## 3 The LCA Commons Approach to Distributed Data Development
OpenLCA can link a power generation process that has the flow Electricity, AC, 120V as an output to the downstream process as a provider of  
Figure 2: A simplified product system graph with inputs and outputs to external systems. that electricity flow. Datasets produced by a distributed network of research organizations can link their data together through the specification of flows. The LCA Commons manages LCA data and information through two integrated software applications: the openLCA desktop modeling software, and the LCA Collaboration Server (CS) web repository (GreenDelta developed both applications are developed by). OpenLCA can perform LCA studies, provides the interface for creating and editing LCA data and models, and manages the information architecture to facilitate data reuse. OpenLCA can serialize models into a number of exchange formats, including the native openLCA JSON-LD, ILCD, and the superseded ecospold v1. The LCA Collaboration Server provides a web repository for openLCA formatted JSON-LD files. The CS application offers search and access functionality for LCI datasets. It displays datasets in an easy-to-interpret format similar to the information organization structure in the openLCA software client. Web services perform information exchange between the openLCA desktop application and the CS repository--LCA datasets can be 'pushed' and 'pulled' to and from the CS directly from the openLCA interface with the click of a button. The web services handle native JSON-LD files, resulting in no information loss due to format conversion when moving information from the desktop client to the server. Participants in the LCA Commons community prepare their data for publication in openLCA. OpenLCA does not provide instructions on how to complete fields provided in the data interface. The LCA Commons has compiled a guidance document with instruction on how to fill in the metadata fields. In addition to completing metadata, the LCA Commons also carries data organizational requirements. The LCA Commons recommends the use of the Federal Elementary Flow List, a standardized list of environmental flows developed by the US EPA consistent with the latest EPA impact methods. The guidelines specify conventions for naming process and flow data types based on recommendations from the ILCD data handbook. The LCA Commons also makes a clear distinction between process and flow objects. Processes consist of models representing activities that perform a function, and flows represent a specific quality of material or energy that can be exchanged between processes. The LCA Commons uses NAICS industry codes for the classification of process and material flows. To ensure correct classification of distributed datasets that can connect to each other, data developers must also use a set of openLCA reference objects that facilitate interoperability. Ensuring consistent flows from provider and consumer processes remain of primary importance. OpenLCA assigns universally unique identifiers (UUID) to independent classes of objects such as flows, processes, and categories. These UUIDs allow the modelers and the software tools to identify specific unique objects. When assigning a flow intended to connect to a distributed dataset, a researcher must use the correct flow and ID, and verify openLCA will successfully make the connection. The user must perform this same activity with every shared reference object: units, flows, people, geographical locations, and NAICS classification codes. The LCA Commons maintains a template of commonly used reference objects to simplify this part of the data curation task. The direct coordination and integrated publication workflow facilitates the building of LCA data products from reusable, distributed LCIA datasets. However, the published data are not curated data products ready to use.