Living in the Pacific North West. Rain wind lots of trees. If it not raining in the fall winter or spring it is still cool and wet for over have of the year. We are plagued with roof moss and black mold growth. Then having to use chemicals to remove the problem over and over. Then there is the high winds coming off the Puget Sound lifting and ripping off a lot of asphalt shingle roofs. In the fall trees leaves and needles just stick to asphalt shingle roofs like glue. Making the growth problem worse. I wanted a black color roof and no more moss and black mold growth. The other thing I did not want was to replace my roof again. First I so blown away how a Black roof has so little heat coming in. WOW that's real nice. It looks so much better than my I was expecting. Yes a Class 4 approved EnergyStar UL2218 Interlock roofing is the only way to go.
Now update April 2016. Starting back in late March. 2016 I notice yellowing starting to happen on my roof. Only to find out it was pollen and to my surprise it did not just come off. On a small roof on the side of my home I tried removing it with a hose and nothing happened. I tired spray soap I used on my kitchen counter that did not work. I then tried a heavy dish soap and water it di make it lose but you still need to use elbow grease to get it off. That not something you can do. I tried calling and emailing and got one call back only to want a picture with no follow up after i sent an email with the picture they requested. So if you have pollen in your area this may not be the product you are looking for. The leaves etc stay off but the pollen sticks as soon as it rains.