12 Important Design Strategies for Hot and Dry Climate Zones
India is divided into five major climatic zones. Hot and Dry climate is seen in western parts of the country where desert like conditions exist. Jaipur, Jaisalmer, Kutch, Gujarat, Parts of Maharasthra are the regions that come under this climate zone. Important Design approaches and strategies for hot and dry climate zones are discussed in this section.
Characteristics of Hot and Dry Climate
- Temperatures: Very hot weather in summer and cold in winter
- Summer- temperatures vary from 40-45 deg C
- Winters – Min temperatures- 5-25 deg C
- High temperature difference between Day and Night
- High Solar Radiation causes glare
- Hot Winds
- Rainfall: Minimal rainfall
- Humidity: Low Relative Humidity
- Winds: Dusty winds often develop into sandstorms
- Groundcover: Dry sandy or rocky ground with less vegetation
- Sky Condition: Cloudless sky
Objectives of Design
Since the temperatures are very high in hot and dry regions, the corresponding strategies are as follows:
- Bring down Ambient air temperatures
- To reduce heat transfer during extreme temperatures (hot in summers and cold in winters)
- Reduce amount of direct solar radiation received by the building.
- Provide adequate shade
- Reduce exposed area
- Increase humidity
- Preserving vegetation
- Conserving water
- Use evaporative cooling
Design Approaches and Strategies for Hot and Dry Climate
1. Building Orientation
Since the design objective is to reduce the exposed area to direct solar radiation, and the Sun moves from East to West, the longer walls of the building should face North and South. Thereby, the building gets minimal exposure. Building orientation also affects the amount of natural ventilation it receives.
2. Plan form
The plan form of the building affects the airflow, ventilation as well as direction of air movement. The heat gain and heat loss depend on the perimeter to area ratio of a building. Greater the ratio, the greater heat during the day and greater loss at night. Similarly, smaller the ratio, lesser will be the heat gain during the day and less heat loss at night.
The main focus is to decrease heat gain in hot and dry climates, therefore, careful activity zoning related to habitable areas and services areas have to be properly zoned with respect to the building plan form ensures heat gain reduction and optimum daylighting.
Appropriate placement of service areas can act as heat or thermal barriers.
4. Building Types- Low/High rise/courtyards
The design strategy also includes whether the building is a low rise or high rise. Buildings which are low rise have a higher footprint whereas high rise buildings have a least footprint.
5. During Construction – Practices
Design strategies for hot and dry climate are even required during construction practices to preserve vegetation, conserve soil as well as to reduce air pollution.
- Protecting the roots from excavation.
- Preserving existing trees with tree guards.
- Providing sedimentation tank to collect and reuse rainwater.
- Preplanned path for movement of materials and labor.
- Preservation of topsoil by temporary plants/grass.
- Placement of barriers to reduce air pollution and spread of waste materials.
Tress prevents infiltration of dusty winds of hot summer. Preserve existing trees as they are
- Less trees on the north to let in daylight.
- More trees on the NW and NE to cut off summer radiation.
- Deciduous trees on the south side for shading in summer and solar access in winter.
7. Openings and Shading
Orientation and Shading are an important factor in reducing heat gain and significant factor as design strategies for hot and dry climate. Shading of windows is necessary for effective day lighting and to cut down heat.
- Shading of opening and wall by jali screen
- Shading of building surface by plantation.
- Installing double glazed units
- Shading of building surface by texture.
- Shading by architectural projections.
8. Passive Cooling Strategies
Passive cooling strategies have to be implemented at the design stage itself to minimize energy loads. Some of the passive cooling strategies are
- Water bodies near the structure or inside the courtyard and they have to be shaded.
- Ventilation of buildings at night
- Central wind tower
- Earth berming
9. Building Materials
Selection of Building Materials is an important factor in the design strategies of hot and dry climate to save trees and vegetation, reduce air pollution, and utilization of lower embodied energy.
- Stones – obtained from sustainable sites – less air pollution and reuse of resources.
- Concrete blocks – use of stone dust and chips – reduces air and land pollution.
- Salvaged timber – saves trees by reducing use of new wood.
- Fly ash blocks – lower embodied energy value – more efficient
- Stabilized earth blocks – lower embodied energy value – more efficient. other materials include waste glass, marble chips, terrazzo, etc.
- use of low VOC Paints
Building walls and materials chosen can reduce heat transfer through walls. Walls with sustainable materials and insulation can act as heat barriers.
Building roof and materials chosen can reduce heat transfer through walls. Roofs with sustainable materials and insulation can act as heat barriers.
12. Energy Efficiency strategies
Various design strategies for hot and dry climate related to energy efficiency includes –
- Control amount of heat reaching building.
- Building orientation
- Shading by projections
- Minimize carriage of heat through building skin
- Reduce internal heat gain and improve daylight
- Use of fixtures with low equipment power density
- Outdoor equipment’s have to shaded
- Use efficient artificial lighting
- Cooling the building
- Passive cooling strategies
- Low energy HVAC technologies
- Solar photo-voltaic installation
- Provision of Solar water heater
- Rainwater harvesting systems
- Decentralized wastewater treatment systems