Promoting Sustainable Design Through Life-Cycle Assessment Applications

LCA software, in conjunction with BIM, provides greater ease in creating high-quality, environmentally responsible design

April 2017

Overview of LCA

As described in ISO14040:2006 Life-Cycle Assessment – Principles and Guidelines, LCA is “a systematic set of procedures for compiling and examining inputs and outputs of materials and energy and the associated environmental impacts directly attributable to the functioning of a product or service system throughout its life cycle.” This includes all stages from the time materials are extracted through manufacture, transportation, storage, use, recovery, reuse, and disposal.

Shown are the simplified life-cycle stages of a building.

This technique for assessing the potential environmental impacts associated with a product (or service) compiles an inventory of relevant inputs and outputs. We can think about inputs as ingredients or processes such as chemicals, energy, labor, water—everything that goes into the system. An output is something like mercury, methane, smoke, phthalates, or emissions. An environmental impact is measured according to potential environmental impact categories, such as global warming, acidification, eutrophication, smog formation, or human health impacts. The purpose of the LCA is to evaluate the potential environmental impacts associated with inputs and outputs and interpret the results of the inventory and impact phases in relation to the objectives of the study.

LCA is part of a larger framework of initiatives for reducing the environmental impact of buildings, which includes current standards such as Passive House, Living Building Challenge, and the 2030 Challenge. As energy codes become more stringent and operations-related environmental impacts drop, the demand for LCA results is increasing. Updated rating systems, such as LEEDv4, reward project teams that utilize whole-building LCA via a new Materials and Resources credit.

LCA analyzes the burdens throughout the entire building life cycle, quantifying the embodied environmental impacts of the building and its constituent materials. The quantitative data gleaned from LCA provides a basis by which architects and construction professionals can provide building owners with practical means and measures for initiating ecological building practices. As described by Kathrina Simonen in her book Life Cycle Assessment, “All building results in environmental impacts. … The challenge of developing truly sustainable or even regenerative buildings has led to a desire to understand building and construction from a systems-based perspective.” As Simonen adds, “Understanding a building or product from the perspective of its entire life cycle is the first step in developing sustainable and regenerative buildings.”

What Is LCA?

At its core, LCA is an in-depth, standardized analytical framework that allows for the quantification of environmental impacts and the comparison of design options. It is a means to study the environmental impacts on whole buildings, building products, and material assemblies. As previously mentioned, this valuable analysis calculates the direct and indirect inputs (such as energy and raw materials) and outputs (such as carbon dioxide and other pollutants) that result from a material or assembly’s manufacturing process, transportation, installation, use, maintenance, and disposal and translates those inputs and outputs into potential environmental impacts (such as global warming potential and smog).

By covering the whole life cycle of a material from the time the resources are extracted through end of use and disposal (“cradle to grave”), LCA can give a more complete picture of the total environmental impacts associated with the built environment.

Who Is Using LCA?

With environmentally responsible design becoming more prevalent in building construction, LCA is being used by architects, engineers, and contractors who want to take this awareness one step further. The deeper analysis that LCA offers allows designers to discover materials that minimize a project’s full environmental impact and evaluate the environmental consequences of specific design decisions. Additionally, because LCA can now be used to earn the LEEDv4 Building Life-Cycle Impact Reduction credit, it is increasingly being adopted or required by clients, architects, and engineers who are striving for LEED-certified buildings.

Benefits of LCA: What Can You Discover?

Building materials consume significant natural resources and energy in their manufacture and deployment. Though architects today are invested in reducing the energy used to operate buildings, few have the resources and expertise to deeply analyze the environmental impacts of their material choices. As energy efficiency becomes more and more crucial to the work of architecture—and energy codes become increasingly stringent—embodied carbon and other environmental impacts of building materials will become a proactively calculated and well-understood factor in reducing the total amount of resources buildings consume.

LCA results answer a multitude of questions that can inform material selection and major design decisions, especially when used early and often during the design process. Some examples of information that can be gleaned from an LCA include:

Does the environmental impact of cross-country lumber transportation outweigh the environmental benefits of building a wood structure in this location?
What are the major contributors to global warming potential in my building, and how can I reduce their impact?
How many kilograms of carbon emissions can I save by increasing the substitute cementitious material (SCM) in my concrete mix?
Which is less environmentally impactful if installed on my project: PIR foam insulation for XPS foam insulation?

