Getting a healthy and comfortable indoor environment in homes in southern Europe is a complicated task. In continental climates, with very cold temperatures in winter and very hot in summer, energy consumption greatly increases with air conditioning significant spending. To propose action guidelines for use of natural ventilation and to develop effective design strategies is essential. Therefore, and given a specific building type block of flats in Madrid, this article focuses on establishing what periods of the year natural ventilation is required to reduce energy consumption in air conditioning, also considering the quality of the outdoor environment and the design of the building. To develop this, a statistical study of the chosen type, that allows studying the direction and the wind speed in the area, is performed. Analysis of wind pressures in holes in the facade is performed by means of numerical simulations of fluid flow (CFD) inside to later infer in the natural ventilation rate required within policy parameters. With the data obtained, a study of energy saving is made as a function of natural ventilation rate established for the building type.