Solar-Ready…and Moving Forward

This photovoltaic (PV) segment of the roofing industry continues to grow while most others decline. This trend is mainly due to rising energy costs and federal stimulus goals of making our country greener. Combine these factors with state and/or local incentives in many areas of the country and the return on a new roof and PV system investment can be less than ten years in some cases. The Database of State Incentives for Renewables & Efficiency (DSIRE) (www.dsireusa.org) provides a “comprehensive source of information on state, local, utility, and federal incentives and policies that promote renewable energy and energy efficiency.”

As with any major building investment, there are number of considerations that must be addressed with a rooftop PV installation: how will the system be mounted on the roof – with penetrations, ballast, or adhesive? Can the building structure support the additional load? What about local codes and permits? How will the watertight integrity of the roof be ensured during and after installation?

When building owners are interested in solar, the roof system must be addressed. The PV system should be installed in an environment that will not require extensive roof maintenance or replacement for 20 to 30 years because the cost to remove and reinstall PV systems in order to (for example) find a leak source can be expensive. Another consideration: the incremental cost of a new roof will be minimal compared to the cost of the complete new PV system – a smart building owner will take care of both at the same time.

Although PV is an electrical application, roofing is the trade that owns the rooftop, and the majority of solar PV decisions/installations are controlled by roofing contractors. In California (where the use of PV is common) many roofing contractors have created in-house PV departments or have working relationship with solar integrators – the experts that design the systems for each specific building.

Solar technology will continue to show gains, both in efficiency and usage. Currently, it is widely accepted in only a few states because of the financial incentives available in those areas. Incentives will continue to expand to other parts of the country, and if the demand for rooftop PV has not hit your area yet, it will within a few years.

USPS-SolarRooftop-1

The Five E’s of High-Performance Roofing

In the final post of our three part series we take a look at High-Performance Roofing (HPR). HPR systems have five important, closely related attributes that make them cost-effective, leak-proof, reliable, long-lasting, and environmentally friendly.

They are called the “Five E’s,” and they can help building owners make informed roofing choices:

  • Energy: HPR systems help reduce energy consumption and improve the energy efficiency of the building envelope. This is a primary benefit of cool roofing, but reduced energy use also contributes to a better environment.
  • Environment: HPR systems help reduce the overall impact on the external environment while also creating and maintaining a healthy, productive indoor environment. This is the key objective of green or sustainable roofing, which also places a premium on energy efficiency and endurance.
  • 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” or “green” a roof is, it still has to protect the building in all types of weather – a reality that is sometimes neglected in sustainability discussions.
  • Economics: HPR systems must be cost-effective based on both initial cost and, more importantly, the entire life-cycle cost. No roofing system will gain wide acceptance if it does not make economic sense to building owners and managers.
  • Engineering: Smart engineering and design are the great enablers of High-Performance Roofing systems, and all four of the other E’s. Engineering impacts everything from intelligent design and installation to life-cycle costs and long-term performance in all weather conditions.

High-Performance Roofing is a critical part of any High-Performance Building. A HPR system is a protective, performance-enhancing umbrella that protects the High-Performance Building from the elements, enables uninterrupted facility operations, and contributes to the health and productivity of the building occupants. HPR is also one of those rare cases where there does not have to be a tradeoff between “green” and performance, or “green” and cost. The best HPR systems cost less over time because they reduce energy bills, minimize environmental impact, require less maintenance, and keep the weather outside, where it belongs.

Frequently Asked Questions about PVC Roofing Systems: Part 2

Q: How are PVC roofing systems sustainable?

A: More than 26 Life Cycle Assessments (LCAs) confirm that PVC roofing membranes are an outstanding sustainable choice for many reasons:

  1. Energy efficiency.
  2. Mitigation of urban heat islands that cause elevated levels of air pollution.
  3. Waste reduction throughout their life cycle: production, shipment, installation, post-consumer disposal.
  • Only 43 percent of PVC membrane composition is derived from nonrenewable fossil fuel feedstocks, compared with other single-ply and built-up systems that contain a much higher percentage.
  • PCV requires less energy to produce than competitive products.
  • They typically last for 20 to 30 years, reducing the rate of waste flow into landfills.
  • There is virtually no scrap in PVC roof manufacturing or installation.
  • PVC roofs can often be installed directly over old roofs.
  • Many PVC roof manufacturers have post-use recycling programs.
  • PVC roofing membranes are inherently recyclable, and are the only roofing material that can be recycled back into roofing products.
  1. Extremely low contribution to greenhouse gases and hazardous emissions, due to closed-loop manufacturing.
  2. There are at least 10 categories in which white PVC roofing systems can help earn points under the LEED® rating systems.

