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Climo GEET 3

Jul 07, 2018

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vivek-puni

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    ORIENTATION

     The greatest pressure on the windward side of a

    building is generated when the elevation is at right angles to the wind direction, so it seems to be obvious the greatest indoor air velocity will be achieved in this case.A wind incidence of ! degree would reduce the

    pressure by !"#. E$TERNA% &EAT'RE(

    )ind shadows created by obstructions upwind, should be avoided in positioning the building on the

    site and in positioning the openings in the building. E*ternal features of the building itself can strongly in+uence the pressure built up.

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    RO(( -ENTI%ATION

    In the absence of an outlet opening or with a full

    partition there can be no eective air movementthrough a building even in case of strong winds.

    &or e*ample, if the air +ow is at ! deg. To an elevation, a wing/wall at the downwind end or a pro0ecting wing of an %/shaped building can more than

    double the positive pressure created.

    )ith a windward opening and no outlet, a pressure similar to that in front of the building will be built up

    indoors, which can ma1e conditions even worse, increasing discomfort.

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    %ac1 of cross ventilation

    Eect of opening

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    2O(ITION O& O2ENIN3( To be eective, the air movement must be directed at the body surface.

    In building terms this means that air movement must be ensured through the space mostly used by the occupants4 through the 5living 6one7. In the 8gure, it is shown that a larger solid surface

    creates a larger pressure build up and this pushes the air stream in an opposite direction, both in plan and section.

    2ressure build/up at inlet

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    As a result, air +ow on the ground +oor may be satisfactory but on the upper +oor it may be directed

    against the ceiling. One possible remedy is an increased roof parapet wall.

    (I9E O& O2ENIN3(

    )ith a given elevational area and a given total wind force:pressure * area;/the largest air velocity will be obtained through a small inlet opening with a large outlet.

     This is partly due to the total force acting on a small area, forcing air through the opening at a high pressure, and partly due to the 5venturi eect74in the broadening funnel :the imagery funnel connecting the

    small inlet to the large outlet;the sideways e*pansion of the air et further accelerates the articles.

    Air +ow in a two storey building

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     This could serve a useful purpose in hot climates, although if the tall bloc1 is not fully closed but is permeable to wind, these eects may be reduced.

    Air stream seperation at the face of buildings

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    Reverse +ow behind a tall bloc1