VELUX America Study Finds Skylights Offer Energy Efficiency to Single-family Homes

Homes that depend more on skylights in combination with vertical windows to provide adequate levels of daylight tend to be more energy efficient, according to a study commissioned by VELUX America.

“A Study of the Energy Impacts of Residential Skylights in Different Climates,” prepared by Group14 Engineering, used computer models based on a 1-story, open plan, single-family home modeled under code-compliant conditions of California’s Title 24 regulations (California Energy Commission, 2008), Residential Package D. The baseline-modeled home has a maximum 20 percent window-to-floor area (with no skylights) with windows evenly distributed on all facades to achieve an average daylight factor of 5 percent.

Researchers added skylights and adjusted the amount and configuration of vertical windows to test how the model would perform in different climate zones, while giving the living space sufficient daylight to allow lights to be switched off. The study explored the effects of these configurations on the utility bills generated by the model homes in Los Angeles and Napa, California, and then expanded the models to Boston, Chicago, Denver, Dallas, Minneapolis, Orlando and Seattle, using their specific code requirements.

It found that by providing daylight from above via skylights, the total fenestration area could be reduced from a maximum 20 percent of floor area to as low as 12 percent of floor area while achieving the same baseline average of daylight factor target of five percent.

This was found to reduce annual heating and cooling energy use and costs in all but two of the 108 models with skylights that the group analyzed. Lighting savings, shading efficiencies, and increased natural ventilation attributable to skylights were not evaluated for simplicity. Further studies are planned to look into quantifying these additional efficiency contributions.
“While we have always known the intangible benefits of adding daylighting from above to homes, this study provides empirical evidence that natural light from skylights can contribute to the home’s overall energy efficiency,” said Stephan Moyon, direct of sales for VELUX America.

An in-depth discussion of the study, as part of a GreenExpo365 webinar titled “How To Reduce Energy Use By Improving Daylighting,” is available online. The full study report is available from VELUX upon request. VELUX continues to study and document the role and effectiveness of skylights in providing daylighting and passive ventilation.

Spray Polyurethane Foam Has Structure-strengthening and Energy-efficiency Capabilities

A high-performance building material, spray polyurethane foam (SPF) is widely used as an effective, lasting roofing solution. With positive benefits, including versatility, thermal insulation, resistance to inclement weather cycling and storms, strengthening of the building envelope, long life span and durability, spray foam has enjoyed increased use among builders and roofing contractors alike.

A roof’s primary purpose is to protect the structure underneath it. As a roofing material, closed-cell SPF acts as a protective roofing mechanism and a thermal insulator. The lightweight material is ideal as a roofing solution when:

 As a roofing material, closed-cell SPF acts as a protective roofing mechanism and a thermal insulator.

As a roofing material, closed-cell SPF acts as a protective roofing mechanism and a thermal insulator.

  • the roof substrate has many penetrations.
  • the roof deck is an unusual shape or configuration.
  • the roof is being applied to a structure located in a severe-weather environment.
  • a lightweight option is needed.
  • a slope application is preferred to provide extra drainage capabilities.
  • keeping the existing roof cover is desired.

STRENGTH AND DURABILITY

SPF is considered a highly durable building material. The physical properties of the foam change little with time, accounting for a life span up to 30 years with regular care and maintenance. SPF roofing systems also strengthen the roof in multiple ways. Roofing spray foams possess a compressive strength of 40 to more than 60 pounds per inch. Spray foam’s adhesion strengthening capabilities are key, especially in locations where severe weather cycling, storms, wind, hail and other conditions are prevalent and commonly cause structure damage. Coastal and hurricane-prone regions are prime examples.

When applied to the interior side of a roof, closed-cell SPF can increase a building’s resistance to wind uplift during severe storms. When SPF is applied to built-up roofing and metal substrates, it increases resistance to wind uplift even further. A study conducted by the University of Florida, Gainesville, in 2007 found that applying closed-cell spray foam under a roof deck provides up to three times the resistance to wind uplift for wood roof sheathing panels when compared to a conventionally fastened roof.

Spray foam is a good solution for unusual configurations and areas with many penetrations.

Spray foam is a good solution for unusual configurations and areas with many penetrations.

