The Human eye can see different colours by selective reflection in the visible region, in other words, we see a red colour because the radiation in the red portion of the visible spectrum is reflected; the remaining radiation in the visible range is more or less absorbed. We can not see in the infrared region of the spectrum, so the human eye can not determine what is going on there by sight. But, we can feel the effects of its energy in the form of heat.
Touch your bitumen driveway, climb on a black tiled roof, or place your hand on your black vehicle when it's been out in the sun for a while. It's quite HOT! In fact, some dark coloured roofing and side wall can attain a temperature of 88 degrees Celsius or more. Why? well it's because these materials absorb a large portion of the infrared radiation from the Sun.
Look at the second chart (Figure 2). We show a standard black acrylic paint versus Energy Star® acrylic paint. Notice the difference in the curves. The normal black paint absorbs the radiation across the whole solar spectrum, where Energy Star® black reflects in the invisible Infrared portion. The colour appears black in the visible portion of the spectrum, but reflects in the invisible Infrared portion. This results in significantly less solar energy being absorbed, which means less heat build-up. |