Energy Performance of Buildings should include a general framework for the calculation of energy performance and building categories together with thermal characteristics of building, air conditioning, ventilation, lighting and appliances aspects considered. These include Active solar systems contribution to domestic water heating based on renewable energy sources, CPH production and District cooling systems. This paper reviews the energy sources available in Egypt, their distribution and utilization in commercial sectors. Assessments of energy use in different air conditioned buildings are given. The paper shows the importance of incorporating an energy performance directive as a Standard in Developing countries such a goal will aid energy savings in large buildings and set regulations to energy efficient designs that are based on Standard calculation methods. It is recommended to: 1. Develop standardized tools for the calculation of the energy performance of buildings 2. Define comparable energy related key values (kWh/m2, kWh per person, kWh per apartment, kWh per produced unit etc.) and to develop a common procedure for an “energy performance certificate” 3. Design, construct and operate a solar decathlon (Building) that can meet the rural and desert requirements and save the diminishing fossil fuel sources. Governmental organizations were established earlier to be responsible for energy planning and efficient utilization, information dissemination and capacity building as well as devising the necessary codes and standards. Energy rationalization and audit exercises were developed and monitored by governmental authorities, universities and research centres for the past two decades with a definitive positive energy reduction and beneficiation. This paper would swiftly explain the importance and significance of energy rationalization, energy efficient systems design, and green energy concepts and the related International, Regional and national energy codes and standards, [1-10].