I am building a 125 sq.ft. greenhouse connected to my house. The main object is to grow orchids (mainly phals & cattleyas). I live in Norway, near the coast, where yearly temperatures range from about 15-80 F. We have a minimum of 5 hours daylight in winter (no sunlight on the house) and 18 hours daylight in summer (16 hours of sunlight on the house). My question is: what kind of glass should I use in the greenhouse? The main object must be to maintain insulation. Indoor lights will of course, be needed, but at the same time, it is important to allow the greatest visible light transmittance. Double pane/argon gas-filled glass is probably good enough to maintain heat in winter. But what about multi-coated Low-E glass? Any help would be appreciated.