Because they extend farther into the sky, window panels in tall buildings undergo more exposure to sunlight and heat absorption. Manufacturers and repairers use glass panels that are Low-E coated to enhance their light reflection. So rather than allow heat gain (which drives up your HVAC bills), tall buildings use energy-efficient glass that shines blue or green when you look at them. In addition to bouncing heat off the building’s surface, shiny glass panels also help reduce radiation and boost the performance of your cooling systems.