Candy McNamee, Author at MBCI Site

Sustainability and Metal Buildings

Posted on October 5, 2017 by Candy McNamee

The movement of the construction industry to create buildings that are more sustainable throughout their life cycle continues to be a fundamental part of a well-designed and well-constructed building. This comes from the building owners who are expecting it, designers who are more skilled at achieving it, construction companies who have incorporated it into their workflows, and manufacturers who have invested significantly in it. These sustainability efforts include the design, fabrication, and construction of pre-engineered metal buildings across the country.

A number of different certification programs (LEED, Green Globes, The Living Challenge, etc.) promote and can independently certify buildings as meeting different levels of “green” or “sustainable” designs. And the recently released International Green Construction Code has been adopted by a number of localities to codify green design and construction. While the details of these programs vary, they all address some fundamental aspects of buildings, and all apply to metal buildings.

Building Site Impacts:

Shop fabrication of metal buildings means the onsite work can be focused to stay close to the building footprint. Once built, the roofs of metal buildings can further reduce site impacts. For example, metal roofs provide an excellent opportunity to collect rainwater so it can be used for non-potable purposes, such as landscaping or toilet flushing. Further, by specifying metal roofing with a high Solar Reflectance Index (SRI) value, the roofing remains cooler than a dark-colored roof and reduces the so-called “heat island effect” surrounding the building.

Reduces Energy Usage:

Metal buildings can also be designed and constructed to create an energy-efficient building enclosure. The Metal Building Manufacturers Association (MBMA) publishes an Energy Design Guide for Metal Building Systems, available at www.mbmamanual.com, which can help in the process. As MBMA points out, builders can “select the best balance of high-performance roof and wall insulation (including fully insulated metal panels), windows and doors, and foundation insulation that works best and saves the most energy and money when considering all the project requirements.” A metal building with a sloped roof can also be the ideal base to support solar panels that can provide an onsite source of renewable energy for the building to capitalize on.

Responsible Material Usage:

The construction industry has become attuned to looking at the impacts of materials over their full life cycle, and this includes the metal building industry. The MBMA has taken the lead on preparing an industry-wide Life Cycle Assessment (LCA) (http://www.mbma.com/Life_Cycle.asp) that includes primary structural steel frames and secondary structural steel (purlins and girts), along with roof and wall products used in metal buildings. MBMA has also prepared Environmental Product Declarations (EPDs) based on the LCA and industry-wide product category rules. By using this information, designers, building owners, and constructors can determine the environmental impacts of metal buildings from the extraction of raw materials through manufacturing and preparation to ship to the construction site (“cradle to gate”). The fact that steel products of all types contain a significant percentage of recycled material, and can be again recycled at the end of the service life of the building, helps present a more sustainable picture of steel than does some other building products. Further, the shop fabrication of components helps eliminate construction waste on the job site.

At MBCI, we take LEED project documentation seriously and issue only project-specific documentation for USGBC submittals, so please contact your sales representative for LEED documentation on existing contracts.

Indoor Environmental Quality:

The interior spaces of buildings are generally considered sustainable when they protect the health and well-being of the people who use the building. In the regard, metal buildings provide some advantages over others. First, many of the metal building components can be pre-finished before ever arriving at the site. This means that onsite finishing, which can release harmful volatile organic compounds (VOCs) or other substances into the air, are notably reduced or eliminated a the building location. Further, the structural flexibility offered by steel construction means that windows, doors, and skylights can be appropriately spread throughout a building to provide natural daylight and exterior views, which have been shown to have great benefits to the people who work in, visit, or otherwise use the buildings.

Overall, it is the full interaction of all parts of a building, including the owners and users of a facility, that will determine the final sustainability of any building. Nonetheless, it is clear that metal buildings can be a great place to start on the sustainability path. To find out more about metal products and systems that can help your next building be more sustainable, contact your local MBCI representative.

