The Three Major Determinants of good Orientation Are: Sun :
The sun is one of the most important determinants in energy efficient building design.
The radiant energy from the sun can be used in both an active and a passive manner to provide heat for a structure.
Orientation should save the interior of the house from strong sunrays.
Heat is more direct from sun during day and indirect during the night time.
Direct heat is influenced by factors like proximity to sea – coast, hills, valleys and sandy deserts etc. or also by elevation above sea – level, soil, vegetation and forests etc i.e., by latitude and altitude of the sun. Intensity of the sun and duration of sunlight has a strong influence on building comfort.
Indirect heat: Heat enters the building through windows and is captured and stored in masonry wall and it is slowly transmitted indirectly into the building and keeps the building warm when the sun can't heat it. Building materials like stone, bricks and tiles absorb heat during day and slowly radiate by night.
Wind:
Direction of prevailing wind plays an important role in orientation as it influences natural ventilation.
The wind direction is not the same throughout the year.
It changes from season to season.
The wind blows from either west or southwest during southwest
monsoon season, i.e June to September and from northeast or north during Northeast monsoon season, ie October to December.
The flow of wind in building is very much governed by the orientation of the window and door openings in the exterior wall.
The window in bedroom should be set in the direction of prevailing wind, but if the bedrooms are directly exposed to the afternoon sun, they are heated by day light intensity and the radiation of heat in night will warm the breeze and make the room hot and uncomfortable. Hence deep verandahs both on south and west sides are necessary.
Aqueous vapour or relative humidity in the air is also important in contributing to comfort to the house.
At sea shore areas air is cool but still temperature cause discomfort due to higher humidity. this feeling is called as sultriness.
Rain:
The climate and the site play a large role in defining the rain exposure that a building is exposed to.
Heavy rain in summer and winter monsoon is typically the largest source of moisture for the building enclosure.
Control of rain penetration and absorption is a fundamental function of the building enclosure, and a major part of its moisture control functions. This can be checked by providing overhead roof or projection in wind direction, plantings, landscaping.
Raised plinth from ground level prevents moisture seepage through floor and entry of flood water or rain water into the house.
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