Edit: I saw someone else building a cabin with similar windows recently. They are double pane, they are just some sort of frameless unit, held together by the strip of black material around the edge. Whether they work probably comes down to how well the installer seals around the edge of the window.
And while the sliding glass doors look like they are single paned, look at the quadruple reflection. Isn't that usually caused by multiple sheets of glass in close proximity?
The external framing is also 2x6, so someone was thinking about insulation. I think it's just that after declaring victory on a well insulated house they then decided to heat the outdoors anyway by directly heating things that are out of doors.
Yes, I'm sure those are at least double pane. Modern windows (especially high end) can be both energy efficient and nice looking. Same goes for their concrete walls--its quite likely that they have insulation in wall cavities or embedded directly in the concrete itself. That being said--I'm sure it still costs a pretty penny to heat in the winter. Its just probably not as bad as you might think.
I knew a person who tried to put in triple-glaze, in New Westminster, BC, and it took a special lien on the property along with special approval from the Province because they weren't allowed by the building codes at the time.
