There Is Evidence Cool Roofs Provide Benefits to Buildings in Climate Zones 4 through 8

FIGURE 1: Reflective roof requirements in ASHRAE 90.1 and IECC only apply in Climate Zones 1 through 3, shown here on the ASHRAE Climate Zone Map. SOURCE: U.S. Department of Energy

FIGURE 1: Reflective roof requirements in ASHRAE 90.1 and IECC only apply in Climate Zones 1 through 3, shown here on the ASHRAE Climate Zone Map. SOURCE: U.S. Department of Energy

Reflective roofs are a tried and true way to improve building energy efficiency and comfort, generate net energy savings and help mitigate summer urban heat islands. Reflective roofs work by reflecting solar energy off the roof surface, rather than absorbing the energy as heat that can be transmitted into the building and surrounding community.

The simple act of switching from a dark to a light-colored roof surface has a number of benefits. Buildings protected by these types of roofs require less energy to cool and help building owners and residents save money. Cool roofs on buildings without air conditioning can save lives during heat waves by lowering indoor temperatures. Cooler city air is safer to breathe and less polluted, which makes cities more livable and less vulnerable during heat waves. Increasing the reflectivity of urban surfaces can also offset the warming effect of green- house gases already in the atmosphere and help us address the challenges of climate change. Taken together, these benefits are worth billions of dollars to the growing number of people that live and work in U.S. cities.

The energy-savings case for cool roofs in warm climates is clear. Widely adopted model building-code systems, ASHRAE and the IECC, address roof reflectivity. ASHRAE 90.1-1999 added a credit for highly reflective roofs with IECC allowing compliance via ASHRAE in 2003. ASHRAE 90.1-2010 added reflectivity requirements for new and replacement commercial roofs in Climate Zones 1 through 3. IECC added the same requirements in its 2012 version. (Figure 1 shows the ASHRAE climate zone map for the U.S.)

There is, however, an ongoing debate about whether cool roofs deliver net energy benefits in northern climates that experience cold winters and warm to hot summers (Climate Zones 4 through 8). Do reflective roofs remain beneficial as the cold weather season kicks in? The same properties that allow reflective roofs to keep buildings cooler in the summer may also cause them to make buildings colder in the winter. Theoretically, buildings with cool roofs could require more energy to reach a comfortable temperature in winter—a consequence known as the “winter heating penalty.” Furthermore, building codes tend to require more roof insulation in colder climates than warmer climates, potentially reducing the energy-efficiency benefits of roof surface reflectivity.

FIGURE 2A: Annual energy-cost savings ($1 per 100 square meters) from cool roofs on newly constructed, code-compliant buildings with all-electric HVAC. SOURCE: Energy and Buildings

FIGURE 2A: Annual energy-cost savings ($1 per 100 square meters) from cool roofs on newly constructed, code-compliant buildings with all-electric HVAC.
SOURCE: Energy and Buildings

The “winter heating penalty” and the impact of insulation are considerations when installing reflective roofs in some cold climates, but their negative effects are often greatly exaggerated. The sun is generally at a lower angle and days are shorter in winter months than summer months. In fact, in northern locations winter solar irradiance is only 20 to 35 percent of what is experienced in summer months, which means the sun has a reduced impact on roof surface temperature during the winter. Heating loads and expenditures are typically more pronounced in evenings, whereas the benefit of a darker roof in winter is mostly realized during daylight hours. Many commercial buildings require space cooling all year because of human activity or equipment usage, thereby negating the little—if any—heating benefit achieved by a dark roof.

Two new studies, along with decades of real-world examples from the marketplace, indicate that reflective roofs are an effective net energy (and money) saver even in our coldest cities.

SNOW’S IMPACT

In a study recently published in Energy and Buildings, researchers from Concordia University in Montreal evaluated the energy-consumption impact of adding cool roofs to a number of retail and commercial buildings in Anchorage, Alaska; Milwaukee; Montreal; and Toronto. The researchers looked at older, less insulated building prototypes, as well as newer buildings built with code-compliant levels of insulation. Unlike earlier work evaluating the impact of roof reflectivity on building energy consumption in cold climates, this new analysis also accounted for the impact of snow on the roof during winter months.

