November 14, 2019
By Stephanie Miller
The Leadership in Energy and Environmental Design (LEED) certification has become an expectation for an increasing number of commercial projects, having grown 107 per cent since taking off in 2010. This does not mean achieving LEED certification is cut and dry. As the U.S. Green Building Council (USGBC) and the Canada Green Building Council (CaGBC) continue to grow—with registration opening for LEED v4.1 as recently as January 2019 in Canada—glazing contractors (GCs) must stay on top of this evolving sustainability guideline to serve as a knowledgeable resource for their clients.
Know the basics of the certification
The first step to moving the conversation forward around glazing in LEED is to talk the talk. For starters, it is important to understand the differences between the many green certification standards inspired by USGBC’s LEED. Programs, such as the Green Building Initiative’s (GBI’s) Green Globes Building Certification and the International WELL Building Institute’s (IWBI’s) WELL Building Standard, offer unique takes on promoting sustainability in the construction sector. They seek to address areas sometimes seen as lacking in LEED. For example, Green Globes requires a third-party, onsite assessment to ensure the building is being constructed as designed. The WELL Building Standard focuses on human outcomes—it measures and monitors features during operation that impact human health and well-being. However, LEED remains the leader in this field to date. After all, LEED has been used to certify more than 80,000 buildings worldwide since its launch in 2000, and it continues to push the conversation on sustainability to the very beginning of a building’s life cycle.
It is also important to know buildings today are certified under LEED v4, launched in Canada in 2014. Among other things, the newest iteration of LEED has expanded its focus on outcomes. The stress on performance management is one way of ensuring buildings designed to its exacting green standards continue to operate at that level. Certain project types, such as schools and healthcare, function under more stringent requirements to keep vulnerable occupants healthy.
It is advisable to keep in mind there is no LEED-certified product. The right materials can contribute to earning LEED credits that together lead toward project certification, and, in many cases—notably Energy and Atmosphere (EA) or Indoor Environmental Quality (IEQ)—glass can be suitable.
A glazing combination for every performance requirement
If there is one question architects ask GCs about glass more than any other, it is without a doubt: “How can we get better performance?”
Whether it is U-value, thermal performance, or visible light transmission (VLT), architects seem to constantly be looking to push the envelope. In many cases, these requests are driven by the stringent performance requirements for achieving LEED certification. For example, in new construction commercial buildings glazing must help to contribute to a five per cent improvement in the proposed building performance rating compared to the baseline building performance rating calculated in accordance with the American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating Engineering Society (ANSI/ASHRAE/IES) 90.1-2010, Energy Standard for Buildings Except Low-rise Residential Buildings. The standard already puts a demand on glazing, with requirements as low as 0.40 U-factor for curtain wall in the prescriptive path in certain climate zones. Those numbers must dip even lower if glazing is to be used in larger allowable ratios than those set by the standard’s prescriptive path.
CaGBC offers multiple pathways to earning LEED certification, and glass selection has a role to play in many of those choices. While it may seem factors such as clarity would need to be sacrificed to get the most energy efficiency from glazing, today’s multitasking glass products mean design professionals can bundle performance factors to earn more credits.
Perhaps the most important message manufacturers would like to convey to owners and designers is no matter the performance requirement the building team is trying to achieve, a combination of materials is available to achieve that goal. This is even true with options that once seemed to offer limited choice.
Take fire-rated glazing, for example. While yesterday’s materials may have obstructed views, today’s products can provide the National Building Code of Canada/National Fire Code of Canada (NBC/NFC)-required protection and the energy performance needed to earn LEED EA credits. The minimum energy performance will vary based on the project type and other building products used, but ultimately must contribute to either a set improvement over the baseline building performance rating calculated via a simulation, or the prescriptive provisions laid out in accordance with ANSI/ASHRAE/IES 90.1-2010.
Think of it this way: Insulating glass units (IGUs) provide optimal energy conservation, but they also offer the option of coupling different glass lites in various configurations. So, if the design team is looking to match fire-rated glazing with a specific esthetic element in non-fire-rated areas, for example, the solution may be as simple as using the same outboard lite as the non-rated sections of the building on the IGU to meet those needs.
Product manufacturers have the capability to determine how to use glass in combination with specific coatings, frames, or insulators needed to meet the performance requirements of any project.
Maximize those wide-open views
Of course, one criterion makes virtually every glass product an easy sell toward earning LEED credits and that is glass’ biggest claim to points: it provides an unhindered connection to the outdoors.
