Automating the calculations of embodied carbon lets users early in the design process consider the LEED Pilot Credit for Procurement fo Low Carbon Construction Materials for LEED BD+C: New Construction. The goal is to provide a common method for calculating the building embodied carbon intensity and encourage the reduction of embodied carbon for new construction. The requirements and associated points are below. This article discusses the method for calculating the whole building embodied carbon intensity with cove.tool and how to show the reduction for LEED. A more detailed description and documentation provided by LEED.
LEED BD+C - MRpc 132
1 point - Low Range Reduction of 0-30%
2 points - Mid-Range Reduction of 30+%
The project team must provide a Building Embodied Carbon Intensity (bECI) Report to be awarded the pilot credit, which includes the following:
- Material embodied carbon intensity baselines (mECIb)
- Actual material embodied carbon intensities (mECIa) for all included material categories as a table.
- Building Embodied Carbon Intensity Baseline (bECIb)
- Actual building embodied carbon intensity (bECIa)
- Embodied Carbon Intensity Reduction Percentage
Example Reports provided by the USGBC.
Analysis during design should be used for guidance purposes to reduce the embodied carbon value of the final design. cove.tool can help automate the calculation totals for each of these items and establish a baseline specific to your project.
- The material baselines (mECIb) published by the Carbon Leadership Forum (CLF) and are provided for common materials in our article on how to approach embodied carbon reduction.
- The initial whole building analysis can be used as the project building embodied carbon baseline (bECIb) for comparison throughout the design process. This should be saved separately for LEED reporting purposes as soon as you have the initial baseline design.
- The final 100% CD design materials can be added as additional products to be the actual material and building embodied carbon (mECIa & bECIa) values from the cove.tool database, contractor procurement data, or estimators data.
Whole Building Embodied Carbon Calculations
cove.tool is leveraging the EC3 database of embodied carbon values for building products and calculating the summation of the embodied carbon values in accordance with the Carbon Leadership Forum method. cove.tool is developing tools to become a full LCA application and currently offers a cradle-to-gate calculation for whole building embodied carbon analysis.
Step 1: Choose materials and where to use them.
The following materials are required if used on the project. All products can be entered into the optimization page under the assigned tab and are calculated based on the embodied carbon value per surface area, volume, or total for each building element. Common value ranges of embodied carbon can be found in our article on how to approach embodied carbon reduction. Enter the embodied carbon values for each baseline product.
- Concrete (Structure Tab)
- Steel (Structure & Envelope Tabs)
- Timber (Structure, Envelope, & Interior Tabs)
- Metal Framing (Envelope Tab - Wall Insulation)
- Glazing (Envelope Tab - Glazing)
- Gypsum Board (Interior Finishes Tab)
- Insulation (Envelope Tab - Wall Insulation & Roof Insulation)
- Carpet (Interior Finishes Tab)
- Ceiling Tiles (Interior Finishes Tab)
Step 2: Whole Building Baseline Embodied Carbon Intensity (bECIb)
Once all of your materials and embodied carbon values are entered for each building element click the Recalculate button. cove.tool automates the calculation of embodied carbon values for the current project dimensions and sums all of the total values into one building embodied carbon intensity as CO2e tonnes. Divide the total number of CO2e tonnes by 1000 and the total building floor area to get the bECIa as kgCO2e/sf.
Additionally, the optimization process provides a comparison of other products to discover the optimal bundle of products that achieve the highest overall performance of energy versus cost. This includes the amount of embodied carbon as tonnes of CO2e, which may not be the least amount of embodied carbon but the best performing of all options.
The Optimize Bundle offers a guiding target for acutal embodied carbon but may not provide all of the elements required for reporting. Optimization bundles offer design guidance throughout the design process. A final deisgn model is needed for actual values to be accurate.
Step 3: Whole Building Actual Embodied Carbon Intensity (mECIa & bECIa)
Make a copy of the current project and upload the final design geometry to represent the final 100% CD design of the building. The baseline product can be used to provide the actual material embodied carbon intensity (mECIa) and the actual building embodied carbon intensity (bECIa). Recalculating the optimization will provide the building embodied carbon intensity in tonnes of CO2e. Multiple the total number of CO2e tonnes by 1000 and divide it by the total building floor area to get the bECIa as kgCO2e/sf.
LEED Table Example for Reporting
To fill in the material table for LEED, the material values in the optimization option tabs provide the embodied carbon values and the geometry page provides the surface areas for each major surface area total.
Step 4: Percentage Difference between Baseline and Actual
Calculate the embodied carbon reduction value as a percentage of reduced embodied carbon intensity. Divide the actual building embodied carbon intensity (bECIa) by the baseline embodied carbon intensity (bECIb) and subtract from 100 to get the percentage reduction of embodied carbon for the whole building.
Step 5: Fill in the LEED Table and submit.
Fill in the LEED table required for reporting with the collected data and submit with your LEED application.