Natural ventilation in historic buildings: the Kalteyer House in San Antonio, Texas. analysis and simulations of natural ventilation

Approximately one-fifth of the planet’s geographical area is characterized by hot-humid climates, while being inhabited by one-third of the total world population. The majority of continental areas have weather conditions outside the thermal comfort zone. This has resulted in considerable and consistent increases in the use of HVAC mechanical systems, with its associated energy costs and environmental impacts, which potentially nullify the benefits otherwise achieved by the energy conservation policies implemented by many industrialized countries. Much can be learned from the study of historical buildings where sensitive design approaches were implemented with respect to natural ventilation strategies. An excellent example of a passive stack effect design employing skylights to take advantage of convective air flow is found in the Kalteyer House located in San Antonio, Texas. San Antonio is situated in Climate Zone 2A, hot-humid. The house under analysis is a three-story plus basement, single-family brick residence, designed at the end of the nineteenth century in Richardsonian Romanesque style by the architect James Riely Gordon (1863-1937). Here, the difference in temperature and pressure between two different zones of the house, enhanced by the presence of the skylight, creates naturally occurring convection air flows without the aid of mechanical systems. Natural ventilation can be an incredible resource for implementing passive cooling of buildings. This paper aims to investigate how to maximize the potential offered by these passive design strategies by developing an understanding of how they have been historically implemented, specifically in the Kalteyer House, and then exploring their potential as a valid alternative for achieving thermal comfort in newly-designed residential buildings. The effectiveness of this passive-cooling strategy is determined through an in-depth case study analysis and critical understanding of the passive system designed by James Riely Gordon, evaluated through CFD software simulations to determine how to maximize the potential of stack ventilation, which is currently underutilized due to the advent of mechanical-cooling systems. The goal of the analysis is to achieve the best performance in terms of thermal comfort with the minimum amount of energy consumption, thus reducing the resulting environmental impact.