DEVELOPMENT OF CECC BASELINES

In the context of this article, benchmarks are defined as future targets based on baseline embodied carbon emissions of a certain year, in this case 2020. Benchmarks can be derived for a given year based on a chosen carbon budget and a mathematically defined relationship of the baseline and budget. Benchmarks are not set in this article.

The Colorado Embodied Carbon Collaborative (CECC) has been working on a method to determine the embodied carbon intensity of certain building-use types based on modeling the basic building systems (structure, enclosure, interiors, MEP, FF&E) using an empirical approach (site system excluded at this time). This approach was chosen after attempts to reconcile the wide range of LCA-derived baselines and benchmarks provided by others, which are dependent on the building scope chosen, life stages considered, and the consistency of modeling across the buildings in the data set. The building information model (BIM) approach will ultimately provide accurate baselines when a sufficient number of accurate models have been built and analyzed. Our intent for this empirical approach to provide logical baselines now that can be gauged against baselines and benchmarks provided by others with different combinations of building scope and life cycle stages. At this time our approach is limited to 12 common building use types meant to represent a large percentage of buildings built today.

The embodied carbon intensity values from our recently completed V1 (April 2025) of this approach have been compared against the current results from two organizations, Perkins&Will, and the Carbon Leadership Forum with general agreement of the results. The baselines proposed are an aggregation of the findings of Perkins&Will, The Carbon Leadership Forum, and CECC.

In order to understand the context of this comparison, it is important to understand the basic assumptions and methods of each. Here is a brief description of each of the three sources, starting with the apparent or actual target setting goal of each source. Both external sources used have broad scopes of work in their articles and these descriptions of their work focus solely on embodied carbon intensity.

1. Perkins&Will, Embodied Carbon Benchmarking Report, 4/22/2025

Apparent target setting goal: To report results of LCAs performed by Perkins&Will. To provide 25th, mean, and 75th percentiles for Structure + Enclosure scope.

Perkins&Will collected LCAs for “over” 89 projects representing 14 building use types from across the United States and Canada. Their methodology is aligned with the CLF Benchmark Study V2. The data includes new construction, building reuse, core & shell, and varying scopes of interior fit-out, and is based on life cycle stages A1-A3.

2. The Embodied Carbon Benchmark Report, April 2025

Apparent goal: To establish reference values of embodied carbon emissions at three quartile levels (25th, 50th, and 75th) for use by firms and agencies to set targets and to compare their results against.

“This report establishes benchmarks and investigates trends in whole building life cycle assessment (WBLCA) through a sample of real-world building projects that were sourced from design practitioners through a rigorous data collection process…. The dataset includes the WBLCA results of 292 buildings in the US and Canada.” It is our understanding that some or all of the Perkins&Will buildings are included in the CLF dataset. Embodied Carbon Budgets (ECB) at the 25th, 50th, and 75th percentiles of the buildings are presented as choices for agencies to use. The term “benchmarks” is used to represent these ECBs. The report also defines benchmarks as reference points against which comparisons can be made. “Baselines are not addressed in this report.” It is important to note that the 292 buildings were designed and built over a range of years starting around 2018.

3. Colorado Embodied Carbon Collaborative (CECC) Baseline Model V1, April 2025

Goal: to establish Embodied Carbon Intensity baselines (2020) for use by our CECC members and other interested firms, and to then develop benchmarks to meet the embodied carbon in buildings’ share of global average temperature targets.

4. Comparison of methodologies used - the chart below summarizes the key aspects of the three sources.

5. Physical Scope

* Scope of fit-out varied by project

**Inclusion of casework unclear

***Casework excluded

6. Life cycle stage reported