Higher counts of air particulates cause increased surface temperatures. Summer temperatures in cities are up to 7 degrees Fahrenheit warmer than in less populated, surrounding areas. Environmentalists designed cool roofs to minimize overheating in urban areas.

Unlike traditional asphalt shingles, cool roofs reflect sunlight into the atmosphere. They are usually white and made of a sheet covering or reflective tiles. When buildings emit heat away from Earth's surface, they prevent the urban heat island effect and reduce indoor temperatures.

Conventional rooftops can maintain temperatures of 150F in the summer, increasing HVAC emissions and utility costs. Cool roofs may reduce heat absorption by 50F, minimizing adverse environmental and health effects. When urban areas install cool roofs, they can reduce the risk of heatstroke and other temperature-related health conditions.

Some building owners feel resistant to installing cool roofing in colder climates because of their effects on indoor winter temperatures. Fortunately, the technology benefits both hot and cold environments, decreasing ecological degradation and energy costs.

Building Cool Roofs in Hot Climates

Cool roofs effectively support heat reduction efforts, minimizing indoor temperatures in the summertime. The traditional design uses a white coating over a flat or low-sloped rooftop. Environmental engineers and scientists evaluated the conventional technology and developed advancements, supporting a broader spectrum of environments.

White efficiently reflects infrared, which makes up roughly half of the sun's energy. While conventional cool roofs decrease a building's infrared absorption, other colors make their way into the material, increasing indoor temperatures.
Professionals constructed alternative roofing structures using light colors
combined with traditional metal, tile, and asphalt shingles.

Instead of a standard cool roofing material, individuals now evaluate their environment and use the more effective systems to decrease ecological degradation. Constructing buildings based on the local environment is more sustainable than other methods. Individuals can also apply the cool roof construction techniques to colder climates, offering summertime benefits.

Building Cool Roofs in Cool Climates

Even in chillier cities in the Northeast, the heightened level of emissions causes extreme summer heatwaves. Construction professionals began converting conventional rooftops into cool roofs, protecting Earth's surface from temperature-derived degradation. While environmentalists evaluated the benefits of the architectural design, others questioned its efficiency in the winter.

Many believe cool roofs abide by the "winter heating penalty" rule. They consider a roof's impact on winter indoor temperatures based on its summertime effects. The rule says reflecting solar radiation in the winter is counteractive, limiting indoor heat and increasing HVAC emissions.

Though cool roofs may have a minimal impact on winter heating costs, the sun interacts with a building differently in colder seasons. In the winter, solar irradiance decreases by nearly 20 percent to 35 percent compared to the summer. The sun also remains at a lower angle and is out for fewer hours, altering its effects on indoor temperatures.

A team of researchers evaluated the winter heating impacts of a cool roof compared to a conventional black version. They added insulation in the ceilings, creating a consistent barrier in each building. In the winter, both structures experienced equal amounts of heat loss.

The study proved cool roofs are beneficial for both hot and cool climates. They achieve their heat reduction goal in the summer while minimizing winter impacts.

Which Projects Benefit From Cool Roofs?

Cool roofs are excellent choices for many commercial renovations or construction projects because they are best equipped for flat or low-slope roofs. Clients with environmentally-conscious goals benefit from this project, but even more clients may be impressed by the potential energy savings for both building owners and future tenants.

Architects and building professionals can make the case for cool roofing—even in cooler climates—by pointing to the unfortunate effects of urban heat islands and uncontrolled energy costs. Facility managers planning to lease their commercial properties can either pass on energy savings to future tenants or absorb them on their own, depending on their lease terms for operational costs. Building owners have an even more straightforward win for their organization.

As with most energy-efficient choices, building professionals can make both an environmental and business case for cool roofs. Since this technique can succeed in nearly any climate in the U.S., cool roofs are ever more popular additions to new construction and renovation projects.

Installing Cool Roofs in Any Climate

Before installing cool roofs, construction professionals should evaluate local environmental factors and find an effective material composition and color, improving indoor temperature control. After examining the ecological effects, they may explore the roof's condition, determining their conversion method.

If a roof is nearing its expiration or has substantial damage, replacing it with a traditional cool rooftop may benefit residents. Professionals can retrofit new roofs with heat-reflecting materials, minimizing waste and HVAC emissions. Individuals may also add a waterproof layer to both roofing systems, enhancing their longevity and efficiency.

Evelyn Long is the editor-in-chief of Renovated. She covers sustainable building trends for homeowners and construction professionals.