History of Passive Solar Energy - Scott Barber
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History of Passive Solar Energy
Scott Barber
East Carolina University
Faculty Mentor: Michael Behm
East Carolina University
ABSTRACT
Passive solar design, an idea within the growing trend of green building, is a creative way to use
the sun to our advantage, both for heating and cooling, based on the design of buildings. As green
building has continued to become more popular, many changes have been made to make the design
and construction of our buildings more environmentally and economically sustainable. This review
focuses on the development in passive solar applications, from its earliest appearances in ancient
Greek buildings to current designs that take advantage of radiation convection or acrylic panels.
There have been many passive solar developments that can be explored, and the innovative technol-
ogy today has brought about great advancements in the past few decades alone.This review presents
a compilation of information from a variety of sources that provide knowledge regarding the his-
tory of passive solar energy. As the popularity of green building continues to grow, it is essential to
develop an understanding of passive solar design, and other green building techniques, in order to
be equipped for the years to come.
and natural gas. This type of deterioration
P assive solar systems are used to
“collect, store and distribute thermal
energy by natural radiation, conduction
is not only evident in natural gas, but
also in many other common sources of
energy. Though many are aware of the
and convection through sophisticated decreasing amount of oil, most people
design and wise selection of building assume there is an endless supply of coal,
materials” [9]. This definition, provided nuclear, and other energy sources. It has
by J.K. Paul, sufficiently explains that been estimated that there is enough coal
the idea of passive solar energy is the use to last about 250 more years[14], enough
of natural processes, such as radiation, oil to last approximately 44 years[5], and
conduction, and convection, to distribute nuclear fuel to last 23 years[12], if the cost
thermal heat provided by the sun. Passive is kept somewhat higher. Even if these
solar energy also involves blocking the sun’s numbers are a low estimate, and enough
rays in order to provide cooling during the energy sources remain for several more
summer. Incorporating solar energy into centuries, there is still a need to find cleaner
our buildings will decrease the amount sources of energy. What many people are
of money we spend on energy as well as unaware of is the damage that our current
extend the time other sources of energy energy sources cause to the environment[4].
will last. The pollution and other byproducts of
Due to increasing oil prices, rising gas manufacturing usable energy from these
prices have become a common sight not raw materials have dramatically affected not
only in the United States, but around the only the atmospheric quality, but they have
world. The exploitation and misuse of our also damaged the surrounding ecosystems,
natural resources is rapidly depleting our oil
2Scott Barber
whether they are forests, prairielands, or manner. It is also helpful to understand
water habitats. Ron Jones, an architectural specific savings in cost for buildings that
expert for sustainable building, explains use passive solar energy. According to a
that humans have begun to further explore document provided by Appalachian State
and understand the relationship between University, a passive solar home could
the built environment and the natural save as much as $160 per year by using
environment. In the past, we simply were simply using movable insulation and low-
concerned about the effect of nature on emissivity glass, glass that radiates low
buildings, but now are realizing the impact levels of radiant thermal energy 11].
our buildings have on the environment. In this paper, I overview the history
This is the key to sustainable design[6]. of passive solar design as well as review
There is a plethora of renewable and analyze technological information
energy sources that provide energy that is regarding the use of solar energy. The
much better for the environment. While goal of this review is to inform the reader
the mining and burning of coal and of historical passive solar energy uses and
uranium leads to smog, acid rain, and air to explain in greater detail what passive
toxins, renewable energy, including solar, solar energy is and how it is applied.
wind, hydropower, geothermal, or even
renewable materials such as agricultural CATEGORIZATION OF PASSIVE
products or biomass, results in little, if SYSTEMS
any, pollution. These types of renewable
sources are becoming a pivotal aspect of the To have a better understanding of
increasingly popular “green” movement. passive solar energy, it is helpful to know
There are three parts of being green: being how to categorize passive systems used for
acceptable economically, ecologically, and this type of solar energy. While there are
socially. These three pillars make up the specific techniques and systems that use the
sustainability movement, and help direct sun’s energy in a passive way, they are all
decisions so that processes and materials defined as being either direct gain, indirect
used are suitable in each of these areas. For gain, or isolated gain.
