The first step of the work was to study the regulatory framework, guidelines, required legislation and standards at the European, Italian and Iranian levels.

Afterward, Design-Builder was chosen as an interface for 3D modeling because is the most powerful graphical interface to EnergyPlus (the software that used for building simulation).

The next step was to investigate the case study which from now on, will be called Real-Case (RC), actually, the RC is an eleven-story multi-family building located in the southwest of Iran, Shiraz, and location of the RC for the study in Italy was assumed to be Turin.

50 various packages of energy efficiency measures were chosen from a wide range of possible measures, this selection was performed by combining, five different levels of thermal insulation, two window types (a double and a triple glazing), two shading system option(a between glass blind and an external blind) and two different high efficient energy systems, in addition to the solar renewable energy source such as PV system installed on the building facade and thermal solar panel on the building’s roof.

Precisely all packages in terms of economic and energy performance were simulated and analyzed in both Italian and Iranian context.

Then the energy consumption and costs of the various packages were investigated and compared in order to evaluate the impact of the selected measures in energy efficiency improvement and global cost, and revealed that obtaining high performance building simultaneously with the cost optimal levels can be fulfilled, but it is noteworthy to mention that the cost-optimal level directly depends on suitable financial subsidies and government policies on renewable electricity price.