Renovação do ar em ambientes residenciais tropicais: comparação entre modelos empíricos para ventilação cruzada

Abstract

Natural ventilation is often adopted in residential buildings, however there is a large variation about ventilation rates and window dimensioning. Literature review shows there are significant differences in recommendations for temperate and cold climates and for warm climates, both humid and dry ones. This paper aimed at identifying the best recommendations for dimensioning openings for natural ventilation in dwellings, having in mind the decreasing areas of dwellings in Brazil. A small detached house designed in the city of Belo Horizonte, Brazil, by students at the UFMG School of Architecture was used as a case study. Some reliable empirical models of wind pressure ventilation were applied for calculations. Six scenarios for dimensioning ventilation openings were compared taking into account building codes, recommendations by national standards and various ventilation rates found in the literature review. The results show that ventilation rates between 20 and 40 air changes per hour in small dwellings reach ventilation areas close to those from building codes and standard NBR-15220 for the city bioclimatic zone; in addition the type of window frame also seems to influence in dimensioning ventilation openings. Further studies need to be done considering other climatic zones, the effects of ventilation rates on the cooling of houses as well as makingmeasurements in loco and researching about regional preferences for natural ventilation in dwellings