A Quasi-Dynamic HVAC and Building Simulation Methodology

Abstract

This thesis introduces a quasi-dynamic building simulation methodology which complements existing building simulators by allowing transient models of HVAC (heating, ventilating and air-conditioning) systems to be created in an analogous way to their design and simulated in a computationally efficient manner. The methodology represents a system as interconnected, object-oriented sub-models known as components. Fluids and their local properties are modeled using discrete, incompressible objects known as packets. System wide pressure and flow rates are modeled similar to electrical circuit models. Transferring packets between components emulates fluid flow, while the system wide fluid circuit formed by the components' interconnections determines system wide pressures and flow rates. A tool named PAQS, after the PAacketized Quasi-dynamic Simulation methodology, was built to demonstrate the described methodology. Validation tests of PAQS found that its steady state energy use predictions differed less than 3% from a comparable steady state model. PAQS was also able to correctly model the transient behavior of a dynamic linear analytical system.