passive techniques


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passive techniques

  2. 2. Introduction • With the arrival of Muslims in India, from twelfth century AD onwards, the merger of local and immigrated architectural techniques resulted into an astounding style. • In the same way, their passive cooling techniques in buildings were merged together to provide new ways to cope with the extremes of the climate. • The buildings consume natural energy in three ways. i. Maintaining the internal environment of spaces to make them comfortable. ii. Controlling the microclimate. iii. Procuring and manufacturing of materials for construction. • Passive cooling techniques are least expensive means of cooling a home which maximizes th e efficiency of the building envelope without any use of mechanical devices. • It rely on natural heat sinks to remove heat from the building. They derive cooling directly from evaporation, convection, and radiation without using any intermediate device. • All passive cooling strategies rely on daily changes in temperature and relative humidity. The applicability of each system depends on the climatic conditions. • These design strategies reduce heat gains to internal spaces-Natural Ventilation Earth Air Tunnels Shading Evaporative Cooling Wind Towers- Passive Down Draught CoolingCourtyard Effect Roof Sprays.
  3. 3. Climatic Characteristics And Microclimatic control • • • • Before discussing the tools of passive cooling techniques used by Mughals, it would be pertinent to have some idea of the climate prevailing in North India. Composite climate occurs in most of the areas ruled by Mughals in North India which is characterized by dominated hot and dry conditions two third of the year and, a somewhat cold and a warm humid season occur in the remaining one third of the year. The gardens of paradise mentioned in the Holy Quran have been the source of inspiration throughout the Islamic world . Mughals also used this tool not only as a symbol but to improve the quality of the immediate surrounding environment of their buildings that is microclimate. The environment outside the building is important to control the inside temperature of the building.
  4. 4. Climatic Characteristics And Microclimatic control Canal of paradise (water channel passing through indoor space) Water body at fatehpur sikri Vegetation around Agra Fort Fountain improves air quality Universal business school, Karjat, Mumbai
  5. 5. Integrated Indoor-Outdoor Living Red fort is entirely surrounded by garden • Universal business school, Birkha bawari, Jodhpur Karjat, Mumbai Not all the spaces in past buildings were maintained naturally comfortable at all times. • With minor inconvenience, the users were suggested to shift from less comfortable spaces to more comfortable spaces depending upon the seasonal changes. Verandah act as buffer between indoor and outdoor spaces. Step wells are the source of summer as well as the shelter for summers.
  6. 6. Integrated Indoor-Outdoor Living In Red Fort, Delhi Emperor’s throne is surrounded by two sets of opening Bamboo roll screens for opening to prevent sun’s penetration. Druk White Lotus school, ladhak
  7. 7. Thermal Mass Thick walls provides thermal insulation. Vaults at nalanda international school, vadodara JDT Islam campus, Calicut Part of domical roof is always shaded. Outer surface shades the wall itself. •When the outer temperature is lowered at night, the high emissive property of the walls allows cooling down the wall surfaces rapidly. Arched ceiling helps to cool internal space of the roof. •Flat roofs get more radiations while vaulted and domed roofs prevent the absorption of heat of the summer’s vertical sun.
  8. 8. Courtyard as a moderator of internal climate Courtyard Courtyard with vegetation and water body enhances humidity. Universal Business School, Karjat, Mumbai Courtyard provide shade.
  9. 9. The Courtyard House, Beawar, Rajasthan Landscaped courtyard
  10. 10. •The natural cooling may be achieved by cutting off the sun’s radiations. •The sunshades not only protect from sun’s radiations through the windows but walls too. Horizontal (deciduous vine) and vertical shading Shading Devices Deep carving causes mutual shading. Deep inclinations protect walls and openings from sun.
  11. 11. Evaporative Cooling Water channel outside building 1. Ground cover 2. Water sprinkler 3. Insulated roof 4. Shading trees 5. Water trough a typical section showing passive solar features of WALMI building, Bhopal •Evaporative cooling is a passive cooling technique in which outdoor air is cooled by evaporating water before it is introduced in the building. Salsabil increases humidity in air •Its physical principle lies in the fact that the heat of air is used to evaporate water, thus cooling the air, which in turn cools the living space in the building. •To enhance the process of evaporation, fountains were used which mixed the moisture to the air and increased the humidity. •At times, salsabilwas used to maintain the water pressure to force the water to come out of the fountain head.
  12. 12. Passive Down Draught Cooling Passive Downdraught Evaporative Cooling in Torrent Research Centre, Ahmadabad. •Passive downdraft evaporative cooling systems consist of a downdraft tower with wetted cellulose pads at the top of the tower. •Water is distributed on the top of the pads, collected at the bottom into a sump and re-circulated by a pump. •These towers are often described as reverse chimneys. •While the column of warm air rises in a chimney, in this case the column of cool air falls. •The air flow rate depends on the efficiency of the evaporative cooling device, tower height and cross section, as well as the resistance to air flow in the cooling device, tower and structure (if any) into which it discharges.
  13. 13. Natural Ventilation •Natural ventilation is the result of differential wind Domed canopy and wide entrance space for air to get cooler. Vent near dome allow hot air to escape. forces on various building surfaces and temperature difference between outside and inside air. •There are several factors which affects the air flow within the buildings such as microclimate, size and proportion of windows, orientation with respect to wind direction etc. •When the air with a greater velocity enters into a wider space, sudden expansion results in lowering down of the temperature of inside spaces of the buildings.
  14. 14. Lattice Screen (Jaali) S C Techno School, Bangalore Jaali ensures privacy and provide diffuse light and view. Jaali work featured in ITM business school, Gwalior •It controls the airflow and lower down the temperature of internal spaces on the other. •When there is sunshine outside in the day, the internal spaces are not clearly visible from outside. •however, the diffused light is spread throughout the interiors. •To get a clear outside view, a cutout is provided at eye level for the viewer sitting on the floor. •Jaali in Mughal buildings mostly have a low sill or sometimes without sill so that the air could move near the floor.
  15. 15. Vernacularism Vernacular features(courtyard with partial water body with rest of the area being landscaped, corridors, local material use, tribal artwork) at Byregowda’s house, kolar, karnataka Indigenous trebeated system Vernacular elements(ruggedness of materials and shapes like bastions, ramparts, terraces and extensive use of water) at Virasate-Khalsa, Anandpur Sahib, Punjab •The technology for construction of buildings like the use of local materials with the help of local artisans made their buildings energy efficient as well. •The style and technology developed by Muslims and especially by Mughals in India had indigenous characteristics of the region with a fragrance of foreign elements wisely induced. •For example, the buildings at Fatehpur Sikri were constructed in red sand stone which was procured from quarries near the site only and buildings were erected by indigenous trabeated technology with the help of local artisans.
  16. 16. Earth Coupling •This technique is used for passive cooling as well as heating of buildings, which is made possible by the earth acting as a massive heat sink. •At depths beyond 4 to 5m, both daily and seasonal fluctuations die out and the soil temperature remains almost constant throughout the year. •Thus, the underground or partially sunk buildings will provide both cooling (in summer) and heating (in winter) to the living space. •A building may be coupled with the earth by burying it underground or berming. Passive Space Conditioning Using Earth Air Tunnel System Earth sheltered home-The Meadow Dance, Hyderabad