Different physical processes for providing thermal comfort for passive buildings include solar radiation, long‐wave radiation exchange, radiative cooling, and evaporative cooling. Solar radiation and radiative cooling are the processes used for both thermal heating and cooling purposes

1. PASSIVE HEATING ANG COOLING
TECHNIQUES
KHUSHI BIBOLIA
L.T.I.A.D.S
Koparkhairne

2. PASSIVE SOLAR HEATING AND
COOLING
Passive solar heating and cooling, sometimes referred to simply as passive solar design
Passive solar design refers to the use of the sun’s energy for the heating and cooling of living spaces by exposure to the sun. When sunlight
strikes a building, the building materials can reflect, transmit, or absorb the solar radiation. In addition, the heat produced by the sun
causes air movement that can be predictable in designed spaces.
These basic responses to solar heat lead to design elements, material choices and placements that can provide heating and cooling effects
in a home.
Unlike active solar heating systems, passive systems are simple and do not involve substantial use of mechanical and electrical devices, such
as pumps, fans, or electrical controls to move the solar energy.

3. A COMPLETE PASSIVE SOLAR
DESIGN HAS FIVE ELEMENTS:
▪ Aperture/Collector: The large glass area through which sunlight enters the building. The aperture(s) should face within 30 degrees of true south and should not
be shaded by other buildings or trees from 9a.m. to 3p.m. daily during the heating season.
▪ Absorber: The hard, darkened surface of the storage element. The surface, which could be a masonry wall, floor, or water container, sits in the direct path of
sunlight. Sunlight hitting the surface is absorbed as heat.
▪ Thermal mass: Materials that retain or store the heat produced by sunlight. While the absorber is an exposed surface, the thermal mass is the material below
and behind this surface.
▪ Distribution: Method by which solar heat circulates from the collection and storage points to different areas of the house. A strictly passive design will use the
three natural heat transfer modes- conduction, convection and radiation- exclusively. In some applications, fans, ducts and blowers may be used to distribute the
heat through the house.
▪ Control: Roof overhangs can be used to shade the aperture area during summer months. Other elements that control under and/or overheating include
electronic sensing devices, such as a differential thermostat that signals a fan to turn on; operable vents and dampers that allow or restrict heat flow; low-
emissivity blinds; and awnings.

4. 5 ELEMENTS OF PASSIVE HEATING AND
COOLING SYSTEM

5. PASSIVE SOLAR HEATING
The goal of passive solar heating systems is to capture the sun’s heat within the building’s elements and to release that heat during periods
when the sun is absent, while also maintaining a comfortable room temperature.
The two primary elements of passive solar heating are south facing glass and thermal mass to absorb, store, and distribute heat.
There are several different approaches to implementing those elements.
PASSIVESOLARHEATING
DIRECT GAIN
INDIRECT GAIN
ISOLATED

6. DIRECT, INDIRECT AND ISOLATED HEAT
The actual living space is a solar collector, heat absorber and
distribution system. South facing glass admits solar energy into
the house where it strikes masonry floors and walls, which
absorb and store the solar heat, which is radiated back out into
the room at night. These thermal mass materials are typically
dark in color in order to absorb as much heat as possible.
The thermal mass also tempers the intensity of the heat during
the day by absorbing energy. Water containers inside the living
space can be used to store heat. The direct gain system utilizes
60-75% of the sun’s energy striking the windows.
For a direct gain system to work well, thermal mass must be
insulated from the outside temperature to prevent collected
solar heat from dissipating. Heat loss is especially likely when the
thermal mass is in direct contact with the ground or with outside
air that is at a lower temperature than the desired temperature
of the mass.
Thermal mass is located between the sun and the living space.
The thermal mass absorbs the sunlight that strikes it and
transfers it to the living space by conduction. The indirect gain
system will utilize 30-45% of the sun’s energy striking the glass
adjoining the thermal mass.
The most common indirect gain systems is a Trombe wall. The
thermal mass, a 6-18 inch thick masonry wall, is located
immediately behind south facing glass of single or double layer,
which is mounted about 1 inch or less in front of the wall’s
surface. Solar heat is absorbed by the wall’s dark-colored outside
surface and stored in the wall’s mass, where it radiates into the
living space. Solar heat migrates through the wall, reaching its
rear surface in the late afternoon or early evening. When the
indoor temperature falls below that of the wall’s surface, heat is
radiated into the room.
Operable vents at the top and bottom of a thermal storage wall
permit heat to convect between the wall and the glass into the
living space. When the vents are closed at night, radiant heat
from the wall heats the living space.
Here solar radiation collection and storage are thermally isolated
from the living spaces of the building. This results in a greater
flexibility in the design and operation of the passive concept. The
most common example of isolated gain is natural convective
loop. In this system solar radiation is absorbed to heat air or
water. The warm air or water rises and passes through the
storage, transferring its heat. The cooler air falls to the absorber
to get heated up again. Thus a 'thermosiphoning' heat flow
occurs.
The collector can be located at any suitable place and oriented
independently of the building for maximum solar gain. Thus
building design can be flexible. The slope of the collector is
generally equal to the latitude of the place. Its area may range
from 20% to 40% of the floor area of the living space to be
heated. The collector consists of an absorber (usually a
corrugated metal plate with black pint that can withstand
temperature upto 120°C) and glazing.
The method of distribution of heat from the storage can either
be by radiation or convection, or it can be directly from the
collector. If water is used as the working fluid, the hot water can
be run through the pipes installed in the floor slab, where heat is
stored and radiated into the living space.
DIRECT HEAT GAIN INDIRECT HEAT GAIN ISOLATED HEAT GAIN