Q: Why do PVC roofing systems last so long?

A: Among the reasons that PVC roofing systems typically last between 20 and 30 years with very little maintenance are the following:

  1. Reflective properties extend the useful life of the roof substrate materials by reducing the rate of deterioration by as much as 75 percent.
  2. Waterproof characteristics that prevent PVC from rotting, rusting or corroding.
  3. Custom prefabricated systems from some manufacturers that help ensure optimal installation and long-term performance.
  4. Heat-welding properties that create seams that are stronger than the membrane itself while eliminating the need for chemicals, torches or other hazardous installation methods.
  5. Inherent flame resistance strengthened by the addition of flame retardant additives, which facilitates Underwriters Laboratories Class A ratings and Factory Mutual Class 1 ratings.
  6. High resistance to chemicals, grease, and other harmful substances that is common on rooftops.
  7. Simple repair procedures normally accomplished by heat-welded patches or seams.

Setting The Bar For Sustainability

Numerous terms and ideas are used to describe products, processes and techniques that are said to be sustainable or provide high performance. Terms such as “green,” “environmentally-friendly,” “recyclable” and “long life-cycle” attempt to define the concept of sustainability. But what really is sustainability? How do you determine whether a product is truly sustainable or not?

Along with the growth of green design programs such as LEED® and Green Globes, there have been efforts by state and local governments to add sustainability guidelines to building codes. The federal government has indicated it plans to add green design guidelines to its building requirements as well.

Guidelines for many performance criteria are established based on standards. There are ANSI standards for PVC sheet roofing, for measuring emittance and for calculating a solar reflectance index. There are LEED standards that attempt to set the bar for high performance building design and construction. There are standards for wind loads and for material strength and thickness. Sustainability standards already exist for a few building products, but not for single-ply roofing. Without specific, complete standards for single-ply roofing, PVC-based products could become part of a broad category that would not accurately or effectively present the complete green picture for vinyl roofing.

The Vinyl Roofing Division of the Chemical Fabrics and Film Association has undertaken an ambitious effort to develop and obtain approval for an ASTM standard for Sustainable Thermoplastic and Thermoset Single-Ply Membrane Roofing. The process is anticipated to take another 6 – 12 months, but in the end the standard will provide solid guidelines as to what constitutes a sustainable single-ply roofing system. Stay tuned for updates as the project progresses.

The High-Performance Trend

High-Performance Roofing is part of a larger trend toward High-Performance Buildings – a hot topic among builders and managers involved in the construction and renovation of school systems, government buildings, and other facilities. The Department of Energy (DOE) has established a High Performance Building initiative that focuses on promoting energy-efficiency nationwide. DOE defines the benefits and objectives of High-Performance Buildings and “whole-building design” as:

  • Energy consumption reductions of 50 percent or more
  • Reduced maintenance and capital costs
  • Reduced environmental impact
  • Increased occupant comfort and health
  • Increased employee productivity

High-Performance Roofing systems can contribute significantly toward all of these High-Performance Building objectives. As part of a High-Performance Building, an HPR system acts as a vital, performance-enhancing umbrella that protects the facility from the elements, enhances the performance of other building components, enables uninterrupted operations, and contributes to the health and performance of occupants.

A high performance building is a complete system made up of sub-systems including electrical, flooring, HVAC, roofing, doors, windows, insulation and many other components. Achieving high performance requires that all these elements work in harmony. This means that every part of the system must perform its own functions without negatively impacting the performance of any other part of the system. Ideally, at least some of the sub-systems should actually enhance the performance of other sub-systems. High performance buildings not only operate at optimal levels, but they minimize the negative effect on the local environment while maximizing the health and comfort of building occupants. Any weak link will cause sub-optimimal performance for the entire system.

