War of the Worlds – The Exploding Sun – Part 2

In my previous post we discussed the most common type of solar module utilized today, crystalline silicon panels, which are encapsulated in glass. Another type of rooftop power generation that produces electric energy is Concentrated Solar Power, or CSP. CSP uses lenses or mirrors to concentrate solar thermal energy onto a small area such as a tower. Typically, the mirrors are positioned on the roof to reflect sunlight to the tower mounted on the ground at one end of the building. The tower houses an engine (usually steam), to drive an electric generator.

CSP requires very clear skies to work most effectively, and steam generation requires a fair amount of water which can be an issue in hot, dry climates. Compared to PV, more maintenance may be necessary due to the moving parts in trackers and generators. But focusing the sun in this way also has several advantages.

First, less space is required for the collection units; so less land or rooftop space is required. The cost per watt for CSP is currently par with PV, but has the potential to be half that of PV. CSP steam generators produce AC power so they can integrate directly into existing infrastructure without power inverters. With natural gas back-up or molten salt heat storage systems, CSP has the potential to operate continuously in the event of extended periods of cloudiness or shading of part of the array. CSP is projected to have a larger share of solar power generation within 10 to 15 years due to its efficiencies and potential reduction in cost (and by extension – the ability to generate power more cost effectively) due to technological advancements.

War of the Worlds – The Exploding Sun – Part 1


The invasion Orson Wells described so vividly on the radio October 30, 1938, was only sensational because of its time and place in history. What did Wells know about future events that we don’t know? Maybe he foresaw last year’s supernova or exploding star (it was best seen between the big and little dippers September 7-9, 2011), or the growth of solar power generation (photovoltaics = PV) or the implosion of Solyndra. Maybe he foresaw the green movement (little “green” men).

Now that I’ve got your attention, what does this have to do with today’s topic? Other than to introduce a discussion on the power of the sun, not much. Over the next two posts I will discuss photovoltaics (PV), a.k.a. solar power, its history, and the types available.

The most common type of solar module utilized today, crystalline silicon panels, are encapsulated in glass. They make up about 95% of all PV systems installed. Monocrystalline cells invented by Bell Labs in 1954 were cut as wafers from specially grown cylindrical silicon crystals. They are still among the most efficient PV systems, but they have poor tolerance for low light, are fragile and, very expensive, and require very heavy frames for rooftop mounting.

Polycrystalline cells are made from multiple sources and are not as dependent on perfect crystal growth. They are less expensive than monocrystallines, extremely fragile, and less efficient at converting sunlight to electricity.

While some crystalline manufacturers claim higher levels, typical silicone-based PVs have power production between 12 and 18 watts per square foot and operate with 14-20% efficiency. High temperature and shade reduce their output.

Thin-film PV systems don’t use crystalline silicon, but very thin layers of materials such as amorphous silicon, a mixture of copper-indium-gallium-diselenide (CIGS), or cadmium telluride. They can be flexible or rigid and can be adhered to a roof covering or rigid material.

First generation thin-films are mounted on a glass substrate and are relatively inexpensive to produce, but they are about 50% less efficient than monocrystallines. A heavy support frame is required and there have been issues with longevity and durability.

Second generation thin-films are mounted on a flexible substrate. They also do not require crystalline silicon and are easier to manufacture than first generation thin-films at the same cost. There is no requirement for special framing or support structures because they are much lighter than other PV systems. These thin-films are rugged and can often be integrated with modern roofing membranes after they are installed.

Because thin-films are typically surface-mounted, heat gain is an issue and these systems can compromise the benefits of reflective roof systems. Thin-film systems have power production of 5 to 10 watts per square foot and operate with 6-12% efficiency. Compared to crystalline silicon systems, thin-films are more effective in low light situations and are less affected by high temperatures.

In the concluding post I will introduce another type of rooftop power generation that produces electricity from the sun: Concentrated Solar Power, or CSP.

The Future of Roofing

Gone are the times that roofing systems were only a simple part of a building. Roofing systems are increasingly trending toward saving money and energy, and providing other environmental benefits. And this trend should continue.

