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Calculating Cool Roof Energy Savings

Posted on September 20, 2016March 29, 2022 by Candy McNamee

Whether it’s providing waterproofing, reducing thermal expansion and contraction, or supplying chemical and damage protection, cool metal roofing has much to offer. Of course, the most substantial benefit is the energy savings gleaned from reduced rooftop heat levels driving down air conditioning loads. In fact, the Lawrence Berkeley National Laboratory’s heat island group projects a whopping $1 billion reduction in cooling costs if cool roofs were to be implemented on a nationwide basis.

To assist architects in determining the kinds of energy savings that can be expected from cool metal roofing, the Oak Ridge National Laboratory (ORNL) has parlayed the data it gathered from a three-year evaluation of metal roofing products into a whole building energy savings calculator.

In addition to energy efficiency, cool metal roofs are known for extended durability and longevity.

Cool Roof Calculator

This calculator is called, simply enough, the Cool Roof Calculator. The easy-to-use tool is described as a quick way to compare overall energy costs and savings for a variety of roof and building conditions. Unlike some energy modeling calculators, which are limited to steep slope residential roofs with attics, ORNL’s tool models the typical low slope commercial roof with insulation placed directly over the deck and under the roofing membrane.

To calculate approximate energy savings offered by a cool metal roof, architects are instructed to input the building’s location, proposed roof R-value, roof reflectance and emittance, base energy costs, equipment efficiencies, electrical demand charges and duration.

While experts suggest that it may be difficult to accurately predict the base use and peak demand without detailed construction and cost information, tools such as the ORNL’s cool roof calculator can be a useful way to gather helpful performance estimations for a variety of building types and locations.

Attempting to do just that, the calculator outputs a number of values to offer an approximate estimate of potential energy savings, broken down into cooling energy savings—a calculation of air conditioning savings from base use and peak demand reductions—and cooling season demand savings, an estimate of the peak demand charge reduction enabled by enhanced roof reflectivity.

Accessible at http://rsc.ornl.gov, users can also compare the energy performance offered by a cool roof vs. a conventional black roof.

“It’s a nice tool to give people a feel for where a cool roof would actually help them and have the greatest impact in terms of energy use,” relates Robert A. Zabcik, PE, LEED AP BD+C, director, research and development, NCI Group Inc., Houston, in a Metal Construction News article.

Roof Reflectance Baseline

Roof reflectance and emittance, requirements and options, can be found in energy codes such as IECC, ASHRAE 90.1, California Title 24, and other local codes. Requirements may vary based on roof slope and climate zone, and may allow for either aged or initial solar reflectance, thermal emittance and/or SRI.

Fortunately, MBCI continues to stay current with individual testing and also maintains third-party tested and verified product listings through entities such as the Cool Roof Rating Council, and the U.S. EPA’s ENERGY STAR®.

Design and Color Trends in New Metal Construction

Posted on September 9, 2016 by Shelby Shipman

Design and color trends in metal roofing products are not exactly black and white. In fact, a whole host of options are available when choosing textures and colors for new metal construction projects, depending on specific criteria. Some are practical, some are aesthetic—but all are shaping how designers are specifying metal products, coatings and paints. Let’s walk through a few of the top trends in the industry now.

More color options for coil coatings

Through vertical integration, manufacturers are offering more color options than ever.

It used to be that coil options were limited to standard stock choices and availability was determined by the coil coaters. Now, with evolving industry strategies, such as NCI’s vertical integration, many more manufacturers are properly positioned to enter into the market with multiple color choices across multiple brands without as much deviation. This also allows manufacturers to quickly adapt to requests for custom colors—both internally or externally.

Ratings and regulations are leading to more energy-efficient choices

Moreover, color requests based on aesthetics and paint systems have evolved based on changing code requirements. For additional benefits, specifiers can turn to many rating systems, such as the Cool Roof Rating Council and ENERGY STAR®, as well as earn LEED points by having specific SRI (Solar Reflectance Index) values.