Given the value of LCA, it is not surprising a need was identified for an automated, integrated, and streamlined LCA tool. Software products, particularly those that are Revit-integrated, have emerged to bring LCA to more users throughout the industry. BIM-integrated LCA is unique in that it allows for the generation of LCA data and feedback at every design phase, allowing users to take advantage of this early integration capability in order to answer questions like those noted above.

LCA Challenges: Process and Benefits of Using LCA Software

As we’ve discussed, quantifying environmental embodied impact typically involves performing an LCA, which can be an unfamiliar and challenging practice for many architects. Until recently, there was no efficient means to evaluate environmental impact of materials during the design and planning process, when it can have the most influence on design decisions and building performance. An architect needs this impact data at the time of material selection, but the laborious process required for calculating embodied environmental impact across a broad range of design decisions prevents this from happening at the appropriate moment in the design process.

Solution

In principle, BIM should enable architects to acquire this information. In practice, however, BIMs are intended to facilitate construction documentation, which does not require the level of detail needed for generating the accurate bill of materials required for LCA. BIM-integrated life-cycle analysis addresses these challenges by allowing users to imbue each assembly with information about the architectural products it contains. For example, a Revit-integrated LCA software quantifies embodied energy along with other environmental impacts, such as emissions to land, air, and water. It can be used for whole-building analysis or for comparative analyses of various design options, and it can account for the diverse range of material classes defined in a BIM, as well as materials that are not modeled explicitly.

Furthermore, recovering materials in a building and reusing them on subsequent projects is a valuable asset. BIM-integrated LCA software can help in that process by providing a means to quantify the recoverable materials and therefore increase the ability to reduce the negative impacts of producing new building materials.

Image courtesy of KT Innovations

LCA applications help architects integrate life-cycle analysis into design by allowing users to define relationships between BIM elements and construction materials.

While working on a Revit model, a user can define relationships between BIM elements and construction materials from the BIM-integrated life-cycle analysis tool database. These relationships are used to quantify environmental impacts across several categories, such as embodied energy and global warming potential.

Using BIM software involves a process of optioning before the building design is fixed, with the designer defining assemblies, formulating questions about materials, and evaluating a variety of alternatives. By plugging into this iterative process, BIM-integrated life-cycle analysis tools allow architects to move from rule-of-thumb calculations of environmental impact to real-time assessments at pivotal moments. The tool facilitates the process of translating Revit materials into discreet building materials and quantities; it then generates a Bill of Materials for the full building or constituent parts, automatically updating quantities as the design changes (assuming materials stay the same, other than size and shape).

Image courtesy of KT Innovations

An output report from LCA software compares the environmental impacts of two design options across several categories.

An output report then summarizes the environmental impacts of the project, according to five of EPA’s TRACI impact categories and three Cumulative Energy Demand categories. The results can be broken down by life-cycle stage, Revit category, and CSI division. TRACI is the Environmental Protection Agency’s Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts.

Once the Bill of Materials has been generated, the BIM-integrated life-cycle analysis tool draws environmental impact information associated with the manufacturing of those materials from the associated databases. It presents this data to the user—sorting, grouping, and displaying information to answer design and material-selection questions at hand. Unlike other environmental assessment tools, which tend to export data to unwieldy spreadsheets, the BIM-integrated life-cycle analysis tool allows users to produce data graphics that are readily comprehensible, transparent, and customizable. In this way, information that is normally abstract becomes very well defined, which allows for much more accurate and nuanced decision making.

Standards and Certifications

As LCAs of the built environment are accepted more and more as an element of sustainable design, most green building rating systems and schemes have incorporated LCA. It has become a given that LCA can play a big role within the overarching industry trend toward reducing the environmental impact of buildings. As previously discussed, energy codes have become more stringent and operations-related environmental impacts have dropped, thereby increasing the demand for LCA results. Updated rating systems, such as LEEDv4, reward project teams that utilize whole-building LCA via a new Materials and Resources credit. Some of the relevant standards and certifications are:

ISO 14040-14044: 2006 for LCA, which is referenced by LEED.
USGBC LEED v4: There are up to three LEEDv4 points achievable for LCA, plus an additional credit for exemplary performance and another for regional priority, where applicable. The software is an effective means of achieving the LEED credits for Building Life-Cycle Impact Reduction by leveraging the design model.
Living Building Challenge certification, provided by the International Living Future Institute, is a rigorous proven performance standard for buildings.
2030 Challenge certification, which states that all new buildings, developments, and major renovations shall be carbon-neutral by 2030.

