Pushing the Envelope Canada

< Previous30 Fall 2024 • Ontario Building Envelope Council FEATURE n n n By Dennis Anderson, National Fenestration Rating Council (NFRC) The National Fenestration Rating Council Moves to a More Practical Condensation Rating M ore than 20 years ago, the National Fenestration Rating Council (NFRC) and its membership developed the conden- sation resistance rating. While this rating was fair, accurate, and credible – consistent with all NFRC ratings – the rating only provided information to compare which products had the higher rating value. The shortcoming of the NFRC condensation resistance rating was that the value could not be used to predict the likelihood of conden- sation forming on the product based on the following factors: rela- tive humidity in the home, dew point temperature in the home, or expected exterior air temperatures during the coldest days of the year. NFRC and its membership corrected that. The approved Index (CI) allows the consumer, manufacturer, building owner, or architect to ﬁnd the fenestration product that reduces the potential for con- densation based on where that window, door, or skylight will be in the United States or Canada. In 2018, Jeff Baker shared a research study by Hakim Elmahdy with the NFRC condensation resistance task group. The paper, “A Universal approach to laboratory assessment of the condensation po- tential of windows,”1 holds the key that resulted in the new NFRC Condensation Index (CI) rating. The CI rating provides the point at which the window will potentially form condensation. This allows the end user to determine the minimum CI rating needed to reduce the likelihood of condensation forming, using Table 7-1 (to the right) from the NFRC 501-2023: User Guide to the Procedure for Determining Fenestration Product Condensation Index Rating. The desired rating for a speciﬁc city or region in North America can be determined with two of the following three indicators: the winter design temperature, the relative humidity (RH%), or the dew point temperature. DOES THE INDUSTRY NEED ANOTHER CONDENSATION RATING? Our stakeholders have asked this question many times and we have all worked together to align our methods. The new CI rating is now active and provides more value and ﬂexibility for product designs than the legacy NFRC Condensation Resistance rating (sometimes mistakenly referred to as “CR”). NFRC has also worked with the CSA Group, formerly the Canadian Standards Association, to publish a revised the CSA A440.2/.3 in October of 2022 to add the ANSI/NFRC 500 simulation method for CI, which aligns with NFRC’s and CSA’s computer simulation method for a condensation index rating. NFRC also participates in a task group at the Fenestration and Glazing Industry Alliance (FGIA) to potentially add a condensa- tion index value via a physical test to the current AAMA 1503-09 test method that will also align with the ANSI/NFRC 500 tested condensation index rating. That the three leading North American fenestration standard organizations are working together to alleviate any confusion or Figure 1: Table 7-1 Winter Design Temperature and Condensation Index. Graphic courtesy of Dennis Anderson.Pushing the Envelope Canada 31 n n n FEATURE concern with multiple condensation test methods and values is a good thing. In August 2020, NFRC held a webinar titled Understanding the New NFRC Condensation Index 2 that provided details for the prac- tical use of the rating and offered insight into how the ratings from other organizations differ from each other. Another source of information is the Condensation Resistance Task Group page,3 which includes links to the original paper by Ha- kim Elmahdy, research documents, and other information. Den- nis Anderson, NFRC’s Senior Manager of Programs spearheaded this rating and can be reached at danderson@nfrc.org for more information. n Dennis Anderson is the NFRC Senior Programs Manager. REFERENCES: 1.National Research Council Canada. “A Universal approach to laboratory assessment of the condensation potential of windows.” Government of Canada. https://nrc-publications. canada.ca/eng/view/object/?id=ec8e38b6-41e4-4fdd-a02e- 4e01a7bcbef1. 2.The National Fenestration Rating Council. “Understand- ing the New NFRC Condensation Index Rating.” YouTube. https://www.youtube.com/watch?v=dBTN-mzWkxA. 3.National Fenestration Rating Council. “Task Groups: Conden- sation Resistance.” https://nfrccommunity.org/group/CRTG.Pushing the Envelope Canada 33 n n n FEATURE Shattering Glass: Unveiling the Hazards By Adam Hosny, Capacity Engineering Limited I was recently involved in a Forensic En- gineering engagement regarding the in- vestigation of a 55-storey building where more than 15 insulated glazing units (IGU’s) spontaneously shattered. As Professionals we must recall that the Engineer shall regard the practitioner’s duty to protect the public welfare as paramount. As you can imagine, glass falling from 50+ storey height poses a substantial risk to pub- lic welfare. When public safety is at risk, it is crucial that you work with the Authority Having Jurisdiction (AHJ) to ensure any ne- cessary measures are immediately taken to protect the public. IGU’s in curtain wall assemblies serve multiple purposes, and their design and in- stallation are governed by the Ontario Build- ing Code (OBC) as follows: 1.The design of the window to take en- vironmental loads are governed under Part 4 of OBC 2012 “Structural Design.” 