I worked security at an office/shopping development for several years, beginning while it was still under construction. Phase One, a long East-facing 3-story building, had been completed, so they started on construction for the next phase, across the street from Phase One, first building a wooden construction fence around the area.
It turned out some of the second-story windows in Phase One were not quite aligned in the same vertical plane as the third-story windows above them. When the morning sun rose to a certain angle, the reflections from the windows would overlap at a particular spot on the wooden fence. The plastic advertising banners attached to the fence melted, and – while we never had an actual fire break out – the wooden fence was blackened and slightly smoking at the focal point.
After several attempts at kluges to solve the problem, the windows on Phase One finally had to be taken out completely and reinstalled with particular attention to how straight they sat in their frames. The fire hazard was eliminated, although if you were walking along the sidewalk at a particular time of the morning, you’d still experience a sudden surprising burst of considerable warmth.
