In the past ten years Costa Rica has experienced the impact from migration to urban areas followed by large increase in the demand for affordable housing in a country where 22% of the population still lives in poverty. This book aims to set environmental guidelines for social housing projects in the warm-humid regions of Costa Rica. The research focuses on providing comfort by means of passive design strategies. Hence an improvement in Costa Rica's social housing scenario should consider design strategies that optimize effective use of spaces, natural ventilation and shading; where air permeability is related to spaces usage and the building's elements ability to provide comfort and low energy consumption.