Download Passive Solar Energy

Passive Solar
Energy
Description
• Passive Solar Energy is the use of energy from
the sun without the help of photovoltaics.
What it does
• Passive solar energy is used to convert
sunlight into usable heat, cause air-movement
for ventilation or cooling, or store heat for
future use. It is commonly used to help meet a
building's energy needs by means of
architectural design, such as special
arrangement of windows, and utilizing
materials such as floors that store heat, or
other thermal mass.
Main Concepts
There are three main concepts of passive solar
energy. They are:
• -Daylighting
• -Passive heating
• -Passive Cooling
Daylighting
• Daylight is the use of natural light to supplement and/or replace
artificial lighting.
• Strategies include:
• The proper orientation and placement of windows
• Use of light wells
• Light shafts or tubes
• Skylights
• Clerestory windows (Window openings in buildings that are well
above ground level and provide sufficient amounts of daylight.)
• Light shelves
• Reflective surfaces
• Shading
• The use of interior glazing to allow light into adjacent spaces.
Passive Solar Heating:
• Passive solar heating happens when sunlight strikes an
object, and in turn, that object absorbs the heat.
• It will occur in a building if windows are oriented
correctly. The most powerful (and common) window
orientation is south, but any orientation within 30
degrees of due south is still adequate and useful.
• For Passive Heating to be most effective, approximately
eight percent of window to floor area is required for
south walls.
• Once the heat is inside the building, various techniques
can be adopted to keep, and spread the heat as
needed.
Passive Cooling:
• Techniques opposite to passive solar heating are utilized. Here,
buildings are designed to keep solar and air heat away.
• Internal heating from animate and inanimate objects is minimized
and dissipated in the environment through ventilation.
• Shading devices (fixed or adjustable) reduce solar radiation. We can
shade a building by natural vegetation and using special glazing in
windows. External shading devices can reduce solar gains by up to
90%, while still admitting a large amount of indirect light.
• External heat gain can also be minimized by good insulation,
reduced window size and by the use of reflective materials in the
walls and roof. During the building design stage, attention should
be paid to cross-ventilation and the direction of prevailing winds,
the source of cooling nighttime breezes.
Possible Uses
• Passive solar energy methods are a very good way to make use of the the
clean and inexhaustible energy from the sun. Passive heating technology is
used as the direct or indirect gain for power consumption.
• It is used for :
• -Well-planned indoor heating techniques
• -Trombe walls
• -Space heating
• -Water heating
• -Thermo siphon (Thermo siphon is the technique that is based on the
natural convection methods circulating liquids without using mechanical
pumps.)
• It is used for the thermal mass (also known as the thermal capacitance or
heat capacity) which is used to store the heat.
• Passive heating systems are also used in more common household things,
such as: solar ovens, solar cookers, solar chimneys, earth sheltering, etc.
Solar Ovens
•
The solar oven works following the principle of the greenhouse effect: the sun’s
short-wave rays cross the two glass walls without losing energy. In touching the
internal walls of the oven which are covered with a non-toxic paint, they are
transformed into heat rays that can no longer cross the glass walls. This creates
an energy trap that allows us to cook or heat meals.
Trombe Walls
• Trombe walls are sun-facing walls constructed
from either stone, concrete, adobe, or an
array of water tanks. These materials can each
function as a thermal mass, and when
combined with insulated glazing on the
outside, and vents running along the
perimeter of the mass, these walls effectively
become a solar thermal collector. Herein lies
the value of the Trombe Wall as a means of
passive solar energy.
Trombe Wall
with an overhang to prevent the hot
summer sun from causing extreme
heat.
History
1838
Edmund Becquerel observed and published
findings about the nature of materials to
turn light into energy. They were considered
interesting, but were not pursued.
1860 - 1881
Auguste Mouchout was the first man to patent a design for
a motor running on solar energy. He designed a device
that turned solar energy into mechanical steam power and
soon operated the first steam engine. He later connected
the steam engine to a refrigeration device, illustrating that
the sun’s rays can be utilized to make ice.
• 1883
Charles Fritz turned the sun's rays into electricity. His solar cell
had a conversion rate of only 1-2%.Another big milestone for
solar energy history.
• 1904
Henry Willsie recognized the need to store generated power
and built 2 huge plants in California. He was the first person to
successfully use power at night, after generating it during the
day.
• 1956
The first commercial solar cell was made available to the
public at a very expensive $300 per watt.
• 1970
The Energy Crisis arose, and suddenly it became important to
find an alternative form of energy, as people realized just how
reliant we really are on non-renewable, finite resources like
coal, oil and gas for our existence and everyday needs.
• Solar energy history was made as the price of solar cells
dropped dramatically to about $20 per watt.
• Today
There is a renewed focus as more and more people see the
advantages of solar energy, as it becomes more and more
affordable.
• Solar electric systems are now used to power many homes,
businesses, holiday cottages, and even entire villages in
Africa.
• We now commonly see solar cells powering anything from
household appliances to cars.
Sustainability
• With an expected lifetime of another five or
six billion years, the sun is virtually a limitless
source of clean energy. The amount of solar
energy reaching the Earth's surface is enough
to fulfill total global power consumption
thousands of times over!
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Advantages
Saves Money
• After the initial investment has been
recovered, the energy from the sun is
practically free.
• It will save you money on your electricity bill.
• Solar energy does not require any fuel.
• The savings are immediate and for many years
to come.
It is Very Environmentally Friendly
• Solar Energy is clean, renewable and
sustainable, helping to protect our
environment.
• Solar Energy does not contribute to global
warming, acid rain or smog.
• It actively contributes to the decrease of
harmful green house gas emissions.
• It's easily generated where it is needed.
A Passive Solar Energy System is
Independent
• Solar Energy can be utilized to offset utilitysupplied energy consumption. It not only
reduces your electricity bill, but will also
continue to supply your home with electricity
in the event of a power outage.
• A Solar Energy system can operate entirely
independent, not requiring a connection to a
power or gas grid at all..
Low Maintenance
• Solar Energy systems are virtually
maintenance free and will last for decades.
• Once installed, there are no recurring costs.
• They operate silently, have no moving parts,
do not release any smells, and do not require
you to add any fuel.
• More solar panels can be added in the future
as your energy needs increase.
Disadvantages
• The initial cost is the main disadvantage of
installing a solar energy system, largely because
of the high cost of the semi-conducting materials
used in building one.
• The cost of solar energy is also high compared to
non-renewable utility-supplied electricity. As
energy shortages are becoming more common,
solar energy is becoming more price-competitive.
• Solar panels require quite a large area for
installation to achieve a good level of efficiency.
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of your energy source.