< Previous20Pushing the Envelope Canada• Spring 2025 FEATURE Aerogel Insulation Coating product was tested, which has a thermal conductivity of 0.044W/mK. The product also boasts anti-condensation properties and sound dampening, which increases its overall contributions to a more efficient envelope. Slentite, designed by Aerogel-it, is a ready to use rigid board insulation with an impressive thermal conductivity of 0.020 W/mK, roughly R-8 per inch. However, the product suffers from a high cost, around $36 per 10.8 inch by 14.2-inch tile, as well as being incredibly fragile. To address the fra- gility concerns, any broken samples were resecured using Tuck Tape, a practice that, through testing, showed negligible effects on the overall thermal conductivity of the material. METHODOLOGY To determine how viable both of these products would be for retrofits, mock wall assemblies were designed to simulate how aerogel products would perform as part of an assembly. These assemblies were designed to mimic common wall designs found in residential construction. Each wall was custom-made to be two feet wide by two feet tall by four inches deep to fit into the testing equipment. Two different machines were used for testing. A Fox200 heat flow meter, which is smaller and limited to only eight by eight by four inch subjects, was used mainly for quick tests of one material at a time. The second is a guarded hot plate (right), which tests the two feet by two feet frames. The guarded hot plate is the more important part of the testing as it is capable of testing large samples. The guarded hot plate works by heat- ing a hot plate in the centre of two iden- tical wall panels, which are sandwiched between two cold plates. This heat differ- ence causes heat flow to occur through the assembly, and sensors then read the amount of heat flow and return a thermal conductivity. The walls are tested under different conditions, with temperatures ranging from -15°C to 55°C, with an average differ- ence in temperature being roughly 40°C. Constructing the assemblies required special considerations to be made due to limitations in terms of depth. Because of this, two by two studs were used in place of a traditional two by four or two by six stud, as it would take up too much space, and thinner extruded polystyrene (XPS) was used when required. The following four walls were tested with the aerogel products. 1.Wall cavity with aerogel panel This assembly is to simulate a tradition- al stud cavity, albeit quite simplified, with aerogel being positioned on the inside face of the wall, which would be how more insu- lation would be added in a retrofit project for an existing wall. The wall is four inch- es thick and is comprised of the following elements: •Gypsum board (1/2 inch), •Aerogel panel (1/2 inch), •Batt insulation (2.5 inches), and •Plywood (1/2 inch). Paint on aerogel coating on a wall assembly. While aerogel is more affordable now than ever, it still has a high price tag, limiting its economic viability in residential construction. Because of this, this research group will focus on its use in building retrofits.Building Science Association of Ontario21 Aerogel Panels, used in place of rigid insulation. FEATURE22Pushing the Envelope Canada• Spring 2025 FEATURE 2.Wall cavity with XPS This assembly is designed solely to act as a baseline to compare the first wall, with all components being the same except for the XPS. The wall is four inches thick and is comprised of the following elements: •Gypsum board (1/2 inch), •XPS (1/2 inch), •Batt insulation (2.5 inches), and •Plywood (1/2 inch). 3.Roof assembly with aerogel coating The roof assembly was chosen as apply- ing the coating to the roof sheathing was one of the main usage cases advertised by the manufacturer. The roof is four inch- es thick and is comprised of the following elements: •Gypsum board (1/2 inch), •2x2 “joists” (1.5 inch), •Batt insulation fill (1.5 inch), •XPS (1/2 inch), •Plywood (1/2 inch), •Aerogel coating, and •Roofing felt paper. 4.Roof assembly without aerogel coating This roof, similar to the case of assem- bly number two, is simply a baseline for the aerogel roof (number three), as it will pro- vide a reference value to measure the aero- gel’s efficiency. The roof is four inches thick and is comprised of the following elements: •Gypsum board (1/2 inch), •2x2 “joists” (1.5 inch), •Batt insulation fill (1.5 inch), •XPS (1/2 inch), •Plywood (1/2 inch), and •Roofing felt paper. By using the results of these compacted assemblies, conclusions on the overall ef- fectiveness of the walls can be determined by scaling up the walls to match common building dimensions. RESULTS To ensure more comprehensive results, testing of each panel assembly was done in four sets of two temperatures, roughly 40 apart, increasing by 10 with each interval: from -15 and 25 at the lowest set point to 15 and 55 At the highest set point. As as- semblies were designed to have each as- sembly