Much has changed over the past 10 to 15 years. For instance, the components industry has evolved from customers merely selecting colors based on preference to a more integrated approach accounting for aesthetics, cost and energy efficiency. Today, owners and architects are more likely to consider a color such as Solar White to save on insurance or receive tax rebates. Environmental considerations and regulations have changed the way customers purchase steel, incorporating such issues as unique regulations for different states and weather conditions, LEED points and reflectivity into the atmosphere.

Insulated metal panels used in higher-end architectural projects

Another design trend in the industry is a move towards insulated panels, mimicking what is typical in the aluminum composite material (ACM) world. High-end car dealerships are known for design with ACM. This includes blocked-off designs that can be elongated, can be different colors or have joints in different places. This application has been ACM’s primary wheelhouse for decades. Now that ACM manufacturers have entered into the insulated metal panel (IMP) industry, more of the design community is considering a thinner, horizontal IMP. The intention is to replicate the appearance of an ACM panel, while reaping the major cost and insulating benefits of IMPs.

Depth of color and texture: the rise of metallic colors

Architecturally, more metallic paints are being used. Historically, metal panels were white, tan or Galvalume. The current trend has expanded to a wider color palette, including mica fluoropolymer. These metallic coatings give depth to the color, adding sheen and sparkle. In fact, there are actually metal flecks in the paint. Metal oxide-coated mica pigments offer up the metallic look and add to the durability.

Vasa Fitness in Lehi, Utah features MBCI’s FW-120 panel in Signature® 300 Silver Metallic paint.

What’s behind this trend? Designers are thinking about metal roofs in a whole new way. They are looking to leverage colors and properties of paint to bring out a unique architectural appearance not previously available.

Conclusion

Trends in metal construction are as broad as the choices of color and coatings. Whether a reaction to energy savings criteria or simply a desire of an educated consumer to bring new life to their project, it’s worth taking the time to investigate all your options when specifying your next metal project.

Metal Roofs and Water Conservation: A Hidden Green Roof Benefit

Posted on May 5, 2016November 28, 2023 by Amy Crenan

When the conversation turns to sustainability, there’s a lesser known benefit to metal roofing that helps with the environment – and the building owner’s operations costs.

There are a number of reasons why metal roofs are sustainable. The most obvious reasons are that they’re long-lasting and durable, recyclable, and they’re a natural pairing with roof-mounted photovoltaic (PV) systems for alternative energy. A metal roof is like the Swiss Army knife of sustainable architectural products because of its versatile environmental benefits.

Conserve Water with Metal Roofing

Yet, one of the more important environmental benefits that sometimes gets overshadowed by these other qualities is a metal roof’s capacity for water conservation.

Many cities in the U.S. encourage water conservation in one form or another. Such practices come in handy during extended water scarcity, like the one California has experienced for the past few years (if not longer, depending on one’s definition of “scarcity”).

Reduce Flooding with Metal Roofing

Other places have the opposite problem. Flooding has most recently occurred in the Houston area, but is also a continuous problem in places like New York City, New Jersey and others. These flooding problems stem from unusually large amounts of rainfall, obviously, but also from the built environment’s inability to cope with rainfall because of the impermeable nature of surfaces in cities.

A metal roof can help when coupled with a storage device that captures the water and delays when it’s sent from the site into the city’s stormwater system. That captured water can be reused onsite for non-potable purposes, such as landscaping and toilet flushing.

Benefits to Reusing Rainwater

The benefits to capturing and delaying the release of rainwater don’t just end with helping a city to better manage rainfall for drought or flooding conditions—stormwater retention also helps a building owner’s checkbook.

Reusing rainwater means paying less for water that the local water utility has had to treat and send into the building. Owners can save some cash on their water bills while simultaneously easing some stress on the utility. It’s win-win.

If you’re familiar with the phrase “they get you coming and going,” well, municipalities are similar with water supplies. Sure, they charge for providing a facility with water, but many also charge to remove water in what’s called a stormwater fee. If that fee is calculated by the amount of water leaving the site (quantity), then reducing the amount exiting via the municipal system will again save the owner money.

