Chapter 09 · Sustainability & AISustainability & AI
Open-weight model
Definition
An AI model whose trained parameters are published for anyone to download, run, inspect and adapt, typically under a licence with varying conditions.
References
This source provides part of the technical or institutional basis for the definition.
This source supports the explanation of how the term is applied, measured or governed in practice.
Overview
What it means
An open-weight model makes its trained parameters available, but that alone does not make the system open source. Training code, architecture details and sufficient information about training data may remain unavailable. The Open Source Initiative's Open Source AI Definition therefore sets a broader test based on the freedoms and information needed to use, study, modify and share the system.
How it is used
Open-weight models let organisations run capable AI on their own infrastructure: useful for sensitive sustainability data, for auditing model behaviour, and for avoiding per-query dependence on a vendor. Licence conditions vary and merit legal review.
Why it matters
The openness debate shapes who can scrutinise, reuse and afford advanced AI. For sustainability assessment and assurance, inspectable models are a governance asset — and the OSAID gives 'open' a testable meaning amid loose usage.