Spray foam also is resistant to progressive peeling failure. Caused by wind, peeling happens at the roof’s edges when wind pulls flashings and copings away from their installed positions. Peeling looks like a tin can after it has been cut around the perimeter. When this happens, a chain reaction may occur and lead to catastrophic building failure. After the roof membrane, panels or tiles pull away, the board-stock insulation is exposed, often with less resistance to the lateral and uplift wind forces. Then the sheathing below and the substructure are subject to movement and wind or water damage, potentially leaving the entire building interior underneath open and vulnerable. SPF roofing is continuous, so it provides a water-resistant layer that is well adhered to the substrate.

When the Gaithersburg, Md.-based National Institute of Standards and Technology examined roofs following Hurricane Katrina, it found buildings with spray-foam roofs performed rather well without blow-off of the SPF or damage to flashings. The 2006 “Performance of Physical Structures in Hurricane Katrina and Hurricane Rita: A Reconnaissance Report” found that only one of the examined SPF roofs incurred notable damage, and that damage was confined to only 1 percent of the total roof system. The report concluded spray foam kept the roofs intact, prevented moisture from entering the buildings, and protected the structures from hail and debris.

Hurricane Katrina played a significant role in one of the largest reroofing projects ever on one of the largest metal-framed domed structures in the world: the Superdome in New Orleans. Katrina destroyed the dome’s second roof; the structure’s original roof was constructed with polyisocyanurate foam covered with a fluid-applied elastomeric coating but was replaced in 1989 with a single-ply EPDM roofing system. After the damages suffered during Katrina, the EPDM roof system was replaced with a spray foam roof system.

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A Trade Association Brings Roofs to the Sustainability Discussion

Roofs, first and foremost, keep water and the elements out of a building. The roofing industry has done this quite well since the modernization of buildings began more than a century ago. Along the way, a number of trade associations—ARMA, ERA, MCA, NRCA, PIMA, SPFA, SPRI—have formed and evolved as materials and trends have changed. Each group provides excellent information relative to its mission and goals. Yet we know change keeps coming.

THE BYRON WHITE COURTHOUSE, DENVER, features a RoofPoint-certified high R-value (R-30) roof for energy savings. A dual-reinforced Derbigum modified bitumen membrane, 90-mil base sheet and a high-density coverboard were installed.

THE BYRON WHITE COURTHOUSE, DENVER, features a RoofPoint-certified high R-value (R-30) roof for energy savings. A dual-reinforced Derbigum modified bitumen membrane, 90-mil base sheet and a high-density coverboard were installed.

Since the turn of the century, the awareness and push for energy efficiency of buildings and the sustainability for materials and building design has grown substantially and has become an important topic in the public forum. Sustainability and environmentalism are universal topics.

Serving as a unified voice for issues involving roofing, energy and the environment, the Center for Environmental Innovation in Roofing was established in Washington, D.C., in 2008. The non-profit organization’s focus is to advocate and promote the use of environmentally friendly, high-performance roof systems, not just within the U.S., but in North America and globally. The center is a member-based association consisting of roofing manufacturers, roofing contractors, roofing consultants, raw-material suppliers and other trade groups within the roofing industry.

To promote the sustainability of roof systems, the center develops resources, products and educational information that can be used by the building industry to advance the longevity, durability and overall sustainability of roofs. Increased awareness of the importance of a building’s roof is critical to the center’s mission. The roof can be a large contributor to the energy efficiency of the building, a long-term asset and, increasingly, a location for energy production (solar, wind).

ROOFPOINT

The center’s premier program is RoofPoint, a guideline for environmentally innovative nonresidential roofing. RoofPoint is used to evaluate new and replacement roofs for commercial and institutional buildings based on their environmental performance during the life cycle of the building the roof covers. This provides a useful measure for what constitutes a sustainable roof during design, construction, operation and decommissioning.

RoofPoint is primarily a rating system, and when certain minimums are met, a roof can become a RoofPoint Certified roof. Certificates and plaques noting RoofPoint certification can be awarded and used to validate a commitment to sustainability and the environment.

RoofPoint is based on current state-of-the-art processes and methods, remaining technology neutral. It does not rank or prioritize materials or systems; however, RoofPoint emphasizes energy efficiency and long-term performance and durability as overarching key attributes of a sustainable roof. Material recycling and reuse, VOCs, water capture and reuse, hygro-thermal analysis, and operations and maintenance are a few of the categories within RoofPoint.

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Reroofing Is One of the Few Opportunities to Improve the Built Environment

All of us get misled by catch-phrases, like “Save the Planet” or “Global Warming” or “Climate Change”. Although phrases like these are well intended, they can be misleading; they really are off topic. Something like “Save the Humans” is more to the point and truly the root of the entire sustainability movement. Let’s face it: The efforts to be more green are inherently aimed at a healthier you and me, as well as our children’s and grandchildren’s desire for continued healthful lives and opportunities.

