In researching the challenges related to sustainability and energy efficiency in the push towards carbon neutrality, it becomes clear that the solutions are increasingly complex and will require collaboration to accomplish any meaningful progress. New high-performance or net-zero buildings will not be enough to achieve the established targets. Given the approximation that two-thirds of the building area that exists today will still be in place in 2050, restoration and reuse will also be a major focus when we talk about the future of sustainable buildings.
Cover Image: Starting in March, 2010, the Alpen and Serious Energy team built a suspended coated film fabrication line inside the Empire State Building. Over the course of 8 months, the team removed and replaced all 6,514 insulated glass units from the windows (rate of 150 per night), to add a low-e coated suspended film in the center of the units to create a triple pane, low-e coated window Photo by James Hose Jr on Unsplash
Both new building construction and existing building treatments will require step-changes in operational performance and the carbon impacts of the materials used. Design, supply chain, manufacturing, and construction are all critically important and interlinked components to delivering results. Working towards these mutual goals will require education, creative thinking, and coordinated progress to implement new ideas. Importantly, the value proposition and the drivers of these innovations are also more complex now as the analysis goes beyond a simple energy efficiency v. cost calculation.
Embodied carbon vs Operational carbon
To talk about the future of building design, we must understand what metrics are being used to define targets. Historically, high-performance and sustainable design were discussed through the lens of energy performance. Energy efficiency is a key metric in creating sustainable operable buildings, but this alone is inadequate to capture all the needed gains required to achieve the Paris Agreement 2050 goals. Today this focus has heavily shifted from only focusing on building energy usage to that of energy, carbon, and waste. Since all factors are intertwined, the building’s full life cycle and circular economy should be studied. Overall energy usage from material procurement, component processing, manufacturing, transportation, delivery, installation, operating use, and disposal all need to be calculated to understand the full impact of carbon and energy and the actual impact the project has on the environment. In simpler terms, these components are being further defined and measured through the analysis of operational carbon and embodied carbon.
Operational carbon refers to the sum of carbon dioxide and other global warming gases emitted during the in-use phase of a building. These emissions are generally referred to as greenhouse gases (GHG) and quantified by their Global Warming Potential (GWP). Operational carbon is a summation of emissions from all energy sources used to keep our buildings warmed, cooled, lighted, and powered. Throughout the rest of the article, operational carbon and energy efficiency will be used interchangeably as it is unlikely to have one without the other.
Embodied carbon, on the other hand, is the total amount of emissions from energy sources during the sourcing, manufacturing, and transportation of building materials to the construction site. GWP of construction materials is reported in material Environmental Product Declarations (EPD) and is used to quantify the initial preoccupancy environmental impacts of a structure. Building restoration can have significant impacts on minimizing embodied carbon through the reuse of existing materials and minimal introduction of new building elements.
Policies are being put in place at all levels of government to regulate operational and embodied carbon in new and existing buildings. An example of operational carbon legislation is New York’s Local Law 97 which requires a 40% carbon reduction by 2030 for commercial buildings larger than 2,323 m2 (25,000 ft2). Buildings that fall within the scope and do not comply will be fined starting as early as 2024. Although it’s only implemented for existing buildings, once a new construction project is completed and occupied it falls under the existing building category.
From an embodied carbon approach, California has implemented a Buy Clean Act (AB262) which defines a GWP limit for specific building materials to limit the amount of embodied carbon that goes into new projects. The key difference in these laws as compared to other types of building regulations comes down to three significant differences. First, the laws are becoming more performance-based versus prescriptive-based. This drives the demand for solutions that measurably reduce energy efficiency and perform achieve targeted goals. Second, these laws are targeting existing buildings, rather than just new construction or when building upgrades occur, and are time-based to achieve results. Lastly, the impact of energy usage is being measured for both the building operating and embodied carbon impacts. Together, these new laws will start driving down measured carbon usage in the construction and operations of buildings.
Drivers for Collaboration
So, what are the key challenges that drive the need for collaboration? Given the design and structure of the industry and pending regulatory pressures on existing and new buildings, there certainly appears to be great opportunities for innovation and development of higher performance products. However, the glass and glazing world is complex with several interconnected sectors. The technology for high performance, dynamic, and robust solutions to these performance figures has been around for some time and market availability is being driven by efforts from all parts of the industry.
- Project Cost: To stay within budget or minimize project cost, glazing/fenestration is often designed to be code compliant but not designed to dramatically exceed code. To push higher performance products, the project cost versus the full carbon impacts needs to be understood to create a compelling use case. First, it takes education on available solutions and building owner interest to start the adoption cycle. With the adoption of high-performance glazing components comes market demand. With demand comes improvements in fabrication capabilities and increase market availability. With increased market availability comes a cost reduction. With cost reduction comes more widespread adoption of high-performance glazing components. It’s the (market) circle of life. But it takes continuous product development from manufacturers, adoption, and promotion of new products from fabricators, and willingness for project teams to design past code requirements to optimize building sustainability. Most of all it takes innovation from all sides.
- Design Impacts: In addition to the adoption of new technology, design impacts can significantly drive cost and results. For example, when moving from double to triple glaze the impacts stretch further than the addition of a glass layer. The movement to a triple IGU results in a thicker profile and larger extrusions. These changes in profile result in heavier design loads and increased embodied carbon from additional glazing materials. Moving to heavy glass units also requires new fabrication equipment and methodologies on the production side. The heavier thicker window can also impact overall window size and design, especially in operable windows. These complexities impact cost, energy efficiency, and embodied carbon demand.