How Energy Codes Influence Metal Roof Panel Selection

Posted on August 3, 2017 by Candy McNamee

On a very basic level, specifiers can look at a climate zone map and get an idea of the metal roof panel best suited to a specific geographic region. The issue, however, is actually much more complex. One must know that overlooking any detail could result, not only in less-than-ideal performance, but also in costly project fail, often related to the project not meeting required energy codes or other standards. With this in mind, an important initial question to consider is how to select metal roof panels that conform to new and fast-changing energy codes and their designated climate zones.

To begin making wise considerations, the architect must know what codes are in play. For instance, is it IECC or ASHRAE 90.1? Which year of the code/standard? Are there additional local code requirements? Even if a state adopts a particular energy code, it doesn’t necessarily mean that all jurisdictions will adopt the code at the same time. Along with this, some local jurisdictions may have their own or additional requirements. To be successful, it is imperative to know what the regional project goals and requirements are. This will require research prior to specifying the metal roof panel and its assembly.

Using IECC and ASHRAE 90.1 for Energy Code Compliance

Three of the basic metal building roof panel types are single-skin standing seam, screw-down and insulated metal panels (IMPs). When using the tables in IECC and ASHRAE 90.1 for metal building roofs it must be remembered that these tables are based on single-skin standing seam roof panels and purlins that are 5′ on center. The tables provide the required R-values and/or U-factors based on climate zones, along with other assembly requirements noted with each tables. In the Appendix of some versions of ASHRAE 90.1, there are allowances for modified roof assemblies, including screw-down metal roofs.

DOE-Developed Climate Zone Map

Often, in certain climate zones, the required R-values and U-factors may be so stringent that the logical first consideration is to use insulated metal panels. IMPs are a great choice for offering high insulation properties in a top-of-the-line product and the R-values and U-factors are readily available for use in compliance calculations.

Keep in mind when deviating from the prescribed assemblies in IECC and ASHRAE 90.1, calculations will be required to show compliance, along with modeling and/or the use of approved compliance software, such as COMcheck.

Making Informed Decisions

Selecting the right metal roof panel is an important step to achieving energy code compliance. Even though energy codes can be complex and are constantly evolving, by making informed metal roof panel selections you will add to the overall success of your project.

Top Five Tips:

Know your code. Find out what energy code is required for your project.
Know your zone. Requirements vary by climate zone. Identify your project’s climate zone.
Understand your options. Deviating from specified assemblies will require approved proof of compliance.
Choose wisely. Research the properties and assembly requirements of any metal roof panel. Use this information in conjunction with energy code requirements to make wise choices.
Call with questions. Call the manufacturer with questions before you get too far down the road.

Reducing Peak Demand Costs with Cool Metal Roofs

Posted on May 9, 2017 by Candy McNamee

Among the many benefits offered by cool roofs—including a decrease in urban heat island effect or increased roof system longevity—perhaps the most significant is a reduction in peak demand energy usage which directly affects building expenses.

Peak demand is the highest point in the day at which a building draws electrical consumption. A facility’s monthly utility rates are largely determined by the power usage level at this time, so anything that can be done to drive usage down will significantly reduce utility costs. As evidenced by their test values, cool roofs are an effective way to decrease air conditioning loads during peak demand times.

Cool roof values are expressed in terms of solar reflectance and thermal emissivity. The combination of these values is used to determine how hot a surface will become by its ability to reflect solar energy and radiate heat away from itself. Cool roofsare capable of reflecting solar heat away from a building by more than 70 percent. In fact, the U.S. Environmental Protection Agency estimates that ENERGY STAR® qualified roofing products can lower roof surface temperatures by up to 50°F.

According to Jeff Steuben, executive director, and Carolyn Richter, communications manager, Cool Roof Rating Council (CRRC), in a recent Florida Roofing article, “Building occupants can experience improved comfort as compared to a conventional dark roof, as the building’s interior is subject to less thermal flux and stays cooler during warm seasons,” and, “Reduced indoor temperatures lead to energy savings from reduced cooling energy loads.”

Along these lines, contractors can also access a CRRC-provided listing of cool roof rebates, codes and voluntary cool roof programs at: www.coolroofs.org/resources/rebates-and-codes.