containing aerogel compared to a baseline assembly, the data is presented as such. The advantage of using aerogel panels within the wall cavity over XPS is clear, with the average R-value increase being 0.700. It's worth noting that the result in the first data set point we received in the compar- ison for the roof assembly was a statistical anomaly that skews the data against the ef- fectiveness of the aerogel coating. Further testing is slated to be performed within the upcoming weeks. If the first set point is included, the average R-value increase is 0.122 , whereas if the first point is excluded, that value almost quadruples to 0.483. ■ Oskar Linkruus is a third-year student in Algonquin’s Bachelor of Science, Building Science Honours program. Nicholas Asistores is a third-year student in Algonquin Col- lege’s Building Science Honours program. Both Nicho-las and Oskar have been working on this aerogel research proj- ect since September of 2024 alongside his Professor, Taofiq Al-Faesly, and fellow student, Oskar Linkruus. Dr. Taofiq Al-Faesly is a distinguished educator and en-gineer with over 30 years of experience in academia and in-dustry, and is a Professor at Algonquin College’s Algonquin Centre for Con- struction Excellence (ACCE) and a Principal Engineer at Alfa Alliance Engineering Inc. REFERENCES: 1.ThermalBlok, “What is Aerogel?” Avail- able: https://www.thermablok.co.uk/ site/wp-content/uploads/2018/03/ What-is-Aerogel.pdf. 2.RoVa Shield, “roVa Shield Insulation - roVa Shield,” roVa Shield - roVa® Shield Aerogel Insulation Coating, 2018. https://rovashield.com/rova-shield-in- sulation/ (accessed Oct. 03, 2024). 3.Aerogel Technologies LLC, “BuyAero- gel.com | SLENTITE® Aerogel Panels for Construction,” Buyaerogel.com, 2024. http://www.buyaerogel.com/ product/slentite/ (accessed Oct. 03, 2024). To ensure more comprehensive results, testing of each panel assembly was done in four sets of two temperatures.Building Science Association of Ontario23 FEATURE By Javeriya Hasan, Emily Saleh, and Terrence Holder, 30 Forensic Engineering, and Austin Todd, Evergreen Building Science Sealing the Gaps: Preventing Window-Wall Water Woes T he increasing frequency of extreme climatic events has heightened the risk of window failures. These fail- ures severely impact building performance, durability, and occupant health and bring with them significant financial costs. The 2012 Toronto’s Future Weather & Climate Driver Study shows that annual weather between 2000-2009 experienced a max- imum rainfall amount of 66 mm in one day. This is predicted to increase to 166 mm between the years 2040-2049. As this time- frame is within the expected life expectancy of current window installations, our current practices should meet future expectations. Installations that were previously adequate may now succumb to wind-driven precipi- tation, causing premature water infiltration. Investigating the causes of such failures is often challenging due to the involvement of multiple collaborators in window design, manufacturing, and installation. The failure timeline of a rainscreen window itself can range from fifteen to twenty years, depending upon the type and manufacturer’s rating and specifica- tions. However, water leakage may not ori- ginate solely from the failure of the window itself, as other factors can contribute to window failures. Understanding the causes of these failures is vital to preventing them. Other than failures originating in windows themselves, it is important to account for the influence of the interface between the window frame and the rough opening that may lead to water ingress (see Figure 1). For rainscreen wall systems, it is important to recognize that an effective drainage of water can occur only with a well-installed and integrated secondary plane at the win- dow-wall interface. INTERFACE ISSUES LINKED TO WINDOW FAILURE At the window-wall interface, prop- er installation entails ensuring the rough opening is level, plumb, and the window is sized correctly to fit into the opening with the necessary draining and sealing materi- als. A key component is the integration of flashing systems, which guide water away from the interface. Ideally first, a sloped sub-sill flashing with a back-dam is installed to prevent water from pooling at the base. Next, a jamb and head flashings are in- stalled in a shingle-lap fashion to create a continuous drainage path. The window is then set into the opening with a bedding sealant along the perimeter, ensuring a watertight seal. Internally, a low-expansion foam sealant or foam rope is applied to fill the gap and provide a bit of R-value while allowing for controlled drainage. Either an approved caulking or tape will provide the modulus needed in the transition joint al- lowing for some movement and keep water from penetrating to vulnerable areas. Proper pathways for water drainage are essential and include sill and jamb flash- ings, weep holes, or drained cavities. Weep