Energy : Passive Solar
Technology in Building
Building Science II
Prepared By:
Asst. Prof. Sweta Amatya
Method of Solar Technology
1. Active solar heating & cooling system.
2. Passive solar system
Heating
Cooling
Heating & cooling
Passive Solar Cooling Techniques
Passive Solar Cooling
Non-mechanical method
Reduce peak cooling of the building
Reduce size of A/C
Thermal Load Directly enters in the building in
3 major ways :
Thermal load in the building Controlled through
1.Penetration of direct Shading Devices,
beam sunlight Deciduous Trees,
Plantation
2.Conduction of heat Shading, Paints
through walls/roofs
Evaporative, Radiative,
3. Infiltration of outside air
Convective Cooling
Passive Solar Cooling Techniques
1. Penetration of direct beam sunlight
This is the main source of heat gain inside the
building.
The entry of direct solar radiation can be controlled
by using
shading devices
deciduous trees
plants
Passive Solar Cooling Techniques
2. Conduction of heat through walls/roofs
This heat gain method of building is directly related
to the temperature difference between the
outside surface and the inside surface.
To minimize the conducted heat ,amount of
absorbed radiation from the outside surface due
to the outside surface temperature should be
minimized.
2. Conduction of heat through walls/roofs
Ways to minimize the outside surface
temperature
I. Shading
II. Paints
I. Shading: Shading by shading devices
Passive solar design works
by utilizing overhangs to
shade house during the heat of the summer
allow sunlight to penetrate the interior of the house
during the winter
I. Shading: Shading by shading devices
It is important that overhangs are properly sized.
L = ¼ H (in southern Latitude)
L = ½ H ( in Northern Latitude)
• It prevents the solar radiation (block,allow etc) incident
on a building
I. Shading: Shading by shading devices
They are used
internally
externally
interplane
They may be
mechanical equipment (like dynamic facades)
Projections(chajja)
Cantilevers, Louvers
Fins, jallis or even textile
I. Shading: Shading by shading devices
• It can be
• Fixed
• Manual
• automatic moveable
• Its primary objective is creating a comfortable internal
environment that is cool in summer and warm in winter
Sun Shading Device: Types
On the basis of their position in a building:-
Internal
External
Interpane
I.Sun Shading device: Types
Internal
Limits the glare resulting from solar radiation
Usually are adjustable and allow occupants to
regulate the amount of direct light entering their space
I.Sun Shading device: Types
External
Most thermally efficient as it controls the amount of
radiation entering the building externally
Horizontal, vertical or egg crate device
Vegetation and other buildings can also act as
shading devices
I.Sun Shading device: External
I.Sun Shading device: Types
South Facade
• Shading devices are normally designed as horizontal
projections above the windows
• the length of the projection is determined as a geometric
function of the height of the window and the angle of elevation
of the sun at solar noon
I.Sun Shading device: External
I.Sun Shading device: Types
West Façade
• Vertical Shading Devices
I.Sun Shading device: External
I.Sun Shading device: External environment
Building
Deciduous tree
Shading
Sun Shading device:
Disadvantages
Difficulties can be experienced in handling the internal shading
devices like curtains and blinds
In use of shading devices like shelves, problems with low angle
winter sunlight penetration can give rise to glare
If the building is highly stylized (e.g. Neoclassical or glass cube), it
may be impossible to reconcile external shading with original style
Shading always blocks a part of the view
Shading: Roof Shading
I.Shading: Roof Shading
• roof receives maximum radiation
in summer, roof requires maximum
attention
• Shading the roof is a very
important method of reducing heat
gain
• Shading provided by external
means should not interfere with
the night time cooling
• mainly important for roof surfaces
which are exposed to the cool night
sky
I.Shading: Roof Shading
Various ways of roof cooling:
• Roof shading by vegetation
• Roof shading by pots
• Removable roof shade
Shading: Roof by vegetation
cover over the roof from the direct radiation
cover of deciduous plants or creepers is a better
alternative
Evaporation from the leaf surface, brings down the
temperature of the roof to a level than that of the daytime
air temperature
• At night, it is even lower than the sky temperature
Shading: Roof by vegetation
Shading: Roof by vegetation (Green roof)
I. Shading: Roof by Pot
Another shading device used in some traditional
building is the entire roof surface area with earthen
small closely packed inverted pots.