The existing PVC roof on the GM After Sales Warehouse, Lansing, Mich., was removed and recycled into new PVC roofing material, a portion of which was reinstalled on this project and helped it achieve RoofPoint certification.

The existing PVC roof on the GM After Sales Warehouse, Lansing, Mich., was removed and recycled into new PVC roofing material, a portion of which was reinstalled on this project and helped it achieve RoofPoint certification.

The discussion about green and sustainability needs some context to make it real and effectual. The question to ask is: How does green construction help humans live a healthier and happier life? The answer is: It is because of the co-benefits of building (and living) in a more environmentally appropriate way.

One key component of building environmentally appropriate buildings is that, collectively, we use less energy. Less energy use means no need to build another power plant that creates electricity while spewing pollution into the air. Less pollution in the air means people are healthier. It also means the water and soil are less polluted. We drink that water and eat what grows in the ground. We also eat “stuff” from the rivers, lakes and oceans. Healthier people means reduced costs for health care. Reduced sickness means fewer sick days at the office, and fewer sick days means more productivity by employees—and, dare I say, happier employees all because of the environmentally appropriate building, or a “human appropriate” building.

So what does all this have to do with roofs? Rooftops, because they are a significant percentage of the building envelope, should not be overlooked as an important and truly significant energy-efficiency measure. Building owners and facility managers should always include energy-efficiency components in their roof system designs. There are few opportunities to improve the building envelope; reroofing is one of those opportunities, and it shouldn’t be missed.

According to the Center for Environmental Innovation in Roofing and building envelope research firm Tegnos Inc., roof systems have the potential to save 700-plus trillion Btus in annual energy use. Too many roofs are not insulated to current code-required levels. If our rooftops were better insulated, these energy-saving estimates would become reality. Imagine the co-benefits of such a significant reduction in energy use!

The RoofPoint certified Bucks County Community College roof, in Perkasie, Pa., features a high-performance multi-layer insulation system that provides high levels of energy efficiency. Staggered joints break thermal discontinuities and a coverboard provides R-value and a durable surface.

The RoofPoint certified Bucks County Community College roof, in Perkasie, Pa., features a high-performance multi-layer insulation system that provides high levels of energy efficiency. Staggered joints break thermal discontinuities and a coverboard provides R-value and a durable surface.

But how do we know we’re doing the right thing? RoofPoint and the RoofPoint Carbon Calculator will help. The RoofPoint Carbon Calculator uses seven inputs to compare an energy-efficient roof with a baseline roof: insulation, thermal performance, air barrier, roof surface, rooftop PV, solar thermal and roof daylighting. The outputs from the Carbon Calculator are total roof energy use, energy savings due to the energy-efficient roof design, energy savings during peak demand, and CO2 offset for the energy-efficient roof design. This can be used to compare an existing roof (the baseline roof) to a new roof design (the energy efficient roof), and this will help verify the energy savings and reduction of carbon output. It’s an excellent tool for verifying how green a new roof can be.

And don’t just take my word on this co-benefits idea. The Economist published an article about the EPA and rulings on interstate pollution. The article cited a claim that by this year, 2014—if pollution rates were half of those in 2005—hundreds of thousands of asthma cases each year could be prevented and nearly 2 million work and school days lost to respiratory illness could be eliminated. And just think, improving your roof’s energy efficiency is key to the reduction of power-plant use and the pollution that comes from them. So, yes, roofs can help your kids and your grandkids be healthy and happy.

Radiant Barrier Combines Energy Efficiency with Moisture Protection

Huber Engineered Woods has released its ZIP System radiant barrier.

Huber Engineered Woods has released its ZIP System radiant barrier.

The most recent innovation from Huber Engineered Woods combines superior strength and stiffness, moisture resistance, and now a radiant heat barrier. The new ZIP System radiant barrier incorporates the signature ZIP System technology with radiant heat protection.

ZIP System radiant barrier combines the energy-efficiency benefits of radiant barrier with the superior moisture protection and simple installation of ZIP System sheathing. The panels are now available for national distribution.