holes may be inadvertently sealed or omit- ted due to improper sealant application, preventing water from escaping. A lack of slope or an incorrect slope in the cavity can direct water toward the interior rather than away from the rough opening. Addition- ally, failing to identify the intended drain- age plane and obstructing it with cladding construction or positioning weep holes in- correctly can prevent proper water egress. Furthermore, installation errors, such as the use of incompatible flashing materials Figure 2: An exterior view of the boom lift used to do water penetration testing. Photos and diagram courtesy of Austin Todd..24Pushing the Envelope Canada• Spring 2025 FEATURE and damaged flashing membranes, are frequently due to poor sequencing during the installation of the weather-resistant barrier (WRB). Interface components like poorly site installed heel and or toe beads foam sealants, tapes, and gaskets can lose adhesion if applied to surfaces that are not adequately prepared (see Figure 2). Differ- ential movement between the window and wall, such as frame deflection due to wind pressure, or forces in opening and shutting windows can stress the flashing membrane or seals, leading to leaks. Penetrations through the interface, for instance, a cable or pipe run beside a window, may be added after window in- stallation, causing holes to be poked in the water barrier. If these holes are not repaired with sealant or flashing, they be- come locations where moisture or water ingress can occur. Additionally, contamin- ants on surfaces (dust, wet wood, cold tem- peratures) during installation can prevent proper adhesion of membranes, tapes, and sealants, effectively nullifying the waterproofing even if installed per detail. Therefore, proper prep work is paramount. Forensic analyses commonly link win- dow leaks to incorrect flashing issues, particularly at corners and wall windows for air and water infiltration: Discrepan- cies between design specifications and construction practices, such as misaligned or mis-lapped flashing, can result in water infiltration, especially during heavy storms. If corner patches or end-dams at the sill are omitted, water can leak at the window frame corners even if the rest of the sill is flashed. Such mistakes may not be obvious after construction, since the assembly is covered by trim or cladding, allowing leaks to go undetected until damage appears later. Sometimes inconsistencies among dif- ferent construction drawings – for example, one plan omitting a flashing that another plan assumes will be there or the assump- tion that the contractor will deal with it – often lead to leakage at the perimeter once built. Design teams should perform thor- ough detail coordination or engage third- party design reviews to catch discrepancies early. For instance, the design might call for a backer rod and sealant joint around the window, but a contractor might skip the backer rod or use spray foam instead. In another scenario, a specified head flash- ing might be left out because the installer assumed caulk was “good enough.” These deviations can compromise the drainage design. Another factor is construction site er- rors, like damage to installed flashing or windows. A worker might damage the flashing membrane or WRB when install- ing adjacent materials (siding, stucco, dry- wall) and fail to ensure its repair, either out of negligence or unknowing that damage occurred. EXISTING TESTING STANDARDS In North America, two primary stan- dards are used to evaluate installed win- dows for air and water infiltration: •ASTM E783: Field Measurement of Air Leakage Through Installed Exterior Windows and Doors. •ASTM E1105: Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform or Cyclic Static Air Pressure Difference. These standards ensure compliance with performance criteria, such as air leakage and water penetration limits, as per the Canadian Supplement to the North American Fenestration Standard Figure 1: An interior view of the set up used for water penetration testing. Photos and diagram courtesy of Austin Todd.Building Science Association of Ontario25 FEATURE (A440S1-19). The ASTM E1105 test uses a pressure chamber to simulate wind-driven rain pressure, covering the entire window assembly, including joints, seals, and tran- sition areas. The pressure control system creates a static air pressure difference, for- cing water to penetrate any weaknesses. Inspectors monitor water infiltration, focus- ing on areas like corners, joints, and frame perimeters. However, these tests typically exclude the transition joint between the window and the rough opening unless pre- viously agreed on by the building envelope consultant as the transition joint would be a modification to the testing standards. As shown in Figure 1 of ASTM E783: Standard Test Method for Field Measure- ment of Air Leakage Through Installed Exterior Windows and Doors, the testing chamber is secured to the glazing