Cool Roofing Longevity

In addition to energy efficiency, cool metal roofs are known for extended durability and longevity, with most products offering a 40-year finish warranty.

In fact, a well-noted extensive study, Natural Exposure Testing in California, conducted by the Oak Ridge National Laboratory, found that pre-painted metal roofing maintained higher levels of reflectance, over a three-year period, due to its ability to shed particulate matter, as compared to conventional roofing materials. Further, pre-painted metal roofing has been found to retain 95 percent of its initial solar reflectance over this same three-year period.
Increasing performance and energy savings, solar reflective pigments in cool metal roofs offer higher total solar reflectance and thermal emittance, even in darker colors. With cool roof technology, the ability for the roof to store heat and radiate that heat into the building after sundown is dramatically reduced.

Heitmann Residence featuring a Cool Metal Roof

Cool metal roofs are proven to deliver environmental and performance benefits, of which the most significant to building owners is their contribution to the bottom line. Although savings will vary based upon geography, materials and insulation, the U.S. Environmental Protection Agency estimates that reflective roofs can save up to 40 percent of a building’s cooling energy costs.

When utilizing the U.S. Department of Energy’s Cool Roof Peak Calculator, contractors will discover that the total value of energy savings offered by a cool roof averages more than $1,000 annually in most climate zones for a typical commercial building. Furthermore, this applies to both cool roofing installed over both existing roof insulation and new insulation.

Proven Strategy

As established by documented study and significant heat build-up reduction levels, cool roofs are a proven strategy for supporting longer lasting roofs, reducing both utility costs and decreasing a building’s environmental footprint as Steuben and Richter conclude, “cool roofs are one of the most effective ways to obtain energy savings and environmental rewards through building envelope design and re-roofing projects.”

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®.

Urban Heat Island, Part 2: How Cool Metal Roofs Benefit Building Owners

Posted on August 22, 2016 by Candy McNamee

In our prior blog post, Urban Heat Islands, Part 1: How Cool Metal Roofs Benefit the Community, we identified the existence of urban heat islands and their contribution to higher air temperatures that are found in urban areas compared to surrounding locations. We also identified a high Solar Reflectance Index (SRI), on a scale of 0-100, as the means to specify materials that can help reduce urban heat islands and benefit entire communities. In this post, let’s focus on the specific benefits to the building owner when cool metal roofs are used.

The Boundy Residence features a cool metal roof

Energy Savings for Cool Metal Roofs

In many commercial and industrial buildings, energy use is one of the largest ongoing operating expenses, meaning that building owners and operators are usually quite interested in lowering or controlling that expense. Cool metal roofs with a high SRI rating can help with that quest. For instance, since air conditioning is commonly a larger cost that heating for many such buildings, it is a natural place to target. Lowering the temperatures at the roof means there is less heat surrounding the building, reducing air conditioning load and directly impacting energy costs.

Comfort in Outdoor Areas

Some building types, such as restaurants, retail, and entertainment facilities, rely on outdoor seating or gathering areas to support their business. If urban heat islands make these spaces uncomfortable to spend time in, the business usually suffers too. Providing these buildings with high-SRI metal roofing can improve the situation.

Long-Term Durability

Building materials can degrade prematurely if they routinely exposed to high heat. The heat can cause them to dry out, become brittle, or simply decompose faster than expected. Using high-SRI roofing is not only good for the longevity of the roofing, it can be good for the durability of the materials directly under the roof as well. Roof sheathing and other substrate materials directly in contact with the roofing receive the same intense solar radiation that the roofing surface does.

Attic spaces below the roofing plane also receive the heat, making attic temperatures in excess of 130 degrees common, causing degradation of materials in those spaces, including mechanical and electrical equipment. That could mean more expansion and contraction of connections and joints or it could mean that air conditioning duct work is being heated, contrary to the efficient operation of the system. In any of these cases, a cool metal roof will help alleviate the negative impacts of solar heat and allow materials to achieve full life expectancy.

