Design performance evaluation has been the center of interest for many social actors since the antique period dating back to Aristoteles and Vitruvius. Numerous performance evaluation models have been developed for assessing design value since then. In this thesis, a Data Envelopment Analysis model is proposed for design performance evaluation in order to support the decision making process of the stakeholders in the built environment. The proposed model is based on the Design Quality Indicator (DQI), Life Cycle Cost Analysis (LCCA) and Data Envelopment Analysis (DEA) methods. DQI is a measure of design quality that measures functionality, build quality and impact assessment of the projects. LCCA is a measure for calculating the life cycle cost (LCC) of the projects. DEA is an efficiency measurement system that depends on the relative performance of the assessed units. In this thesis, a DEA model based on LCCA and DQI is developed for design performance evaluation. LCC values are used as the inputs and DQI values are used as the outputs. Accordingly, the design performance efficiency is conceptualized as the value of design calculated by the ratio of the DQI to the LCC. The developed model is applied to a sample of housing projects in İzmir. Efficient coded design values and relatively inefficient coded design values are determined. Input and output oriented strategies are then developed and discussed for improvement purposes. The proposed model constitutes an effective decision support tool for a thorough evaluation of the design performance of the given projects.