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Code Requirements for Cool Roofs with Climate Zone Specifics

Posted on June 8, 2015 by Brad Johnson

There is still a lot of discussion—some agreeable and some not so agreeable—about the necessary color of our rooftops. One side of the discussion revolves around keeping the surfaces of our built environment “cool,” so there’s a movement to make all rooftops “cool” by making them white, or at least light-colored. Those on the other side of the discussion claim that cool roofs are necessary to reduce a building’s energy use. Cool roofs can be a really good idea, but let’s not mix up the reasons why cool roofs matter—are we cooling the urban areas (that is, reducing urban heat islands), or are we saving energy costs for individual buildings?
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The average building height in the United States is less than two stories, but “white roofs” are mostly desired in dense, urban areas…and how many buildings here are less than two stories? Tall buildings are typically found in dense, urban areas, with shorter buildings dominating the fringe urban areas. In the suburbs and rural areas, one- and two-story buildings are more the norm. So we have a mix of building heights in the United States, but the conflict is that the “cool roof” focus is often where the tallest buildings exist.

And unfortunately, a cool roof on a 20-story building isn’t going to reduce its energy use, especially if the code-required amount of insulation exists on that roof. Rather, reducing energy use of a 20-story building hinges on the energy efficiency of the 20-story-tall walls—R-value of walls, percentage of windows, and solar blocking eaves, just to name a few items. Conversely, the energy efficiency of a one-story big-box store comes down to its roof. And for these buildings, roof color definitely can make a difference. However, our building codes don’t differentiate based on building proportions, but only on geographic location—and that’s problematic. But as designers, we can improve on the code requirements.

The 2015 International Energy Conservation Code provides specific information about cool roofs, which are required to be installed in Climate Zones 1, 2, and 3 on low-slope roofs (<2:12) directly above cooled conditioned spaces. There are two ways to prescriptively comply with this requirement: use roofs that have a 3-year-aged solar reflectance of 0.55 and a 3-year-aged emittance of 0.75. Notice that initial (i.e., new) reflectance and emittance are not specified; long-term values are more important. The second method to comply is to have a 3-year aged solar reflectance index (SRI) of 64. SRI is a calculated value based on reflectivity and emittance. It’s important to understand why a cool roof is desired and to make appropriate design decisions.

To locate metal roof products that meet the IECC requirements, go to http://coolroofs.org/products/results and use the search function to narrow your results or view our finishes’ SRI ratings on our Cool Metal Roofing page.

Part II – Transparency in Building Products

Posted on April 28, 2015 by MBCI

A huge buzzword in the building products industry these days is transparency. The green building movement, which has previously focused on high-performing buildings with a strong emphasis on energy efficiency and fossil fuel use reduction, has increasingly put its cross hairs on occupant exposure risk in the last few years. Although that change alone is probably enough to start some controversy, how this new emphasis is being implemented is really fueling the fire for new arguments. If you read our last blog, Part I – The importance of consensus in building standards, then you should be familiar with how building codes are developed in a consensus-based forum in which all affected parties have some say. However, many of the movers and shakers of the green building movement have bypassed that forum by folding the requirements they want to emphasize into voluntary programs of their own creation. At the same time, they lobby owners and building officials to carry some level of compliance to these programs, offering a benefit of being able to say their buildings or communities are “green” by displaying plaques on the façade or being listed on a website.

Although that tact seems fair on the surface, it really puts a lot of power into the hands of self-proclaimed experts to decide on the definition of “green” they want to use for their program. As we discussed in Part I, the ANSI consensus process requires policy-making organizations to transparently prove their competence in subjects they affect with their policy. Furthermore, they also have to publicly announce the formation of a committee (called a “Call for Committee”) they designate to create and maintain this policy. They must also allow members of the public to submit curricula vitae for consideration to join the committee without necessarily being a member of the organization. This introduces a mechanism to balance the power the committee is usurping by having control of the policy going forward. Unfortunately, no such mechanism exists for many of the authors of voluntary green building programs and the negative aspects of this are particularly pronounced in the area of building product transparency.

