Computational fluid dynamics (CFD) investigation of the thermal efficiency of micro climate conditioning of a typical workstation

Abstract

Energy efficiency of buildings is becoming more critical, evidenced by the fact that building rating schemes and minimum efficiencies are now referenced in section J of the Building Code of Australia (BCA), and it would be reasonable to assume these requirements will be expanded in due course. This project aims to investigate micro climate air conditioning as an alternative to conditioning the entire space in order to provide a more efficient system to be implemented in typical office workspaces. Conventional air conditioning systems typically are based on supplying conditioned air at low velocity from ceiling mounted registers. The basis for a micro climate system is to provide low air quantities at a higher velocity and slightly higher temperature locally at the workstation level. Computational Fluid Dynamics (CFD) computer programs provide a predictive tool to simulate the resultant thermal output from an air conditioning system. The effectiveness of a micro climate system was tested in a typical open plan office workstation. Phoenics CFD software was used to provide results on the expected thermal gradients in the space which was then compared against the data compiled from two data loggers located both at the workstation and the ceiling level. Reasonable correlations between the CFD analysis and the data loggers output were achieved. A number of assumptions were made in order to develop the CFD model, which appear to have been substantiated particularly for the summer conditions. A number of variables were changed to improve the performance of the system; some of these were immediately implemented with favourable results.