pressure distribution

Building airtightness is a critical aspect for energy-efficient buildings as energy performance of a building can be reduced significantly by poor airtightness. The Pulse technique has been regarded as a promising technology, which measures the building airtightness at a low pressure of 4Pa by rapidly releasing a 1.5-second pulse of air from a pressurised vessel into the test building and thereby creating an instant pressure rise that quickly reaches a “quasi-steady” condition. However, questions have often been asked on the test viability due to the nature of the test.

Methods of manipulating building envelope wind pressure distributions for application in the natural ventilation of high-rise buildings are presented using computer simulation methods. CFD was used to simulate the external flow while the multi-zone method was used to compute the flow distribution in the building interior. First, a 2-D CFD study was conducted to explore various techniques of manipulating the building envelope wind pressure distribution.

When conducting airtightness tests of buildings, you must ensure that all building parts to be measured have air connection, so that the test object can be considered as one single zone. This also applies to large buildings like office buildings, schools, old people homes, indoor pools, etc. with several floors and rambling floor plans. Openings that are too small for a constant air flow from the leakages to the measuring device can prevent an even pressure distribution.

A 1: 20 scale model of a low-rise naturally ventilated building was tested in a wind tunnel. External pressure coefficients were determined for an open model with various combinations of ridge, sidewall and end wall openings, as well as for a sealed model. The pressure distribution is influenced by all structural modifications at various wind angles. The differences between the open and sealed models were pronounced especially at the ridge and the leeward sidewall.

ln the paper a numerical program package is described to calculate incompressible, unsteady, three-dimensional, viscous and turbulent flow fields around sharp edged obstacle. By this the velocity and pressure distributions in the flow field and on the surfaces of square-formed bodies in a plane channel can be determined, as well as the frequencies of periodic vortex separations The channel consists of two plates extended to infinity. On the lower plate the square-formed body, which is identical with the building model, is placed.