Staying Cool

Edd McGatha, facilities director of the Children’s Medical Center of Dayton, had a unique opportunity when it came time to select roofing materials for the organization’s new outpatient care center in Springboro, Ohio. He and his team wanted to choose materials that would improve the patient experience at the clinic while laying the groundwork to meet LEED certification.

McGatha and his team examined various roofing materials that would help achieve certification objectives and decided on cool roof materials – highly reflective materials that stay cooler in the summer sun compared to traditional roofs. Cool roofs can also help reduce energy costs, improve occupant comfort, cut maintenance costs, increase the life of the roof and contribute to the reduction of the heat-island effect. This is all said to have been installed by a local superior roofing service, to ensure the job was done properly.

PVC, TPO and Cool-Metal Roofing

McGatha and his team worked with a local Duro-Last representative to choose a white, 40 mil PVC sheet ASTM D4434, Type IV, fabric-reinforced membrane, ideal for flat and low-sloped roofs.

“PVC has been around for awhile,” McGatha says. “Modern PVC materials are shown to have no negative environmental qualities. Half of the materials come from recycled components. It’s a good product and has durability.”

PVC materials aren’t the only cool roof materials available on the market that are ideal for flat and low-sloped roofs. At Kaiser Permanente’s new Modesto Medical Center in Modesto, Calif., building designers opted for Firestone Ultra Ply TPO (thermoplastic polyolefin) .060 membrane.

Rather than following LEED-certification guidance in their selection of roofing materials, the planners used the Green Guide for Health Care – a self-certifying tool for healthy and sustainable building design, construction and operations written specifically for healthcare organizations.

The healthcare provider has installed more than 100 acres of TPO material on rooftops at its various facilities, according to Tom Cooper, national manager of sustainable building design and research with Kaiser.

“It became Kaiser Permanente’s design standard eight years ago,” Cooper says.

Metal roofing materials, where the secret to achieving “coolness” and energy efficiency is in the material’s reflective coatings, can be paint or granular systems.

“There is a misconception that metal isn’t cool, but when we’re talking about cool metal roofs, we’re usually talking about a family of different products like steel, copper, aluminum and zinc and different solar-reflecting coatings on those materials,” says Scott Kriner, president of Green Metal Consulting, who also serves as technical advisor for the Metal Initiative.

Cool metal roofs are ideal for steep-sloped, low-rise buildings with small wall surfaces that are less than four stories, Kriner says.

In addition to the environmental benefits metal offers, it also has aesthetic benefits with color and texture choice for visible steep-sloped roofs. On high-rise buildings, where the roof is not visible, the metal will likely be flat and in a natural finish or painted white. There are now many companies that offer metal roofs as an option for homeowners, such as this Leesburg Roofing Company in Florida.

Above sheathing ventilation installation techniques, where metal panels can be raised slightly off of the deck to create a chimney effect, can boost some of the energy efficiencies of the roofing material. This is something houses with chimneys can achieve naturally, with some help from a maintenance firm.

Cool Roof Maintenance

A cool roof, regardless of materials used, must be kept clean in order to support the material’s ability to reflect solar heat.
Metal roofs can self-clean for the most part, but not entirely. Rainwater runoff on sloped metal roofs can help to remove dirt and debris. Paint coatings and most natural metal surfaces keep mold and mildew away.

“With regard to a metal roof’s maintenance, it is good practice to inspect the roof and remove things that accumulate on the roof, such as tree branches, leaves or debris,” Kriner says. “There will also be a continual need to maintain good flow in gutters, downspouts and drains. It’s also good to check the caulking, sealants and flashing around penetrations.”

Like any other roof, cool roofs can be vulnerable to accidents and foot traffic. Duro-Last’s product literature warns that the roof not be used for storage. Inclement and extreme seasonal weather patterns can also impact maintenance.

“There is thermal movement with metal roofing in extreme heat, but concealed clips that fasten to the support structure allow for unimpeded movement of the metal panels,” Kriner says.

McGatha and his team at Dayton Children’s took precautions against punctures in the roof membrane by adding walk-off mats for technicians who need to access the roof. They also installed ice guards.

Since the roof’s initial installation, facility workers have tweaked the flow of the walk-off mats and added more ice protection.

“You have to design your facility’s roof with sensitivities to your specific geography and climate, but it’s hard to anticipate ice and walking patterns.” McGatha says. “You can’t just [install the roof] and forget about it.”

McGatha says the cost of the PVC cool roof at Dayton Children’s Outpatient Care Center was only slightly more than the cost of a traditional roof. He anticipates a return on investment will come from reduced utility expenses and wear and tear on the roof’s sub-structure.

From Kaiser Permanente’s perspective, installing a TPO cool roof has no impact on first costs, Cooper says. However, the organization has seen a 10 percent savings in energy expenses.

Installation cost estimates can range from $70 to $650 for every 100 square feet of for metal roofs, compared to $110 to $200 for membrane-roof materials, Kriner says. In addition to energy and life cycle cost savings, some states and local municipalities offer cool roof tax rebates and incentives.

Taking Another Direction

Cool roof materials aren’t necessarily always the right choice for every hospital. Facility layout and design may influence the choice of roofing materials. Consulting experts first is never a bad idea. You may even come to the conclusion that asphalt roofing options suit your needs better.

Phoenix Children’s Hospital is currently in the midst of an expansion and chose a highly efficient roofing ballast and insulation, instead of cool roof materials, to keep heat gain at a minimum.

“Cool roofs are typically, if not always, comprised of a high-reflective paint or reflective materials – the idea being that they reflect the sun/heat away from the building,” says Dave Cottle, executive director of planning design and construction for the hospital. “The use of such materials on the lower level roofs of our facility would reflect up into patient rooms and increase the heat gain into the rooms. On the higher roofs, there are safety issues, because it would reflect into the flight path of helicopters trying to land on the helipad.”