Window Types & Frame Performance

Windows are the weakest thermal link in most facades. A wall might achieve 0.2 W/m²K while the glazing beside it struggles to reach 1.0, so a large area of glass can dominate a building's fabric loss even when the walls are excellent. Understanding what makes one window perform far better than another, and why the frame matters as much as the glass, is essential to controlling both heat loss and solar gain. This lesson covers the glazing generations, the whole-window U-value, and the frame and spacer choices that decide real performance.