Supports LEED Certification

In the Sustainable Sites category of the LEED rating system, Heat Island Reduction can be selected as a credit to receive either one or two points toward certification. This credit relies on both roof and non-roof strategies and looks for calculations of solar reflectance (SR) and demonstrated Solar Reflectance Index (SRI) levels on specified products.

Favorable Payback

All of these benefits above can translate to financial benefits to the building owner or operator. Any cost premium incurred for selecting a high-SRI cool metal roof can likely be realized very quickly in energy cost savings, increased business, or maintenance and durability savings. In addition, the benefits of human comfort and achievement of LEED or other sustainability goals can be realized for the life of the building.

Urban Heat Islands, Part 1: How Cool Metal Roofs Benefit the Community

Posted on August 4, 2016 by Candy McNamee

Summer in the city usually means it’s hot – hotter than surrounding areas. Those who have investigated this phenomenon have identified the presence of “urban heat islands” – places that heat up disproportionately to those nearby.

One reason for this is the predominance of dark asphalt pavement and dark-colored roofing. The significance is that dark surfaces are known to absorb sunlight and re-radiate it back as heat. That’s how thermal solar panels work, but it is also dramatically apparent when walking across a black asphalt parking lot in the summer sun. The heat is coming not only from the sun above, but from the pavement below.

If nearby buildings have dark-colored roofs, the same is happening there. Studies have shown that this re-radiated heat can build up in urban areas and raise the surrounding air temperature by up to 5 degrees Fahrenheit on average. So while it might be a tolerable 85 degrees and pleasant a few miles away, the urban core could be sweltering in a self-induced 90 degrees – even higher on those dark roofs and parking lots.

Measuring Solar Heat

How do we know what materials help or hinder these urban heat islands? First, all materials will absorb and reflect varying amounts of solar radiation based primarily on the color and reflectance of a material. The way to measure that variation is based on ASTM test standards E903 and C1549. These tests are used to determine the solar reflectance (SR) of materials, which is expressed as the fraction of solar energy that is reflected on a scale of 0 to 1. Black paint, for example, has an SR of 0 and bright white titanium paint has an SR of 1 (highest reflectance).

Reducing Heat Islands with Cool Metal Roofs

Taking things one step further, the Solar Reflectance Index (SRI) has been developed as a measure of the ability of a constructed surface, particularly roofs, to stay cool in the sun. It relies on both an initial SR value as well as a thermal emittance value being determined for a material or product. Using ASTM E1980 and values from the Cool Roof Rating Council Standard (CRRC-1), an SRI of between 0 (common black surface) and 100 (common white reflective surface) can be determined. The higher the SRI, the higher the amount of solar radiation that is reflected and thermal radiation minimized, thus creating a comparatively cool surface.

Metal roofing is particularly well suited to achieve high SRI values, minimize heat build-up, and reduce urban heat islands. Recognizing this, many manufacturers test metal roofing products and publish the SRI results, allowing professionals and consumers to make informed decisions. Of course, other roofing materials are tested for SRI values too, but few test as effectively and economically as metal roofing.

(For specific information about the radiative properties of MBCI’s colors, consult our listings in the respective databases on the CRRC and ENERGY STAR websites.)

Benefits to the Community

Specifying and building with high-SRI metal roofs has benefits beyond just the immediate building—reducing urban heat islands keeps excess heat from building up in the surrounding community too. Higher summer temperatures can be detrimental to plants, trees, and people who are outside in urban areas. By using cool metal roofs that reduce the surrounding air temperature, plants don’t lose water as quickly, people are more comfortable, and trees are less stressed. Cooler air temperatures around a building also means air conditioning does not need to work as hard or as often. That translates into less energy use and fewer greenhouse gas emissions from electricity to run the air conditioning—both of which could significantly contribute to cleaner air in the community.

Results

By recognizing the existence of urban heat islands and their impact on people and the environment, those of us in the design and construction field can choose to do something about them. By specifying and installing high-SRI cool metal roofs, the environment benefits, people benefit and our buildings benefit.

Learn more in our blog post, “Code Requirements for Cool Roofs with Climate Zone Specifics.”

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.