example, when installing wind turbines, Direct gain is the simplest application of
to completely fit within sustainability, one passive solar energy, where the space of the
must take into consideration these three building is directly heated by the sunlight,
ideas to ensure that the turbines will be which most often enters through windows
economically efficient, environmentally within the south-facing wall for buildings in
friendly, and socially acceptable. While a the northern hemisphere[7]. Ideally, in this
wide variety of renewable sources exist, approach, the materials within that space
they are not developed enough currently ought to be capable of storing heat and
to provide materials and systems that the air flow throughout the room should
are beneficial within the three pillars distribute the heat. A representation of
of sustainability. However, one type of direct gain is shown in Figure 1, which also
renewable energy does have the necessary depicts the difference of the angle of the
progress to be used and still be considered sun during the summer and winter, and
sustainable: passive solar energy. While how an overhang can be incorporated into
many people are aware of active solar the building design for further temperature
energy systems, such as solar panels, passive control.
solar energy is a division of solar energy
that uses the sun’s energy in a more natural
3Explorations | Biology and Biotechnology
and temperature regulation.
Isolated gain, depicted in Figure 3, uses
solar collection and thermal storage that
are separate from the actual living space,
moving heat to the living space through
natural or forced convection. Ventilation
is also essential in this method of passive
solar heat gain. An advantage to isolated
gain systems is that they can be added to
new and existing buildings[2].
Fig. 1. Direct gain passive solar energy.
For indirect gain, sunlight is most often
received by a south-facing wall, and as air
moves throughout the internal space, the
heat will then be transferred from the wall
to the living space[7]. For increased control
of indoor temperature, ventilation at the
top and bottom of the wall or other thermal
mass is included, assisting in regulating
the temperature. Figure 2 clearly displays Fig. 3. Isolated gain passive solar energy.
indirect gain, the use of a thermal mass for
solar heat gain, as well as vents integrated Regardless of the type of heat gain
into the thermal mass for air circulation utilized, passive solar energy provides heat
and heat distribution. at little to no cost, aside from the slight
variations in the design and construction
of the building.
HISTORICAL APPEARANCES OF
PASSIVE SOLAR
Solar power has benefited civilizations
for centuries, and the knowledge from our
past provides foundational understanding
of the sun’s energy to bring about our
current understanding of solar power.
The earliest known application of solar
energy arose during the 15th century
B.C. by the Egyptian ruler Amenkotep
III, who “supposedly possessed ‘sounding
statues’ that operated when the air in their
Fig. 2. Indirect passive solar energy. base pedestals expanded after exposure
Thermal wall with ventilation for airflow to sunlight”[3]. Though this was merely
4Scott Barber
an accomplishment of aesthetic value, Code commenced “sun rights” in order to
solar energy has also been used to distill guarantee everyone would have access to
water as well as dehydrate agricultural the sun. The last known use of solar energy
plants. Solar energy has been used in even before the 1700s appears in North America.
more advanced, practical ways by many The Anasazi Native Americans built their
civilizations to provide heat for homes, homes in the side of the cliffs in what is
light fires, and even cauterize wounds. In now known as the Colorado Plateau, where
the 5th century A.D., Socrates realized that Utah, Colorado, Arizona, and New Mexico
“in houses that look toward the south, the meet[9]. These south-facing buildings were
sun penetrates the portico in winter, while placed within the side of the cliff to avoid
in summer the path of the sun is right over the sun in the summer, but make use of
our heads and above the roof so that there is the sun during the winter. It is clear that
shade”[8], and that initiated the use of solar there was an early understanding of using
energy to heat homes. the sun for energy, and this knowledge
Though the first recorded application of and technology surrounding it increased
solar energy is in the 15th century B.C., the significantly beginning in the seventeenth
next appearance wasn’t for several hundred century.
