CFD-Assisted Design and Optimization of Solar Chimneys for Elementary School Classrooms

A passive ventilation system using solar chimneys was designed to provide ventilation to several classrooms in an addition to an elementary school in Washington, DC. The primary design objectives were to provide enhanced indoor environmental quality and a learning opportunity for students. This paper explores the design process, describes obstacles faced in implementing the design, and presents the results of the simulations. The multivariable optimization approach taken to the design, using a detailed airflow model in EnergyPlus and CFD, attempted to find the design parameters such as chimney height and opening areas that result in the highest number of occupied hours per year with adequate ventilation flow rates. EnergyPlus results show potential HVAC energy savings of up to 5%, and up to 1,200 occupied hours that the classrooms could have adequate natural ventilation. CFD results complement these simulations by demonstrating the ranges of exterior temperatures and ventilation flow rates that are thermally comfortable. Comprehensive analysis with simulation tools allowed an optimal design for this complex, multi-variable problem.