Social and environmental constraints have challenged the reintegration of factories inside urban areas. An interesting opportunity to overcome these is presented in the continuous emergence of sustainable manufacturing concepts. To improve local and sustainable aspects of their value creation, urban factories utilize proximity. Benchmarking good practices locally can be a great way to support eco-designers, but a first step would be to describe existing value chains of urban factories. To do so, the present paper proposes a new model to determine relevant parameters to consider for the design of urban factories. Additionnally, the model provides eco-designers with a characterization structure.