In addition to the white Thermoplastic PVC and TPO membranes used in many commercial cool roof applications, there is also research in the field of cool asphalt shingles. Asphalt shingles make up the majority of the North American residential roofing market, and consumer preferences for darker colors make creating solar-reflective shingles a particular challenge, causing asphalt shingles to have solar reflectances of only 4%-26%. When these roofs are designed to reflect increased amount of solar radiation, the urban heat island effect can be reduced through the reduced need for cooling costs in the summer. Though a more reflective roof can lead to higher heating costs in the colder months, studies have shown that the increased winter heating costs are still lower than the summer cooling cost savings. To satisfy the consumer demands for darker colors which still reflect significant amounts of sunlight, different materials, coating processes, and pigments are used. Since only 43% of light occurs in the visible light spectrum, reflectance can be improved without affecting color by increasing the reflectance of UV and IR light. High surface roughness can also contribute to the low solar reflectances of asphalt shingles, as these shingles are made of many small approximately spherical granules which have a high surface roughness. To decrease this, other granule materials are being investigated, such as flat rock flakes, which could reduce the reflectance inefficiencies due to surface roughness. Another alternative is to coat the granules using a dual coat process: the outer coating would have the desired color pigment, though it may not be very reflective, while the inner coating is a highly reflective titanium dioxide coating.