compon- ent’s frame, excluding the rough opening (see Figure 3), just like it was tested in the lab using ASTM E283. Although current de- sign standards seldom specify rough open- ing performance, this compliance test veri- fies that the installed glazing meets speci- fied performance criteria. If the component fails, typically the manufacturer and/or installer is responsible for remediation to ensure compliance. This connection should resist air leakage and water penetration at the design wind loads for the region, as wind-driven rain is the primary cause of infiltration. Additionally, it should be in- stalled to meet or exceed the expected life cycle of the window component. Shifting from compliance testing to performance testing by incorporating con- struction-phase quality control of the rough opening connection (i.e. via mock-ups and oversight during construction) is a pro- active investment in a building’s durability and long-term performance. The cost of addressing air and water seals during con- struction is negligible compared to post-oc- cupancy repairs. Compliance testing mere- ly verifies that glazing manufacturers and installers deliver the specified product, while performance testing ensures the building owner is delivered a project that does not leak. However, it is also not un- common for mock-ups to be missed in the process, leading to undetected deficiencies that compromise long-term performance and necessitate costly remediation after occupancy. THE WAY FORWARD Importantly, lab ratings of windows prove the product’s capability, but prop- erly executed field installation ensures those same levels of water resistance for the building. Minimizing window failures demands cooperation among all collab- orators, including architects, contractors, manufacturers, and envelope consultants. As forensic case studies reveal that water leakage commonly results from multiple factors, particularly at interfaces with walls and roofs, pinpointing the water entry lo- cation(s) is complex due to interactions between building components, and lack of access to control layers after project com- pletion. Priority should be placed on iden- tifying interface areas and resolving poten- tial issues to prevent costly failures. From a macro standpoint, the window-wall inter- face merits special attention that should be viewed as an inherent weak spot in the building, which could lead to water intru- sion and merits special attention on getting correct from the start. As industry expectations evolve, there is an opportunity to advance standardized education on best practices. Field testing presents an avenue for learning, as it can expose deficiencies and allow them to be corrected. By demonstrating areas for improvement through field testing, trades- people not only contribute to better-per- forming buildings today but also apply this knowledge to future projects – ultimately enhancing the quality and durability of the built environment. ■ Dr. Javeriya Hasan is an Associate at 30 Forensic En- gineering, specializing in Civil and Structural Engineering and Building Science. Emily Saleh is a Senior Associate with 30 Forensic Engineering’s Civil and Structural Engineering Group, specializing in Building Science. Terrence Holder is the Technical Director of the Civil and Structural Engineering and Building Science and Building Envelope groups at 30 Fo- rensic Engineering. Austin Todd is the Founder and President of Evergreen Building Science Inc., and a building science and sustainability professional. Figure 3: General arrangement of air leakage test apparatus.26Pushing the Envelope Canada• Spring 2025 FEATURE By Julie Szabo and Jason Sanchez, Wiss Janney, Elstner Associates, Inc. Transitions T he air and water control layers are fundamental to building enclos- ure performance. Within many commonly used exterior opaque wall as- semblies, the air and water control layers are provided by a single material with a combined function, indicated as an air and water barrier (AWB). When integrating glazing into the wall assembly, transitions between the AWB and fenestration 1 as- semblies are created. It is at these transi- tions where the majority of post construc- tion issues originate. As such, these tran- sitions need to be carefully designed and coordinated during construction, since these transitions typically include the work of multiple installers. Discontinuities be- tween the AWB and the fenestration can result in air and water infiltration to the building interior. Like many building materials, selection of fenestration systems for specific wall assemblies is a process in which perform- ance characteristics such as structural cap- acity, the resistance to air infiltration, water penetration, and thermal attributes are evaluated along with aesthetics and cost. However, the integration of the system(s) under consideration with the adjacent ex- terior wall assembly is often overlooked in the selection process. 