FIGURE 2B: Annual energy-cost savings ($1 per 100 square meters) from cool roofs installed on older buildings with all- electric HVAC. SOURCE: Energy and Buildings

FIGURE 2B: Annual energy-cost savings ($1 per 100 square meters) from cool roofs installed on older buildings with all- electric HVAC.
SOURCE: Energy and Buildings

Snow has two impacts on the roof that are relevant to understanding the true impact of roof surface reflectivity on energy consumption. First, snow helps insulate the roof. As a porous medium with high air content, snow conducts less heat than soil. This effect generally increases with snow density and thickness. Second, snow is white and, therefore, reflective. At a thickness of about 4 inches, snow will turn even a dark roof into a highly reflective surface (approximately 0.6 to 0.9 solar reflectance).

When snow is factored in, the benefits of cool roofs in cold climates be- come much clearer. Figure 2a shows the net energy savings and peak electricity reduction with and without snow for cool roofs installed on newly constructed, code-compliant buildings, assuming all-electric HVAC. Figure 2b shows savings from cool roofs installed on existing, older vintage buildings. The paper, available from the journal Energy and Buildings also includes results with gas HVAC systems.

INSULATION’S EFFECTS

Another argument often heard against reflective roofing in cold climates is that buildings in northern climates tend to have higher levels of roof insulation that reduce or negate the energy-savings impact of roof surface color. A new field study and model analysis of black and white roof membranes over various levels of insulation by the City University of New York and Princeton University and Princeton Plasma Physics Lab, the latter two of Princeton, N.J., clearly rebuts the “insulation versus reflectivity” tradeoff.

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NRCA Encourages Homeowners and Business Owners to Check Rooftops for Heavy Snow and Ice Dams

In anticipation of the severe winter storm that will hit the East Coast, the National Roofing Contractors Association (NRCA) is encouraging homeowners and business owners to check their rooftops for heavy snow and ice dams that can cause major damage to a structure’s roof and gutters.

Ice dams are a problem with significant snow accumulations during extended periods of below-freezing temperatures. They form when roof areas become warm enough to melt snow, typically because of the combination of the insulating effect of heavy snow accumulation and heat loss from a home’s interior.

Melted snow runs down the roof under the snow cover and refreezes along overhangs where the roof surface temperature is lower. The water from the melting snow becomes trapped behind the dam of ice and can back up under shingles and infiltrate the underlayment, leading to leaks in the structure.

If ice damming presents an urgent problem and demands immediate action, it is advisable to remove the snow accumulated on the roof to prevent additional water backups. However, snow removal from a rooftop should be attempted only if it can be done safely from the ground level with a roof rake or an extended-handle broom. NRCA does not recommend using ice picks, shovels or any tool with sharp edges that may damage roof coverings.

NRCA strongly recommends contacting an NRCA member if the snow or ice cannot be safely removed from ground level.

For additional information about winter weather roof maintenance and to find a local NRCA member roofing contractor, visit NRCA’s Everybody Needs a Roof website.

Snow-retention System Is for TPO and PVC Membranes

Sno Gem Inc. introduces the Sno Barricade TPO and PVC Membrane Deck Mount Bar snow-retention system.

Sno Gem Inc. introduces the Sno Barricade TPO and PVC Membrane Deck Mount Bar snow-retention system.

Sno Gem Inc., a snow-retention system manufacturer, introduces the Sno Barricade TPO and PVC Membrane Deck Mount Bar snow-retention system. It is a membrane-coated and pre-skirted continuous-bar snow system (patent-pending) for new construction or retrofit applications.

The base plates are custom-coated in either TPO or PVC with a standard white, gray or black. Custom colors are available to match the roofing membrane. To ensure an easy installation, Sno Barricade Membrane-Coated Diamond Series System is available with a pre-skirted target patch, heat-welded directly to the TPO- or PVC-coated base plate. Installers can heat-weld Sno Gem’s target patch to the membrane of the roof, reducing labor cost on a watertight system.

Sno Barricade Systems are available in 1- or 2-inch bar size with single, double or triple bar retention. Square or round bars are offered to best match a building’s aesthetics. The Sno Barricade Plate, an accessory to the system that prevents snow and ice from sliding under the bars, is available in mill finish or custom colors.

Snow-retention System Is Aesthetically Pleasing

Sno Gem Inc. has introduced Sno Blockade, a permanent snow-retention system that is aesthetically pleasing on standing-seam metal roofs.

Sno Gem Inc. has introduced Sno Blockade, a permanent snow-retention system that is aesthetically pleasing on standing-seam metal roofs.

