Improving living conditions in buildings is a constant concern for mankind. In this context, integrating energy efficiency techniques into building projects has become an obligation to reduce future costs. This paper presents an in-depth study on improving energy performance in an apartment in the Moroccan city of Kenitra on the fifth floor of a six-story structure. The approach adopted is based on a detailed analysis of current conditions and dynamic simulations using TRNSYS software to assess the impact of various passive measures. The main objective is to reduce energy consumption while ensuring a comfortable and healthy indoor environment for the occupants. The study demonstrates the significance of design, material selection, and envelope features in sustainable building.