POWBAM0 Mechanical Power Balances for Multi-zone Building Airflow Analysis

Abstract Conventional methods of multi-zone airflow analysis ignore mechanical energy conservation in forming the system equations governing building airflows. As a result, airflows computed using these methods generally violate this fundamental conservation principal and thereby falsely create or destroy kinetic energy within building zones. While the impact of this fundamental oversight has yet to be fully evaluated, it need not be tacitly accepted. This paper will present a rigorously detailed theoretical approach that imposes both mass and mechanical energy conservation to the problem of multi-zone airflow analysis and, through comparisons with results computed using computational fluid dynamics (CFD) and the conventional approach to multi-zone airflow analysis, will demonstrate that a power balance approach can predict building airflows that satisfy both of these fundamental conservation principles while offering greater capabilities than that of the conventional approach. Furthermore, it will be shown that the conventional approach is a special limited case of the practical application of the power balance approach. A computational prototype, POWBAM0, based on the theory will be introduced.