ENERGY EFFICIENT ARCHITECTURE PASSIVE HEATING AND COOLING CONCEPTS ROOF POND ROOF RADIATION TRAP SYSTEM EARTH SHELTERED STRUCTURES EARTH AIR TUNNELS

1. ENERGY EFFICIENT ARCHITECTURE
SHABANA KOTTA
ROLL NO:34
S9 B.ARCH
EKCCOA MANJERI

2. Elements of passive heating:
1.Aperture
The large glass area, usually a window, through which sunlight
enters the building. The aperture faces within 30 degrees of true
south and should avoid being shaded by other buildings or trees
between 9 am to 3 pm each day during heating session
2.Absorber
A hard, darkened surface of the storage element, is the second
element of the design. The surface sits in direct path of sunlight,
which hits the surface and is absorbed as heat
3.Thermal mass
The materials that retain or store the heat produced by the
sunlight. Unlike the absorber, which is in the direct path of the
sunlight, the thermal mass is the material below or behind
absorber’s surface
4.Distribution
Method by which solar heat circulates from collection and storage
points to different areas of house
5.Control
During summer months, roof overhangs are used to shad the
aperture. Other elements can be used to control the under- and/or
overheating include electronic sensing devices, operable vents and
dampers, low-emissivity blinds, and awnings.
Passive heating :
Refers to technologies or design features used to heat
buildings without power consumption. Building design
attempts to integrate the principles of physics into building
exterior envelope to speed up heat transfer into a building.

3. Concepts of passive heating:
Direct Solar Gain is heat from sun being collected and
contained in an occupied space. Direct solar gain is
important for site that needs heating, because it is simplest
and least costly way of passively heating a building with
sun. Avoiding direct solar gain is important in hot climates.
Massing and orientation are
important design factors to
consider for passive heating.
Consider these factors early in the
design so that the surface areas
exposed to sun at different times of
day, building dimensions, and
building orientation can all be
optimized for passive comfort.
Thermal mass is a material's resistance to change in
temperature. Objects with high thermal mass absorb
and retain heat. Thermal mass is crucial to good
passive solar heating design, especially in locations that
have large swings of temperature from day to night.
Trombe wall is a system for indirect solar heat gain that
is a good example of thermal mass, solar gain, and
glazing properties used together to achieve human
comfort goals passively. It consists of a dark colored wall
of high thermal mass facing the sun, with glazing spaced
in front to leave a small air space
Windows and other apertures bring in heat from
sunshine. Apertures and shading must be
intelligently placed to take advantage of the sun's
heat in cold locations and seasons, not overheating
in hot seasons.
Shades can keep the heat and glare of direct sun from
coming through windows. They can also keep direct
sunlight off of walls or roofs, to reduce cooling loads.

4. Design strategies reduce heat gains to internal spaces.
1. Natural Ventilation
2. Shading
3. Wind Towers
4. Courtyard Effect
5. Earth Air Tunnels
6. Evaporative Cooling
7. Passive Down Draught Cooling
8. Roof Sprays
Passive cooling :
Passive cooling systems are least expensive means of
cooling a home which maximizes efficiency of 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
electrical devices.
All passive cooling strategies rely on daily changes in
temperature and relative humidity. The applicability of
each system depends on the climatic conditions.
1.Natural ventilation
To provide a good natural ventilation, openings must be placed
at opposite pressure zones. 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.

5. 2.Shading
Most effective method of cooling a building is to shade
the windows, walls and roof from direct solar radiation.
Heavily insulated walls and the roofs need less shading.
Can use overhangs on outside facade of building.
3.Wind tower
In a wind tower, the hot air enters the tower through the openings
in tower, gets cooled, and thus becomes heavier and sinks down.
o Extend the overhang beyond the sides of the window to
prevent solar gain from the side.
o Use slatted or louvered shades to allow more daylight to
enter, while shading windows from direct sunlight.
o Reduce solar heat gain by recessing windows into wall.
o The inlet and outlet of rooms induce cool air movement.
o In the presence of wind, air is cooled more effectively and flows
faster down the tower and into the living area.
o After a whole day of air exchanges, the tower becomes warm in the
evenings.
o During the night, cooler ambient air comes in contact with the
bottom of the tower through the rooms.
o The tower walls absorb heat during daytime and release it at night,
warming the cool night air in the tower.
o The system works effectively in hot and dry climates where
fluctuations are high.
o A wind tower works well for individual units not for multistoried
apartments.