White is the New Green

While in London in 2009, President Obama’s Energy Secretary Steven Chu, told his former colleagues at the Lawrence Berkeley National Laboratory that painting roofs white to reflect sunlight can make a huge difference to global warming.

Energy Secretary Steven Chu

“There’s a friend of mine, a colleague of mine, Art Rosenfeld, who’s pushing very hard for a geo-engineering we all believe will be completely benign, and that’s when you have a flat-top roof building, make it white. “Now, you smile, but he’s done a calculation, and if you take all the buildings and make their roofs white and if you make the pavement more of a concrete type of color rather than a black type of color, and you do this uniformly . . . it’s the equivalent of reducing the carbon emissions due to all the cars on the road for 11 years.”

Continue reading The Future of Roofing

Why Photovoltaic? Why Now?

Photovoltaic (PV) systems have been around for a while now, but the growth of rooftop PV installations has increased dramatically over the past few years. What is causing this surge?

There are many reasons PV systems make sense now and for the future. Energy costs will continue to escalate, and supply will continue to be chased by demand. Expanding the use of renewable energy sources such as PV can help meet some of the demand and relieve some of the cost pressures on electricity.

Rooftops are a good place to locate PV systems because they are typically little used and are free from obstructions that can hamper PV performance. Utilizing rooftops can also reduce land use, making it available for other purposes, or simply as green space.

PV is a clean, unobtrusive energy source, meaning that it does not pollute while it produces energy; eliminating the environmental issues associated with many other forms of electricity generation. The question arises as to whether the net benefits from PV electrical generation outweigh the monetary and environmental costs associated with production, installation, and disposal of a PV system. That analysis has not been done, but it could prove interesting.

Incentives from federal, state, and local governments and from utility companies can ease the financial burden of an investment in PV, plus encourage its introduction and the development of more cost competitive PV technologies. A good source of information on incentives is the Database of State Incentives for Renewables and Efficiency at www.dsireusa.org.

Increased use of PV can help reduce some dependence on foreign sources of fuel, leading to less potential for hardship due to supply disruptions.


While improving energy efficiency in buildings is essential (by way of reflective coatings, better insulation, high efficiency windows, day lighting, etc.), it cannot be the only component in pursuing Zero Net Energy Building design. Sources of renewable energy are necessary to supplement conventional sources.

Finally, as the cost of conventional energy sources goes up and availability goes down, the cost of solar electrical production is approaching parity with most conventional sources.

PV systems can be expected to last 20 years or more, so they should be paired with a roof system that doesn’t require much routine maintenance and has a similar lifetime.

Solar on Life Support? Not So Fast…

“The reports of my death are greatly exaggerated.” So said Mark Twain more than a century ago. Despite the recent and well-publicized demise of Solyndra, the photovoltaic industry might echo Twain’s remark, given the rousing attendance at this year’s Solar Power International (SPI) show in Dallas. More than 1100 exhibitors displayed their wares to an estimated 20,000 attendees at the Dallas Convention Center, October 17-19.

The Duro-Last booth was busy, as we demonstrated to visitors how the Duro-Last roofing system is “solar-ready,” with prefabricated flashings that easily provide a watertight fit around PV mounting racks and other rooftop penetrations.

We were joined in the booth by Duro-Last independent sales reps Daniel and Leah Lakstins (West Texas) and Buddy Wilson (East Texas). Also dropping by on my watch were representatives from Duro-Last authorized contractors Jaco Roofing & Construction (Clute, Texas) and LaFerney, Inc. (Kingsport, Tennessee).

Kevin Kelley and Drew Ballensky warming up pre-show to greet the throngs of visitors to the Duro-Last booth at SPI!

Recycle Your Roof: A Reality Made Possible By Duro-Last® Roofing and Oscoda Plastics®

PVC is one of the most widely used plastics in the world. It has been used in the medical industry for over 50 years in flexible containers and tubing. And it has been used in roofing systems since the early 1960s. But what happens when the roof has come to the end of its useful life? Oscoda Plastics, Inc., a sister company to Duro-Last Roofing, Inc., has been recycling PVC, primarily manufacturing scrap from Duro-Last, since 1989 and turning it into PROTECT-ALL Commercial Flooring. PROTECT-ALL is a commercial grade flooring system that is slip resistant, durable, easy to maintain, and provides stain and fire protection.

