"Nowadays, the energy crisis is one of the controversial issues around the world. Regarding the fact that the largest energy end use in the world belongs to the construction and residential sector, it seems necessary to analyze the energy flow in the buildings. The most sustainable energy design technique is to conserve energy as much as possible. There are various methods to reduce the use of conventional energy from fossil fuels to meet the energy requirement for the building. Various strategies including photovoltaic-thermal systems and insulation systems with the aim of minimizing building energy in different climate conditions (Cold-weather/Hot weather) were presented and assessed in the first chapter. A comprehensive work was carried out to investigate the effect of adding nanoparticles as concrete additives on both pore structure and thermophysical properties of the concrete at different ages. Besides, the behavioral models using Genetic Algorithm (GA) programming were developed to describe the time-dependent behavioral characteristics of nanoparticle blended concrete samples in various compressive and tensile stress states. Chapter 3 deals with the traditional energy saving techniques to highlight the potential of learning from traditional architecture and adopting their experiences to fulfill modern expectations. In this regard, Iranian classical architecture, particularly at hot arid climate, is taken into account. On the other hand, geothermal energy as one of the most significant alternative sources of thermal and electrical energy have been discussed. To address the growing demand of power generation and its related challenges of the existing electrical power grid, Smart Grid (SG) systems comes as a solution that lays in taking the world forward to reach energy independence and environmentally sustainable economic growth. The final chapter provides various information about the smart grid systems and the efficiency of such systems is analyzed through a detailed case study"--