This article appeared in Architectural West July/August 2007.
Clay Tile Can Easily Meet Cool Roof Standards
by Lyla Lawry, Marketing Coordinator, MCA
Clay tile roofs are rapidly growing in popularity, particularly in the western United States and the sun-belt climates. Long recognized for bringing beauty and character to the appearance of a building, certain clay tile roofs offer another valuable feature, they’re “cool roofs.” No longer bound by the limits of color, these clay tile roofs are becoming one of the fastest-growing sectors of the marketplace.
Over 90% of the roofs in the United States are dark-colored. Dark roofs are heated by the summer sun and can raise the summertime cooling demand of buildings. These low-reflectance surfaces may reach temperatures of 150°F to 190°F. According to Dr. Hashem Akbari, who has led several studies at Lawrence Berkeley National Laboratory (LBNL), “The difference between the surface and ambient air temperatures may be as high as 90°F for low-reflecting roofs, while for highly reflective roofs with similar insulative properties (cool roofs), the difference is only about 10°F.” Cool roofs do not absorb radiation, therefore cooling the environment and reducing energy usage. Studies in California and Florida have shown that replacing these dark roofs with reflective “cool roofs” can save residents 20 to 70% in annual energy use.
The energy cost savings of cool roofs are accompanied by the reduction of air pollution. In populated areas, natural vegetation is gradually replaced by buildings and roads, the surfaces of which absorb solar radiation and become extremely hot, which in turn warm the surrounding air. This “heat island” effect causes more demand for air-conditioning, which leads to higher emissions from power plants and increased smog formation. Dr. Akbari’s studies have reported that this increase in air temperature is responsible for as much as 20% of population-weighted smog concentrations in urban areas.
In addition to their solar reflectance, clay tile roofs often have enhanced air circulation compared to other roofing types because ambient air can circulate below as well as above the tile. This enhanced air circulation helps the roof shed solar heat more readily. Similar to a Space Shuttle heat shield, which is made up of thousands of small ceramic tiles, some ceramic clay roof tiles reflect the heat of the sun away from the roof and attic, keeping the living and working areas cooler.
But how do these cool roofs look? While certain European and Middle Eastern cultures have long known the benefits of white residential roofs, North Americans generally consider such a feature unattractive. Although reflective white materials may find acceptance on flat-roofed commercial buildings, U.S. homeowners typically demand non-white roofs for aesthetic reasons.
Maruhachi Ceramics of America (MCA), located in Corona , California , a manufacturer of clay tile roofs earning the Energy Star® label, has solved the problem. No longer is it necessary to sacrifice color for cool (reflective). MCA offers clay tile in 32 colors that reflect solar radiation and emit thermal radiation (reflectivity and emissivity) at a rate that exceeds the requirement in California to qualify as a cool roof. And, when considering blends, the array of colors for these cool roofs is endless. MCA’s beautiful Energy Star clay tiles are widely used in commercial properties, like the Irvine Spectrum Center, and resorts, hotels, restaurants, churches, as well as private residences. Without compromising solar reflectivity, architects, homeowners, and developers can display the colors and blends of clay tile roofs with the modern-day need for energy efficient “cool roofs.” “MCA has some of the highest reflectance available with their roofing tiles,” Dr. Akbari notes. “Energy Star roofing materials must have a minimum of 25% reflectivity that will not decrease below 15% after three years. For Title 24, the California Cool Roof standard is 40%. MCA satisfies those requirements easily.”
According to Bob Hale, sales manager, MCA, “The increasing awareness of energy and environmental issues is leading architects, homeowners, and builders to demand a more ‘environmentally correct’ product. MCA clay tiles are qualified by the U.S. Green Building Counsel’s Leadership in Energy and Environmental Design (LEED) program, which, among other things, promotes integrated, whole-building design practices, and recognizes environmental leadership in the building industry.” In addition, the tiles are extremely durable, reducing the need to reroof, and thereby reducing landfill waste. “More and more architects and builders are becoming aware that, at no additional cost, Energy Star clay roof tiles can help reduce the heat island effect, while at the same time meet the demand for the ever-important designer look. This combination of energy savings and aesthetics can be seen in MCA’s custom color blend commercial projects throughout the United States, including the Bellagio Hotel in Las Vegas, and the Hyatt Regency in Huntington Beach,” says Hale.
With a growing market awareness of the benefits of “cool” roofing, driven in part by utility and green industry promotion and code bodies, and the availability of an array of attractive styles and colors, clay tile roofing is in demand. This market growth isn’t expected to slow down anytime soon. Cool roofs present an important market opportunity that competitive manufacturers and sellers should not miss. From large commercial to small residential facilities, designers, builders, and owners can have it all: beauty, charm, style, and color… all in a cool roof. •••