Here is a neat spin on low-e windows. Normally one picks the kind of Low emittance coatings depending on your local conditions; different types of Low-E coatings have been designed to allow for high solar gain, moderate solar gain, or low solar gain. It's done by sputtering a coating on one side of the glass inside a sealed double glazed unit. (more tech here)
But what if you live in a temperate climate with hot summers and cold winters? You want to keep out the heat in the summer and let it in during winter. How do you get the best of both worlds?
Dr. Heinz Kunert of KSD Fenster in Germany figured it out in 1990, in one of those slap-upside-the head "why didn't I think of that" simple solutions- he put the glazing in a pivot so it can be rotated to reflect the heat out in summer, inwards during winter. Too bad they have the lamest website ever and no distribution that we can see, all the window manufacturers should have a version of this.::Eco-Logical Innovations or ::KSD Fenster , who make them in the Black Forest. via ::Eco-Geek