Pressure Differences and Airtightness in Tall Buildings – Theory & Reality

Airflow in to, out of, and within buildings is a fundamental factor of building design and operation, as building airflow patterns impact occupant health and comfort, building durability, and energy consumption. This airflow is impacted by the airtightness of building elements and pressure differences created by stack effect, wind, and mechanical ventilation systems. Importantly it is the combination of these factors that will determine the resulting airflow patterns at a building.
This paper provides a summary of key aspects of the relevant theory including analysis of typical pressure differences and distributions of airtightness. The interactions of these factors and the resulting airflows that would be predicted by theory are compared with the measured results at a high-rise multi-unit residential case study building. Overall, this study aims to improve the general understanding of factors affecting airflows in buildings and how these factors combine to influence the performance of building mechanical ventilation systems. The results of the study allow for general recommendations with regards to the design of ventilation systems, building enclosure airtightness, and compartmentalization strategies.

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