wind effect

Airflow through openings in a cross ventilated building scale model was investigated in a windtunnel and by numerical predictions. Predictions for a wind direction perpendicular to the building showed an airflow pattern consisting of streamlines entering the room, that originated from approximately the same upstream area in the undisturbed boundary layer and a direction of the flow into the room dependent on opening location with velocity vectors pointing away from the stagnation point.

There has been considerable interest in the interaction between buoyancy and wind pressure gradients on the overall structure of natural ventilation flows. Indeed, it has been shown that when wind and buoyancy forces act in opposition, it is possible that for certain wind speeds, multiple steady states may emerge, with a stable wind dominated and a stable buoyancy dominated regime being possible for identical conditions; while at lower wind speeds, the buoyancy dominated flow develops and higher wind speeds, the wind dominated flow develops.

Wind-driven cross-ventilation in a single-zone cubic building with two large openings is investigated using a computational fluid dynamics approach. We analyzed the driving force and the ventilation flow rate due to wind as a function of the relative location and geometry of the two ventilation openings. The aim is to understand how well the conventional simple macroscopic method predicts the ventilation flow rate and when the simple method fails. Parametric studies were completed using building envelope porosity as the primary variable of interest.

This paper investigates the single-sided natural ventilation through a VELUX centre pivot roof window under natural weather conditions. The aim of the investigation is to develop an empirical formulation for air flow rate through a roof window based on CFD and tracer gas decay measurement methods. CFD can separate buoyancy and wind effects in the calculation of the air flow rate through a window opening, but it is difficult to isolate wind effect from buoyancy forces during measurements.

For static smoke exhaust systems, such as horizontal ceiling vents, buoyancy of the smoke layer is the driving force for smoke removal. However, wind effect should also be considered, as the smoke layer interface height can be raised up or pulled down, depending on the conditions. Key equations on calculating the smoke exhaust rates and the required vent area will be reviewed first in this paper. Modifications of those equations with wind effects are discussed. An atrium is taken as an

This paper reports some findings from IEA ECBCS Annex 35 about wind driven flow through building openings. Wind tunnel studies have been performed on simplified buildings, in order to know if pressure distributions on sealed buildings can be used to predict airflow through facade openings. A new parameter, the catchment area, is introduced by author.

Results of a CFD simulation of the wind-assisted stack ventilation of a single-storey enclosure with high and low-level ventilation openings are presented and compared with both the laboratory measurements and the analytical model of the flow and thermal stratification developed by Hunt and Linden (2001). Comparisons show that close quantitative agreement is obtained between the thermal stratification predicted by the CFD and the analytical model and experimental measurements.

In many cases natural ventilation is used to ensure an acceptable indoor environment. However it is difficult to design a building for acceptable ventilation rates and indoor comfort without the proper tools or guidelines. The passive building simulation tool Building Toolbox was extended with natural ventilation models for the design of natural ventilated buildings. The simulation tool was verified with actual measurements during three case studies to ensure its integrity and to illustrate its applicability in this field.

The wind and buoyancy pressure driving forces for natural ventilation of buildings are very low, typically less than 10 Pa. Depending upon the prevailing climatic and thermal conditions, or even the location of a building on a site in relation to other surrounding buildings and landscape, the predominant pressure force incident on a purpose-provided natural ventilation opening can either be closer to the lower range of pressure differentials (< 2 Pa) or vary over a wider range of higher pressures (2 - 10 Pa).