Roof Algae increases the temperature of the roof and attic.
Here is a segmented roof with various material and colors
This is a thermal image of the segmented roof. Notice the blue area (window) at the far left. Look above there at the snowy white area. That is roof algae! Look at the other picture and you can see. White is hottest and blue is coolest. Compare with Blue squares (white roofing material) on roof and White Squares (Darker roofing material).
This is the temperature in the attic space for each roof segment.