Climatic Zones of India

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Introduction

Regions having similar characteristic features of climate are grouped under one climatic zone. According to a recent code of Bureau of Indian Standards, the country may be divided into five major climatic zones: Hot & Dry (mean monthly temperature >30 and relative humidity <55%); Warm & Humid (mean monthly temperature >25-30 and relative humidity >55-75%); Temperate (mean monthly temperature 25-30 and relative humidity <75%); Cold (mean monthly temperature <25 and relative humidity – all values); Composite (This applies, when six months or more do not fall within any of the other categories).


Brief Description

Buildings in different climatic zones require different passive features to make structures energy-efficient. Some features that can be adopted in particular zones are listed below.

Hot and dry

The hot and dry zone lies in the western and the central part of India; Jaisalmer, Jodhpur and Sholapur are some of the towns that experience this type of climate.

In such a climate, it is imperative to control solar radiation and movement of hot winds. The design criteria should therefore aim at resisting heat gain by providing shading, reducing exposed area, controlling and scheduling ventilation, and increasing thermal capacity. The presence of “water bodies” is desirable as they can help increase the humidity, thereby leading to lower air temperatures. The ground and surrounding objects emit a lot of heat in the afternoons and evenings. As far as possible, this heat should be avoided by appropriate design features.

Some of the design features for buildings in this climate are:

 Appropriate orientation and shape of building

 Insulation of building envelope

 Massive structure

 Air locks, lobbies, balconies, and verandahs

 Weather stripping and scheduling air changes

 External surfaces protected by overhangs, fins, and trees

 Pale colours and glazed china mosaic tiles

 Windows and exhausts

 Courtyards, wind towers, and arrangement of openings

 Trees, ponds, and evaporative cooling


Warm and humid

The warm and humid zone covers the coastal parts of the country, such as Mumbai, Chennai and Kolkata. The main design criteria in the warm and humid region are to reduce heat gain by providing shading, and promote heat loss by maximizing cross ventilation. Dissipation of humidity is also essential to reduce discomfort.

Some of the design features for buildings in this climate are:

 Appropriate orientation and shape of building

 Roof insulation and wall insulation

 Reflective surface of roof

 Balconies and verandahs

 Walls glass surface protected by overhangs, fins, and trees

 Pale colours and glazed china mosaic tiles

 Windows and exhausts

 Ventilated roof construction, courtyards, wind towers, and arrangement of openings

 Dehumidifiers and desiccant cooling


Moderate

Pune and Bangalore are examples of cities that fall under this climatic zone. The design criteria in the moderate zone are to reduce heat gain by providing shading, and to promote heat loss by ventilation.

Some of the design features for buildings in this climate are:

 Appropriate orientation and shape of building

 Roof insulation and east and west wall insulation

 Walls facing east and west, glass surface protected by overhangs, fins, and trees

 Pale colours and glazed china mosaic tiles

 Windows and exhausts

 Courtyards and arrangement of openings


Cold

Generally, the northern part of India experiences this type of climate. the design criteria are to resist heat loss by insulation and controlling infiltration. Simultaneously, heat gain needs to be promoted by admitting and trapping solar radiation within the living space.

Some of the design features for buildings in this climate are:

 Appropriate orientation and shape of building

 Use of trees as wind barriers

 Roof insulation, wall insulation, and double glazing

 Thicker walls

 Air locks and lobbies

 Weather stripping

 Darker colours

 Sun spaces, greenhouses and trombe walls


Composite

The composite zone covers the central part of India, such as New Delhi, Kanpur and Allahabad. The design criteria are more or less the same as for hot and dry climate except that maximizing cross ventilation is desirable in the monsoon period.

Some of the design features for buildings in this climate are:

 Appropriate orientation and shape of building

 Use of trees as wind barriers

 Roof insulation and wall insulation

 Thicker walls

 Air locks and balconies

 Weather stripping

 Walls, glass surfaces protected by overhangs, fins, and trees

 Pale colours and glazed china mosaic tiles

 Exhausts

 Courtyards, wind towers, and arrangement of openings

 Trees and ponds for evaporative cooling

 Dehumidifiers and desiccant cooling


References:

http://www.mnre.gov.in/

http://www.sustainable-buildings.org/images/New_Home.pdf

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