The GIA Efficiency Ratio for Affordable Units is a property development finance metric that assesses how effectively Gross Internal Area (GIA) is utilised for affordable housing provision within a scheme. It calculates the proportion of internal floor space attributed to affordable units relative to total GIA, expressed as a percentage or ratio. This measure is often reviewed by lenders, investors and planning authorities when testing project viability and compliance with affordable housing requirements. In property development finance UK, the ratio informs stress testing, scenario modelling and long-term value assessments for mixed-tenure schemes.
This sits beneath Scenario-Based Outputs, introducing a more specific variant of the measure without changing its core interpretation. It is commonly considered alongside Design Compliance with NDSS, as both are closely related measures used to assess similar aspects of performance or risk.
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