One of the most common ways green building programs administer transparency is through the use of a “red list,” which is essentially a list of banned substances. Using California Proposition 65 or Europe’s RoHS as a model, many of the NGO-based programs related to buildings have some type of requirement that aims to reduce or eliminate the use of ingredients that could possibly be harmful to building occupants. In many instances, these same NGOs offer third-party listing programs that a building manufacturer can join and have their products declared as meeting the requirements. Many people see this as a conflict of interest since an NGO, typically funded through donations, is in a position to act as a gatekeeper, allowing in only those companies or industries that support the NGO financially or align themselves with the NGO’s agenda.

But there is a deeper, more disturbing aspect: Although the list itself may start out as a publicly accepted and scientifically based enumeration of toxic ingredients, NGOs often add other substances that are not known, or in some cases, even suspected, to be toxic in order to dissuade architects from specifying certain products or deploying certain construction methods. Quite often, the NGO will develop the red list in closed discussion forums where manufacturers have no ability to provide evidence to substantiate that their products are indeed safe. At best, a manufacturer can ask the NGO to consider exceptions or modifications. But ultimately, a manufacturer has no assurance that their case has been adequately considered because they are not allowed to attend the forum. Sadly, this is what passes for transparency in green construction more often than not lately.

This lack of due process came to a head in 2013, when members of congress began to express concern that LEED, the green building program used by the military and the General Services Administration, was not an ANSI-based standard. In response, the GSA formally announced that they would take public comment on the subject and decided nine months later that they would continue to specify LEED but other ANSI-based programs would be considered going forward as well. Meanwhile, the military announced that they were developing their own standard, distancing themselves from LEED. This quelled the discussion for a while and allowed other, even hotter subjects like healthcare to take the spotlight. But concern lives on that the lack of transparency in the development of LEED and similar programs is leading the public down a dangerous, politics-as-usual road.

However, the news is not all bad. There are several organizations that use an ANSI-based process to develop and maintain their programs so that the requirements can readily be incorporated into public policy. ASHRAE, ICC, and a newcomer in the U.S., The Green Building Initiative, have all invested the tremendous amount of time and effort it takes to develop their standards in an ANSI-based public forum, and their respective programs offer a building owner or code official a great alternative to vague voluntary programs subject to interpretation by self-proclaimed experts. We will explore several of those options in our next blog.

Metal Roofs & Walls a Big Plus When It Comes to Net Zero Energy

Posted on April 14, 2015 by Amy Crenan

Kickapoo Tribe Government & Community Building features MBCI’s CF Architectural Insulated Metal Panel

Are you familiar with “Net Zero Energy?” No, it’s not that sense of power you got from using that early dial-up Internet browser of the 1990’s (The company, by the way, is still in existence, and comes up in searches for the term Net Zero. Who knew?). The Net Zero Energy I’m speaking of is the enviable, sustainable state achieved when the creation and use of energy within the same building system are equal.

Though achievable, the cost and capacity for producing energy within a building system is greater than that of creating energy efficiency in one. The good news is that metal roofing and ,a href=”http://www.mbci.com/products/wall-products/”>wall panels are extremely useful on both sides of the equation.

On the energy efficiency side, insulated metal panels (IMPs) provide roof and wall systems with the thermal and radiative performance needed for sustainable design. Insulated wall and roof panels provide continuous insulation and eliminate thermal bridges. As building and energy codes become increasingly more stringent, insulated metal panels are an ideal choice for thermally efficient building envelopes.

Baker Hughes features MBCI’s CF Mesa Insulated Metal Panels

On the other side of the equation, a common method of generating energy is through the use of photovoltaics (PVs), and metal roofs provide the best possible surface to host a photovoltaic (PV) array. Solar photovoltaic systems and solar water heating systems can be installed on a metal roof, penetration-free, resulting in high performance with minimal risk. Both the use of IMPs and the installation of PVs on metal roofs can be used with proper designs to maximize building energy efficiency.

