Building performance is a function of a number of variables each of which is important to analyse concurrently when conducting a POE study. The development of framework for assessing buildings is significant as it will provide an evaluation tool for ensuring sustainable buildings. This study developed an index for evaluating the overall performance of office buildings in Nigeria. A Total of 51 professionals in the built environment were surveyed. The data obtained were analysed using content analysis technique, pair wise comparison (one sample t-test) and regression analysis. The results showed that; the performance criteria which are pertinent to the performance of office building in order of their importance were building integrity (54.54), indoor air quality (53.69), safety and security (64.04), thermal (46.77), spatial (7.27%), visual (44.01), spatial (43.33) and acoustic performance (43.62); priority placed by individual professional, architects rated safety and security and building integrity (18) most important and acoustic least (9) important, builders rated IAQ and visual performance (20) most important and building integrity (8) least important, estate surveyors ranked safety (21) and building integrity (17) performance most important and acoustic performance (7) least important, mechanical engineers rated safety (22) and building integrity (0) performance most important and acoustic performance (7) least important. A regression model based on the TBP criteria identified was developed (TBP Index = 13.36ð+12.57ŋ+12.46Ɣ+15.34ω+12.38ɸ+15.58φ+18.30ψ). It was concluded that safety and security was rated most significant of all the performance mandates, followed by indoor air quality, building integrity, thermal performance, spatial performance, visual performance and acoustic performance.