6. 4.Courtyard effect
Due to incident solar radiation in a courtyard, the air gets
warmer and rises. Cool air from the ground level flows
through the louvered openings of rooms surrounding a
courtyard, thus producing air flow.
At night, the warm roof surfaces get cooled by convection
and radiation. Courtyard as a moderator of internal climate
If this heat exchange reduces roof surface temperature to wet
bulb temperature of air, condensation of atmospheric
moisture occurs on the roof and the gain due to condensation
limits further cooling.
If the roof surfaces are sloped towards the internal courtyard,
the cooled air sinks into the court and enters the living space
through low-level openings, gets warmed up, and leaves the
room through higher-level openings.
5. 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.
The room maintained at comfortable temperatures (approx.
20-30 degree Celsius) round the year by the earth air tunnel
system, supplemented, when-ever required, with a system of
absorption chillers powered by liquefied natural gas during
monsoons and with an air washer during dry summer.

7. 6. Evaporative 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. Presence of a water body such as pond, lake, and sea
near building or a fountain in courtyard can provide cooling effect.
7. Passive Down Draught Cooling
In this system, wind catchers guide outside air over water-filled pots,
inducing evaporation and causing a significant drop in temperature
before air enters interior.
Such wind catchers become primary elements of the architectural
form also. Passive downdraught evaporative cooling is particularly
effective in hot and dry climates.
Evaporative cooling has been used for many centuries in parts of
the middle east, notably Iran and turkey. It has been used to
effectively cool the Torrent Research Centre in Ahmedabad.

8. 8. Roof Sprays
Roof-Spray cooling systems are being extensively used to reduce
the air-conditioning usage in industrial and commercial buildings.
In buildings without air-conditioning, evaporative roof spray
cooling systems help to reduce the interior temperatures. The
spray cooling systems also have been found to increase roof life
and decrease maintenance.
Roof ponding
Roof pond is a passive cooling technique based upon the increased
heat capacity of cheap and widely available water.
In general, the pond is covered during day to prevent heating, and
open at night to be cooled. Roof ponds can be inexpensively
constructed by enclosing water in plastic bags, metal or fiberglass
tanks with rigid transparent plastic covers.
Hot arid climates require ascending order of water-concrete
insulation thickness, in the summer and in descending order of
thickness in the winter. For typical cold cli-mate ascending order of
thickness is more appropriate.
The performance of the system appears to be satisfying; No
auxiliary heating or cooling systems were employed during the 9
month test in California .
Studies indicate that the indoor temperatures can be maintained
below 30 C in summer while the maximum dry-bulb temperatures
are above 40 C for hot arid climate of Delhi.

9. Roof Radiation Trap:
The Roof Radiation Trap, which utilizes solar energy for heating of
buildings in winter and nocturnal radiation for cooling in summer.
The radiation trap consists of fixed insulating layer separated
from the flat roof and glazing, protected by hinged insulating
panel, in the southern gap between the roof and the fixed
insulation. This fixed insulating layer is covered by corrugated
metal sheets, painted white, which serve as nocturnal radiators in
summer. The radiation trap is integrated with the building,
thermally as well as architecturally. The hot air in the space
between the flat roof and the fixed insulation is blown into a
thermal storage of gravel, under the floor or inside the building.
stored heat 'recovered' by forced convection during cloudy days.
Earth sheltered structure:
An earth shelter is a structure
(usually a house) with earth
(soil) against the walls, on the
roof, or that is entirely buried
underground.
Earth acts as thermal mass,
making it easier to maintain a
steady indoor air temperature
and therefore reduces energy
costs for heating or cooling.

