Natural Ventilation in Low-Cost Housing:
With the spread of sustainability concepts, due to the global energy crisis and the unrestrained consumption of natural resources, the importance of rational use and reduction of energy consumption has been intensified, albeit in short steps. This concern has taken up bioclimatic concepts in buildings, especially housing buildings for low-income people, aiming at improving the quality of housing production in terms of its habitability.
The objective of this research is to theoretically and experimentally study the natural ventilation in a housing building, which fits into the low-cost pattern. The use of Computational Fluid Dynamics to predict natural ventilation was adopted as a tool to perform these analyses. Experiments were carried out by visiting the study area to collect data on air velocity, temperature, and relative humidity in all rooms of the residence in order to carry out the intended analyses. Computer simulation of natural ventilation considering the building with the doors and windows open and with fixed geometry was performed.
Results proved that the proposed mathematical model was able to reproduce, with rich details and physical coherence, the internal and external airflow inside the building, indicating better internal ventilation performance in environments that have door and window openings, with recesses, revealing the importance of cross ventilation to reduce the internal temperature and consequent improvement in thermal comfort. The idea is to help civil engineers and specialists in the economically viable design of low-cost buildings from the economic, social, and thermal comfort points of view.
The Brazilian housing problem has its historical roots in its rapid urbanization process, which ignored planning actions, especially concerning housing production issues, reflecting an expressive and historic housing deficit.
The housing issue is one of the great challenges of Brazilian cities, due to the need to build a large number of low-cost and good-quality housing units, in a short period of time that are adequately served by urban services. The country has a considerable housing deficit, and there is a need to meet this demand, especially in the low-income population groups, which despite being targets of policies and programs of social interest, are still far from meeting the existing demand.
Santos explains that housing is a basic need and aspiration of human beings, vital for the principle of human dignity, and for this reason, the right to housing constitutes a basic right for every citizen. It is important to emphasize that the offer of decent housing should not be limited to providing an environment in which to live.
According to the United Nations, in a document prepared by the UN-Habitat, there are seven basic components that must be considered for the promotion of adequate housing: security of tenure; availability of services, equipment, and infrastructure; availability at affordable prices; habitability; accessibility to all social groups; location (access to employment, health, and social facilities); and cultural adequacy.
In the architecture of buildings aimed at housing purposes, for the full satisfaction of users and supplying their needs, it is not enough to consider only dimensional and quantitative parameters of the environments so that adequate housing conditions are achieved. For these spaces, there is the concept of habitability, which goes beyond, involving aspects related to the comfort of users, considering the most diverse aspects.
Therefore, solutions must be sought that minimize unpleasant sensations, without disregarding functionality and aesthetics. Among the various aspects, the following can be mentioned: (a) distance between the slab and the roof, dimensions of the openings in the facades, windows, and doors; (b) orientation of the house in relation to the wind direction; and (c) location of doors and windows in relation to the wind direction (direct or cross ventilation). There is also the effect of the relationship between the dimensions of the doors and windows. For example, air inlets larger than air outlets produce better air movement and distribution.