Two energy-conscious roof replacements and satellite imaging to detect underground pipe leaks helped a Georgia county win recognition as an environmental steward.

In January 2018, the Atlanta Regional Commission certified Rockdale County as a 2017 Green Community at the silver level, up from bronze. The Green Communities program was the first in the nation seeking to transform a region by promoting sustainability through a certification program for local governments.

Thirteen cities and seven counties have been certified under the program, which encourages local governments to invest in sustainability by conserving water, adding green space, collecting hazardous waste and conserving electricity.

Rockdale County (population 90,000) about 30 miles east of Atlanta operates a 22.1 mgd water treatment plant and five wastewater treatment plants with a combined 8 mgd capacity. The Quigg Wastewater Treatment Facility (6.6 mgd design, 4.6 mgd average) uses a modified activated sludge process followed by filtration before discharge to the Yellow River.

Sustainable measures beyond the cool roofs and satellite imaging include creating an Energy Star strategy and advertising its status as an Energy Star partner to county employees and residents, installing a 1,500-square-foot rain garden that treats about 10 percent of the water from a former manufacturing site, and providing educational materials about glass recycling.

Same price, lower costs

The county installed thermoplastic polyolefin roofs on the chemical building and the belt press building at the Quigg plant. The two roofs total 12,000 square feet. The cost to replace both roofs was $64,500, about what the replacements would have cost with a traditional membrane system.

“Since the buildings are industrial in their focus, we have not performed an in-depth study into the exact amount of energy savings we have realized, but my estimate would be around 8 to 10 percent, based on average savings in Atlanta reported by the U.S. Department of Energy,” says Andrew Hammer, deputy director of facilities and maintenance.

The cool roofs at Quigg are white, but not all cool roofs are. Crystal Jackson, principal planner of sustainability for the natural resources group at the Atlanta Regional Commission, says, “It’s the materials they’re made of that make them more reflective. They are rated by Energy Star, the same organization run by the Department of Energy that rates appliances.”

The advantage for the building, Jackson says, is that a cool roof can reduce energy bills by decreasing air conditioning needs. Keeping the roof temperature lower can also extend roof service life.

Community benefits

Jackson notes that there are community advantages in cool roofs, such as reducing the effect of urban heat islands: “The more cool roofs we have, the cooler our temperatures are going to be overall. The less air conditioning we use in summer because we have cooler roofs, the less electricity needs to be produced, and along with that we have less power plant emissions.”

The commission requires governments that install cool roofs to put up signs about them in order to get credit in the Green Communities program.

The Atlanta Regional Commission encourages more than 70 green measures in energy efficiency, green space, transportation, land use and water efficiency. “Cool roof is one we include in our energy efficiency section because it’s easy for local governments to do as they are replacing roofs,” Jackson says. “It’s really not much more expensive, if at all. It’s just one of those things that you need to know to ask for. Any additional cost would be offset by the lower utility bills and the longer life of the roof.

“It’s just something that makes natural sense. If you are going to have to replace your roof anyway and there is a product out there that can help you lower your energy bills that doesn’t cost any more, they usually go for it.”

Leak detection from space

The switch to satellite imaging for leak detection saved the Water Department significant time and money detecting leaks, says Deirdre Blackard, water quality, compliance, and technical services manager for Rockdale County. The county took part in a pilot project with Hydromax USA/Utilis to participate in the satellite survey.

After the satellite imagery is acquired, the results are overlaid on a map of the water system and then analyzed. The technology tracks the spectrographic signature of chlorinated water to locate subsurface leaks. “It’s a little bit like smoke testing for a sewer system, except performed from outer space,” Blackard says.

The report indicated 452 areas where leaks were suspected, locating them within 165 feet. Hydromax USA/Utilis technicians then field-verified the findings using traditional acoustic methods and found the results were 55 percent accurate. Rockdale County internal crews completed a 10 percent random sample investigation and found that the accuracy rate was actually about 61 percent. A total of 280 leaks were scheduled for repair.

The timesavings and money savings were significant. A complete survey of Rockdale County’s 640 miles of water mains using traditional methods would have taken 6.5 years. The satellite method produced a report on the entire system in less than six months and saved the district more than $1 million on leak detection.

“We can now prioritize leak verifications and then schedule and track repairs,” Blackard says. “We also document the amount of water loss we stop to track the success of our water loss control plan and programs. This goes a long way toward reducing the real water losses we are experiencing within our system.”

Will it pay?

The U.S. Department of Energy defines a cool roof as one that has been designed to reflect more sunlight and absorb less heat than a standard roof.

Cool roofs can be made of various materials and can be installed on any type of building, but climate and the condition of the existing roof must be considered in deciding whether a cool roof makes economic sense.

The DOE reports that in summer, a cool roof could stay more than 50 degrees F cooler than a standard roof, reducing the need for air conditioning. Standard roofs can reach 150 degrees F or more on a sunny summer day.

Studies on cost-effectiveness and sustainability indicate that in hot or warm climates, a cool roof can reduce energy from air conditioning in a single-story building by up to 15 percent. The DOE also credits cool roofs for keeping interior spaces cooler in buildings that are not air conditioned, increasing occupant comfort.

In addition to energy savings, cool roofs can save money by allowing HVAC equipment to be downsized and extending life of the roof. A DOE online estimator, the Roof Savings Calculator (https://rsc.ornl.gov), can help determine the value of converting to a cool roof.

Even in warm climates, the DOE warns that the energy savings from a cool roof would probably not justify the expense of converting an existing roof that is still in good condition.