- Retrofit Limitations: While the first two design hurdles apply to all construction projects, measures to enhance existing building performance can be even more limited. This can be due to several factors, such as
a. National Historic registration limits on construction,
b. Limitations of existing structural load capabilities,
c. Push to reuse existing building elements, such as sash and framing, to minimize additional embodied carbon impacts
Traditional treatments for existing buildings generally fall within two categories: 1. Adding secondary glazing to existing windows, or 2. Installing new higher performing replacement windows. While adding secondary glazing has a reduced impact on a building’s embodied carbon it doesn’t typically achieve the highest operating performance (as compared to full replacement). The typical addition of a clear lite or introduction of a monolithic Low-E product without a hermetic seal most times will not bring performance up to modern new construction standard requirements.
Alternatively, fully replacing existing windows with new, high-performance, glazing will have a significant impact on the operational performance of the structure. In doing so, however, you may require the introduction of a double-glazed system where there was not one previously. This can introduce significant embodied carbon from not only the glass itself but modifications to sash and framing.
New concepts and collaboration
The thin triple is one example of a collaborative effort that is starting to come to market. This concept isn’t new as the patent technology was created in 1991 via a group with Steve Selkowitz from LBNL. However, there are now several different market sectors and drivers helping support this technology adoption. The concept can help ease triple glazed units (TGU) into the market by creating a TGU that would fit into the existing DGU (double glazed unit) form factor. This allows you to upgrade the energy efficiency of the window without fundamentally changing the design and component elements. This allows you to maintain the same DGU extrusions and window design and only change the glazing components.
As the definitions of sustainability and carbon usage v. energy efficiency have become more complex, the potential gains and benefits of this thin triple product become more interesting as well. The primary focus of easing the adoption of a TGU into the DGU market remains clear but there are some additional benefits to now consider. For one, the embodied carbon impact scales with glass weight so using a thinner and lighter glass component creates less GWP emissions due to the lower weight. Therefore, the thin TGU design improves both the operational efficiency while also reducing the embodied carbon impact of the window design. The thinner glazing component also utilizes narrower extrusions and framing channels, which would also result in lower material demands (lower embodied carbon) from the framing design. The thinner and lighter-weight materials also potentially reduce the structural elements to support the building skin, which also has the potential to further reduce the embodied carbon impacts of the structural design. Finally, the thin triple can also be used to upgrade existing buildings where there is an outdated DGU design. Not only does this type of product then dramatically improve the operating efficiency, but also greatly reduces the embodied carbon impacts by enabling material reuse of the existing framing.
For the thin triple to be a reality, this takes an orchestrated effort from a wide variety of partners on the supply chain. NSG Pilkington has made continuous strides to bring lightweight and thin technologies to the market. The manufacturing, handling, logistics, and size components are all critical to having the right building blocks in place to create this product. NSG Pilkington has also been an innovator in such glazing technologies as vacuum insulated glazing (VIG), buildingintegrated photovoltaics (BIPV), and other technologies which help support these collaborative and performance-boosting solutions. Quanex has helped develop spacers and materials to help create and frame these new high-performance and transitional edge concepts. Alpen High Performance Products – a leader in high-performance glazing – has stirred interest in using thin glass both for the thin triple concept as well as for ultra-lightweight, high-performance secondary interior window inserts. Handling, fabrication, and manufacturing of these new high-performance products are critical in understanding the viability of thin glass use. Lawrence Berkley National Lab (LBNL) has for years been highlighting the use of lightweight, thin, non-structural layers for significant improvements in thermal performance and is now helping connect all the potential partners in this supply chain and help identify potential barriers or weak points in the supply chain that need development. Incentives for the adoption of new high-performance products have been implemented already by the California Advanced Homes Program (CAHP) and the Northwest Energy Efficiency Alliance (NEEA) which further help drive adoption.
The thin triple is a great example of innovation in the glazing world, but many other emerging glazing technologies such as vacuum insulated glazing (VIG), dynamic glazing, and power generating glazing are also making similar progress with collaborative development efforts. Once this full value creation is understood in terms of operational carbon, embodied carbon, design, project impact, and occupant benefits, these new technologies start to highlight the real potential of innovation to create solutions for the climate crisis.
Given the breadth of available technology for high-performance and/or lower carbon impact designs as well as the emerging regulatory demands on operational and embodied carbon impacts, it seems that the time is right for expanded efforts and collaboration to help commercialize these ideas. One such concept is the Partnership for Advanced Window Solution (PAWS) which is a public and private partnership made of a variety of volunteers from stakeholders in this climate change and window transformation space. Together, the group goal will be to expand these proven strategies and technologies to expand the use of these concepts. Initial efforts will focus on regional programs to help promote highly insulating windows (~R5) for residential markets, both new and retrofit, but the program can promote a wide variety of technologies that contribute to the emerging carbon savings goals.
The future of sustainable design is dependent on innovation and collaboration from all sectors of the building, construction, and design industry. As progress is made in technology developments a push for adoption is equally, if not more important. Remember those code requirements are minimum requirements; if we want to design for tomorrow’s world, we shouldn’t use today’s requirements as a threshold for optimum performance. There is room for development, adoption, and growth for everyone involved.
This article was originally published in IGS Magazine’s Summer 2021 Issue: Read the full Magazine here for more thought-leadership from those spearheading the industry
Author: Dr. Kayla Natividad
Dr. Kayla Natividad, WELL AP, LEED Green Associate has been with Pilkington North America as an Architectural Technical Service Engineer since 2016. She received her PhD in civil engineering with a focus in structures and research in glass design. Since joining Pilkington North America, a major focus of her work has been directed towards sustainability and green building initiatives. She is an active member of many industry organizations and participates in codes and standards development for North America. Kayla has and continues to promote green building through education and advocacy of glass technology.