Climatic Aspects

Influence of climate on the selection of site for buildings has been discussed. Effects of wind, solar radiation, humidity and rainfall were also described. In this section orientation of buildings and sun shine-control through shading devices will be discussed. Climatic design is important in India. Since, we cannot afford to air condition or mechanically control the climate of our public and private buildings, we should take maximum advantage of the available natural conditions. 

Orientation of Buildings 

we have given broad guidelines for the orientation of buildings based on global and site climates. These guidelines in a more elaborate form are given as follows : 

• In hot-dry climates, the largest dimension of a building should preferably face north and south, as these elevations receive the lowest heat loads from radiation. 
• In warm-humid climates natural ventilation is the predominant criterion for orientation. The buildings tend to have long elongated shapes with single row to allow for cross-ventilation. The rooms shall preferably face the south in India. 
• In monsoon climates the weather changes from season to season and designers face a difficult task. Experience shows that the buildings are best designed to meet the requirements of the cold season. A courtyard type, low-rise development is suitable. 

It is obvious that the orientation of buildings is based on following three major factors : 

• Sun as a source of natural light and radiant heat, 
• Natural breeze, and 
• Rainfall regime: 

Local site conditions sometimes override the available guidelines, and even specialized functional requirements have their due influence; for example, for schools north light has been recommended  for class rooms, and north orientation is suitable for clothing shops, libraries and studios where relatively steady illumination is necessary. In factories, north-light trusses are utilised, and every room in a hospital requires admission of natural light. preferably from the south. 

We have studied in that the solar radiation causes heat absorption by direct action in the day. The materials used in the building absorb heat during day time and slowly radiate during night, causing discomfort. Protection against this by using shading devices and providing cross-ventilation are important. 

In parts of India which lie within the tropics, February to June forms the summer, and the subsequent four months is the rainy season. Wind prevails from south-west. Bed rooms are oriented to west or south-west to take advantage of the prevailing wind, but protection against solar radiation must be ensured. Shady trees and bushes on the sunny side should be planted and properly designed sun-breakers should he utilised. 

In a hot-humid climate, it is essential to have verandas on the east and the west faces of the building. In the next section, we shall study the design of shading devices.