2 Once the fenes- tration is selected, the specific detailing of the AWB and fenestration transition can be complex, especially on projects where multiple types of fenestration are used. Often in the contract documents, both the fenestration assembly and the AWB are represented schematically with the specific details being refined during the submittal process when coordination between the trades occurs. Since this transition is critical to enclosure performance, the focus on integration of the AWB and fenestration should begin during design so it is not an afterthought during construction which can potentially increase time and costs. As a starting point to design and in- stall the AWB transition to different fen- estration assemblies, the function of the fenestration type, with respect to air con- trol and water management, should be understood. This will determine where and how to provide the continuous air and water seal. The continuous seal should be located at the “wet-dry line” of the fenes- tration assembly; the location of which is a function of the air and water management within the fenestration type. The following concepts should be fol- lowed to provide a continuous air and water seal at the transition between the AWB and fenestration: •Identify the available substrate for in- stallation of a continuous air and water seal, •Determine the material to be used at the transition, •Align the air and water seal at the wet-dry line of the fenestration assembly, •Confirm the access and installation method of the air and water seal, and •Verify continuity. CURTAIN WALL A curtain wall assembly is a non-load- bearing wall assembly that is hung on the Sheet metal cavity closure used to close off the wall cavity and provide an extension of the AWB to which to seal the fenestration. Photos courtesy of Julie Szabo.Building Science Association of Ontario27 FEATURE structure of the building, usually spanning multiple floor levels at a façade 3 or used in punched openings, typically in mid- to high-rise buildings. There are two main types of curtain walls; stick-built which are field constructed; and unitized which are shop fabricated in units and fit together onsite. Both types of curtain walls share the same air and water management concepts, which occurs within the glazing pocket where the insulated glass unit (IGU) is located. Water is managed in each glaz- ing pocket and is weeped to the exterior. The weeps allow air into this area. As such, the wet-dry line of a curtain wall assembly occurs at the interior edge of the glazing pocket in alignment with the interior sur- face (surface number two) of the IGU and the edge of the solid frame extrusion sup- porting the IGU. This area is commonly referred to as the “shoulder” of the curtain wall frame. It is at this location where the continuous air and water seal between the curtain wall and AWB should occur. In the most basic form, the air and water seal can consist of a sealant joint between the shoulder of the curtain wall frame and the AWB. Installation of this de- tail requires that the AWB and underlying adjacent wall assembly are in alignment with the curtain wall shoulder to provide adjacent substrates for the sealant joint. Where this alignment is not possible (or where obstructions exist limiting access), the air and water seal can be achieved by using a preformed transition membrane, sealed onto the edge of the frame inside the glazing pocket. The transition sheet material used for this purpose must be able to span the gap between the curtain wall and AWB, unsupported, and manage the expected movement at this joint. Preformed silicone sheets have been de- veloped by several manufacturers for this purpose. As with any installation, compat- ibility and adhesion of materials should be confirmed. STOREFRONT SYSTEMS Storefront assemblies (storefront) are typically used in single story, floor-to-ceil- ing applications in non-residential areas of buildings, commonly as commercial en- trances and windows. Like a curtain wall, air and water management in this system generally occurs within the glazing pocket. However, these assemblies typically use open channel frames with interconnected glazing pockets that can allow air and water within the assembly to the interior most edge of the frame. Any bulk water or moisture within this area is collective- ly drained down the mullions to a sub-sill where it weeps out. As such, the wet-dry line for storefronts is located at the interior edge of the storefront frame. Although the wet-dry line is at the in- terior (glass) side of the storefront frame, storefront frames are typically an open channel which is not designed to manage water. The AWB transition should be con- figured to close off this side of the frame and prevent air and water from entering this space from the adjacent opaque wall. This can be achieved by providing the con- tinuous seal between the AWB and the exterior edge of the storefront frame, how- ever it is dependent