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Hot and dry climatic study with appropriate case study

The document summarizes the design of Balkrishna Doshi's Sangath Architects Studio building located in Ahmedabad, India. Key features include being partially sunken underground, using vaulted roofs, maximizing natural light through skylights and diffusers, extensive landscaping and water features, and utilizing local and waste materials to minimize costs. The passive design strategies have proven highly effective at maintaining comfortable indoor temperatures through natural ventilation and insulation from the hot, dry climate.

Data & Analytics◦
HOT N DRY SUBBMITTED BY- PRAKHAR SINGH SUBBMITTED TO- AR. SONAL SINGH
PRAKHAR SINGH 3RD SEMESTER 2ND YEAR BARN1AR19005 SOA ITM UNIVERSITY GWALIOR
• 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.
• Appropriate orientation and shape of building. • Insulation of building envelope. • Massive structure. • Air locks, lobbies, balconies, and verandas. • 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. Some of the design features for buildings in this climate are:
Building Design Details • Detailing building fenestration design and construction details to promote shading, insulation and heat loss. Materials • Choosing materials which are local, durable, utilize waste, have low embodied energy content, use less water for processing and help insulate the building.
SHADING STRATEGIES • Shading from the sun and well designed shading devices are a primary need in the hot-dry climate. It is well established that a majority of the solar heat gain comes from radiation through openings. When designing shading devices for windows, the required horizontal and vertical shadow angles need to be established. They are dependent on both the orientation of the window plane and the sun path.
Horizontal shadow angle (HSA: characterizes the vertical shading device) • This is the horizontal angle between the normal of the window plane or the wall surface and the current sun azimuth angle. It is relevant for designing vertical shading devices such as fins. Vertical shadow angle (VSA: characterizes the horizontal shading device) • This is the angle that a virtual plane containing the bottom two points of the wall/window and the centre of the Sun makes with the ground when measured normal to the window plane. It is required when designing horizontal shading devices such as overhangs.
Shading by single vertical shade is not feasible as the shade depth becomes prohibitive. Hence the width is subdivided and several louvers are designed. If 6 divisions are created, i.e. effective width to be shaded is 250mm Calculate HSA and VSA at different times during designated period for each facade. We need to design a shading device for the lowest possible VSA (horizontal shade) and the lowest possible HSA (vertical shade)
Azimuth line (the sun’s position vis-a-vis the north direction Altitude lines (shows the sun’s elevation over the horizon) Lines showing the sun’s movement on a certain day of the year Lines showing the hour of the day on the day’s sun path
Wind-Rose Diagram-
Passive cooling-techniques- Natural ventilation- • Outdoor breezes create air movement through the house interior by the 'push- pull' effect of positive air pressure on the windward side and negative pressure (suction) on the leeward side. •In order to have a good natural ventilation, openings must be placed at opposite pressure zones. •Also, designers often choose to enhance natural ventilation using tall spaces called stacks in buildings. •With openings near the top of stacks, warm air can escape whereas cooler air enters the building from openings near the ground. •The windows, play a dominant role in inducing indoor ventilation due to wind forces.
Wind tower- •In a wind tower, the hot air enters the tower through the openings in the tower, gets cooled, and thus becomes heavier and sinks down. •The inlet and outlet of rooms induce cool air movement. •In the presence of wind, air is cooled more effectively and flows faster down the tower and into the living area. •After a whole day of air exchanges, the tower becomes warm in the evenings. •During the night, cooler ambient air comes in contact with the bottom of the tower through the rooms.
EARTH AIR TUNNELS- •Daily and annual temperature fluctuations decrease with the increase in depth below the ground surface. •At a depth of about 4 m below ground, the temperature inside the earth remains nearly constant round the year and is nearly equal to the annual average temperature of the place. •A tunnel in the form of a pipe or otherwise embedded at a depth of about 4 m below the ground will acquire the same temperature as the surrounding earth at its surface. •Therefore, the ambient air ventilated through this tunnel will get cooled in summer and warmed in winter and this air can be used for cooling in summer and heating in winter.
Evoporating cooling- •Evaporative cooling lowers indoor air temperature by evaporating water. •It is effective in hot and dry climate where the atmospheric humidity is low. •In evaporative cooling, the sensible heat of air is used to evaporate water, thereby cooling the air, which, in turn, cools the living space of the building. •Increase in contact between water and air increases the rate of evaporation. •The presence of a water body such as a pond, lake, and sea near the building or a fountain in a courtyard can provide a cooling effect. A TYPICAL SECTION SHOWING PASSIVE SOLAR FEATURES OF WALMI BUILDING,BHOPAL •The most commonly used system is a desert cooler, which comprises water, evaporative pads, a fan, and pump.