2.Additionally, windows (mainly curtain walls and window walls) at the edge of a buildings slab act as a guard rail and must resist guard loads where glass is located under the minimum height requirement. Thus, they are also governed under Sup- plementary Standard SB-13 “Glass in Guards.” 3.The window acts as an environment- al separation and the design is also governed by Part 5 of OBC 2012 “En- vironmental Separations.” Part 5 also refers the designer to Part 4 of the OBC for environmental load calculations. 4.Additionally, the curtain wall is subject to testing under the North American Fenes- tration Standard/Speciﬁcations (NAFS) for Windows Doors and Skylights and Nickel Sulphide Inclusions in Glass and Canadian Regulations The unique butterﬂy crack shatter pattern is an indicator of the NiS failure.34 Fall 2024 • Ontario Building Envelope Council meet the requirements of CSA A440S1. This testing is intended to ensure that the windows meet structural performance re- quirements as well as control of air leakage, condensation and rain penetration. 5.The installation of windows are governed by CSA A440.4 “Window Door and Skylight Installation.” There are several factors that could cause glass in curtain walls to break. In some cases, it could even be a combination of several fac- tors. Some factors include: •Environmental loading: Excessive wind loading. •Size: Columns shorten under axial load over time. If not properly considered, the shortening of the building can compress the curtain wall frames and shatter the glass. •Size: Breakage due to excess temper- ature change and lack of expansion and contraction constraints. •Size: Edges of glass being damaged. •External impact: Sudden impact loading such as bird strike, debris, etc. •Nickel sulphide inclusion: An impurity in the material that occurs during the manufacturing process. While each of these factors must be ex- plored, this glass breakage was most likely due to the occurrence of nickel sulphide in- clusions (NiS). WHAT IS NICKEL SULPHIDE INCLUSION (NIS)? To properly understand NiS, it is im- portant to understand the process of manufacturing tempered glass. To produce tempered glass, annealed glass is heated to a temperature of ~600°C, then quenched. High-pressure air blasts the surface of the glass to cool the outer surfaces rapidly relative to the center. As the center of the glass cools, it tries to pull back from the already cooled outer surface. This causes the center to remain in tension with the outer surfaces having a counterbalancing compression stress. After tempered glass is formed, the stress proﬁle through the thickness of the glass becomes parabolic as seen in Figure1. With the original Annealed Glass, there is a possibility that a nickel sulphide stone forms in the tension zone due to nickel contamination. These stones can vary in size from 0.05 mm to 0.1 mm. When the resultant tempered glass exposed to varying temperatures in the ﬁeld, the NiS inclusion changes in size and can grow such that inter- nal tensile stresses exceed the counterbalan- cing compression stress and shatter the glass. The highest risk of occurrence is in the ﬁrst 10 years of the tempered glass life. The event is loud (shatters at the speed of sound), with the light breaking near instan- taneously into thousands of tiny pieces. HOW TO DETERMINE A NIS FAILURE If a light shattered due to NiS inclusion, there is often a tell-tale: “The Butterﬂy Ef- fect” or a “Butterﬂy Pattern.” The Butterﬂy Effect is the phenomenon that the world is interconnected such that one small occur- rence can cause major consequences in a FEATURE n n n Shattered glass due to a nickel sulphide inclusion failure. Photos and graphics courtesy of Adam Hosny. Figure 1: Tempered glass formed through the stress proﬁle of the thickness of the glass, which becomes parabolic.Pushing the Envelope Canada 35 n n n FEATURE much larger, complex system. Similarly, we often invoke St. Venant’s Principle: local vs. Global effects. One must consider the local aspects of a structure as well as the global; both must be carefully considered. With respect to a NiS failure, the Butter- ﬂy Effect yields the Butterﬂy Pattern. A small (0.05 mm to 0.1 mm) NiS inclusion causes the failure of the entire IGU. Ironically the ori- gin of the glass failure resembles a butterﬂy. The fracture starts with a small straight line, then branches out on each side and continues to branch repeatedly in a chaotic manner. This unique shatter pattern provides strong evidence of NiS. With reports of a loud bang, it is near deﬁnitive. Best practice is to conﬁrm NiS through laboratory