on the location of the storefront within the wall assembly and the type of cladding. Commonly, a closure is required, that is integrated with the AWB to align the AWB with the exterior edge of the storefront frame and provide a sub- strate for this continuous seal. SUPPLEMENTAL SEALS Redundancy of the air and water seals at these transitions can also be provid- ed. Although not performing the primary function of air and water control, a seal be- tween the fenestration frame and cladding can be provided to shed water and provide protection from bulk weather while con- cealing the primary seal. On the interior, a supplemental air seal can also be provided between the frame and AWB to prevent interior conditioned air from reaching the edge of the frame bordering the thermal break where condensation can occur. This is typically more critical in cold weather con- struction. ■ Julie Szabois an Associate Principal at Wiss, Janney, Elstner Associates, Inc., with over 20 years of experience in building sci- ence and building enclosure consulting. Jason Sanchez is a Senior Associate at Wiss, Janney, Elstner Associates, Inc., with 18 years of experience in building enclosure consulting where his work focuses on project management and technical advisement. REFERENCES: 1.Per the Fenestration & Glazing Industry Alliance (FGIA), fenestra- tion includes “Openings in or on the building envelope, such as windows, doors, secondary storm products, curtain walls, storefronts, roof windows, tubular daylighting devices, sloped glazing and skylights, designed to permit the passage of air, light, or people.” It is at the perimeter of these various elements where the transition between the opaque wall and the fen- estration assembly occurs. 2.Slaton, Deborah, and David S. Pat- terson. “Integrating fenestration with the wall: Failures.” The Construction Specifier: The Official Magazine of the Construction Specifications Insti- tute (CSI). https://www.construction- specifier.com/integrating-fenestra- tion-with-the-wall/. 3.AMAA Membrane cavity closure used to close off the wall cavity and provide an extension of the AWB to which to seal the fenestration.28Pushing the Envelope Canada• Spring 2025 By Chuck Bundrick, Tremco Construction Products Group Propelling Sustainable Building Restoration with Deep Energy Retrofits in Canada A s the global focus on sustainabil- ity and climate change intensifies, Canada is experiencing a new trend in building restoration- deep energy retrofits. Buildings are the third largest contributor of greenhouse gas (GHG) emis- sions in Canada after the oil and gas and transportation sectors. 1 Therefore, existing structures, including single-family homes, multi-unit residential buildings (MURBs) and commercial buildings, have been tar- geted for energy-conscious renovations. A deep energy retrofit is achieved when renovation activities reduce a building’s site energy usage by at least 40 per cent. 2 With legislative measures stimulating the adoption of decarbonization initiatives, local programs are incentivizing and sup- porting owners, architects and contract- ors through the implementation of deep energy retrofits. Likewise, the construction and design industries seek to ease this pro- cess for stakeholders by introducing sus- tainable building technologies that accom- plish these retrofits more efficiently. One such solution is the use of prefabricated exterior wall panels to reclad buildings with improved insulation, thermal performance, airtightness and watertightness. This article reviews the drivers behind energy performance regulations, how the built environment factors into reaching key milestones and tactics to streamline the adoption of deep energy retrofits. SETTING THE STAGE FOR WORLDWIDE ENERGY CONSERVATION AND REDUCTION Designated as a global emergency by the United Nations, 3 the pollution from greenhouse gas emissions, which include carbon dioxide, methane and other harm- ful gases, has led to substantial, often irreversible, environmental damage. In 2015, the historic Paris Agreement was ratified by world leaders at the UN Climate Change Conference to commit to collective climate action to reduce emis- sions and limit the Earth’s temperature increase to “1.5°C above pre-industrial lev- els.” 3 Today, 195 parties have signed onto this legally binding international treaty, but to attain its goals, global greenhouse gas emissions need to reach net-zero by 2050. Net-zero means cutting emissions to as close to zero as possible and substituting coal, gas, and oil-powered energy sources with more renewable energy sources, such as wind and solar. Worldwide, the Paris Agreement has triggered an increase in sustainable policies. In 2021, the Canadian Net-Zero Emissions Accountability Act went into effect “to reduce GHG emissions by 40- 45% per cent below 2005 levels by 2030 and to achieve net-zero emissions by 2050.” 