Once the flow-pressurization characteristics of a building are known, the largest uncertainty in predicting air infiltration is the effect of wind shelter from nearby buildings. To study the effects of wind sheltering a large data set of hourly air infiltration and meteorological measurements were made for a row of test houses located on an exposed rural site. This configuration produces strong variations in wind shelter as the wind direction shifts from along the row to perpendicular to it.
Existing models for predicting air infiltration account for three dominant variables, namely envelope leakage characteristics, indoor-outdoor temperature difference and wind speed. Building shape, wind direction and sheltering, also influence the wind induced component of air infiltration. In this report, these variables are examined analytically and experimentally using wind tunnel data and field infiltration measurements. A sensitivity analysis of a power law infiltration relationship reveals that these factors are most significant at small temperature differences.
This wind tunnel investigation studies the effects of surrounding buildings on the wind pressure distribution over a 1 1/2-storey single-family house. Pressure coefficients obtained in the tests have been used for the calculation of air change rates and associated heat losses from the house for a range of wind speeds and internal-external temperature differences. For these calculations leakage areas in the building envelope have been assumed to be uniformly distributed.
This paper describes a set of velocity measurements which were made within a series of models of rectangular enclosures whose dimensions in plan were varied, the heights of the walls being held constant. The airflow's speed was measured at each of the points of a rectangular grid and the arithmetic mean of these measurements was adopted as a measure of the enclosure's performance in providing shelter from the wind, and was used to compare the effectiveness of one geometry against another. It was found that the degree of shelter could be optimised by a correct choice of geometry.
This paper discusses the flow of air around ideal (cubic) structures on plane surfaces subjected to a turbulent boundary layer wind. These winds are shown to follow a power-law variation with height, while winds significantly effected by thermal stratification follow a log-linear distribution. Discussion of stagnation zones, flow separation, and pressure changes is included, with possible effects upon air quality and infiltration. Also discussed are variations in building design and addition of neighboring buildings, both which produce very complex winds, yet to be quantized.
Flow patterns at ground level in groups of buildings result from the complex interaction between the wind (impact, average speed distribution with height, and turbulence) and the buildings themselves (shapes, sizes, arrangements, etc.). The
Windbreaks probably are more important for reducing infiltration of cold outside air into houses than for reducing convective heat losses. It is difficult to estimate the magnitude of tree effects on energy use for space conditioning on a year-round basis, but past studies suggest that trees have the potential to reduce winter fuel consumption by 10-25%. Describes several studies of trees as windbreaks and for summer shade. Discusses location of trees with respect to buildings.
This paper explains the physics of air flow patterns, the aerodynamics of buildings and their implications for effective ventilation. Ventilation influenced design strategies of sunshading, daylighting and landscaping are discussed.
Evaluates the space-conditioning energy conservation potentials of landscapes designed to ameliorate building microclimates. The physical bases for vegetative modifications of climate are discussed, and results of past study of the effects of vegetation on space-conditioning energy consumption in buildings are reviewed. The state-of-the-art of energy-conserving landscape designs is assessed and recommendations are presented for further research. Landscaping mobile houses and single family dwellings is considered.
Login