windbreak

Describes a study to map the ground wind conditions in the housing area Kroksback in Malmo, and to study the effect of various proposed measures to improve the wind environment. Studies local ground wind conditions by field measurements using the Swedish Institute for Building Research (SIB) mobile measuring unit and by comparative model tests in the SIB wind tunnel laboratory. Estimates wind speed and direction by means of a simple indicator device.

Uses wind tunnel model studies of houses to determine how best to reduce the surface pressure variations from wind and the associated air infiltration emphasizing the correct placement of suitably modelled coniferous trees. Finds that tree crowns convert the directed kinetic energy of approaching wind into random turbulent energy, which reduces pressure gradients on the windward walls, a prime region for air infiltration.

Suggests use of windbreaks to protect solar collectors and open air swimming pools and to protect buildings from the wind, thus contributing significantly to energy savings. Provides detailed knowledge concerning operation and effects of windbreaks: aerodynamic characteristics, effect of porosity of a windbreak on reduction of wind speed, effect of height and length, angle of incidence of the wind, effects of wind speed, ruggedness of the terrain and thermal stability of the atmosphere.

Reviews work done on the physical and biological effects of wind-breaks and shelter-belts, outlining main results. Discusses reduction in mean speed of wind, turbulence produced by shelter-belt, shading and humidity. Outlines some biological consequences of shelter-belts. Gives bibliography containing forty-seven references.

Refers to earlier work by Mattingly, Peters, Harrje and Heisler which indicated the possibility of reducing air infiltration by using sheltering devices such as fences, neighbouring buildings and trees. Reports use of wind tunnel air infiltration model to explore the effect of trees in a windbreak on a model home. Presents results of tests determining the effect on wind-induced air infiltration of the variation of various windbreak layout parameters. Introduces concept of turbulence generation as the mechanism of tree wind sheltering.