The Rise of Cool and Sustainable Roofing

The Rise of Cool and Sustainable Roofing

Demand is growing for high-performance roof systems that meet standards for performance and longevity while also being energy efficient and sustainably constructed. Drew Ballensky lays out the details of next-generation roofs in Eco-Structure Magazine.

For nearly 10 years, the hottest trends in commercial roofing have been "cool" and "sustainable" roof systems. These concepts have been embraced by a growing number of industry associations and government agencies, and virtually every type of commercial roof system is under pressure to demonstrate it is energy efficient and environmentally friendly.

As cool and sustainable roofing continue to gain wide acceptance, they are driving significant change in the design and manufacture of roof systems, product innovation, marketing strategies, owner and manager selection priorities, and market dynamics. These trends, reinforced by a growing number of revised building codes and legislation, are creating demand for a new class of HPR, or high-performance roof, systems that can satisfy traditional performance criteria, including installed cost, performance and longevity, as well as newer criteria, such as preservation of the environment, energy efficiency and life-cycle costs.

Regulatory Pressures

The energy conservation and environmental benefits of cool roofing have resulted in federal, state and local government initiatives designed to encourage or mandate the use of high-performance reflective roofing materials and systems. The Energy Star Reflective Roof Products Program, led by the U.S. Environmental Protection Agency, Washington, D.C., is perhaps the most visible program, but there are several others.

In 1999, Executive Order 13123 was issued to provide guidance for roof selection of federal buildings. Now known as Federal Acquisition Regulation Case 1999-011, this regulation mandates federal office buildings reduce energy usage 65 percent by 2010. It also requires federal industrial buildings and laboratories to reduce energy consumption 45 percent by 2010. Federal agencies also must use Energy Star products when available, and other material decisions must be based on energy and life-cycle cost analyses.

In April 2005, President Bush signed legislation offering tax deductions to owners of private commercial buildings that exceed Standard 90.1 of the Atlanta-based American Society of Heating, Refrigeration and Air-Conditioning Engineers, which set minimum requirements for energy-efficient building design. Adopted by the federal government in 1994, ASHRAE Standard 90.1 sets the roof solar reflectance minimum for government facilities at 70 percent and the minimum thermal emittance level at 75 percent.

All but a handful of the 50 states have established regulations and/or incentives to encourage cool roofing or energy efficiency in buildings. For instance, the Georgia White Roofing Amendment requires the use of additional insulation for roof systems that do not have reflectance and emittance of 75 percent or higher. In California, Title 24 is a wide-ranging green-construction bill that took effect in October 2005. Title 24 specifies any low-slope roofing project that requires a construction permit must have a minimum initial thermal emittance of 75 percent and a minimum initial solar reflectance of 70 percent as rated by the Cool Roof Rating Council, Oakland, Calif.

Chicago was one of the first cities to change its buildings codes to promote cool roofing. In 2003, the Chicago Energy Code mandated new low-slope roofs have a minimum initial and weathered reflectance of 25 percent. After Dec. 31, 2008, low-slope roofs must meet or exceed Energy Star criteria.

Through green-building legislation that references familiar programs, such as the Washington-based U.S. Green Building Council's LEED and Portland, Ore.-based Green Building Initiative's Green Globes, many states and cities also are considering revisions to their building codes.

The Five E's

Although precise definitions still are evolving, HPR protective umbrellas share five important characteristics that make them energy efficient, environmentally friendly, cost effective, leak proof, reliable and long-lasting. Think of them as the "Five E's."
  • Endurance: HPR systems must meet or exceed traditional performance standards in terms of longevity, all-weather reliability, water absorption, wind and fire resistance, low maintenance and simple repair. No matter how cool a roof is, it still has to protect the building in all types of weather.
  • Economics: HPR systems must be cost effective based on initial cost and, more importantly, life-cycle cost. Roof systems must make economic sense to building owners and managers before they will become widely accepted.
  • Energy: HPR systems help reduce energy consumption and improve the energy efficiency of the building envelope. This is a primary benefit of cool roofing and a critical aspect of sustainability.
  • Environment: HPR systems help reduce the overall impact on the external environment while creating and maintaining a healthy productive indoor environment. This is the primary objective of sustainable roofing, which also focuses on energy efficiency and endurance.
  • Engineering: Smart engineering and design are the great enablers of HPR systems and the other E’s. Engineering impacts everything from intelligent design and installation to life-cycle costs and long-term performance in all weather conditions.

Meeting HPR

There are several key questions to ask roofing contractors and/or manufacturer’s represent- atives to determine whether a roof system is high performance. The following should be asked to ensure your prospective roof system meets each of the five E’s:

Endurance

1. What is the range of durability for this type of roof system?The durability of roof systems varies widely depending on the manufacturer, competence of the roofing contractor, climate and other factors. This is why roofing expert Carl Cash, principal of Simpson Gumpertz & Heger Inc., Waltham, Mass., suggests building owners consider the durability range of various systems -- a better indication of how long the best roof systems in each category can be expected to last. For more information, read Cash’s book, Roofing Failures.