7. PASSIVE SOLAR COOLING
Passive solar cooling systems work by reducing unwanted heat gain during the day, producing non-mechanical ventilation,
exchanging warm interior air for cooler exterior air when possible, and storing the coolness of the night to moderate warm
daytime temperatures. At their simpliest, passive solar cooling systems include overhangs or shades on south facing windows,
shade trees, thermal mass and cross ventilation.
Passive Cooling involves designing buildings for cooling load avoidance. Design strategies that minimize the need for
mechanical cooling systems include proper window placement and daylighting design, selection of appropriate glazing for
windows and skylights, proper shading of glass when heat gains are not desired, use of light-colored materials for the building
envelope and roof, careful siting and orientation decisions, and good landscaping design.
SHADDING
CONVECTION COOLING
THERMAL MASS
VENTILATION
PASSIVE
SOLAR
COOLING

8. PASSIVE COOLING TECHNIQUES
SHADING
To reduce unwanted heat gain in the summer, all windows
should be shaded by an overhang or other devices such
as awnings, shutters and trellises. If an awning on a south
facing window protrudes to half of a window’s height,
the sun’s rays will be blocked during the summer, yet will
still penetrate into the house during the winter. The sun is
low on the horizon during sunrise and sunset, so
overhangs on east and west facing windows are not as
effective. Vegetation can be used to shade such windows.
Landscaping in general can be used to reduce unwanted
heat gain during the summer.
THERMAL MASS
Thermal mass is used in a passive cooling design to
absorbs heat and moderate internal temperature
increases on hot days. During the night, thermal mass can
be cooled using ventilation, allowing it to be ready the
next day to absorb heat again. It is possible to use the
same thermal mass for cooling during the hot season and
heating during the cold season.
VENTILATION
Natural ventilation maintains an indoor temperature that is
close to the outdoor temperature. The climate determines
the best natural ventilation strategy. In areas where there
are daytime breezes and a desire for ventilation during
the day, open windows on the side of the building facing
the breeze and the opposite one to create cross
ventilation. When designing, place windows in the walls
facing the prevailing breeze and opposite walls. Wing
walls can also be used to create ventilation through
windows in walls perpendicular to prevailing breezes. A
solid vertical panel is placed perpendicular to the wall,
between two windows.
CONVECTION COOLING
The convective cooling is designed to bring in cool night
air from the outside and push out hot interior air. If there
are prevailing nighttime breezes, then high vent or open
on the leeward side will let the hot air near the ceiling
escape. Low vents on the opposite side will let cool night
air sweep in to replace the hot air. It’s still possible to use
convective cooling by creating thermal chimneys. Thermal
chimneys are designed around the fact that warm air
rises; they create a warm or hot zone of air (often through
solar gain) and have a high exterior exhaust outlet. The
hot air exits the building at the high vent, and cooler air is
drawn in through a low vent.

9. EVAPOURATION COOLING
Evaporative cooling is a process that uses the effect of evaporation as a natural heat sink. Sensible heat from the air is absorbed to
be used as latent heat necessary to evaporate water. The amount of sensible heat absorbed depends on the amount of water that
can be evaporated.
Evaporative cooling can be direct or indirect; passive or hybrid. In direct evaporative cooling, the water content of the cooled air
increases because air is in contact with the evaporated water. In indirect evaporative cooling, evaporation occurs inside a heat
exchanger and the water content of the cooled air remains unchanged. Since high evaporation rates might increase relative
humidity and create discomfort, direct evaporative cooling can be applied only in places where relative humidity is very low.
Where evaporation occurs naturally it is called passive evaporation. A space can be cooled by passive evaporation where there are
surfaces of still or flowing water, such as basins or fountains. Where evaporation has to be controlled by means of some
mechanical device, the system is called a hybrid evaporative system.

