The goal of this thesis is to simulate actual building using two known tools, from existing Energy Performance Certificate (EPC) software to dynamic simulators. The research addresses the variation between necessary inputs and the outputs supporting technology options for design improvement, particularly during the heating and cooling seasons. The thesis assesses the hourly and quasi-steady-state simulation methods and analyzes the impacts of changes in specific building design parameters and low energy/bioclimatic technologies. The simulations consider building geometry, construction details, HVAC systems, occupancy patterns, and climate data. The study evaluates the building energy simulation tools Termolog and DesingBuilder an interface of EnergyPlus on two case study buildings.