Windows are the most complex and interesting elements in residential design and owners are often confused about how to decide the most efficient window for their residence since there are many complex issues that are difficult to balance. Understanding the energy and associated cost implications of different window systems will help the users, owners or contractors to make the best decision for their particular case, whether it is a new building or a window replacement. However up-to-date, reliable and accurate, time and cost data can be provided from various sources such as manufacturers, contractors, and research institutions, time and cost data regarding the residential window systems are not well-organised in Turkey. A research project was completed to develop a dynamic model to select energy and cost efficient windows for residential buildings, namely “Energy and cost efficient window selection model for residential buildings in different climatic regions of Turkey - HiPerWin”. The challenge was to attain a basic source which supports the user to provide the energy and cost data required for the decision making in the selection of the residential window systems. The ultimate objective of the research project was to develop a Relational Database Management System (RDBMS) which incorporated the whole data and processed data into information regarding the window systems and helped the comparison of the alternatives. Hence query parameters were presented for helping the users to define the built environment and housing unit characteristics of their own case to find out the appropriate window alternatives by comparing the total annual heating/cooling energy consumption and associated capital and ownership costs. In the context of the research project, the alternatives of the Insulated Glazing Units (IGU) with different optical and physical properties were generated. The performance values which demonstrate the insulation and solar control capabilities of the IGU’s were calculated by using Window5 software. In accordance with having many parameters such as climate, building type, orientation, window area, shading devices and window components, a comprehensive parametric study was conducted for providing the energy use and associated cost data of each case by using a powerful whole building simulation tool EnergyPlus. The analysis was performed for the biggest cities; Ankara, Istanbul and Izmir having the highest degree of mass housing potential and representing temperate-arid, temperate-humid and hothumid climates, respectively. Standard representations of buildings (i.e. building model) required for simulations, involving geometrical and semantic properties were stored in the HiPerWin data base and with the help of the query parameters which were associated with the entire data of the building model a particular case can be defined. The present value of future cost of window systems was calculated by using the factors and indices, both operational energy costs calculated from the energy simulations and the capital and operating unit costs of window systems. The capital unit cost includes purchase, installation and finance costs, while operating unit cost includes ownership, maintenance and energy consumption costs and salvage value if applicable. Lastly, window selection model which uses the building model, the energy data provided by the simulation results and the cost information calculated using the energy and related data was developed. The RDBMS and query parameters allow users to define their particular cases and compare the energy and cost performances of appropriate window systems in consideration. The HiPerWin model provides the user to select the most energy and cost efficient window system for their own case by considering the issues which have influence on the residential window performance. The results of the research project is critically important for the purposes of satisfying the requirement of comparative information pertaining to heating/ cooling and total energy consumption and particularly present value cost data of window systems in Turkey. Making the energy and cost efficient window system selection prevalent will contribute to the national economy by enabling the usage of the limited resources which supports the sustainable design on country base.