2. In terms of maintenance and repair, how often, how much and how easy? Every year of useful service free of major maintenance and repair work reduces the life-cycle cost of any roof. Be sure to ask about a roof system’s recommended annual maintenance procedures and costs.

3. How long and how good is the warranty? Warranties reveal many strengths and weaknesses. Small print and exclusions can highlight potential problem areas, such as ponding water, consequential damages and repair/replacement procedures in case of failure. Don’t be fooled by the length of a warranty; read the fine print for hidden costs and exclusions.

Economics

1. Is a life-cycle cost analysis available that includes all installation costs, estimated maintenance/repair costs and potential energy savings during the life of the roof? In 2004 a 20-year life-cycle-cost comparison was prepared by independent Midwest roofing contractors; the study was sponsored by Duro-Last Roofing Inc., Saginaw, Mich. It compared the life-cycle costs of a reflective polyvinylchloride single-ply with the averages for a black ethylene propylene diene terpolymer and built-up roof system for a fully warranted, 50,000-square-foot reroof in the Midwest.

Software programs, how-to books and guidelines are available to assist in completing life-cycle cost analyses for commercial roof systems. Building owners also should ask their roofing contractors to provide an analysis for each system under consideration. Many manufacturers currently provide this information.

Energy

1. Does the roof meet criteria set by EPA’s Energy Star Reflective Roof Products Program? Visit www.energystar.gov/index.cfm?c=roof_ prods.pr_roof_products to determine whether a roof system you’re considering is listed. If it isn’t there, the roof material probably does not meet the Energy Star minimum standard that requires low-slope roof products to have an initial reflectance of at least 65 percent and a reflectance of at least 50 percent after three years of weathering. You also can use EPA’s online calculator (roofcalc.cadmusdev.com/) to determine potential energy savings for your building. An energy-efficient building using an HPR system is a step toward mitigating the urban-heat-island effect.

2. Does the roof meet ASHRAE Standard 90.1? If it does, you may be eligible for tax deductions. If it doesn’t, it isn’t an HPR system. ENVIRONMENT 1. Does the roof earn points toward USGBC LEED credits? A building can receive one point toward LEED certification if its roof system meets the standards under Sustainable Sites Credit 7.2 -- Heat Island Effect: Roof. A combination of design characteristics, including roofs, can earn points in several credit categories, including Stormwater Management, Minimum Energy Performance, Renewable Energy and Construction Waste Management.

2. Is a roof tear off required?Certain lightweight HPR systems can be installed -- fully warranted -- directly over the existing roof to reduce installation and disposal costs while slowing the rate of landfill buildup.

3. Is the roofing material recyclable? Oak Ridge National Laboratory, Oak Ridge, Tenn., recently estimated 9 to 10 million tons (8 to 9 million metric tons) of nonrecyclable roofing waste is sent to U.S. landfills every year. Ask whether the roofing manufacturer has a recycling program.

4. Does the roof system help create a comfortable, healthy, productive environment inside buildings?IAQ is an increasingly important issue regarding health and improved productivity of building occupants. Cool, vegetated and, perhaps, solar-integrated HPR systems moderate indoor temperatures even in buildings without air conditioning. Vented roof systems can help reduce moisture and mold while relieving positive air pressure, allowing buildings to "breathe."

Engineering

1. Is this a fully integrated roof system that provides watertight performance while enhancing the performance of other building components? A high-performance building is a complete system that includes electrical, flooring, HVAC, roofing, doors, windows, insulation and other interactive components. Likewise, a high-performance roof is a fully integrated system that protects the building from the elements and actually enhances the performance of other building components, such as thermal insulation and the HVAC system. Check the warranty to ensure the entire roof system is covered.

2. Does the manufacturer use premium components and state-of- the-art manufacturing processes to enhance energy, environmental, endurance and economic performances? Specification of premium materials enhances a wide range of performance criteria, including reflectivity, emittance, ultraviolet radiation resistance, water resistance, fire and wind resistance, tensile strength, thermal expansion and dynamic puncture resistance. Environmental performance is enhanced by incorporating materials that are recyclable and reduce the total embedded energy index and by using closed-loop manufacturing processes that minimize waste and toxic emissions.

3. Is this a custom prefabricated roof system? Prefabricated roof systems designed to fit each roof reduce installation time and labor costs, virtually eliminate roof membrane scrap, and minimize job- site errors by producing seams and other critical components under quality-controlled factory conditions.

The Future Is Now

The demand for cool and sustainable roofing is transforming the commercial roofing market by creating a need for HPR systems that provide optimal functionality with respect to endurance, economics, energy and environment. This trend directly is tied to the growing demand for energy-efficient, environmentally friendly high-performance buildings nationwide. The high-performance future already is here. The eco-structural challenge -- ecological and economical -- is to specify HPR systems and continue improving every aspect of these systems and high-performance buildings.

Drew Ballensky is general manager of Duro-Last Roofing Inc.’s Sigourney, Iowa, plant and spokesman for the Duro-Last Cool Zone High-Performance Roofing system.