SANGATH ARCHITECTS STUDIO Balkrishna Doshi's own studio, Sangath, features a series of sunken vaults sheathed in china mosaic as well as a small grassy terraced amphitheater and flowing water details. Having been considered the building that fully describes himself, Sangath is a complete combination of Doshi's architectural themes from his previous work including complex interiors and structures, ambiguous edges, vaults and terraces. More about Sangath after the break.
PROJECT DETAILS- • SANGATH means “moving together through participation.” • It is an architect studio. • Location- Thaltej road, Ahmedabad. • Clint- Balkrishna Doshi sir. • Period of construction- 1979-1981. • Site area- 2346 meter square. • Total build-up area- 585 meter square. • Project cost- Rs. 0.6 Million (1981).
• The architectural studio comprising reception areas, a design studio, office spaces, workshop, library, conference room, and other ancillary spaces has been designed to naturally manage the forces of nature. •There are spatial, constructional, and landscape responses to combat the vagaries of nature in the hot dry climate. • In Ahmedabad, the summer temperature reaches 45 °C and the heat is very intense. • It is the heat rather than the breeze that becomes critical. • Natural comfort conditions can be achieved by protecting spaces from the heat and glare of the sun
DESIGN CONCEPT AND FEATURES- •Design concerns of climate ( hot n dry). •Extensive use of vaults. •Main studio partly bellow the ground (sunken). •Very less use of mechanical instrument. •Special materials are used resulting in a low cost building costing it. •Lot of vegetation & water bodies. •Continuity of Spaces. •Use of lot of diffused sunlight. •Complete passive design. •Grassy steps which Doshi uses as informal Amphitheatre.
Sandwiched construction of vault - •With the help of movable formwork, the vaults of “Sangath” were constructed with hollow clay tiles sandwiched into walls. •Inexpensively purchased, the outer skin is covered with broken glazed tile pieces from a manufacturer’s waste material. •This procedure has a precedent in the great Catalan architect Antoni Gaudi’s benches of his Park Guell in Barcelona. • Doshi’s use of this traditional technique reduces the heat inside the building
• So, not only is the re-use of waste material an important element of Third World methodology, it is also one of the most efficient ways to reduce the large percentage of sunrays.
Vaulted roof form - • The roof form creates an efficient surface/volume ratio optimizing material quantities. • The higher space volume thus created provides for hot air pockets due to convective currents that keep lower volumes relatively cool. • The ventilating window at upper volume releases the accumulated hot air through pressure differences.
SECTION- PLAN-
Subterranean spaces - •The building is largely buried under the ground to use earth masses for natural insulation.
Indirect/diffused light - •Sun light brings heat and haze with it. •To maximize daylight (intensity of illumination) and to diffuse heat and glare, the light is received in indirect manner by diffusing it. •There are three ways by which natural light is drawn within. •By upper-level large openings towards north direction, which is cool, and consistent light is reflected off the clouds. •Skylights, which are projected masses from the roof, reflect the light on the white inner wall surface, which further radiates light into the room. •Innermost spaces are lit up through small cut outs in the roof slab, which are then filled with hollow glass blocks that take away the glare and transmit diffused light .
LANDSCAPING- • Lawns and vegetative cover all around create a favourable microclimate by absorbing solar radiation and providing a cooler passage of air through humidity.
Water channels • Rainwater and overflow of pumped water from the roof tank are harnessed through roof channels that run through a series of cascading tanks and water channels to finally culminate in a pond from where it is recycled back or used for irrigating vegetation. • Water cascades also provide interesting visual experiences.
Use of secondary waste material - • Paving material is a stone chip waste while the roof surface is glazed tiles waste, both available as waste material from factories at no cost. • These have been creatively hand-crafted and integrated into the design by fully using waste material. • The application is also skill- oriented and involves as well as promotes craftsmen and our traditional heritage.
Performance - •The above measures have ensured excellent climate control in terms of keeping the inside cool and increasing the time-lag for heat transfer. •There is a difference of about 8 degree C between the interior and exterior roof skin temperatures. The time-lag for heat transfer is nearly six hours. •The natural elements are harmoniously blended with the built environment, and water recycling and waste material reuse have ensured cost economy as well as environmental consciousness.