Watch this short video on how a 20-year-old Duro-Last roof was recycled into PROTECT-ALL flooring and used again, now on the deck sheet folding floor at Duro-Last’s Saginaw production facility.

If you would like additional information on how to recycle your Duro-Last roof, visit this link for additional information.

Greenbuild 2011 Wrap Up

The 10th anniversary of U.S. Green Building Council’s Greenbuild International Conference and Expo was held October 4th – 7th at the Metro Toronto Convention Center in Toronto, Canada. Greenbuild is the largest expo dedicated to green building with over 20,000 attendees and 1,000 exhibitors. Duro-Last® was one of those exhibitors and has been for the last eight years.

This year the show floor traffic felt a bit slower than in past years. It may be because it was in Canada, or that the two halls were a great distance apart. The last day did seem busier in the South hall where Duro-Last was, and our booth had good traffic most of the day with several promising opportunities.

We had a video running in the booth showcasing a 20-year-old Duro-Last roof that had been recycled into PROTECT-ALL® flooring (manufactured by sister company, Oscoda Plastics®, Inc.), which was very interesting to many attendees. You can watch the three-minute video by clicking on this link.

Ken Claes, Midwest Sales Coordinator, at the Duro-Last booth.

I had the opportunity to attend two educational sessions this year. The first was Green Schools that Teach: Whole-School Sustainability. This was a report on a case study conducted by Stephanie Barr and Brian Dunbar from the Institute for the Built Environment and Katharine Leigh from Colorado State University. They studied five LEED certified schools that they called “whole-school sustainable.” One interesting part of their study included an educational program where the students took part in understanding sustainable practices. For example, one school has a volatile organic compounds (VOC) monitor and every day at 10:30 am and 12:30pm students noticed the VOC indicator rose significantly. They wondered why this happened and found out that every day at that time all of the students were using anti-bacterial hand sanitizer. They are now conscious of this and are changing their habits to make their air quality better.

The second session I attended was, Are there any sustainable materials? Exploring the role of materials stewardship in sustainable built environments. This was an interactive session with speakers Lindsay James from Interface, Inc., Sarah Brooks from The Natural Step Canada, Gail Vittori from Center for Maximum Potential Building Systems, and Jennifer Atlee from BuildingGreen. I thought we were going to learn about specific sustainable products, but it was more of a general discussion about sustainable products, and whether there truly are any out there. “Biomimicry,” a new term to me, looks to nature and natural systems for inspiration, and in nature, there is no such thing as waste – anything left over from one animal or plant is food for another species. One of the oldest examples of biomimicry is Velcro which was invented by Swiss inventor George de Mestral in 1941 after he removed burrs from his dog. This got the group thinking about products used in the building industry that reflect biomimcry.

I have had the opportunity to attend Greenbuild three years now and it is still exciting to see what companies have come up with to contribute to green building practices. As always I will be looking forward to Greenbuild 2012 in San Francisco, California.

If you attended Greenbuild this year please leave your comments below in how the show was for you and your organization.

View from above the north hall.

Are You Ready for Solar? Integrating Single-Ply Roofing With Photovoltaic Arrays

The growth of rooftop photovoltaics (PV) has exploded over the past few years, aided by incentive programs, technological improvements, and the need for alternative sources of energy. Rooftops can be an excellent place to install PV because they are usually unused and unobstructed spaces. But utilizing a rooftop to locate PV is not without its risks – one of which is the potential to compromise the integrity of a critical component of the building envelope: the waterproof barrier that is the roofing system.

PV and roofing systems that have been effectively integrated will work in harmony to provide clean energy, savings in energy costs, and protect the building and its contents for many years. It is important for a building owner to be aware of all the elements to consider when selecting a roofing system to go under a rooftop PV system. Examples of some issues include foot traffic, roof access for repairs, access for fire fighters, access for HVAC service, excess heat impacts on the roof, weight, snow and seismic loads, fire ratings, wind, hail resistance, drainage, and building codes.