10. VENTILATION
Ventilation moves outdoor air into a building or a room, and distributes the air within the building or room. The general
purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the
building and removing the pollutants from it.
Types of
ventilation
Natural
ventilation
Mechanical
ventilation

11. NATURAL VENTILATION
What is natural ventilation?
Natural forces (e.g. winds and thermal buoyancy force
due to indoor and outdoor air density differences) drive
outdoor air through purpose-built, building envelope
openings. Purpose-built openings include windows,
doors, solar chimneys, wind towers and trickle
ventilators. This natural ventilation of buildings depends
on climate, building design and human behavior.
The effectiveness of natural ventilation varies based on:
• Dominant wind speed and direction
• Surrounding environment
• Building footprint and orientation
• Outdoor temperature and humidity
• Window sizing, location, and operable
WIND DRIVEN VENTILATION
as wind blows across a building, it comes
into contact with the windward wall,
which develops a positive
pressure. Simultaneously the opposite
wall, also called the leeward
wall, develops a negative pressure. If
there are any openings on the windward
and leeward walls of a home, fresh air
will enter through
the openings on windward wall and exit
through the
leeward openings. With stronger wind
and larger openings, more air can pass
through the building.
STACK VENTILATION
also known as buoyancy or
thermal ventilation, is primarily induced
by temperature differences within a home.
As air in a home heats up it becomes less
dense, which causes the air to rise. This
warm air will leave your home through a
window or opening located higher in the
home, which results in cool fresh
air entering through lower
openings. Because stack ventilation does
not rely on the wind, it can take place
with relatively stable air flow on hot
summer days with no wind.

12. MECHANICAL VENTILATION
What is mechanical ventilation?
Mechanical fans drive mechanical ventilation. Fans can either be installed directly in windows or walls, or
installed in air ducts for supplying air into, or exhausting air from, a room.
The type of mechanical ventilation used depends on climate. For example, in warm and humid climates,
infiltration may need to be minimized or prevented to reduce interstitial condensation (which occurs when
warm, moist air from inside a building penetrates a wall, roof or floor and meets a cold surface).
Benefits of this system:
•Improved indoor air quality. Balanced ventilation systems supply fresh air to the living and
sleeping areas of homes while exhausting stale air at an equal rate from the bathrooms. This
proactive approach to ventilation can result in improved indoor air quality.
•Improved comfort. Buildings with tight construction and balanced ventilation systems can have
fewer drafts and a constant supply of outdoor air resulting in improved comfort.
•Improved health. Stale air can cause health problems. It can be responsible for symptoms such
as headaches, drowsiness, and respiratory problems. These symptoms are more common in
homes with poor ventilation and moisture control. Continuously providing fresh air can result in
the improved health and well being of the occupants.
•Lower utility bills. Less energy is consumed to operate ventilation systems than to heat and cool
excessive amounts of outdoor air that infiltrates leaky homes. Additional savings are captured
when these systems are equipped with either a sensible or total heat exchanger. This can result
in lower utility bills, making homes less expensive to operate.
•Balanced ventilation systems can be equipped with a heat exchanger that recovers most of the
heating and cooling energy from the exhaust air.

13. EXAMPLES
1.Eave overhangs at Twin Rivers Charter School in Yuba
City, Calif., shade windows during the summer, while
allowing solar heating during the winter.
To increase the energy efficiency of a building, a variety of
active and passive design strategies can be incorporated.
Active strategies usually consist of heating and cooling
systems, while passive design measures include building
orientation, air sealing, continuous insulation, windows and
daylighting, and designing a building to take advantage of
natural ventilation opportunities.
2.The building envelope of Legacy ER in Allen, Texas, was
optimized for energy efficiency in the hot Texas climate.
The climate in which a building is located may dictate the
type of windows needed.
Building orientation and exterior shading options are
important considerations when locating windows and
glazing. It can be more difficult to control direct solar heat
gain and glare at skylights, but it helps to orient skylights to
maximize daylighting from the north. Typically north-facing
glazing is best for quality daylighting, but daylighting
strategies can also be very effective for south-facing glazing
(and can help for west and east-facing glazing as well).

14. THANKYOU
REFERENCE
https://www.slideshare.ne
https://www.new-learn.info/
https://www.ncbi.nlm.nih.gov/
https://sustainability.williams.edu/