COMMON MISCONCEPTIONS

Misconception: The impact of materials in a building is mainly in its structure.

The truth is: The impacts are widely distributed throughout a building’s envelope, thermal and moisture protection, and interior partitions, all of which can be substituted or optimized.

Misconception: The impact of materials is hard to reduce.

The truth is: It’s hard to reduce what you are not measuring. With the right methodology, reducing material impacts and scoring LEED points is easier than most people realize.

Misconception: LCA is too complex to integrate into our design practice.

The truth is: With the right tools and workflows, LCA can become as standard as energy or daylight modeling.

Image courtesy of KT Innovations

LCA results answer a multitude of questions that can inform material selection and major design decisions, especially when used early and often during the design process.

TAKEAWAYS FOR THE PRACTITIONER

Start early.
LCA are challenging and have to be done continuously throughout the whole process. To be serious about LCA requires you do it all the way through construction. This will allow you to ensure fidelity between the materials you’ve specified in order to achieve a life-cycle reduction and what actually gets built. Keeping an eye on it through the entire process (“cradle to grave”) is paramount to achieving the desired results. Also, keep in mind you are doing these assessments while decisions are being made. Something like your structural system has a huge impact in terms of your LCA and is usually a decision that is made very early on in the process; therefore, you want to make sure you are modeling those and making that decision with full knowledge of what system you’re selecting.
Keep a record.
Keep all your output reports and track performance over the entire design process to demonstrate and document your baseline performance and track the achievement of the requisite reductions for the LEED reviewers.
Experiment early and often.
Using the smallest appropriate functional unit, test different materials and design options to determine the potential for impact reduction through material substitutions, design options, and modifications before integrating the new design into the whole-building model.
Include the whole design team—not just the designer.
Effectively using the data by LCA requires the entire design team, from the client to the architect to the construction manager. Just because a design team proposes a better-performing material doesn’t mean it’s feasible. Involving the whole design team in the LCA process ensures everyone understands the information and the implications of selecting particular materials.

Case Studies

The following section provides examples that illustrate the importance of LCA, demonstrate that top architectural firms are using LCA on major projects, and highlight the magnitude of benefits realized from LCA, particularly with the use of BIM-integrated life-cycle analysis tools.

RESEARCH FACILITY AT THE UNIVERSITY OF CALIFORNIA, DAVIS

Based in California, Siegel & Strain Architects is an award-winning design firm that specializes in architecture, sustainability, historic preservation, and research. Though the firm has had a strong environmental focus for many years, it has only recently begun to use BIM-integrated life-cycle analysis tools to gain a better sense of its projects’ environmental impact, specifically carbon emissions. “We have been working to understand embodied carbon emissions since 2009,” says the firm’s founding partner Larry Strain. “We think that this LCA tool will help us achieve this understanding with a higher degree of accuracy.”

Siegel & Strain’s most complete LCA analysis was conducted on a highly insulated, high-performance research facility at the University of California, Davis. The 8,500-square-foot, zero-net-energy building was completed in 2013, but the design team decided to use BIM-integrated LCA as part of a post-building assessment to understand the global warming potential of its materials. In addition to evaluating the embodied environmental impacts of the steel and concrete that were primarily used in the building’s construction, the team also wanted to examine the long-term implications of the large amounts of polyisocyanurate foam insulation that made the building so thermally efficient and helped it achieve its zero-net-energy status. While this foam was successful in increasing the facility’s operational efficiency, the LCA report revealed a huge embodied carbon impact associated with its manufacturing process. “Looking at the project’s life-cycle tradeoffs, we are now questioning the use of such large amounts of foam to achieve net-zero-energy status,” Strain said.

