Cool Roofs Help You Stay Cool!

A cool roof is one that reflects the sun’s heat and emits absorbed radiation back into the atmosphere. The roof literally stays cooler and reduces the amount of heat transferred to the building below, keeping the building a cooler and more constant temperature. Imagine wearing a white or a black T-shirt on a hot day. By wearing the white T-shirt you will remain cooler than if you wore a black T-shirt because it reflects more sunlight and absorbs less heat. Cool roofs like a white T-shirt, keep the internal temperature of the building cooler.

However, a cool roof need not be white. TAMCO offers many “cool color” products which use darker-colored pigments that are highly reflective in the near infrared (non-visible) portion of the solar spectrum. With “cool color” technologies there are roofs that come in a wide variety of colors and still maintain a high solar reflectance.

Solar Reflective Coatings

A roof is a building’s first line of defense in controlling energy consumption. A solar reflective coating is a roof surface coating that lowers the surface temperatures of the roof dramatically, resulting in greater comfort inside the building and less demand on air conditioning equipment, resulting in lower energy costs. These solar reflective coatings are typically a white roof coating consisting of a polymeric binder blended with pigments and other additives or silver containing asphalt, pigment flakes and pure aluminum resulting in a silver reflective coating. Solar reflecting coatings provide two main benefits: 1) protection of roof membranes, for longer roof life cycles; and 2) reflectivity of solar radiation (amount of solar energy that is reflected away from a surface), for lowering of air conditioning costs.

White Roofs Reflect The Sun’s Heat And Black Roofs Soak It In

That’s the key advantage offered by a white solar reflective roof surface. Testing conducted on a sunny day at 100°F ambient temperature shows that the surface temperature of a roof topped with a black membrane can reach 180°F while a gravel roof can be as hot as 145°F. A roof with a solar reflective coating will reflect the sun’s heat, staying significantly cooler at 90°F, contributing to a cooler indoor environment and reducing peak cooling demand up to 15 percent. As “green” building standards (such as California’s Title 24 requirements) become more prevalent, products that contribute to reduced environmental impact become more necessary.

Solar reflectance isn’t the only property to look for in a roofing material. It should also have a high infrared emittance (the amount of absorbed heat energy that is radiated from a surface) to help the roof shed heat by re-radiation.

Solar reflective coatings can either be applied to the roofing membrane at the factory, such as TAMCO’s Cool Roof line of solar reflective roof membranes, or after the roof is applied to the building. The advantage of a factory pre-coated roof surface is that it allows for a hassle-free, one-step field application. Once the roof system is applied, the job is complete. This one-step installation helps reduce labor costs because there are no costly time delays for application of multiple coats. Applying the roof solar reflective coatings after the roof system is complete is typically accomplished with the use of a roller, brush or with conventional airless spray equipment and the coating dries to a tough, flexible elastic film.

Look for solar reflective membranes and coating products that meet ENERGY STAR® requirements, are rated by the Cool Roof Rating Council, and contribute credits under the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED®) Green Building Rating System™.

Cool Roofs Are Way Cool And Offer Many Sustainability Benefits

A cool roof reflects and emits the sun’s energy as light back to the sky instead of allowing it to enter the building below as heat. In many climate zones, a cool roof can substantially reduce the cooling load of the building, providing several direct benefits to the building owner and occupants:

• increased occupant comfort, especially during hot summer months
• reduced air conditioning use, resulting in energy savings typically of 10-30%, and
• decreased roof maintenance costs due to longer roof life.

In addition to these well known benefits to the building owner, cool roofs benefit the environment and public health in far more ways. As recognition of these benefits has become more widespread, cool roof requirements are appearing in building energy codes and green building programs across the nation.

Climate Change Mitigation

Cool roofs directly reduce green house gas emissions by conserving electricity for air conditioning therefore emitting less CO2 from power plants. Cool roofs also cool the world independently of avoided carbon emissions, simply by reflecting the sun’s energy as light back to the atmosphere, thereby mitigating global warming. A Lawrence Berkeley National Laboratory study found that world-wide reflective roofing will produce a global cooling effect equivalent to offsetting 24 gigatons of CO2 over the lifetime of the roofs. This equates to $600 billion in savings from CO2 emissions reduction.

Urban Heat Island Mitigation

Cities can be 2° to 8°F warmer than surrounding areas due to dark materials, including roofs, which absorb the sun’s light energy as heat during the day and release it at night as heat. This phenomenon removes the opportunity for air to cool down at night and results in higher temperatures being maintained longer. By immediately reflecting solar radiation back into the atmosphere and re-emitting some portion of it as infrared light, cool roofs result in cooler air temperatures for the surrounding urban environment during hot summer months.

Reduced Smog

Cool roofs, through mitigation of the urban heat island effect and reduction of ambient air temperatures, in turn improve air quality. Smog is created by photochemical reactions of air pollutants and these reactions increase at higher temperatures. Therefore, by reducing the air temperature, cool roofs decrease the rate of smog formation.

Public Health Benefits

Lower ambient air temperatures and the subsequent improved air quality also result in a reduction in heat-related and smog-related health issues, including heat stroke and asthma.

Peak Energy Savings And Grid Stability

Because cool roofs reduce air-conditioning use during the day’s hottest periods, the associated energy savings occur when the demand for electricity is at its peak. Therefore, use of cool roofs reduces the stress on the energy grid during hot summer months and helps avoid shortages that can cause blackouts or brownouts. In addition, for building owners that pay for their energy based on the time of use, they save energy when it is at its most expensive – and hence, save more money!

Secondary Energy Benefits

Cool roofs directly reduce the air conditioning use for buildings by reducing heat gain in the building below, but they also indirectly reduce air conditioning use in urban areas by helping lower ambient air temperatures. Therefore, with cooler daytime temperatures, buildings and vehicles use less air conditioning and save additional energy. In turn, this results in a reduction in the CO2 emissions from electricity generating power plants.