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Cool Path to Energy-Saving Opportunities
The best facility managers are always looking for ways to save energy in their institutional and commercial buildings. More than ever, many are starting to look straight up.
Roofs can save buildings large amounts of energy. The cool roofing market is expected to reach $11.8 billion by 2028, according to Exactitude Consultancy, a market research company, as facilities strive to adopt more environmentally friendly, renewable and sustainable roof systems. According to roofing manufacturers, building executives and facility managers need to be knowledgeable about the latest trends in order to achieve those goals.
“Kettles that produce asphalt and coal tar fumes have been minimized and replaced with cold-process materials,” says Kathleen Terlecky, senior roof design manager at Simon Roofing. “In addition, low volatile organic compound (VOC)-emitting products that are more friendly to the environment have become more popular, and are now a requirement in many states.”
For Terlecky, energy efficiency is a fundamental part of building design and construction as it can result in cost savings for years to come. Increasing energy efficiency after a building has been built is more costly to all parties involved. The days when heating and cooling costs were a relatively insignificant line item on a building owner’s budget are long gone, suggests Emma Nealy, marketing manager for Versico Roofing Systems. Oil prices remain high and unstable.
“Natural gas and coal prices are also on the rise,” Nealy says. “All of these increases and instability have led to higher heating and cooling costs, and property owners are doing all they can to keep them in check through the use of energy-efficient building materials.”
Reflect and absorb
Cool roofs are designed to reflect more sunlight and absorb less solar energy than a dark-colored roof, which means they will transfer less heat to the building space beneath the roof.
“The building then remains cooler, and requires less energy to keep the space cool,” Terlecky says.
Cool roofs are recommended for use in the climate zones located in southern climates, where the number of average cooling days is greater than heating days.
“Much like reflective (cool) roofs, a dark-colored roof will absorb much of the heat from the sun and transfer that heat to the building interior,” says Terlecky. “This is more energy efficient in climate zones located north of the Mason-Dixon line, where they typically have more heating days than cooling days.”
In order to save energy and cut costs, a roofing system should not only consider utilizing a cool roof or dark roof, but should also meet the thermal resistance for the climate zone. A new roof would include insulation rated with a thermal-resistance value that would eliminate the amount of heating or cooling that could escape from the building through that roof.
“This thermal resistance is called the R-Value,” Terlecky says. “Per the NRCA (National Roofing Contractors Association), the primary function of insulation is to provide thermal resistance. Heat is a form of energy, and energy can be measured using a British Thermal Unit (Btu).”
As heat flows from warmer to cooler areas, a significant amount of energy can leave a building through an inadequately insulated roof assembly in winter, and enter through an inadequately insulated roof assembly in summer. A conditioned building with an inadequately insulated roof assembly therefore requires additional expenditure of energy to compensate for the inadequately controlled heat flow.
“(Cool roofs are) one of the biggest roofing trends, and are quite literally shifting the industry,” says Kristin M. Westover, technical manager, Specialty Installations at GAF. “There is a wide range of technologies to support cool roofing, including single ply, asphaltic and coating systems.”
Ultimately, the cost savings potential is influenced by a number of factors, including climate zone, utility rates, insulation levels, HVAC equipment and more. “Budgeting for the maintenance of your roof can vary anywhere from an average of five cents to eight cents per square foot,” says Westover.
Westover explains that increasing roof reflectivity through coatings is a big opportunity for building owners as it can reduce energy and save money. A cool roof reflects the sun’s rays, unlike a dark roof, which absorbs them and transfers heat to the building below. While a sunlight-absorbing black roof can reach up to 190 degrees in the summer, a reflective roof's temperature can be as much as 55 degrees lower.
“Extreme heat is becoming a serious threat for more communities, and local governments and businesses are trying to find ways to beat the heat while avoiding skyrocketing air conditioning costs,” Westover says. “This past summer, more than 100 million Americans were under an extreme heat advisory in July alone. Cool roof coatings are a cost-effective method that works in tandem with other energy efficiency strategies to help cool buildings.”
Managers should be thinking about how cool roofs can become part of a property or community-wide cooling strategy to reduce heat islands.
“Cool roof coatings combined with solar-reflective pavement coatings, applied to streets, parking lots, and other paved areas will collectively reduce heat islands rather than focusing on just one type of surface,” Westover says.
Out of sight
Too many managers overlook the energy savings they could acquire from their roofs, says Brian Blaquiere, marketing communications director for Sika Corporation.
“I absolutely think that one of those things about roofs is that they’re out of sight, out of mind,” he says. “It’s way up there and you’re not thinking about it, but are instead looking at all the things in front of you — LED light bulbs or recycling or whatever you do to be sustainable. I think the roof just happens to be one of those things that isn’t in anyone’s sight, so they don’t necessarily think of it being a way to also reduce overall costs.”
Oftentimes managers view roofs as an easy way to cut costs, but it’s also the first line of defense from the elements, whether it’s rain, heat or sun.
How much energy a cool roof can save is depends on several factors.
“It’s very dependent on where that building is,” Blaquiere says. “It depends on what part of the country the roof is in, whether it’s a low-rise or a high-rise, whether it gets full sun or sun only in the afternoons, stuff like that. There are a lot of factors that play into how much reduction in energy a cool roof can provide.”
The results also depend on how much insulation is in place.
“It’s not just the white roofing membrane in general,” says Blaquiere. “It is also, did they go with a white energy-smart roof or did they go with a grey or tan, or something like that? It’s very subjective.”
Choosing a light-colored roof to reflect the ultraviolet rays and not retain any of the sun’s heat is one of the easier options, Blaquiere suggests. Managers can also utilize their roofs by putting solar arrays on it.
In order to maximize sustainability, some building managers make sure that the membrane they are opting for includes some sort of recycled content. That way “you know that some other product is not going into a landfill,” Blaquiere says. “Some manufacturers will actually have a roof take-back program, where they will recycle an old roof and recycle a percentage of it back into new roofs so that the roof itself is never going into a landfill, it’s just going into new products for the future.”
Howard Riell is a freelance writer based in Henderson, Nevada.