Of course, metal roofing, known to last 40 years or longer, is the only type of roof that can be expected to outlive the PV system mounted on it, which results in virtually zero maintenance and a very low in-place cost for the roof and PV system together. A sustainability win, a durability win, and, of course, an aesthetic win. The result is anything but a zero sum game.

Find out more about MBCI’s Insulated Metal Panels

Part 1 – The Importance of Consensus in Building Standards

Posted on March 3, 2015 by MBCI

Most people understand the purpose of a building code: To ensure the safety of the occupants and to establish the minimum accepted performance level of the building and its systems. Fewer people understand that because building codes are adopted into law by a governing body, technically referred to as an Authority Having Jurisdiction or AHJ, they are an in fact an extension of the law or ordinance that brings them into effect. Knowing that, you should not be surprised to learn that like laws, building codes in America can’t just be arbitrarily made up by somebody having the authority and know-how to do so. Instead, they must have gone through some type of consensus process in which all affected entities or their representatives have the opportunity to participate. This concept, called Due Process of Law, is central to many governmental charters such as the Magna Carta and The Constitution of the United States of America and is designed to ensure that a person’s individual rights are not unfairly taken away.

Under the US Constitution, laws are written by Congress and interpreted by judges. Members of Congress are elected by their constituents and judges are either appointed by elected officials or elected themselves. Similarly, building codes are written by consensus bodies, like the International Code Council or ICC, and interpreted by Building Officials, who are generally appointed by elected officials. The code development process used by ICC is one where any interested member of the public can participate and is guaranteed a forum to propose changes and comment on the proposed changes submitted by others using a system governed by Roberts Rules of Order. After discussion and debate, the code committee votes on the individual proposals and those that pass are incorporated into the code, guaranteeing due process. (Actually, it’s quite a bit more complicated than this but for purposes of this blog, let’s just leave it at that.)

However, building codes commonly do not actually spell out all of the requirements for buildings and building systems. More and more, the code will delegate low-level detailed requirements to a different type of document called a standard, and then brings the requirements contained within by referencing the standard in the code by name. Likewise, these standards then must also be developed through a consensus process administered by an adequate standard development body. But because all standard development bodies are structured a little differently, it is not realistic to mandate that consensus process directly. Instead, another independent body called The American National Standards Institute or ANSI, certifies standard development bodies as having a sufficient consensus processes to be deemed as meeting the incorporating code requirements for due process. Examples of these bodies are the American Society of Civil Engineers (ASCE) who develop ASCE 7, the document that determines the minimum load requirements for buildings; the American Society of Testing and Materials (ASTM) a group widely known for developing material and testing specifications for general use; and the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), who develops ASHRAE 90.1, the document that spells out the minimum building energy efficiency requirements. If you are an architect or engineer, all of these acronyms should sound very familiar to you.

Another acronym that you are probably familiar with is LEED, which stands for Leadership in Energy and Environmental Design. It is developed and maintained by the US Green Building Council (USGBC) and is the premier green building program in the world. Interestingly though, the development landscape changes drastically when it comes to green construction programs like LEED. You see, the USGBC is not an ANSI accredited standard developer and thus LEED is not an actual official standard, hence the use of the word “program”. How then is it possible that USGBC can have so much say in how buildings, particularly publicly owned buildings, get built? The answer is that they get around this limitation by structuring LEED as a voluntary program and then lobbying the potential owners of buildings, like the US and state governments, into using their program by executive order rather than legislating the requirement directly. If you’ve watched TV at all in the last year, particularly with respect to immigration reform, you know how controversial this approach can be. Nevertheless, it is perfectly legal in this context.

