Climate change represents the biggest challenge in a global scale. Architecture should be able to adapt to this new conditions and ensure comfort and energy efficiency. The main goal of this research is to adapt existent public buildings and reach hygrothermal comfort for two climate change scenarios in Costa Rica. To determine the study zone three areas were analyzed: ecological, demographic and regional economic. Subsequently case studies are chosen through criteria to evaluate the impact of the intervention. A scaled bioclimatic analysis is done for each case and through a comparative analysis two cases are selected to be simulated. Hourly Weather Data files are created for the year 2080 by using observed data from “Instituto Meteorológico Nacional” (IMN) and projected data from “Centro de Investigaciones Geofísicas” (CIGEFI). Lastly, two adaptation proposals are done for each case, a mild one and a complete redesign; it’s behavior is evaluated using the software DesignBuilder® and design recommendations are proposed. Keywords: bioclimatic architecture, climate change, hygrothermal comfort, adaptation, simulation.