In this study, heat transfer in conventional single skin facade and double skin facade system was studied experimentally and numerically by using one dimensional time dependent approach and the effects of the facade systems on building energy performance especially heating energy was investigated. In this context, a mathematical model considering user behavior and window aluminum frame element effect was build by zonal analysis method to calculate the heat transfer in single and box type closed cavity double skin facade systems, and build model was experimentally verified. Experimental study was conducted in office spaces having single and double skin facade systems in Ege University, Civil Engineering Building's south facade in January 2017. Next, verified model was used to study the heat transfer in the facade systems for Izmir's climatic condition by using monthly average daily data. The change in thermal performance of single and double skin facade systems due to the climatic condition during a year was investigated by using the 10 year average climate data of Izmir (Mediterranean climate). It was found that double skin facade system acts as an insulator preventing extreme indoor temperature values, thus contributing to the indoor comfort level against changing outdoor conditions.