Overview of LCAx’s Data Model
Objectives of LCAx
The goal for LCAx is to make an open, machine- and human-readable data structure and format for exchanging LCA projects, assemblies, impact data and results. The goal is to create a data structure that can contain information at a building component level, so that the data structure can be used for detailed analysis of the elements that make up a whole building LCA.
Key Principles and Concepts
The LCAx data structure is a nested hierarchy of objects, each with their own set of key-value pairs. The structure is organized into 4 levels:
- Project
- Assembly
- Product
- Impact Data
In the following sections each level will be explained.
The data structure is described in detail with a JSON Schema, which ensures compatibility with modern web standards and
ensures field correctness and type validation.
The JSON schema can be found here
Comparison with Other LCA Data Models
The existing landscape of whole building LCA data models can be divided into two categories:
- Data models for LCA calculation software
- Data models for LCA reporting
All LCA calculation software have an underlying data model.
The models are however proprietary, as most the LCA software is, or too tightly coupled to the software.
Data models used for LCA reporting are typically categorized by aggregating building components into larger groups to enable comparisons across geography and methodologies. These models tend to be open and accessible to allow reporters to hand in data.
Components of LCAx
The data structure of LCAx can be thought of as four different levels: Project, Assembly, Product and Impact Data.
The project level is the outermost level, which contains a collection of assemblies that each have one or more products inside. Each product contains impact data.
This hierarchical system makes the data structure flexible, doesn’t limit the number of elements contained with and mimics the conceptual structure of a building.
A building (project) has building components (assembly), which consists of layers (product), each layer being a material (impact data).
The 4 Levels of LCAx’s Data Structure
Project Level
The project level contains general information about the project, such as location and owner.
At the project level it is possible to declare information about the nature of the project. For example what classification system, LCIA standard, life cycle stages or what impact categories are considered in the project. In that way it is possible to get an overview of what is and should be inside the project. It doesn’t mean that declaring for example a classification system prevents other systems from being attached to an assembly, but it declares what is the main system, which must be present at all assemblies.
The same can be said for life cycle stages and impact categories. EPDs usually contain multiple values, but some projects might only care about GWP and A1-A3.
At the project level it is also possible to assign descriptive information about the project in the “Project Info” field. This data can be used to classify and categorize the project for example in connection with data analyses or aggregation.
The project level also has a field for LCA results, which are an aggregation of the results at the assembly level.
Assembly Level
The Assembly level is made up of a collection of assemblies, which represents a project’s construction components or built-ups. It holds fields and information related to this level.
Assembly quantities are absolute for the whole project, meaning if an assembly has a quantity of 200m2 then there is 200m2 of this assembly in the whole project.
Each Assembly can have multiple classification systems associated with it, but one has to correspond to the project declared classification.
Assemblies can also contain LCA results, which are the aggregation the LCA results from the contained products.
Product Level
A Product is an element of an Assembly.
There can be more than one product associated with an assembly. A Product has a reference service life and an impact data. Transport information can also be associated with the product, which also can hold a piece of impact data.
The quantity of the product is relative to the assembly it belongs to and not absolute to the whole project.
Products can have LCA results, which are aggregations of the impact data values and the product quantity.
Impact Data Level
Impact Data is as the name implies the container for (environmental) impact data. Impact Data contain all the environmental data that is needed to calculate the LCA.
The data can be of different origins. Both EPDs, generic data and tech flows are accepted.
EPDs come in many data formats e.g. ILCD+EPD and PDF, and it is not our intention to replace those formats but meanly create an exchange format that is easily human and machine-readable.
Component Classification
Component Classification is not tightly coupled to LCAx.
LCAx accepts multiple classification schemes in parallel at the assembly level, because it recognizes that it might not be possible to align classification schemes across stakeholders.
Advantages and Limitations
The hierarchical structure of the LCAx data model provides flexibility in organizing and representing data at various
levels, from project-wide information down to individual product components.
This flexibility allows for detailed analysis and customization to suit specific project requirements and stakeholder needs.
The ability to define and store data at a granular level, such as building components and material quantities, enables
detailed and precise life cycle assessments.
This granularity facilitates accurate environmental impact calculations and supports comprehensive decision-making
regarding product design, material selection, and resource optimization.
The standardized data format and schema of LCAx ensure transparency and consistency in data representation and interpretation. Clear documentation of methodologies, assumptions, and data sources enhances the credibility and trustworthiness of LCA results, fostering confidence among users and stakeholders.
The reliability and accuracy of LCA results depend on the quality and availability of input data, including life cycle inventory data, impact assessment methodologies, and characterization factors.
Data gaps, inconsistencies, or inaccuracies is not something LCAx addresses directly, but will require additional analysis and processing.
Integration with existing LCA software tools or databases may pose compatibility issues due to differences in data formats, standards, or conventions.