testing. HOW DO WE PREVENT THIS ISSUE? Prevention may not be possible. Risk of NiS breakage may be reduced through heat soak testing. This involves sustained heating of the tempered glass to between 200°C to 300°C. This test accelerates the growth of the NiS inclusion in attempt to purposely shat- ter the glass. While expensive, this has been showen to signiﬁcantly reduce the risk of NiS induced breakages. Currently there is no North American standard for heat soak testing, however, in- dustry best practice and SB-13 requirements are to perform the heat soak test to the European Standard EN 14179-1. HOW DOES OUR CODE ADDRESS THIS ISSUE? Prior to the 2012 OBC, buildings in Ontario were allowed to employ simple tempered glass IGU’s. This changed after several high-proﬁle failures from 2010-2012 in Toronto caused the Ministry of Municipal Affairs and Housing (MMAH) to act. The MMAH studied the issue through industry engagement and released Supplementary Standard SB-13. The objective of SB-13 is to provide re- quirements for the design and construction of glass in guards and reduce the probability of breakage of glass panels and injury to per- sons in the vicinity of a building as a result of failing broken glass. The requirements of SB-13 is now listed in Figure 2. This table under SB-13 provides require- ments in Ontario that all glass near the edge of a buildings slab be heat strengthened laminated or heat soaked tempered. CEL was involved in the forensic investi- gation of the high-proﬁle failures in Toronto which caused MMAH to develop this sup- plementary standard. The simple truth is that at the time of construction, the tempered IGU panels met all OBC requirements. It is the failure of the code to address a serious concern which lead to SB-13. IGU’s and curtain walls are an evolving area of professional practice for Engineers and Architects. As research progresses, so must our Code evolve. The main objective of the Code, as set out in Division A, Part 2, is to limit the probability that as a result of de- sign or construction, a person in or adjacent to the building will be exposed to unaccept- able risk or hazards. We, as Professionals, must continue to advance the profession with our knowledge and expertise to further protect public safety. n Adam Hosny, M.Eng., P.Eng., is a Structur- al Engineer & Partner at Capacity Engineering Limited. His practice focuses on Structural Engineering with a special interest in Building Envelope design, failure diagnosis, and testing. In his role at Capacity Engineering, he is re- sponsible for structural and building envelope forensic investigation, structural design, and is the lead engineer on Tarion RB 19R reviews. Figure 2: Table 2.1.1.1 of Ontario Building Code SupplementaryStandard SB-13 “Glass in Guards.” TABLE 2.1.1.1. SELECTION OF GLASS IN A GUARD FORMING PART OF SENTENCE 2.1.1.1(2) Location of Glass in a GuardType of Glass Required Glass located beyond the edge of a ﬂoor or within 50 mm of the edge of a ﬂoor. Heat strengthened laminated glass. Glass located more than 50 mm inward from the edge of a ﬂoor. Heat strengthened laminated glass. Heat soaked tempered glass. Glass located more than 150 mm inward from the edge of a ﬂoor. Heat strengthened laminated glass. Heat soaked tempered glass. Tempered glass not more than 6 mm thick. Column 1236 Fall 2024 • Ontario Building Envelope Council FEATURE n n n By Nensi Baboci, RJC Engineers Beyond Electricity: Application of Copper Alloys for Dome Roof Construction C opper dome roofs are among some of the oldest rooﬁng systems employed in historic and modern building con- struction. The use of copper in rooﬁng dates back to the original Pantheon constructed circa 27-25 BCE in Rome, Italy and has since been employed on various monumental and heritage buildings around the world. The Holy Trinity Russian Orthodox Church in Toronto, Ontario, is a unique local case study where this historic rooﬁng material was used to rejuvenate a city landmark. The church was originally constructed in 1922 as a Jewish Synagogue by Architect Benjamin Brown in the Romanesque archi- tectural style and was partially reconstructed in the Russian Orthodox style between 1966 and 1969 and listed as Heritage Property in Toronto in 1973. There are also two small wood-framed towers at the northwest and southwest corners of the building that employ a painted lead-coated copper cladding and are complete with two small copper domes each approximately 160 square feet in size. The main roof features a large central wood- framed copper dome roof of approximately 1,500 square feet that extends beyond the center of the main low-slope roof. An evaluation of the existing rooﬁng sys- tems revealed the existing copper rooﬁng ap- peared to be of original construction and had reached the end of its service life. The pro- ject team recommended wholesale rooﬁng replacement of both the low-slope rooﬁng systems and the copper domes with proﬁles matching existing to keep the heritage deﬁn- ing character of the building, and