There are sometimes aesthetic concerns about cool roofing materials. The materials at this point are bright white, which is often considered unattractive. White roofs are even deemed unacceptable on some flat rooftops where they will not be seen by the majority of people, since there are sometimes building codes restricting what can be seen from surrounding hills or taller buildings. Finally, cool white roofing materials can show dirt and biological growth. Most of these products contain agents to make them self-washing to encourage the action of rainwater to remove dirt particles.
Coatings also contain chemicals to reduce the formation of algae or mildew.
The fear of reduced reflectivity remains, especially in areas of high dust and pollen and low rainfall. Evidence indicates reflectivities are reduced by less than 10 percent. Even with this reduction, cool coatings stay significantly cooler than traditional roofing materials. Cool roofing is not a simplistic concept. The development of products and markets for cool coatings faces significant technical and industrial challenges, as well as market and sociological barriers.