In addition to shading, this arrangement provides
increased surface area for radiation emission and
insulating cover over the roof, which obstructs heat
flow into the building .
Shading: Roof by Pot
Roof shading by
inverted earthen pots(Gujrat, India)
I.Shading: Removable roof shade
• Another inexpensive and effective device is a
removable canvas cover mounted close to the roof
• During daytime it prevents entry of heat and its
removal at night, radiative cooling
• Painting of the canvas white minimizes the radiative
and conductive heat gain
Shading: Removable roof shade
I.Shading: by texture
Shading: by texture
Highly texture walls have a portion of their surfaces
in shade
It will be cooler than a flat surface
2. Paints
If the external surface of the building are painted
with such colors which have minimum absorption of
solar radiation but the emission is high then the heat
transmitted into the building is reduced considerably.
3. Effect of infiltration of outside air
The effect of infiltration of outside air can be reduced by
following ways:
i. Evaporative cooling
ii. Radiative cooling
iii.Convective cooling
3. Effect of infiltration of outside air
Evaporative cooling
It is a passive cooling technique in which outdoor air
is cooled by evaporating water before it is
introduced in the building.
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.
Evaporative Cooling
Evaporative Cooling
Evaporative Cooling
Evaporative Cooling
3. Effect of infiltration of outside air
Evaporative cooling
However passive evaporative cooling can also be
indirect.
The roof can be cooled with a pond, wetted pads or
spray, and the ceiling transformed into a cooling
element that cools the space below by convection and
radiation without raising the indoor humidity.
3. Effect of infiltration of outside air
Evaporative cooling
It is possible to cool a small building by placing
wetting pads in the windows or porches, facing
the wind direction
Water bodies created by fountain pools or flowing
channels along with the natural wind, provide
cooling for living spaces
3. Effect of infiltration of outside air
Evaporative cooling
One way of doing this is to bring the outdoor air
into the house through a moist filter or pad
This method has been used in dry climate, where
water is not scare
3. Effect of infiltration of outside air
Evaporative cooling
Sprays can also be used to achieve optimum
natural cooling
In this approach, water is pumped to sprinklers
along the peak of a house and allowed to trickle
down a sloping roof.
3. Effect of infiltration of outside air
Evaporative cooling
The rate of evaporation is greatly enhanced in such
a system because a much larger surface area is
exposed to the night air.
Roof sprays rely on a little external power to get
the water to the roof and hence do not qualify as
completely passive systems.
Evaporative Cooling
Roof top sprinkler - combined radiative and evaporative cooling can be integrated together to
increase the rate of cooling
Roof top sprinkler
3. Effect of infiltration of outside air
Radiative cooling system
3. Effect of infiltration of outside air
Radiative cooling system
Radiative cooling refers to cooling by exposure of any
element of the external envelope of the building to
a cool night sky.
The accumulated heat during the day is lost by
radiation to the cool nights, thereby cooling the
envelope.
The envelope thus acts as cold storage during the
day, drawing the heat away from the living space.
3. Effect of infiltration of outside air
Radiative cooling system
Roof Ponds
In general, any radiating surface interacts with the
surrounding atmosphere and most of the
radiation emitted by the surface is absorbed by
the atmosphere.
Roof ponds, use of open able false ceiling are also very
effective summer cooling strategies
3. Effect of infiltration of outside air
Radiative cooling system
Roof Ponds
3. Effect of infiltration of outside air
Radiative cooling system
Roof Pond
In the cooling cycle, insulating panels remain closed
by day to reject unwanted solar heat.
The cool ponds act as "thermal sponges", absorbing
room heat conducted through the interior ceiling
supporting them.
3. Effect of infiltration of outside air
Radiative cooling system
Roof Pond
At night panels are rolled back, exposing the ponds to
the black body of the night sky and to the cooler night
air and breeze.
The ponds lose heat by radiation to the night sky and
by natural convection to the air.
3. Effect of infiltration of outside air
Radiative cooling system
Roof pond
Roof pond systems are particularly effective in regions
of low humidity and clear summer nights.
Water is usually stored in large plastic or fiberglass
containers covered by glazing and the space below is
warmed by radiant heat from the warm water above.
3. Effect of infiltration of outside air
Radiative cooling system
Roof pond
Six to twelve inches of water are contained on a
flat roof.
These require somewhat elaborate drainage
systems, movable insulation to cover and uncover
the water.