design was started. One of the design considerations of cop- per rooﬁng was the tendency of the thin copper sheets to buckle when they are com- pressed and result in what is known as oil can- ning of the copper sheets. This phenomenon, which is common to all crafted metals, can occur due to a combination of many factors, which cannot be controlled at any period, but View of tie-in detail at the bottom of the dome to permit future low-slope roof replacement. Aerial view of the main roof and two west towers at Russian Holy Trinity Orthodox Church during the construction of the central copper dome. Photos courtesy of RJC Engineers.Pushing the Envelope Canada 37 n n n FEATURE can be reduced with proper design consider- ations and the employment of knowledge- able heritage restoration contractors. Copper is known for its high resistance to corrosion due to its ability to reach weath- ering equilibrium by forming a patina layer when it encounters weathering agents, which, over time, give it its well known-green color- ation. This allows the copper to maintain a long service life with relatively low-mainten- ance compared to modern membrane-type rooﬁng systems. One of the design challenges of this pro- ject was to ensure that the transition between the bottom of the copper dome to the low- slope roof below would permit future low- slope rooﬁng replacement. The intent of the design was to allow low-slope roof replace- ment without having to modify any parts of the copper dome, while providing sufﬁcient clearance for future increase in the low-slope rooﬁng insulation levels. In addition, given the ability of copper to react with dissimilar metals, it was important to select the proper ﬂashings during the design of the tie-in detail between the roofs. The design of this project utilized thinner and more malleable copper sheets to con- struct the more elaborate decorative elements of the central and tower domes, compared to the thicker and heavier sheets used for the construction of the primary dome roof- ing systems. In addition, copper alloys, such as lead-coated copper (LCC), were used in applications where the client preferred the long-term appearance of the copper to re- semble the color of lead (dark grey) and in applications where the client planned to paint or coat the copper in the future, as LCC often does not require additional surface treatment prior to coating. Consideration for underlay- ment membrane products and detailing was also of high importance, as copper roofs can reach high temperatures which can readily de- grade typical rooﬁng membranes. Copper dome roofs provide long-lasting protection and beauty to heritage buildings. It is critical to have a good understand- ing of the material properties, installation methods and design challenges of copper dome rooﬁng systems as well as employ knowledgeable craftsmen to ensure they are properly installed for long-lasting per- formance. n Nensi Baboci, B.A.Sc., M.Eng., P.Eng., is a Project Engineer at RJC Engineers. Overview of completed central copper dome. View of thick copper sheets at the central copper dome during construction. View of hand seaming underway during construction. Copper dome roofs provide long- lasting protection and beauty to heritage buildings.38 Fall 2024 • Ontario Building Envelope Council FEATURE n n n Siloed Codes and Siloed Design: What is Most Important? By Anton Van Dyk, Layton Consulting H ave you ever had an argument or debate with someone on what is most important? Have you just gone around in circles getting nowhere as you both saw your bias as most important? A few yeas ago I was introduced to a “context” exercise. It was designed to bring awareness that with the lack of context both can be right and both can be wrong. The exercise uses fruit. By ask- ing “what is the best fruit?” you can get a plethora of answers and a debate will ensue. Now if I ask, “what fruit has the most vitamin C?” it will narrow the answer down and reduce the overall debate to the facts. You’d be surprised to ﬁnd out that it isn’t orange or lemon, but guava! Now let’s bring this idea into our industry. If I asked “What is a high-performance window?” I would get Passive House, U0.8, U1.22, triple glazed, low SHGC, high SHGC, OITC 35, PG50, Class CW, tilt and turn, casements vs. sliders, European product, and the answer just kept ﬂowing. The issue was, I put no context to the question. What that did was gave me a perspective of what the individuals in the audience determined what was most important to them. My goal was to ﬂush out the bias in the room. With this in mind, I started to see natural trends pop up in other meeting with manufacturers, designers, and regulators. What every- one felt was most important would dominate the situation and in some cases at a negative outcome to another individual needs. We were having a “best fruit” debate about building materials. So, I started to call this Siloed Design or Siloed Codes. This is where an individual ampliﬁes what they feel is most important in the moment without