Passive
Solar Heating
Passive solar heating is the most effective way
of heating a building. This is because, very often, the
total amount of solar heat that reaches your home or office
is greater than the amount of energy consumed in the
building.
Unlike mechanical methods of heating, passive solar
heating is actually built right into the building as an
integral part of the structure. This very often adds little or
nothing to the initial construction cost. It also adds real
value to the home, needs little or no maintenance, and is very
reliable.
With passive solar heating you can greatly
reduce your heating costs and still be very comfortable,
with no extra work. You still need a primary/secondary heat
source, but your heating bills will fall dramatically.
The building itself collects and distributes
the heat, making it highly efficient. The walls, windows,
floors and other features absorb solar heat and release it
during the night. Experience has taught us how to maximize
the benefits by adapting the construction to fit the angle
of the sun, the orientation of the house, etc.
Requirements for solar heating
You need a south facing exposure, at least in
the Northern Hemisphere, so the heat can be collected. The
building must have a clear line to the sun to receive
maximum absorption.
The other main requirement is a material to
absorb the heat for later distribution. The material can be
the actual building itself, or additional structures placed
in the path of the sunlight.
Designing passive solar heating
systems
Just because one particular method works one
place does not mean that it will succeed somewhere else. It
is necessary to evaluate the site and climate of you own
place. For example: what works in New Mexico will be much
different that in Oregon!
Direct Gain of solar
heat
This is the simplest form of heating. In this
case the solar heat is absorbed by the walls, floors, etc.
The heat will naturally be stored in the core of the
structures, and released at night as heat loss. This heat
loss is what keeps you warm at night.
A good direct gain system will be able to heat
the house for several days in the event of cloudy days. Your
system needs to allow a lot of heat in and little heat out
in order to be efficient. Good windows and window covering
are recommended.
Additional structures, such as extra walls,
barrels of water, etc., can be used to collect more solar
heat. This heat is also released at night, providing free
heat. This is really a type of passive solar heat; there
are no moving parts, pumps or fans.
Indirect
Gain
This interesting system uses structures such as
walls or water barrels that are placed between the living
area and the sun. Because they are in a rather confined area
the room temperatures can climb substantially. This extra
heat is circulated by means of natural convection.
The air flow from hot to cold naturally causes
the heat to circulate throughout the living area. During the
night the vents can be closed so the process is not
reversed. In this way the heat is kept where you want it
instead of returning to the area outside the room. The
absorbing wall also radiates heat into the living area.
Isolated Gain of solar
heat
This system of passive solar heating uses an
external solar panel to collect heat. The heat is
transferred by natural convection into a storage area. This
storage area, or heat sink, later radiates heat into the
living area.
In order to attain the natural
convection, the
space to be heated must be higher than the storage heat
sink, which must be higher than the solar panel. You could
always use pumps or fans, but then you do not have a true
passive solar heating system.
Conclusion
Passive
solar heat can be an effective and inexpensive way to
supplement or primarily heat your living space. It just
takes some careful planning, especially in the building
stage.
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