A poorly designed and improperly matched roof system is a candidate for failure, and can lead to damage to a building and its contents and possible premature removal of a PV system for repair and/or replacement of the roof.

The best single-ply roofing systems are those that are able to integrate with virtually any type of PV system and mounting method, and provide years of leak-free performance while the PV system is generating power. You can learn more about what it takes for a roofing system to be “solar-ready” by downloading our “solar-ready” roofing system flyer.

Painting Within the (Green) Lines

“Green,” “environmentally friendly,” “eco-friendly,” and “sustainable” are all buzz words that have become an integral part of the design community. Another used sometimes is “greenwashing.” Greenwashing is when almost any action or product, regardless of its impacts on living beings or the environment, is portrayed as green.

The American Institute of Architects is concerned with Greenwashing, so since January 1, 2009, new or on-going continuing education programs registered with the AIA that have “green,” “sustainable,” or similar words in the title must be pre-approved to be sure the program truly does cover green issues. To qualify for Sustainable Design (SD) credit, at least 75 percent of the program must cover SD issues. Duro-Last® has six programs registered for SD credit.

In response to the expansion of the green movement and the broad claims of environmental responsibility, the Federal Trade Commission recently updated its Guides for the Use of Environmental Marketing Claims, also known as the FTC Green Guides. Here are some general guidelines to follow based on the revised Guides:

Avoid blanket statements like “green,” environmentally friendly,” and “eco-friendly,” because these are difficult or impossible to substantiate. Deceptive statements like, “This product is environmentally preferable,” or the general reference “eco-friendly” should also be avoided because it is unlikely that a marketer can substantiate these claims.

Be careful to qualify claims such as:

“Recyclable” – The FTC follows a three-tiered analysis to evaluate this claim:

1. Substantial majority of consumers have access to recycling facilities

2. Significant percentage of consumers have access to recycling facilities (the statement should be qualified by, for example, adding the text (appropriate for Duro-Last’s recycling program): “when membrane is returned to Duro-Last following the Recycle Your Roof program guidelines.”)

3. Less than significant percentage of consumers have access to recycling facilities (the statement should be qualified with text such as: “this product is only recyclable in specified regions of the U.S.”)

“Free-of…” or “Contains no…” – These claims are often deceptive and have no bearing on a product’s overall environmental impact. Competitors of Duro-Last frequently make claims such as “PVC-Free” or “Chlorine-Free” in their negative marketing. In fact, there is no substantiation that products without PVC or chlorine are better or worse for humans or the environment generally.

Made with Renewable Energy or Materials – Statements like this should always be qualified if the entire product/system is not made with renewable energy or materials.

Carbon Offsets – Scientific evidence should support any claims regarding carbon offsets or emission.

The “green” approach to building design and construction will continue to spread, and it’s important for consumers to understand which green claims are “within the lines,” and which really should be washed away.

Yet Another Green Design Tool

Many are at least somewhat familiar with green design programs such as LEED® and Green Globes. The ENERGY STAR® Roof Products Program and the Cool Roof Ratings Council have been providing lists of qualified or rated products for years now, however, recently there have been some questions about another design guide and what it has to say about cool roofing.

The Advanced Energy Design Guides were developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). The guides are a series of publications designed to provide recommendations for achieving energy savings above and beyond the minimum code requirements of ANSI/ASHRAE/IESNA Standard 90.1-1999. They are intended for contractors and designers of small buildings and provide a simple approach to achieve energy savings without utilizing complex calculations or analysis.

The guides give general recommendations in the Building Envelope sections stating that cool or “solar reflective” roofs help reduce energy usage. They do not offer the specificity of LEED or Green Globes, rather they make general recommendations like “increase roof surface reflectance and emittance.”

They also provide useful charts and climate maps that indicate relative performance of various types of roofing products and areas of the country that may benefit most from cool roofing systems.

The Advanced Energy Design Guides are available as free downloads from www.ashrae.org/aedg. Highly reflective white membranes, such as what’s used in the Duro-Last® Cool Zone® roofing system offer a great opportunity for owners of small buildings to achieve real energy savings.