. But, before you begin, you must do a bit of home work to find out what it is that you truly envision for your project. Like many others who have gone this route, I have accumulated quite a book collection about historical architecture and pattern books. Of those, the two books that I found most helpful in the beginning of our project were: A Field Guide to American Houses (this one because it included all of the American architectural styles in one easy to read text) andGet Your House Right (it provides information for lay persons who are interested in learning more about classical architecture).