Roof pond
condition of
Solar Radiation condition of opened covering
closed covering
Pond or
water drums
Pond
Pond cover
Roof pond
Roof pond
Roof pond
3. Effect of infiltration of outside air
Convective Cooling system
3. Effect of infiltration of outside air
Convective Cooling system
The next step in natural cooling is to take advantage of
"convective" cooling methods - those which use the
prevailing winds and natural, gravity-induced
convection to ventilate a house at the appropriate
times of the day
The straightforward convective method admits cool
night air to drive out the warm air
3. Effect of infiltration of outside air
Convective Cooling system
If breezes are predominant, high vents or open windows
on the leeward side (away from prevailing breeze) will let the
hottest air, located near the ceiling, escape.
To get the best cooling rates, leeward openings should have
substantially larger total area (50% to 100% larger) than those
on the windward side of the house.
Location of cool air inlet vent that receives predominant
cool summer breezes
Use of high ceiling vaults, and thermal chimneys to
promote rapid air changes for natural ventilation
Wind turbines can be used to increase the ventilation
rate of rooms
3. Effect of infiltration of outside air
Convective Cooling system
An even better approach is to use solar radiation
to induce a more rapid flow.
One of the many possible approaches uses a Trombe
wall vented to the outside
3. Effect of infiltration of outside air
Convective Cooling system
Sunlight striking the concrete wall will heat the
air in the space between glass and wall to
temperatures above 150°F.
This very hot air rises quickly and escapes,
drawing cool air into the house through vents on
the north wall.
An indirect gain mass wall can be used to
significantly increase ventilation rates in adjoining
spaces
3. Effect of infiltration of outside air
Convective Cooling system
Another convective cooling strategy is the drawing
of outdoor air is drawn through tubes buried in the
ground and dumped into the house.
Made of material that allows easy thermal
transfer, these tubes are buried several feet deep to
avoid the warmer daytime surface temperatures.
Warm outdoor air entering the tube gives up its
heat to the cooler earth, and cools substantially
before entering the house.
By using
underground
air chambers,
significant
sensible
cooling can be
obtained.
Natural Ventilation system
Natural Ventilation system
A primary strategy for cooling buildings without
mechanical assistance is to employ natural ventilation.
positioning of windows,
the nature of elevations,
the disposition of internal divisions, and
the position of external obstructions
all affect the passage of air through enclosed spaces.
Natural Ventilation system
The effect of various configurations
and types of obstruction on the
internal flow of air.
Natural Ventilation system
i. An obstruction set at a distance from the window is likely
to produce a more even spread of air movement through the
room.
ii. A barrier such as a tree may cause acceleration of air
underneath it, with a wider band of moving air beyond.
iii. The combination of a tree and a hedge, for example,
may have the effect of reversing the flow of air.
iv. External obstructions may also be used to re-direct the
flow of air, where the main windows do not face the
flow of air.
v. This can also be affected by the way the windows open.
vi. Louvers are a useful way of maximizing the flow of
air through openings. However, louvers usually have to
be closed if there is wind-driven rain.
Earth contact cooling system
Because of thermal storage capacity of earth, the daily
and even annual temperature fluctuations keep on
decreasing with depth below the ground surface.
This technique is essentially used for cooling the air
in the hot and dry climates.
In summer during the day, the temperatures inside the
ground are much lower than the ambient air
temperatures. If the part of the building is placed into the
earth or earth bermed, the building losses heat to the
earth and building cools.
Earth contact cooling system
Describe the system which architecture to
follow to design an energy efficient
building for hot climate. (15)
2.Ha Ha Haus, Australia
Location: Alphington
(Wurundjeri Country), Australia
Climate: Warm summer climate
Designed by FIGR Architecture
and Design
•Passive design strategies implemented???
3. Sheikh Khalifa Medical City,
Abu Dhabi
The Sheikh Khalifa Medical City
is a 3-million-square-foot
medical city complex designed
by Skidmore, Owings & Merrill
LLP (SOM
Location: Abu Dhabi
Climate: Arid desert climate
•Passive design strategies implemented???
Max House, India
Max House was designed by Studio
Lotus and is a LEED Gold-certified
eight-storey corporate campus. The
project was completed in 2020
Location: New Delhi’s Okhla Industrial
Area
Climate: Monsoon-influenced humid
subtropical
•Passive design strategies
implemented????
THANK YOU