ZIP System radiant barrier panels block up to 97 percent of radiant heat transfer which can lower attic temperatures by as much as 30 degrees. The all-in-one sheathing allows for a faster, more efficient installation, providing an instant 180-day rough dry-in. Homeowners also can reap the benefits of ZIP System Radiant Barrier, as the roof panels reduce home cooling costs up to 12 percent.*

ZIP System radiant barrier roof panels are available in 1/2-, 5/8-, and 7/16-inch thicknesses. ZIP System roof panels eliminate the need for felt paper, resulting in a more efficient building process.

*All testing. Testing was done in accordance with ASTM standard and test methods. The Florida Solar Energy Center/University of Central Florida Publication #FSEC-EN-15-87 titled “Radiant Barriers: A Question & Answer Primer.” Studies represent cases in the Southeast and may not be representative of other regions. Savings also depend on the amount of heat the roof and attic contribute to a home’s cooling load.

Center for Environmental Innovation in Roofing Sponsors Sustainable Energy in America Factbook

The Center for Environmental Innovation in Roofing is pleased to announce that The Business Council for Sustainable Energy in partnership with Bloomberg New Energy Finance have released the 2014 installment of the Sustainable Energy in America Factbook. “The 2014 Factbook documents the upward trajectory of energy efficiency, natural gas and renewable energy, using the latest data from 2013, and the edition adds yet another year of data to document the long-term transition to cleaner, lower-carbon sources of energy production,” according to the group’s press release.

The 2014 Factbook is a unique and dramatically powerful tool to communicate the impact of our industry on the larger U.S. energy sector by providing quantitative and objective reporting, a broad definition of clean energy that includes energy efficiency, and filling important data gaps to capture the full contribution of clean energy technologies.

“The Factbook plays a vital role in chronicling this fast-moving transformation, which is creating whole new industries and thousands of new jobs in the energy efficiency, natural gas and renewable energy sectors,” states Lisa Jacobson, president of The Business Council of Sustainable Energy.

The center is a proud sponsor of the 2014 Factbook and a board member of The Business Council for Sustainable Energy.

Reroofing Is One of the Few Opportunities to Improve the Built Environment

All of us get misled by catch-phrases, like “Save the Planet” or “Global Warming” or “Climate Change”. Although phrases like these are well intended, they can be misleading; they really are off topic. Something like “Save the Humans” is more to the point and truly the root of the entire sustainability movement. Let’s face it: The efforts to be more green are inherently aimed at a healthier you and me, as well as our children’s and grandchildren’s desire for continued healthful lives and opportunities.

The discussion about green and sustainability needs some context to make it real and effectual. The question to ask is: How does green construction help humans live a healthier and happier life? The answer is: It is because of the co-benefits of building (and living) in a more environmentally appropriate way.

One key component of building environmentally appropriate buildings is that, collectively, we use less energy. Less energy use means no need to build another power plant that creates electricity while spewing pollution into the air. Less pollution in the air means people are healthier. It also means the water and soil are less polluted. We drink that water and eat what grows in the ground. We also eat “stuff” from the rivers, lakes and oceans. Healthier people means reduced costs for health care. Reduced sickness means fewer sick days at the office, and fewer sick days means more productivity by employees. And, dare I say, happier employees are all because of the environmentally appropriate building, or a “human appropriate” building.

So what does all this have to do with roofs? Rooftops, because they are a significant percentage of the building envelope, should not be overlooked as an important and truly significant energy-efficiency measure. Building owners and facility managers should always include energy- efficiency components in their roof system designs. There are few opportunities to improve the building envelope; reroofing is one of those opportunities, and it shouldn’t be missed.

According to the Center for Environmental Innovation in Roofing, Washington, D.C., and building envelope research firm Tegnos Inc., Carmel, Ind., roof systems have the potential to save 700-plus trillion Btus in annual energy use. Too many roofs are not insulated to current code-required levels. If our rooftops were better insulated, these energy-saving estimates would become reality. Imagine the co-benefits of such a significant reduction in energy use!

But how do we know we’re doing the right thing? RoofPoint and the RoofPoint Carbon Calculator will help. The RoofPoint Carbon Calculator uses seven inputs to compare an energy-efficient roof with a baseline roof: insulation, thermal performance, air barrier, roof surface, rooftop PV, solar thermal and roof daylighting. The outputs from the RoofPoint Carbon Calculator are total roof energy use, energy savings due to the energy- efficient roof design, energy savings during peak demand, and CO2 offset for the energy-efficient roof design. This can be used to compare an existing roof (the baseline roof) to a new roof design (the energy-efficient roof), and this will help verify the energy savings and reduction of carbon output. It’s an excellent tool for verifying how green a new roof can be.