In the past, this was not always the case. For example, early fire-rated glazing was known for the distinctive patterning of wire encapsulated within the lites. The crisscross of wire sent a clear message of security rather than natural outdoor beauty. Today’s more sophisticated fire-rated glazing materials are virtually indistinguishable from standard glass in their clear appearance, yet offer code-required protection in the event of a fire.
This is good news when it comes to LEED, and its ultimate goal of creating connections to the outdoors.
On the technical side, projects achieving daylighting in 75 per cent of regularly occupied spaces (for schools, it is 75 or 90 per cent of classroom spaces) can secure points toward LEED v4’s IEQ credit. An additional point can be achieved by ensuring a direct line of sight to the outdoor environment via vision glazing between 762 and 2286 mm (30 and 90 in.) above the floor for building occupants in 75 per cent of all regularly occupied floor areas. On top of that, 75 per cent of all regularly occupied floor areas must have at least two of the following four kinds of views:
These open spaces should be paired with manual or automatic glare-control devices in all regularly occupied spaces. In layman’s terms, this means installing blinds, sunscreens, louvres, or double-duty electrochromic (EC) glazing solutions that will net the glass additional LEED points. The goal of this requirement, of course, is to ensure the incoming daylight does not impact the thermal or visual experience during times of the day when the window is subject to direct light.
What these views do on the human side is also powerful. Ample research supports the fact that a connection to the outdoors and natural lighting can boost productivity, promote healing, and improve the overall mood of building occupants.
So right away, glass becomes a valuable part of many projects. The key is simply to ensure its performance and esthetics meet the requirements set in other areas to maximize credits.
Leave no points unexplored
While performance is key, there are ways beyond EA and IEQ credits to maximize the glazing specification to earn an extra LEED point.
For starters, certain types of glazing configurations and frame designs can contribute to an improved acoustic performance. Sound reduction capacity is typically given as sound transmission class (STC) or outdoor/indoor transmission class (OITC) of the glass panels or framed glass assembly. Higher numbers mean a greater drop in decibel levels coming through the wall or window. In schools, for example, exterior windows with an STC rating of at least 35 can help designers secure an additional point closer to certification.
Additionally, glass can help the project earn points as a sustainable material. The trick is to request an environmental product declaration (EPD).
LEED v4 Material and Resources (MR) credits can be earned by specifying products containing recycled or sustainably sourced materials or are permanently installed. These products must come with an EPD confirming its sustainable life-cycle impact and has been critically reviewed by a third-party such as Underwriters Laboratories (UL) Environment. The EPD documentation relies on data gathered during a life-cycle assessment (LCA). The LCA feeds information on a number of environmental impacts of products over their life cycle into the EPD.
One might think of an EPD as a food label outlining nutrition facts—it is a transparent way of showing the consumer exactly what they are ingesting (or, in the EPD’s case, installing).
For example, a project may earn a point for using products meeting “responsible extraction criteria” for at least 25 per cent of the total project cost. Products sourced (i.e. extracted, manufactured, and purchased) within 160 km (100 mi) of the project site are valued at 200 per cent of their base contributing cost.
Then, there are the health product declarations (HPDs). They are impartial tools building owners can trust to accurately report a product’s contents and each ingredient’s relationship to the ‘bigger picture’ of human and ecological health. It defines the chemical makeup of a product to provide confidence its ingredients will not have a negative impact on the health of building inhabitants. This tool is a relatively easy way to earn points toward LEED v4’s Material Ingredients (MI) credit.
It is recommended to not make assumptions here as to what materials may earn these extra points. Standards prevent fire-rated glass from including recycled content, but in some cases, the finished units’ steel frames incorporate the necessary amount of post-consumer recycled content. For example, certain fire-rated glass products use an environmentally friendly chemical mixture that reacts in the event of fire. This can be an important differentiator for a project, and an HPD will hold all the details.
It is always worthwhile to ask the manufacturer for a list of products with EPDs or HPDs, or its take on maximizing a project’s LEED credits. After all, the extra point may be all it takes to turn a Gold project into Platinum.
Lead clients to more LEED credits
The biggest takeaway is no performance requirement (or esthetic) is off limits when it comes to glass. By understanding the variety of ways in which glass can contribute to LEED v4 credits, industry professionals can sell larger portions of their services in areas designers may not yet have considered.
Stephanie Miller leads marketing and communications for Vetrotech Saint-Gobain in North America. Miller can be reached via e-mail at firstname.lastname@example.org.
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