“A Balanced Urbanism: Social Utilization Units (UASO) as a Mechanism for Redistributing Value in the Consolidated Urban Fabric.

Abstract

This article addresses a structural gap in contemporary Spanish urban planning: the absence of a continuous and operational mechanism for capturing urban value generated within consolidated urban areas. While the existing legal framework has proven effective in value capture within large-scale development and transformation processes, it lacks adequate tools to intervene in the existing city, where most urban value is currently produced.
Through a systematic analysis of the Spanish legal framework and a comparative examination of four international models—Vienna, London, New York, and San Francisco—the paper demonstrates that systems capable of capturing value in consolidated urban contexts rely on explicit rules linking increases in development rights to social return obligations, particularly in the provision of affordable housing.
On this basis, the article introduces the Social Development Units (UAS) model as a geometric, universal, and proportional rule that allows the reorganization of total development rights on a parcel-by-parcel basis. The model preserves the owner’s consolidated rights while requiring any additional market-rate development to be balanced by its equivalent in protected housing. This mechanism is formalized through a canonical social equilibrium equation and is fully compatible with Spain’s Public Land institutions.
The paper concludes with a comprehensive practical example demonstrating the technical, economic, and legal operability of the UAS model in consolidated urban land.