This really has not been a significant issue to date because LEED does have a consensus process (albeit not an ANSI accredited one) and LEED credit requirements have been fairly uncontroversial in past versions. However, LEED v4, the latest generation of the wildly popular green building program, changed all of that by adding credits that are less about design and functionality of the building and more about transparency with respect to building product ingredients to ensure occupant health and comfort. Let’s be clear: Most reasonable people, including building product manufacturers, don’t have a problem with increased transparency and want more occupant comfort and health. But it is how LEED defines “transparency” in version 4 has many people up in arms and they point to the hypocrisy of developing a definition to the word “transparency” during a closed-door meeting with no manufacturers at the table as what is wrong with green building as it exists today. My next blog will explore that concept further.

Separating Fact from Fiction: Let Your Meter be Your Guide

Posted on January 22, 2013 by MBCI

Being a building scientist is kind of like being a librarian. You have to separate fact from fiction. Case in point: The Green Building Movement. I’ve been a building designer for 20 years and I have never seen the kind of change and repositioning of building science in the time that I’ve seen in just the last five years. And of course, with that come agendas, minutia, politics and confusion. It’s unavoidable. So, when people ask me about green building, I feel the duty to encourage them to stick to what is tangible and measurable and try to stay out of speculation. Yeah, ok, that’s pretty obvious advice. But it cuts deeper than that because you actually have to track meaningful, FACT-BASED metrics.

Consider the regional material credit in LEED. The purpose of that credit is to avoid burning fuel to transport raw materials to the project site. So, if the final manufacturing location of a product is within a 500 mile radius of the project and you can prove that the material used in the product was extracted and/or harvested from the earth within that circle as well, you get credit for using it. But does that truly guarantee the minimum carbon footprint? Most products used in buildings have been through a long and complex supply chain of co-mingling and transportation between intermediate points and the simplistic criterion of only considering the end points of that chain isn’t going to guarantee any level of performance, so why track the metric?

At the other end of that spectrum is energy use. This is NOT the same as energy efficiency, mind you. The definition of efficiency is the amount of work done divided by the amount of resources consumed to achieve that work. If my efficiency is 1, then I’ve wasted nothing. If it’s zero, I’ve wasted everything. It seems like a good metric to use, but it isn’t always obvious what number to use in the numerator (that’s the top number in a fraction, by the way) which makes efficiency somewhat subjective as a metric.

Electricity use on the other hand, is an absolute metric. You use electricity and have to pay for it. You have a meter to tell you how much you’ve bought. That’s a pretty convenient thing because you don’t need a fancy computer with wireless controls and bells and whistles (which use electricity, by the way) to print a graph of your electricity usage. All you have to do is get up off your derriere and look at it. (Yes, it is unfortunate that meters are outside but you need the sun exposure to produce Vitamin D anyway.)

So when it comes to things like roof top solar, the subject of my last blog, the energy you make directly offsets the energy you use. The meter “spins” slower or even backwards (net-metered solar installations use digital meters, but whatever) and at the end of the month, less electricity is used. Simple, predictable and efficient; there is no question what your impact is.

Now when it comes to energy used for climate control, you are in a quandary. The energy you use is going to be highly dependent on the outside conditions, so how do you account for that? Well, the fact of the matter is that weather, although it varies quite a bit from day to day and year to year, follows a very consistent pattern over time and some things you can do will always make a difference.

Most commercial buildings are under insulated. We know that from studies conducted over many years by the government. The reason is simple: Commercial buildings are not usually built by the electricity bill payer, so the motivation to invest in things like extra insulation and insulated windows is not there. Therefore, if you should inherit a commercial building for your business, before you move in, you should probably peel back those ceiling tiles and tap on that glass to see what is between you and the outside world.

Should you discover that you need a little extra help, there are some great products on the market these days and one of them is spray-foam insulation. However, if the building is old enough and needs a new exterior finish on the roof or wall anyway, consider an all-in-one solution like an insulated metal panel. This product combines one of the most durable exterior materials around – coated steel – and the same great insulation performance as the spray-on foams without the special equipment. Plus, the excellent air barrier performance minimizes air infiltration. And here is a tip: Roof or wall, choose an exterior color that fits your climate. Consider using lighter colors in the south and darker colors in the north. That can make a substantial difference if the building is under insulated. The poor meter won’t even know what hit it.