Helping Clients and the Planet

Metal roofs with water collection systems aren’t going to miraculously solve all flooding and drought concerns, but every little bit helps. Sustainability strives to meet the triple bottom line of people, planet, and profit—and metal roofs have the capacity to meet all facets of the triple bottom line for more than what typically gets talked about. So, once you know the client’s goals and concerns on your next project, be sure to have a conversation of your own to find out how a metal roof can help achieve the client’s vision.

Metal Roofs and Solar Energy: An Ideal Match

Posted on March 23, 2016 by Candy McNamee

Everyone is talking about—and doing something about—sustainability. Metal roofs fit nicely into the sustainable-material equation because of their myriad traits, such as recyclability, reflectivity, longevity and durability. Another major component in the sustainability equation is renewable energy—the production of energy from renewable resources like sun and wind. A metal roof is the ideal location for solar energy production on homes, commercial buildings and recreational applications.

Why Solar Panels and Metal Roofs?

One of the key factors for long-term success of rooftop solar energy is the quality of roof under the solar panels. Roofs under photovoltaic (PV) systems should be durable and have an equivalent service life to the solar panels. However, too many traditional roof systems do not have a service life that matches, let alone exceeds, the service life of the PV panels. This is where metal roofs excel.

Service Life of Metal Roofs

A study of roof system longevity presented at the Fourth International Symposium on Roofing Technology by Carl Cash, a principle at Simpson Gumpertz & Heger, showed that metal panel roofs have the longest service life when compared to asphalt-based roofs and single ply roofs. The study showed that the average life of metal panels is 25 years. BUR and EPDM were second and third, respectively, at 16.6 and 14.1 years of average service life. Exceeding the Cash study, a more recent study conducted by the Metal Construction Association (MCA) and Zinc Aluminum Coaters (ZAC) Association showed the longevity of low-slope unpainted 55% Al-Zn alloy coated steel standing seam roofing (SSR) systems is 60 years.

Service Life of Solar Panels

Solar panels will last 25 to 30 years. In fact, some of the very first PV panels from the 1960s and 1970s are still producing energy. While their efficiency might decrease over time, solar panels will make electricity for many decades. For the most cost-effective rooftop solar energy installation, the longevity of the roof should be equivalent, or greater, than the solar panels so that the roof doesn’t need replacement during the life of the solar energy system. Metal panels are the most reliable, long-term roofing system for solar energy installation projects.

Built to Last

Solar Roof Panels on Real Salt Lake City Stadium

Simply put, installing solar energy on rooftops that don’t have an equivalent service life is a mistake, especially for solar projects that cover a large portion of the rooftop. The cost of decommissioning, removing, and replacing rooftop solar energy can cost 20% to 100% of the original installed cost. The cost tends to align with the percentage of rooftop covered with solar panels. Much of the cost to remove and reinstall is labor, but an older solar energy system will likely need some new components—most likely new wiring—when reinstalled, also adding to the cost.

Rooftop solar installations continue to grow year over year. And with the extension of the federal investment tax credit for five years, expect more solar energy installations on roofs. Pair solar energy with a metal roof, and you’ve hit a sustainable “home run.”

Learn other ways to implement Net-Zero Energy strategies into your building and learn how MBCI’s products contribute.

Sustainability Begets Resiliency…In Practice

Posted on August 4, 2015 by Brad Johnson

Sustainability is the buzzword started by USGBC that is pushing us to design and build environmentally friendly buildings. And that’s a good thing. However, from a practical—and roofing—standpoint, what we can most readily do with roofs is design them to be resilient. Roof system resiliency is the tangible aspect of sustainability that the “regular” population can get their heads around. Resiliency—the ability to bounce back—is understandable.

Loosely speaking, a resilient building can withstand an extreme weather event and remain habitable and useful. It follows that a resilient roof system is one that can withstand an extreme weather event and continue to perform and provide shelter.

What makes a metal roof system resilient? It needs to be tough and durable, wind and impact resistant, highly insulated and appropriately reflective, and perhaps be a location for energy production.