Sno Gem Inc. has introduced Sno Blockade, a permanent snow-retention system that is aesthetically pleasing on standing-seam metal roofs. Choose between a 1- or 2-inch bar, available in standard mill finish aluminum or painted in a powder coating or Kynar finish. Sno Blockade fastens to almost any standing-seam metal roof system, employing the company’s WaveLock technology with three points of attachment without penetration, in conjunction with the Sno Blockade clamp. To reduce melting snow and ice from sliding underneath the bar, the company offers the Blockade Plate, which is installed on the upslope side of the bar. The standard Blockade Plate width is 3 inches but custom sizes are available.

Asphalt Roofing Provides Comprehensive Weather Protection for a Luxury Condominium

Working with the unique variables of a region and its climate poses a significant challenge to roofing contractors. Installing a roof system that looks beautiful and can stand up to ice, snow and freezing temperatures takes an expertise that only comes with experience. This is the case in the snowy and picturesque mountains of Park City, Utah. The city is a winter haven for skiers who vacation there, but the extended snow and cold season can deliver a beating to a roof.

The concrete tile roof and poorly ventilated deck were causing major problems for the building owner, not to mention the residents who live and rent there. Heat was escaping through the roof, causing the snow to melt and refreeze at the eaves.

The concrete tile roof and poorly ventilated deck were causing major problems for the building owner, not to mention the residents who live and rent there. Heat was escaping through the roof, causing the snow to melt and refreeze at the eaves.


The Grand Lodge at Deer Valley Resort, a luxury condominium development at one of North America’s top-ranked ski resorts, sits at an elevation of 9,000 feet in the mountainous area. Along with the breathtaking views comes an average annual snowfall of 350 inches. As a result, the 40,000-square-foot concrete tile roof of the lodge had begun to fail after only six years of intense weather and needed to be replaced immediately.

The concrete tile roof and poorly ventilated deck were causing major problems for the building owner, not to mention the residents who live and rent there. Heat was escaping through the roof, causing the snow to melt and refreeze at the eaves. Dangerous icicles would form, and noisy chainsaws were frequently needed to cut through the ice on the 5-story building. In 2013, the owner of the condominium decided to completely redesign the roofing system. IronClad Exteriors Inc., a Sandy, Utah-based roofing company had successfully installed roofs for Deer Valley in the past and was contacted by Deer Valley Resort Management to consult on the new design.

“Due to insufficient insulation and poor ventilation on the existing roof, ice dams were forming, tiles were cracking and the roof was falling apart,” says Eric Kircher, owner of IronClad Exteriors. “There was an architect involved in redesigning the roof … . I was asked to take a look at the design, and I recommended an asphalt shingle roof instead.

Kircher advised that a full asphalt roofing system with proper insulation and moisture protection would be able to withstand the harsh weather of the ski resort.

“Asphalt was the ideal material for the reroof for reasons that involve aesthetics, safety, and the long-term health and viability of the roof,” he notes. “I recommended a shake style because it really fit the architecture and look of the roof while being able to protect the building and residents from the weather conditions.”

Over the span of six months, IronClad Exteriors tore off the tile roof and installed a system they had used many times to help homeowners in the area protect their homes from ice and snow.

Over the span of six months, IronClad Exteriors tore off the tile roof and installed a system they had used many times to help homeowners in the area protect their homes from ice and snow.

Installation

Over the span of six months, IronClad Exteriors tore off the tile roof and installed a system they had used many times to help homeowners in the area protect their homes from ice and snow. FlintBoard ISO NB (Nail Base) Composite Polyisocyanurate/OSB Roof insulation was installed over the plywood deck, followed by a 3- by 10-inch fascia board. WinterGuard HT advanced waterproofing underlayment and DiamondDeck High Performance Synthetic Underlayment were then added to provide important moisture resistance. Finally, the Presidential Shake TL asphalt shingles provided a beautiful look that matched the lodge’s breathtaking surroundings. The project was completed in November 2014.

The Grand Lodge’s new asphalt roof also contains a unique feature that sets it apart in form and function. IronClad installed 11,000 copper snow guards that offer another layer of weather protection. Snow freezes around the copper pieces and keeps it from sliding down the roof to form dangerous ice dams at the eaves. Lodge residents no longer have to walk underneath potentially hazardous icicles or listen to the sounds of manlifts and chainsaws that are used to remove them.

“The roofing system we designed had the unique ability to withstand that type of cold environment,” Kircher notes. “There will be no heat loss contributing to ice and snow on the eaves, and the insulation protects the interior of the lodge. These are high-end condominiums with finished ceilings and no attic space at the top where you can put more insulation, so the insulation had to be installed on the existing roof deck to prevent ice dams.”

