Embodied carbon refers to the total greenhouse gas emissions associated with building materials. It accounts for the emissions released at all stages of a product’s life cycle—including the extraction of raw materials, manufacturing, transportation, maintenance, and disposal.
In recent decades, the architecture and construction industry has made great strides in reducing operational carbon—the emissions associated with heating, cooling, and powering buildings—but embodied carbon has received less attention. Reducing these “upfront” emissions is one of the most pressing challenges for the profession.
Thankfully, tools are becoming more sophisticated at helping architects make more thoughtful and sustainable material selections. One of these tools is the Tally Life Cycle Assessment (LCA) App—or Tally for short.
Whether a consultant or building owner, you may hear about the Tally when working with an architect. This article will explain the tool, its framework, and how it contributes to a building project.
What is the Tally Life Cycle Assessment App?
Tally is a tool that helps architects and engineers evaluate the embodied carbon of building materials. When integrated into the design process, it can lead to more informed decisions about materials and reduce the overall carbon footprint of new construction and renovations.
While other tools can analyze embodied carbon, Tally is the most popular. It is more intuitive than other options and integrates into Building Information Modeling (BIM) workflows.
Tally contains a database of materials and products. Designers can input relevant material quantities—either manually or by connecting with BIM software—that correspond with the database. Tally then creates a carbon impact estimate from the combined data and quantities.
This information can help designers identify high-carbon materials and explore alternative options before finalizing selections.
The TRACI Framework
To measure a building material’s total environmental impact, Tally uses a framework known as TRACI (Tool for the Reduction and Assessment of Chemical and Environmental Impacts).
TRACI accounts for several impacts, including:
- Global Warming Potential: The potential of contributing to greenhouse gas emissions, specifically CO2.
- Acidification Potential: The potential to cause pH imbalances in water.
- Eutrophication Potential: The potential for oversaturation of nutrients like Nitrogen in flora and fauna.
- Ozone Depletion Potential: The potential damage to the Ozone Layer.
- Smog Formation Potential: The potential of causing ground-level smog.
Tally accounts for each stage of a material’s life cycle. Although a finalized material may seem harmless, its production may contribute to one or more problem areas—harming wildlife habitats and human health.
The goal is to seek materials with the fewest negative impacts. Materials with multiple poor scores should be reconsidered by design teams.
Using the Tally on a Building Project
Tally gives designers the data necessary for analyzing many design decisions. It can help them understand the building’s embodied carbon footprint, the trade-offs between different material options, and the building components with the greatest environmental impact.
LEED and LBC Verification
Reducing embodied carbon through material selection is a component of building certification systems like Leadership in Energy and Environmental Design (LEED) and the Living Building Challenge (LBC).
For example, LEED projects can earn points for reducing embodied carbon below baseline standards. In these situations, Tally can help verify material choices and ensure the building contributes less harm than comparable projects.
Informing Large-Scale Decisions
While Tally can help verify choices, it is most effective when fully integrated into the design process. The tool can identify areas of improvement, helping designers make intentional changes before finalizing decisions.
Early in the process, it can help optimize building components that use large quantities of materials, such as structural systems. Wood is one of the few materials to remove carbon from the atmosphere, making it a good candidate for large-scale impact. However, more carbon-intensive systems like concrete may be necessary for certain buildings to meet strength requirements.
When materials like concrete are necessary for a building, Tally is helpful in replacing the harmful composition of the materials. Replacing Portland Cements with Fly Ash or Slag can be calculated precisely to meet structural needs and reduce impact. These useful variables can be paired with material cost and production.
This experimentation can also help with other large-scale material decisions. For example, buildings contain large quantities of insulation. Materials like Mineral Wool, Extruded Polystyrene (EPS), and Polyisocyanurate tend to have lower embodied carbon levels than materials like Expanded Polystyrene (XPS) and spray foam.
Tally can compare the environmental impacts of each option, helping clients make the most sustainable decision within their price point.
When comparing 5" and 8" joist spans, the 8" has less Global Warming Potential.
Quick Material Studies
In addition to major Schematic Design decisions, Tally can provide quick material studies later in the process.
For example, the calculator helped the Stanley Center for Peace and Security choose cladding for their new headquarters in Muscatine, Iowa. Initially, the project’s stakeholders considered many options, including a stone veneer, Aluminum Composite Panel, and wood siding. By providing an overview of the environmental impact of each option, the project’s stakeholders were able to consider sustainability alongside price, durability, and aesthetics.
From window treatments to interior finishes, every design decision has an environmental impact. Tally can help you make intentional moves at each stage of the process.
Balancing Embodied and Operational Carbon Reduction
Architecture is like baking. Each material is like an ingredient that works together to create the final product. If a chef wants to create a low-calorie dessert, she will need to assess each ingredient and find a way for them to work together.
Tally empowers design teams to achieve this goal by assessing a material’s environmental impact at each stage of its life cycle. When combined with cost assessments, it can help clients make more informed decisions throughout the design process.
This type of analysis can be as valuable as those that reduce operational carbon emissions. Ideally, the design team will find ways to reduce a building’s upfront carbon emissions while optimizing its operational performance. Learn more about operational carbon reduction by reading about performance modeling.