An extreme weather event typically means high winds. A resilient metal roof system needs to withstand above-code wind events. Remember, codes are minimum design requirements; there is nothing stopping us from designing metal panel roofs above code requirements! If a building is located in a 120 mph wind zone, increase the design/increase the attachment as if it were in a 140 mph wind zone. And, very importantly, increasing the wind resistance of the edge details is critical to the wind resistance of a roof system.

Toughness is important. Increasing the thickness of a metal panel roof system increases resistance to impacts and very likely increases service life (of the metal panel, at least). Tough and durable seams are important, too. A double-lock standing seam is one of the best seam types for metal roofs. A little bit of extra effort at the seam can go a long way for durability, weatherproofing, and longevity.

Highly insulated and appropriately reflective are also traits of resiliency. High R-value means less thermal transfer across the roof assembly. Two layers, staggered or crisscrossed, provide a thermally efficient insulation layer. Using thermal breaks between the metal panels and the metal substructure adds to the thermal efficiency. Reflective roofs help reduce heat transfer through the roof assembly. The effectiveness of a roof’s color and reflectivity to save energy depends on many items, such as location, stories, and building type.

Enhanced wind resistance, improved impact resistance and toughness, high R-value, and reflectivity and color are passive design elements that increase the resiliency of a building’s rooftop. And let’s not forget that rooftop energy production can provide electricity to critical components of a building, such as a freezer section of a grocery store. Hurricane Sandy put resiliency on the public radar; resilient buildings are here to stay.

All Those Sustainability Acronyms Mean Something, Right?

Posted on July 7, 2015 by Brad Johnson

By now I’m sure you’ve heard about PCRs, LCAs, and EPDs. Simply put, a PCR is a set of product category rules; an LCA is a life cycle analysis; and an EPD is an environmental product disclosure. But what do they mean and what’s the purpose of it all? In the broadest sense, these are mechanisms used for the sustainability movement. The most granular is the EPD, which is a product-based discussion (i.e., disclosure) of the environmental effects caused by a specific product or product type. Architects and building designers use EPDs to compare products in order to select the most environmentally friendly products to be used in environmentally friendly buildings.

Developing an EPD can only happen after the creation of a set of product category rules (PCR). A PCR sets the rules for creating LCAs and EPDs. An example of a PCR is “Product Category Rules for Preparing an Environmental Product Declaration (EPD) for Product Group: Insulated Metal Panels & Metal Composite Panels, and Metal Cladding: Roof and Wall Panels,” which was developed by UL through the efforts of the Metal Construction Association (MCA).

Only after a PCR is developed can a verifiable LCA or EPD be developed. An LCmA and EPD are similar but different. An LCA uses industry-average data, and an EPD is specific to a product or product type. For example, “LCA of Metal Construction Association Production Processes, Metal Roof and Wall Panel Products” provides industry-average information about the environmental aspects of three key products: steel insulated metal panels, aluminum metal composite material panels, and steel roll-formed claddings. This LCA is based on 24-gauge material.

EPDs are typically more product specific. (An EPD is typically based on an LCA, so most often LCAs are developed prior to EPDs.) For example, the EPD titled “Roll Formed Steel Panels For Roof and Walls” provides similar environmental data as an LCA, but includes information about 29-, 26-, 24-, 22-, 20- and 18-gauge materials. This provides additional product specific information that can be used by designers when an industry average is not adequate. And importantly, more LEED points are garnered from a product-specific EPD than an LCA because of the specificity. LEED is certainly a driver of this!

LCAs and EPDs used in the roof industry are often focused on cradle-to-gate analysis, and exclude the use phase and end-of-life phase. Ideally, an LCA or EPD should include the use and end-of-life phases so architects and designers have a complete cradle-to-grave analysis. Without the use phase, designers are allowed to freely select the service life of a metal roofing product, for better or worse, without industry guidance. And, the advantages gained through metal recycling at the end of life are also omitted from MCA’s LCA.

It’s all about standardized disclosure of environmentally based product data.

Learn more about MBCI’s LCA, EPDs and other sustainability efforts, here.