Though working with a BIM-integrated life-cycle analysis tool was not Siegel & Strain’s first experience with LCA, other methods the firm used in the past came with some disadvantages. “In 1997, we hired a consulting firm to conduct an LCA of an affordable housing project we were designing,” Strain says, but he notes that “we were somewhat overwhelmed by the amount of data we received, and it was difficult to draw conclusions from the results.” To simplify the process, the firm conducted its own LCA of a town center project using the Inventory of Carbon and Energy (ICE) database. While this LCA was much more straightforward and easier to understand, Strain says that it was also “very labor intensive compared to using a BIM-integrated life-cycle analysis tool.”

In contrast, Strain explains, this automated tool provided the simplicity of an in-house LCA but with even greater utility to design than an LCA consultant. “The interface was surprisingly comprehensive and simple to use,” Strain says. “It enabled us to quickly identify objects and subsystems within our Revit model that we wished to include in our analysis and made the process of assessing the LCA data very palatable.” Strain also adds that the functionality “extends beyond merely providing a tool for itemizing building components and has proven to be a valuable design and analytical resource.”

Having used a BIM-integrated life-cycle analysis tool for a post-building assessment, Siegel & Strain now looks forward to using it during the design phase of future projects in order to make better material choices in its projects, such as a new 50-unit net-zero housing development project. Strain says, “The client has expressed an interest in having us track the embodied global warming potential for the development so that we can work toward net-zero-energy status for the full life cycle of the project, instead of just the occupancy and operations phase. This tool will help us to better understand and lower the embodied carbon emissions of our projects, and also disseminate what we learn to the design and construction industry.”

Source: Larry Strain, Siegel & Strain Architects

Photo courtesy of Siegel & Strain Architects/Jasper Sanidad

Jess S. Jackson Sustainable Winery Building at University of California, Davis

BIM-INTEGRATED LIFE-CYCLE ANALYSIS AT THE UNIVERSITY OF WASHINGTON

While constructing three new residential buildings for the University of Washington, the project’s architect of record used a custom BIM-integrated life-cycle analysis tool to better understand the environmental impacts of their design choices.

Although LCA as a technology has been available for a number of years, it wasn’t used very broadly in architecture until recently, largely because there were very few tools that were accessible or practical for designers. In the past, the architect would have used a professional-grade LCA software that, while effective, required hours of manual input. The time required to run these analyses was so great that LCA was most often used after a building was already completed.

Newer BIM-integrated life-cycle analysis tools, however, gave the architects the ability to quickly analyze the environmental implications of the different materials and designs used in the project. This ability proved especially useful during the work for the University of Washington, an environmentally conscious university located in Seattle’s temperate rainforest climate. With a project that includes three residence halls, including a dining hall, community laboratory and maker space, lounges, music rooms, and study spaces, the design team needed to figure out how to incorporate all of these features while still meeting the university’s financial and sustainability goals. To do this, the team used a real-time LCA tool to understand the impacts of their material and design decisions, and to gain a broader view of what aspects of the building were the most environmentally impactful.

For example, the team used the tool to determine that it could reduce the overall environmental impact of the residence halls by 20 percent if it used concrete with 50 percent fly ash, instead of the regional standard of 25 percent fly ash. This adjustment to the concrete mixes alone resulted in reductions across all life-cycle categories and earned the project an Exemplary Performance credit for LEEDv4 Whole Building LCA. Similarly, when deciding between three different rainscreen designs, the LCA analysis helped the architects discover that one of the options was significantly less environmentally impactful than the others.

In addition to targeting reductions that decrease the buildings’ environmental impact, the data generated also helped facilitate conversations between the architects, the university, and other project team members.

While the University of Washington project is still ongoing, its buildings are on track to receive LEED Gold certification.

Source: KieranTimberlake

Image courtesy of KieranTimberlake

North Campus Housing at University of Washington in Seattle

HOUSTON ADVANCED RESEARCH CENTER

Walter P Moore is an award-winning structural engineering firm headquartered in Houston. Understanding that creating sustainable designs is one of the foremost challenges of the building sciences today, the firm values sustainable solutions that can be integrated for high-performance buildings and infrastructure. It is this commitment that led its team to incorporate a BIM-integrated life-cycle analysis tool into the structural design process of a two-story, 18,000-square-foot office building for an independent research hub.