The installation process went smoothly despite the challenges brought on by Park City’s weather. Snow can begin to fall as early as September and lasts through the spring, providing little time for construction projects to take place. Fortunately, IronClad had extensive experience with the roofing systems needed in Park City.

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Snow-retention System Designed Specifically for New Elementary School

Alton Hall Elementary School, Galloway, Ohio, recognized the need for snow retention and specified the Sno Barricade from Sno Gem Inc. to be attached to the standing-seam roof.

Alton Hall Elementary School, Galloway, Ohio, recognized the need for snow retention and specified the Sno Barricade from Sno Gem Inc. to be attached to the standing-seam roof.

Providing a safe and healthy environment for students is clearly a high-ranking consideration in the construction of an elementary school. Architects for the Alton Hall Elementary School in Galloway, Ohio, recognized the need for snow retention and specified the Sno Barricade from Sno Gem Inc. to be attached to the standing-seam roof.

“We specified the Sno Barricade because of its proven durability and performance,” says Mike Parkinson, associate project manager at SHP Leading Design of Cincinnati. “We’ve used the Sno Barricade on dozens of projects. I can’t remember the last time it wasn’t on one of our projects. The system is designed specifically for each project by Sno Gem. With the design criteria, they run calculations for the project and prescribed a two-rail system around the entire roof to protect the occupants from potential sliding snow and ice.”

With a layout of the standing-seam metal roof, considering slope, length of run, panel width, annual snowfall and other factors, Sno Gem calculates the best snow-retention solution. “Every metal roofing layout is different and each one requires its own calculations,” notes Jim Carpenter, vice president of Operations at Sno Gem. “Our calculations are based on results obtained from extensive testing of our clamps.”

After receiving the design criteria, Sno Gem ran calculations for the project and prescribed a two-rail system around the entire roof.

After receiving the design criteria, Sno Gem ran calculations for the project and prescribed a two-rail system around the entire roof.

For the Alton Hall Elementary School, the Sno Barricade was prescribed by Sno Gem. Rush Architectural Metal Erectors Inc. of Washington, Pa., installed 1,850 linear feet of the Sno Barricade around 100 percent of the perimeter of the building. R.A.M.E. also installed the Barricade Plate on Alton Hall. The Barricade Plate is an accessory designed to hold back thinner amounts of ice and snow that could pass beneath the bar. The Barricade Plate is installed on the upslope side of the bar in the middle of the panel. It’s held in place by a tek screw, not visible from the ground. Like the Sno Barricade, the Barricade Plate is available in a color to match any roofing panels.

The Barricade Plate is an accessory designed to hold back thinner amounts of ice and snow that could pass beneath the bar.

The Barricade Plate is an accessory designed to hold back thinner amounts of ice and snow that could pass beneath the bar.

“Sliding snow and ice is a dangerous problem building owners don’t have to deal with any more because of engineered snow-retention systems,” adds Albert Rush, owner of R.A.M.E. “The Sno Barricade attaches easily and securely without penetrating the panel, so it doesn’t compromise any roofing warranties. The addition of the Barricade Plate provides peace of mind for the occupants, as well as the school district.”

Snow-retention Components Further Slow Snow from Sliding Off a Roof

SnapClip II from S-5!

SnapClip II from S-5!

SnapClip, SnapClip II or SnapClip III are optional components that can be added to your S-5! ColorGard snow retention system to further retard the migration of snow. It has a special integrated rubber “foot” to prevent abrasion of the panel’s finish. SnapClip snaps onto the back of the crossmember and extends down to the flat of the roofing panel.

Snap the SnapClip onto your ColorGard crossmember after installation. One or two clips are used between seams. Mount the SnapClip to the back of the crossmember using the lock that results with the rubber “foot” resting properly on the panel surface. When applying downward pressure on the part, the “toe” should engage the surface of the panel just before the “heel.” Screw SnapClip into place utilizing the provided stainless steel self-tapping screw.

SnapClip II has two locks and is especially made for seam heights of 1 inch (25 mm) and 1 3/4 inch (44.5 mm) snap. It will also fit 2-inch (51 mm) vertical seams but not 2-inch (51 mm) horizontal.

SnapClip III has three different locks and will work on seam heights of 1 3/4 inch (44.5 mm) up to 3 inches (76 mm).

SnapClip should not be used on copper roofs.