understanding the impact of another individuals needs. Like in any relationship, give and take is fundamental. Without empathy, you are going to struggle to get your point across. As more and more regulators adopt “climate emergency” policy into codes and standards, you will see a trend in codes move in this direction, but at what consequence. Two good examples that I see too often is when an acoustic design for windows demands a ¾ inch to 1 inch air space in the insulated glazing unit (IGU). This will introduce convection currents in the air space resulting in a reduction in U value performance. Maybe to a level that no longer applies to the Step/Tier code. When you renovate a window from double to triple glazing, the sash size may be reduced due to weight limits for durability on hardware and the operable window no longer meets egress. In this case, an individual must determine what is most important: energy or life safety. For some this might appear obvious, but I have heard Pushing the Envelope Canada 39 n n n FEATURE individuals say the “climate emergency” is also life safety. There is no simple answer other then recognizing ﬁrst that there are multiple needs to be met. Another example is when regulation and/or design pushes you into a high-risk environment. For example, the move towards project speciﬁc thermal modeling for more accurate U values and solar heat- gain coefﬁcient (SHGC) ratings is trending for total home energy cal- culations. This is a move away from standardization using the Nation- al Fenestration Rating Council (NFRC) or the Canadian Standards Association (CSA) rating for a manufacturer. Now their outcomes in performance must be calculated for each project. This will put risk onto a manufacturer that they meet the actual targets they are not used to providing as the industry has functioned using standardization such as NFRC values performed by a lab. The other high risk that this triggers is a contractual risk. When you move away from standardization in performance metrics such as NFRC, a manufacturer will need to provide a product cost that meets a project speciﬁc outcome. The question is, when is this calculation done, before a contract is signed or after? In theory, this needs to be done before, but that will add signiﬁcant costs to the estimating process, driving up overheads and increasing construction costs. Or it can be done after a contract awarded, which brings on risk in the event that the manufacture cannot hit the project speciﬁc outcome with their frame and glass features. The third example is a recent one where I was asked to review a new “wildﬁre reliance” code that would be implemented in regions at risk of wildﬁre. When I saw the fenestration section, I realized very fast that the product they were requiring to be used, would strug- gle to meet the U value requirements that the building codes were mandating. The new debate is fall production vs. egress. This one is still being debated at a high level and as it comes with the risk of people falling out of buildings and people not being able to escape from a building in case of ﬁre, you can see how hard this decision is. These are just a few examples of why any change in how we func- tion as an industry needs a full spectrum assessment of all impacts. We cannot take what is most important to one individual and run with it. Like any change in any business, knowing its impact on people and the overall community is step one. My goal in the industry is to be the voice for the integration of what is required and to assist with how the decision is made on what is most important. We cannot ignore one issue for the beneﬁt of another so all we can do is be educated on their impacts and use this to make good decisions as a team. This is why I stress importance on knowing the code and how to use the code to make decisions. n Anton Van Dyk has over 25 years of building envelope related consulting and construction experience which includes consulting on multi-million dollar building envelope rehabilitation projects on exist- ing occupied buildings and small scale repairs. New construction ex- perience consists of mixed use wood and concrete frame construction for low and high rise buildings along with specialty projects such as an addition to a library, and the design of a modern performing arts centre. As Building Codes have evolved at a rate faster than ever, Anton's cur- rent focus is assisting fenestration manufactures, speciﬁers, and install- ers understand the paths of code compliance in British Columbia and throughout North America. Anton has worked with multiple window and glazing products ranging from curtain wall, window wall, storefront, ﬁberglass and vinyl tilt-and-turn, and common nail-on ﬂange windows. He has helped develop window testing protocols and is actively involved in the ﬁeld testing of windows. We cannot take what is most important to one individual and run with it. Like any change in any business, knowing its impact on people and the overall community is step one. Next >