Don’t just take my word on this co-benefits idea. The Economist recently published a blog about the EPA and rulings on interstate pollution. The article cited a claim that by 2014—if pollution rates were half of those in 2005—hundreds of thousands of asthma cases each year could be prevented and nearly 2 million work and school days lost to respiratory illness could be eliminated. And just think, improving your roof’s energy efficiency is key to the reduction of power-plant use and the pollution that comes from them. So, yes, a roof can help your kids and your grandkids be healthy and happy.

Green-building Innovation Is Important, But So Is Refinement

In March 2006, I swore allegiance to the wildly popular green-building movement. I even put the kibosh on my favorite joke about recycling in the landfill—you know, so not to deprive future generations of fossil fuels and diamonds. Nice.

I’ve worked in facility management at Duke University Health System for 26 years. In this profession, being overly pragmatic is an occupational hazard. So, why did an “old-school” guy (no pun intended) show up at a green love fest alongside folk with funny-colored hair and way too many bumper stickers? Quite simply, I came to the party to plea for intellectual honesty.

Unfortunately, early on, the sustainability movement offered myriad earth-friendly materials often with little thought to their durability or life cycle. Similarly, early building rating programs focused largely on the merits of individual products without factoring their proper integration into functional systems or assemblies. Consider, for example, the many thousands of squares of reflective “cool roofing” membranes applied over non-durable assemblies. A LEED-applicable roofing membrane that fails prematurely because of inferior quality or misapplication does not look very sustainable buried in a landfill.

It’s no longer 2006, and the greenie you’re partying with may be a blue-haired, retired architect. It’s encouraging so many in the building industry, and particularly the roofing industry, have embraced the concept of durability as the essence of green and sustainable building design. Moving beyond mere branding “strategery,” sustainability can be good for the bottom line. On the Duke campus, a 2007 roof replacement used forward-thinking design to divert 718 tons of solid waste. Salvaged materials from this effort included 296,000 board feet of XPS insulation, which was repurposed in new roofing construction on three Duke buildings. It’s our story. And it’s simply good business.

It has been said “architecture is storytelling.” The story of our 2007 roof replacement project settled forever how Duke University Health System will conduct itself in regard to sustainable roofing design and environmental stewardship. We distilled our story into the following “Guiding Principles of Sustainable Roofing”:

  • 1. Favor insulations or insulating assemblies that are highly resistant to water and physical damage.
  • 2. Favor roof assemblies that position the roof membrane directly over a permanent or semi-permanent substrate.
  • 3. Favor roof designs that prohibit or highly discourage the entrapment of water within the roof assembly.
  • 4. Favor membrane and insulation designs capable of in-place reuse or recycle in future roof iterations.

Through the years, these guiding principles have produced a dramatic improvement in roofing performance on our campus. In particular, our emphasis on adaptive reuse of materials will minimize our impact on the environment, as well as reduce future demand on hospital resources–resources best used in support of outstanding patient care or cancer research, not funding a premature roof replacement. Interestingly, the U.S. General Services Administration, Washington, D.C., has recently incorporated our guiding principles in facilities standards for future public building construction. Now our story has legs.

In April 2013, I attended the Energy Efficient Roofing Conference in Charlotte. I was invited to participate in the program, offering a building owner’s perspective about emerging roofing technologies. The focus, primarily, was energy-efficient roofing as a value proposition: how to achieve it and how to sell it. The format leaned heavily on panel discussions, which produced large amounts of banter and at times outright tension regarding the subjects at hand. It was as if someone handed a microphone to the elephant in the room. Has the proposition become a “solution” in search of a “problem”?

Don’t misunderstand; everyone can see the benefits in much (but not all) of the new energy-efficient roofing innovations and building codes. But should we be excited about reflective or solar membranes on massively thick R-30 minimum insulation while still far too many roof installations will fail prematurely because of shortsighted design and construction? If quality and durability are of utmost value, do you—the roofing contractor— know how to achieve it and how to sell it? Should you care?

Back in 2006, I believed everyone was trying to “out green” each other; durability be damned. Today, I wonder if the problem is that everyone wants to “out innovate” each other. As we’ve witnessed with green, the danger when innovation means everything is that it can soon mean nothing.

Innovation is exciting and necessary, but so is refinement. Refinement may be the most powerful strategy of all, yet it remains under emphasized. The most effective way to celebrate refinement is by creating new stories–new institutional memories. Roofing contractor, you are the biographer. Run with that.