Located in The Woodlands north of Houston, this research facility was designed by Gensler to be the headquarters for the Houston Advanced Research Center (HARC). Because HARC works to illuminate and address problems surrounding air quality, clean energy, and water quality and supply, it’s important that its headquarters not only provide office space but also exemplify the sustainable technologies to which the research hub dedicates itself. To meet its client’s sustainability goals while also targeting a LEED Platinum rating, Walter P Moore used a BIM-integrated life-cycle analysis tool to conduct a whole-building LCA that both minimized the research facility’s embodied impacts and earned the building LEED Whole Building LCA credits.

Beginning in the project’s schematic phase and continuing throughout the design development phase, the structural design team used the LCA tool to compare different structural systems and investigate which assemblies and subassemblies were the most environmentally impactful. “Because ‘steel’ buildings contain a significant amount of concrete and ‘concrete’ buildings contain a significant amount of steel, we found that the most effective reductions occurred within subassembly optimizations,” says Dirk Kestner, Walter P Moore’s director of sustainable design. This focus led the team to an early realization that concrete and, more specifically, the Portland cement in concrete contributed most significantly to the entire building’s embodied environmental impacts. With this information in mind, the team reduced the use of concrete overall and specified that the remaining concrete should more efficiently use Portland cement. Doing so achieved more than 15 percent, 20 percent, and 25 percent reductions in the LEED categories of Smog Formation Potential, Global Warming Potential, and Acidification Potential respectively.

In addition to reducing embodied environmental impacts, the software also facilitated communication between the various groups within the project’s team. “It’s important for the full design team and the contractor to understand the LCA goals for the project prior to beginning the Construction Administration phase,” Kestner notes. Because the results are output directly into clear and legible graphs, there’s very little translation needed between different project groups. This in turn allows each of a project’s groups to have more input during the design and construction process. “It was very helpful to have a contractor involved in the schematic LCA discussions,” Kestner says, adding that its contractor’s involvement helped the entire project team “understand possible cost and scheduling ramifications.” Additionally, involving the full project team in an LCA conducted as early as possible in the design phase allows the LCA to be “routinely monitored and refined as the design progresses,” says Kestner, who also notes that contractors specifically can “ensure that the material assumptions made in a whole-building LCA are followed during procurement.”

Source: Dirk Kestner, Walter P Moore

LCA data chart from the HARC office building.

Image courtesy of Walter P Moore

LCA data from the HARC office building illustrates the relative environmental impacts of structure and enclosure assemblies of the eventual design (#2) with a baseline design. Due to poor soil conditions, the team chose a lighter structural frame, which reduced concrete volume in the foundation elements. It also optimized the concrete mix proportions for all concrete used in the project.

Key:
Yellow: Concrete
Green: Metals
Pink: Thermal and Moisture Protection
Blue: Openings and Glazing
Purple: Finishes

Conclusion

The bottom line is that people are beginning to realize that environmental impacts do not come from operations alone. As the value of LCA in the context of sustainable building practices is becoming more widely acknowledged, architects need to find the tools and resources to conduct analyses throughout the entire life cycle of a project in order to gain the greatest benefit for both the owner and the environment as a whole. If there’s one takeaway from the lessons of this course, it is the imperative architects have to influence their clients, staff, or students to care about LCA.

Resources

Cole, Raymond. “Transitioning from green to regenerative design.” Building Research and Information, 40.1 (2012): 39–53. Print.

Rowe, Jonathan. “New Tools for Whole Building Life Cycle Assessment.” Triple Pundit. 30 Oct. 2013. Web. 15 March 2017. www.triplepundit.com/2013/10/keeping-pace-speed-design-new-tools-building-life-cycle-assessment.

Robyn M. Feller is a freelance writer and editor specializing in the architecture, design, and construction industry. www.linkedin.com/in/robynfeller

Tally^® is the first life-cycle assessment application that calculates the environmental impacts of building material selections directly in an Autodesk^® Revit^® model. It has been used by hundreds of designers to conduct whole-building LCAs and build more sustainably in accordance with LEEDv4 and other rating systems. Trials are available at choosetally.com.