LCA and embodied carbon
Life Cycle Assessments, or LCAs, measure the environmental impacts (including embodied carbon) of materials we use, including the energy used to extract it to the emissions caused by its demolition.
In a typical code building with a 60 year lifespan, the operational carbon is a larger contributor to carbon emissions. When we look at a high performance project, the embodied carbon starts to be a larger portion of the overall percent of emissions. However, we know that there is a time value to carbon. The Intergovernmental Panel on Climate Change (IPCC) issued a report that states we need to drastically cut carbon emissions by 2030 if we are to meet the Paris Agreement. If we use this initial embodied carbon lens, then embodied carbon emissions far outweigh operational; illustrating the importance that we must consider both the operational carbon and embodied carbon when designing.
We recommend evaluating your facades with this time value of carbon lens (Initial Carbon lifespan) in this tool but give you the option of using a typical 60-year lifespan as well.
How to use this tool
Kaleidoscope is designed to supplement, not replace, whole-building LCA in early design phases. It is meant to be a reference for order of magnitude of early LCA decisions allowing designers to quickly compare the embodied carbon impacts of various standard building systems and design options.
This tool compares typical industry building systems in an apples-to-apples manner by using the same module and system boundary for each building system. Tally was used to generate the LCA analysis.
Multiple lenses are available to view the data. One lens is removing Module D, or the LCA impacts associated with reuse potential outside the system boundary. We suggest removing Module D due to the uncertainty of the end of life of materials. As well as when we take into account the time value of carbon, and view data for only the initial carbon, the product will ideally still have a useable lifespan. For the 60 year lifespan we give you the choice to include Module D, as it is optional in American ISO LCA standards.
The “All Impacts” graph shows all environmental impacts in one graph using weighting per the impact category’s importance1. While global warming potential is the most crucial to combat climate change, it is important to consider other environmental impacts.
- Global Warming Potential………….. 54%
- Non-Renewable Energy Demand… 18%
- Eutrophication Potential…………….. 11%
- Smog Creation Potential…………….. 7%
- Acidification Potential…………………. 6%
- Ozone Depletion Potential…………… 4%
The envelope system boundary accounts for apples-to-apples by using the same module (4’x14’), structure (not included, except if additional steel is needed, such as a shelf angle for masonry veneer systems), wall backup from interior drywall to air/vapor barrier, detailing strategy using thermal breaks, and most importantly the same R-value (IBC code minimum R-15.625). THERM was used to verify the R-value of each system.
All flooring assemblies use a 10’x10′ system boundary, and includes the floor finish and any underlayments if necessary. It does not include the structural floor slab. An additional lens is provided to view the data based on compliance with Payette’s Material Health Policy.
All ceiling assemblies use a 4′ x4′ system boundary, studied from the center of the ceiling module. It includes the finish materials and all support systems. It does not include the structural slab. An additional lens is provided to view the data based on compliance with Payette’s Material Health Policy.
All partition assemblies use a 10’ x 13’-6” system boundary, studied from the center of the partition module, and does not include structure except where steel is needed for connections (such as a staggered angle for CMU walls). It includes the finish materials and all support systems. It does not include the structural slab. Data is presented in linear feet for a 13′-6″ partition. An additional lens is provided to view the data based on compliance with Payette’s Material Health Policy.
1 Environmental Impact Importance (%) by Voting Interest and Time Horizon Source: Life Cycle Impact Assessment Weights to Support Environmentally Preferable Purchasing in the United States; Environmental Science and Technology, Gloria, Lippiatt, & Cooper.