Optimization of ventilation system design and operation in office environment, Part I: Methodology

Ventilation principles that integrate flexible and responsive elements have grown in popularity in office buildings due to increasing concerns about the impact of indoor environment quality on office workersʹ well-being and productivity, as well as concerns over the rising energy costs for space heating and cooling in the office building sector. Such advanced elements as underfloor air distribution (UFAD), passive swirl diffusers, and demand controlled ventilation have posed challenges to system design and operation. This paper is concerned with the development and implementation of a practical and robust optimization scheme, aiming to assist office building designers and operators to enhance thermal comfort and indoor air quality (IAQ) without sacrificing energy costs of ventilation. The objective function was constructed in a way attempting to aggregate and weight indices (for thermal comfort, IAQ, and ventilation energy usage assessment) into one indicator. The path taken was a simulation-based optimization approach by using computational fluid dynamics (CFD) techniques in conjunction with genetic algorithm (GA), with the integration of an artificial neural network (ANN) for response surface approximation (RSA) and for speeding up fitness evaluations inside GA loop.