Contrary to some popular myths, HPR systems that are cool and sustainable do not necessarily involve additional costs. In fact, one essential definition of a High-Performance Roofing system is that it reduces life-cycle costs (LCC) significantly without substantial tradeoffs in performance or longevity.

In our final installment we will discuss the Five E’s of High-Performance Roofing.

What We Mean When We Say Green

The term “green roof” has become narrowly defined in recent years to refer to “vegetative roof.” But “green roof” can also mean “sustainable roof” – one that provides long-term environmental benefits that building owners want roofing systems to deliver for their high-performance facilities: high reflectivity; recyclability; able to accommodate photovoltaic systems; able to help facilities obtain LEED credits; etc. This brief video discusses these benefits and more. For additional information about green roofing, visit www.whiteequalsgreen.com.

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What Really Makes a Roof Cool?

Cool roofing and sustainable (or “green”) roofing emerged as separate, but closely related, commercial roofing industry trends about ten years ago. Today, both cool and sustainable roofing continue to gain momentum, and they are driving change in commercial roofing market dynamics, roof system design and manufacture, product innovation, industry initiatives, selection priorities, building codes, and legislation. They are also sparking a considerable degree of discussion, disruption, and controversy due to their ongoing impact on the commercial roofing industry.

The overall objectives of cool and sustainable roofing have become widely accepted as desirable, sometimes mandatory, criteria for the design, manufacture and selection of commercial roofing systems. Cool and sustainable roofing have both been embraced by a host of industry associations and government agencies, many of which are trying to define the “roofs of the future” – including:

As industry groups continue to develop universal definitions and objectives for cool and sustainable roofing, government agencies at the federal, state and local level are implementing more standards, regulations and incentives to encourage or mandate the use of energy-efficient and/or sustainable roofing systems. These actions, combined with simple but powerful economic factors, are creating increased demand for a new class of High-Performance Roofing (HPR) systems that can satisfy traditional performance criteria – such as installed cost, performance and longevity – as well as relatively newer criteria – such as life-cycle costs, energy efficiency, and preservation of the environment.

In our next installment, we will discuss the High-Performance Roofing trend.

Factors To Consider When Purchasing A Roofing System: Environmental Impact

The drive for environmentally-friendly products extends to the commercial construction arena, including roofing systems. In this post, we will discuss some of the energy aspects of roofing: reflectivity, emissivity, and the solar reflectance index.

Environmental Impact – Part B

Rooftop reflectivity has received substantial attention during 2009, perhaps most notably in Energy Secretary Steven Chu’s remarks recommending that the world’s roofs be painted white. The upshot is that a roofing material’s ability to reflect solar energy has environmental implications, including its contribution to (or mitigation of) the urban heat island effect and impact on emerging carbon markets, among others. In fact, a roofing system’s energy efficiency is really determined by a couple of interrelated attributes.

Reflectivity (technically, albedo) is the percentage of solar energy reflected by a surface. The higher the reflectance value, the more solar energy that will be reflected from the surface.

Emissivity is the measure of how effectively a material sheds the heat it has absorbed. Materials with a high emissivity value may absorb energy easily, but they also radiate large amounts of it back into the atmosphere.

Roofing systems that provide both high reflectivity and emissivity are most likely to have a significant impact on a building’s energy cost. Some systems can reduce a building’s energy consumption by up to 40%.

The solar reflectance index (SRI) is a tool that evaluates reflectivity, emissivity, and other factors to determine a roof’s overall ability to reject solar heat. Its calculation is defines by ASTM E 1980-01 and is based on a formula that includes values for solar absorptance, solar flux, emissivity, the Stefan Boltxman constant, and other coefficients.

Standard black (reflectivity 5%, emissivity 90%) has an index of 0, and standard white (reflectivity 80%, emissivity 90%) has an index of 100. Very “hot” materials can actually have negative values and very “cool” materials can have values greater than 100. Materials with the highest SRIs are the coolest choices for roofing.

