Gonzalo Rodriguez-Garcia

As part of its efforts in the Federal Life Cycle Assessment Commons (Federal LCA Commons), NIST is expanding its Construction Materials (CONMAT) repository to include 72 regional benchmark mix designs for concrete initially published by the National Ready Mix Concrete Association (NRMCA). These models account for variations in the composition across regions as well as for different electricity and transportation providers as modeled in public datasets. In total, 873 unique concrete models were developed. A Life Cycle Impact Assessment (LCIA) was conducted on these models to evaluate the importance of the different factors affecting a regionalized mix design. Key among them is the mix design itself, defined by compressive strength and the type of aggregate used, while location specific variables played a much smaller role. The NRMCA region, which defines the quantities of materials used a concrete mix design, is the most important of these geographical variables, followed by electricity and transport. Despite the small effect the latter two have on the total impact of mix designs, its inclusion in the CONMAT repository represents a first step towards region-specific models and can support the development of more accurate product claims. In addition, the resources developed to generate these models are presented. They can assist in automating bulk or parametric LCA models for concrete and could be adapted for developing LCA models for other materials, products, or services

Given the increasing prevalence of using Environmental Product Declarations (EPDs) for product comparisons and selection, both domestically and globally, there is a need to ensure the results reported in EPDs are useful for such comparisons (i.e., transparent and standardized to ensure quality decision making). One challenge that was identified more than a decade ago was the lack of common data sources, which could undermine the comparability of EPDs and similar claims. Federal agencies have targeted this issue through the development of public secondary datasets and gap assessments of currently available public life cycle inventory (LCI) datasets. This study follows the framework for the identification and quantification of public data gaps developed and applied to construction materials in NIST TN 2338 and expanded in and applied to a building system component (photovoltaic panels) in NIST TN 2350. This study addresses the final application of one semiconductor, a residential photovoltaic system. The LCA models developed in NIST TN 2350 are used as the photovoltaic panel components needed in this study to model the entire photovoltaic system. The scope of this study is to (1) refine the framework to identify public life cycle assessment (LCA) data gaps by evaluating multiple impact categories using two impact assessment methods, (2) identify and quantify the impact of each data gap of the components of an entire building system (i.e., rooftop residential photovoltaic system), and (3) provide qualitative rankings of data gaps both within each stage of the production supply chain and for the entire assembled system. The study concludes with a series of recommendations to strengthen and further develop public LCI datasets.

Given the increasing prevalence of using Environmental Product Declarations (EPDs) for product comparisons and selection, both domestically and globally, there is a need to ensure the results reported in EPDs are useful for such comparisons (i.e., transparent and standardized to ensure quality decision making). One challenge that was identified more than a decade ago was the lack of common data sources, which could undermine the comparability of EPDs and similar claims. Federal agencies have targeted this issue through the development of public secondary datasets and gap assessments of currently available public life cycle inventory (LCI) datasets. This study complements public data gap assessments completed by the Environmental Protection Agency (EPA), Department of Energy (DOE), and NIST by focusing on three goals. First, develop and implement a repeatable process to create a machine-readable database of information reported in EPDs for a product category. Second, analyze the database to review reported data sources for various processes in all EPDs within the product category to determine which data sources are currently in use and assess whether public sources can replace commercial data sources while identifying any gaps in public LCI data. Third, use the results of the LCI data analysis to provide insights on developing representative inventories for common practice in existing EPDs for a product category. This study provides results for four product categories: cement, concrete, asphalt, and gypsum.

Given the increasing prevalence of using product declarations issued by manufacturing companies for product comparisons and selection in the private and public construction sectors, both domestically and globally, there is a need to ensure the results reported in product declarations are useful for such comparisons (i.e., transparent and standardized to ensure quality decision making). One challenge that was identified more than a decade ago was the lack of common data sources, which could undermine the comparability of product declarations and similar claims. Federal agencies have begun to address this issue through the development of public secondary datasets and gap assessments of currently available public life cycle inventory (LCI) datasets. This study follows and expands the framework for the identification and quantification of public data gaps developed in NIST Technical Note 2338. The scope of this study is to (1) expand the framework to identify public life cycle assessment (LCA) data gaps by evaluating multiple impact categories, (2) identify and quantify the impact of each data gap across the production supply chain of single-crystalline photovoltaic (PV) panels, and (3) provide qualitative rankings of data gaps within the stage of the production supply chain, and for the assembled panel. Additionally, there is a brief assessment of potential data gaps based on commercial inventories, and of data gaps in the production supply chain of multi-crystalline silicon PV. This study concludes with a series of research recommendations to strengthen to further develop public LCI datasets, indicating future work to continue this effort.

Carbon dioxide removal (CDR) systems are an integral part of sustainable pathways limiting global warming to less than 2.0 °C. When the sole purpose of CDR is capturing and storing atmospheric CO₂, carbon registries offer detailed procedures to calculate the carbon removal credits. However, the registries do not address how to distribute CO₂ flows when CDR provides additional services. Standardized, transparent rules for distributing CO₂ flows among CDR services are required for the formation of efficient private and public carbon markets. The lack of such rules could result in double counting if those reductions are allocated to more than one service, decreasing the trustworthiness of carbon removal credits or deterring the delivery of an additional low-carbon service, thus limiting the economic viability and deployment of CDR. We examine allocation rules in carbon registries and carbon accounting guidelines, including their life cycle assessment (LCA) principles. We evaluate physical (mass-based) and non-physical (economic) allocation methods using a generic CDR system and find both to be unworkable. We then develop a mass balance (MB) approach which can reliably allocate captured and stored carbon (CSC) between carbon removal credits and other services based on the value CO₂ removal in those markets. This practical approach to allocation can be used in a transparent way to provide flexibility that would allow CDR services to capture the value of the multiple services they provide and, through this, promote the deployment of these sustainable alternatives.