10. INDIRA PARYAVARAN BHAWAN Jor Bagh , New Delhi
This is a project of ministry of environment and forests for construction of
new office building at new Delhi. The basic design concept of the project
is to make the net zero energy green building.
ACHIEVEMENTS:
1. 40% savings in energy
2. zero electricity billing
3. 55% savings in water
4. zero net discharge.
5. largest roof top solar power system in any multistoried
building (930kwp)
6. first in government sector targeted for both ratings of
green building (5star griha leed India platinum)
Plot area:9565sq m
Max ground coverage:30%
F.A.R: 200
Height:35m
Built-up area : 3,1400 m2
Year of completion : 2013
CRITERIONS :
1. Preserve and protect landscape during construction
2. Design to include existing site features
3. Reduce hard paving on-site and/or provide shaded hard-paved surfaces
4. Enhance outdoor lighting system efficiency and use renewable energy
system for meeting outdoor lighting requirements
5. Plan utilities efficiently and optimize on-site circulation efficiency
MEASURES FOR SITE:
1. Wider Front Setback (22m) to protect front tree line
2. Preserve the integrity of the green street
3. Preservation of the local ecology
4. Tree only 19 cut and 11 Trees Transplanted
5. Excavated Soil reutilized at other construction sites and the Zoo
6. The IPB office building for the ministry of environment and
forests has been planned in 2 parallel blocks facing the north
south direction, with a large linear open court in the center.
7. The Building blocks create a porous block form to optimize
8. air movement throughout the site and the N- S orientation
allows for optimum solar access and shading.
BUILDING ORIENTATION:
Effective ventilation by orientating the building e-w and by
optimum integration with nature by separating out different blocks
with connecting corridors and a huge central court yard.

11. BUILDING PLANNING AND CONSTRUCTION:
1. More than 50% area outside the building is soft with plantation
and grassing.
2. circulation roads and pathways soft with grass paver blocks to
enable ground water recharge.
3. Reduce landscape water requirement
4. Reduce water use in the building
5. Efficient water use during construction
6. Optimize building design to reduce conventional energy demand
7. Optimize energy performance of building within specified comfort
limits
8. Utilization of fly-ash in building structure
9. Reduce volume, weight, and construction time by adopting
efficient technologies (such as pre-cast systems)
10. Reduce landscape water requirement
11. Drip irrigation
12. Use of native species of shrubs and trees having low water demand
in landscaping
13. Low lawn area so as to reduce water demand.
14. Reuse of treated water for irrigation Reduce water use in the
building
15. Low discharge fixtures
16. Dual Flushing cistern
17. Waste water treatment
18. Reuse of treated water for irrigation and cooling towers for HVAC
19. Rain water harvesting Efficient water use during construction-
20. Use of curing compound
21. Site and Water Mgmt Strategies Appropriate Shading from Summer
Sun, while allowing in winter sun
22. Optimize building design to reduce conventional energy demand.

12. o Energy efficient light fittings to reduce energy demand
o part condenser water heat rejection by geothermal
mechanism. This will also help in water conservation
in cooling towers for hvac system
o variable chilled water pumping system through vfd.
Vfd on cooling towers fans and ahu.
o Pre cooling of fresh air from toilet exhaust air through
sensible & latent heat energy recovery wheel
o entire hot water generation through solar panels.
o Maximum daylighting
o regenerative lifts.
o Use of lux level sensor to optimize operation of
artificial lighting.
o Solar powered external lighting.
Geothermal Cooling
o Condenser water heat shall be rejected to earth by
boring at suitable depth &sending hot water at 100 F
(37.8 C)& back at 900 F (32.2 C).
o Enormous water saving since no makeup water is
required. And makeup water pumping & treatment cost
get eliminated.
o Saves cooling tower fan energy.
Active Chilled Beams
Working Principle:
Supply air flows through nozzles in small air jets which
induce room air to flow around the coil & air gets cooled.
Advantages :
Reduces power consumption
Easy Installation
No noise as no moving parts
Easy Air balancing activity
No filters maintenance
Save architectural space height
.