A new Energy Code for office buildings in Israel, currently under development, will be presented. This code is based on a prescription approach, which can easily be applied as a tool for the design of office buildings through all the design stages including the early ones. The prescription approach suggested is based on the results obtained from an energetic-economic optimization model that provides a recommended prescription for office building under given constraints. A sensitivity analysis of the optimized solution follows. The sensitivity analysis allows modifications of the recommended prescription allowing for the creation of a wide range of design alternatives and in addition to figure out what are the design variables with the highest impact on the building energy consumption and cost. The way of using the prescriptions as a building code is explained as well as the method to determine the energetic rank of the chosen solution.