1 To assist with the practical and finan- cial implications of these measures, na- tional, province and city-based strategies and programs have begun to take shape. For example, the Canada Green Buildings Strategy (CGBS), 1 the Better Buildings Part- nership in Toronto, 4 Better Homes Ottawa, 5 and Energize Vancouver 6 offer a variety of resources, rebates, grants and loans to stakeholders across residential and com- mercial buildings. HOW BUILDINGS IMPACT CARBON EMISSIONS Building renovations, especially in densely populated areas, are pivotal to reducing both embodied carbon and oper- ational carbon emissions in the construc- tion sector. The term “embodied carbon” refers to the sum of carbon dioxide emis- sions tied to material extraction, manu- facturing, transportation, and installation throughout the construction process and lifecycle of a building. ‘Operational carbon emissions’ are those generated throughout the building’s ongoing use and mainten- ance, such as from heating and cooling. While energy conservation throughout new construction is important, it has been found that retrofitting occupied buildings saves between 50 and 75 per cent of life- cycle carbon emissions compared to con- structing the same structure new. 7 In either case, tactics to reduce em- bodied carbon in building design and construction extend to reducing waste, incorporating recycled or reclaimed prod- ucts, and using low-carbon, carbon-neu- tral or carbon-storing materials. Togeth- er, the tangible improvements of deep energy retrofits can lead to dramatic urban transformation. Deep energy retrofit panel installation. Photo courtesy of Tremco CPG Inc. FEATURE Building Science Association of Ontario29 FEATURE THE IMPORTANCE OF THE BUILDING ENVELOPE IN DEEP ENERGY RETROFITS Decarbonization at the rate needed to hit the global milestones requires drastic changes to the aggregate building stock. Minor building repairs and upgrading in- terior elements, such as lighting, mechan- ical systems and appliances, are helpful, but are not sufficient to meet international standards in the given timeframe. Deep energy retrofits take a whole-build- ing lens and involve these advancements plus more extensive changes to the exter- ior shell of a building and incorporate more renewable energy sources. These adap- tations look to optimize all the structure’s unique facets, which vary depending on the building typology, location, construc- tion materials and occupancy. The goal of most retrofits is to execute these improve- ments in a short period of time to minimize the time, space, labour and money spent. Recognizing the importance of the entire building envelope as the primary barrier between the interior and exterior conditions is critical to the success of a deep energy retrofit. The external building performance impacts the ultimate effect- iveness of the structure’s internal heating and cooling mechanisms. The positive en- vironmental impacts of an energy-efficient HVAC system are essentially negated if the building envelope has significant thermal bridging and air leakage. A high-performance building envelope is dictated by numerous factors, including the wall systems’ thermal mass, quality and continuity of insulation, airtightness, and watertightness. The National Institute of Standards and Technology (NIST), in part- nership with ASHRAE, Oak Ridge Nation- al Laboratory (ORNL), and the Air Barrier Association of America (ABAA), posits that improving airtightness is one of the most cost-effective ways to decrease energy loads. 8 PANELIZED CLADDING SOLUTIONS TO SPEED ENERGY SAVINGS To alleviate the threat of wasted energy in the building enclosure, deep energy retrofits can incorporate exterior paneliza- tion for an air- and water-tight façade with increased R-value. Exterior wall panels are prefabricated in a factory under controlled settings for greater quality control, so they can be shipped to the jobsite and mount- ed on the building whenever the project is ready. The off-site assembly method pro- motes year-round restorations and mini- mizes weather-related delays. Over-clad systems, often comprised of a framing material, drainage, insulation and a durable architectural finish, can even be installed without removing the preexisting cladding. Once brackets are mechanically attached to the vertical slab in the field, the panels are ready to be hung in place. Then, installers mount and detail the window as- semblies. Expansion joints are sealed with a flexible thermal barrier which can accom- modate any slight building movement. This speed enables buildings to achieve an air- and water-tight envelope almost immedi- ately after hanging the panels. Prefabricated wall panels can eliminate harmful thermal bridging, maximize oper- ational efficiency, decrease occupant dis- ruption, and reduce on-going utility costs for the owner. The wall systems also have infinite artistic possibilities, giving architects complete design versatility to refresh the building’s appearance to the owner’s de- sired aesthetic. Next >