White or light-colored ceilings reflect the sun's heat rays, keeping the attic and the rooms below cool when it's hot. As a result, the building's cooling load decreases, helping home and business owners stay comfortable and save money on their energy bills. A ceiling that absorbs heat is usually black or is located on the darker side of the color spectrum. For a cold roof, one that deflects UV radiation and discourages heat retention, go in the opposite direction of the white spectrum.
White roofing products stay cooler in the sun and reflect between 60 and 90% of sunlight. However, since approximately half of the sunlight comes as invisible “near infrared” radiation, we can increase the solar reflectance of dark materials by using special pigments (colorants) that preferentially reflect this invisible light. These “cold-colored” products usually reflect between 30 and 60% of sunlight, remaining cooler than conventional colored products (although not as cold as white). Other factors, such as roof material, insulation, and the integrity and age of the roof, come into play.
However, in very hot climates (Florida, Texas, Arizona), the color of the roof definitely affects the cooling load of a home. The study found that in most of the locations analyzed, the temperature of the roof coating below the black shingles was 10 to 15 degrees F. In cold climates, roofs can accumulate moisture through condensation, and cold roofs may be more susceptible to accumulating moisture than dark roofs on the roof design. Metal roofing is easy to find in black and white colors, and may be the future of roofing due to the declining cost of metal as a material.
The amount of energy you'll save depends on several factors, such as the climate and environment of your home, the degree of insulation of the entire roof, the type of roof you have, and the efficiency of your heating and cooling system. Andre Desjarlais, William Miller and their associates have installed representative refrigerated roofing materials at Oak Ridge roofing testing facilities. Metal roofs come in a variety of colors, so you should be able to find the best roof color for your metal house. You'll also find that metal roofs last more than 70 years, while asphalt roofs MUST be replaced every 15 to 20 years.
Tiled roofs are a growing preference in more expensive homes in western and southern states. As a result, in northern areas, black roofs or “warm roofs” are the best roof color in terms of cost-effectiveness and environmental friendliness. This website provides unbiased articles on many common roofing materials, installations, inspections, defects, repairs and products. They agreed that the color of the roof alone has a minor effect on the overall energy balance of a well-insulated home in their area (Iowa), in winter or summer.
Green roofs are “inverted roofs”, meaning that the waterproofing membrane is located beneath plants and most roof components. Metal roofs with vertical seams are formed by joining metal panels with raised vertical joints; joined panels cover the roof.