The Duro-Last Cool Zone® roofing system, a PVC membrane, has initial reflectivity and emissivity measurements of 87.5% and 95%, respectively, and a resulting SRI value of 108.

Here are the SRIs of some other roofing materials as measured by Lawrence Berkeley Labs and the Florida Solar Energy Center:

Roofing System

SRI

Reflectivity

Emissivity

White EPDM

84

69%

87%

Kynar-Coated

Metal, White

82

67%

85%

New, Bare

Galvanized Steel

46

61%

4%

Light Gravel

On BUR

37

34%

90%

White Granular

Surface Bitumen

28

26%

92%

Dark Gravel

9

12%

90%

Black EPDM

-1

6%

86%

Is Roofing Part of Your Energy Management Strategy?

Significant Savings Drive Demand for Cool Roofing

Cool Roofing Options and Choosing the Best Cool Roofing System

There are two primary types of cool roofing products on the market today: (1) reflective paints and coatings; and (2) single-ply roofing systems. Paints and coatings based on either acrylic or elastomeric chemistry can be an effective short-term solution for reducing energy costs, but most facility owners looking for long-term, low-maintenance solutions opt for a complete single-ply roofing system.

Many roofing products are on the market, which can make choosing the right one a challenge. Fortunately, several objective tools are available to help with the process. Choosing a system from the approved list of products in the EPA’s ENERGY STAR® Roof Products Program or from the Cool Roof Rating Council (CRRC) ratings chart is a good way to narrow down the selection process. Products on the ENERGY STAR list undergo rigorous testing before approval to ensure that they meet the established standard for reflectance.

In addition, the ENERGY STAR Roof Products Program has developed an energy savings calculator that projects the potential savings from installing a cool roof compared with alternative “non-cool” systems.

Here is a short list of important factors to consider when selecting a cool roofing system:

  1. Reflectance/emittance performance, both initial and after three years.
  2. Long-term track record of durability and performance.
  3. A good warranty backed by a solid, well-established manufacturer.
  4. Climate and weather extremes in a given location.
  5. Maintenance requirements and ease of repair.

In our next installment we will discuss: Single-Ply Cool Roofing Systems

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Is Roofing Part of Your Energy Management Strategy? Part 2

How Cool Roofing Works

The trend may be new, but mankind has understood for centuries that white or light-colored surfaces are cooler than dark surfaces. Those stunning, ancient, all-white Mediterranean and Middle Eastern cities are not only aesthetically pleasing, they are also surprisingly cool and comfortable even on the hottest days of summer. Economic and environmental pressures have inspired a renewed interest in the heat-reflective properties of white surfaces, and recent research into the dynamics of urban heat islands, or UHIs – the phenomenon where even small cities are typically three to ten degrees warmer than nearby suburbs and countrysides.

The UHI chain of cause and effect is clear: As temperatures increase, more electric power is needed for air conditioning and more fossil fuel is consumed, which leads to higher levels of air pollution. The probability of smog rises five percent for each one-half degree increase in ambient temperature above 70°F.

Meanwhile, Oak Ridge National Laboratory (ORNL) has conducted several related studies to evaluate various materials for solar reflectance and emittance.

  • Reflectance, also known as albedo or reflectivity, is the percentage of solar energy reflected by a surface. The higher the percentage of reflectance, the more heat energy will be reflected from the surface.
  • Emittance, or emissivity, is the percentage of heat energy a material can absorb and then shed in the form of infrared radiation. Materials with low emittance tend to heat up more easily because they collect and trap heat. It is interesting that while many black materials have very low reflectance, they can exhibit very high emittance.

Although there is no industry-wide definition of a cool roof per se, the Environmental Protection Agency’s (EPA) ENTERGY STAR® Roof Products Program has established a minimum standard for products to qualify. The EPA standard requires that low-slope roof products have an initial reflectance of at least 65 percent, and a reflectance of at least 50 percent after three years of weathering. The ENGERGY STAR Program also requires products to carry warranties similar to, or better than, those offered by the same manufacturer for similar non-reflective roof products. ENERGY STAR ratings can be found on their web site, www.energystar.gov.

In our next installment we will discuss: Cool Roofing Options and Choosing the Best Cool Roofing System.