years, where the historian, Plutarch, Up to that point in history, through the
documented that virgins used cone-shaped 1200s, passive solar energy was used by
metal objects to start ritual fires during the Egyptians, Greeks, Persians, Hindus, and
7th and 8th centuries B.C.[3]. During this the Native Americans, following ancient
time the sun was used to distill water and architectural teachings of Aristotle,
dehydrate agricultural plants. A famous Xenophon, and Vitruvius [9]. In the ancient
use of solar energy, while the event is still historical appearances of passive solar
surrounded with reservations and disbelief, energy uses, the architecture was geared
occurred in 212 B.C., when Archimedes used towards using the sun and wind to alleviate
a “burning mirror” to set invading Roman the extremes of the climate, but due to a lack
ships on fire. A similar story was recorded of glass, they were unable to utilize the sun
in the 12th century, where Proclus, a Greek, to the extent we can today. However, though
supposedly accomplished this achievement most ancient civilizations lacked glass and
during the siege of Constantinople when other technology that we use today, they
the Bitellius fleet was invading, using many still made significant progress and provided
mirrors. understanding and a good foundation for
While there is no sure way to know whether future developments regarding the use of
or not these feats happened, the recording of solar energy.
this event sparked much curiosity, and soon Beginning in the 17th century, interest
more applications of the sun’s energy were grew in regards to using the sun as an
being recorded in history. For example, in energy source, and though there was not a
77 A.D. Romans used “burning glasses” to large amount of development within passive
cauterize wounds and light fires[3]. Another solar techniques, significant progress was
one of the earliest applications of passive made in active solar systems. The increased
solar energy was in the Roman atrium and awareness of solar energy brought about
heated bathhouses in the first through the by the experimentation with solar energy
fourth centuries, where large south facing served also to make people conscious of the
windows let in the sun’s warmth to heat the use of solar energy passively, as well, though
pool[9]. Solar energy became so well-known there isn’t as much historical recording of
in the 6th century A.D., that the Justinian passive solar energy during this time. In
5Explorations | Biology and Biotechnology regards to active solar energy systems, the It was in the late 19th century that passive first “solar engine” was invented in 1615 by solar energy began appearing more often Salomon de Caux. This engine used glass and in more noteworthy means. In 1880, lenses to heat up an airtight metal vessel theories surrounding solar houses began to with water and air to produce a small water appear, and it was in Salem, Massachusetts fountain[3]. Though this lacked practical that the idea of a glazed, south-facing wall, use, it is significant because it was the first as well as incorporating the requirements published documentation of solar energy for air flow between the glazing and the after the fall of the Roman Empire. Also wall first arose. Not only that, but professor in the 17th century, physicist Athanasius E.L. Morse was approved for a patent “for Kirchas experimented with starting fire the combination of a dark colored massive with mirrors, and German mathematician wall, an air space, glazing…and adjustable Tschirnhaus worked with lens-type items dampers by which the flow of air could be to concentrate solar energy to melt various controlled”[9]. materials[3]. Overall, the 17th century A few years later, in 1896, the included various experiments from thermosyphon water heater was invented, different specialists who sought practical the oldest and most widely used passive applications of solar energy. solar device in the world, which was utilized In the 18th century, there was more in World War I in Southern California experimentation from many various to provide hot water to army camps[9]. professionals around the world. French Many other southern states adopted this scientist George Buffon worked to technology, as well as Japan and Australia, determine whether or not the Archimedean but the extension of natural gas lines and feat could have been accomplished, the cheap availability of electricity resulted and determined that setting ships on in a nearly complete elimination of its use. fire was possible, but not very probable However, due to increased prices in other considering the lack of technology in energy sources for providing hot water, this 212 B.C.[3]. Another Frenchman, Claude device and its “active but similar offspring," Poillet, provided significant information and the forced circulation solar water that would assist in the development and heater, are beginning to be used more[9]. application of both active and passive These new developments provided more solar energy. He determined the intensity information, but also created specific of the sun in reference to the geographical ways that passive solar energy could be position, and it is this association which implemented into people’s daily lives. For has been regarded “at least as important in example, a home built in Massachusetts solar utilization as the hardware itself ”[3]. was one of the greatest steps in passive It was in 1767, just a few decades later, solar design during the last few centuries, that the first solar collector was invented, providing a concrete and successful use of built by Horace de Saussure, a Swiss passive solar energy. Overall, the 1800s scientist. This collector was used to heat provided more research in solar energy than food, and was used by Sir John Herschel in perhaps any other time in history. However, the 1830s, during his expedition in South the following centuries resulted in a greater Africa[13]. There continued to be a variety diversification of the applications and uses of research and investigation in regards to of solar energy. solar energy during this time, all providing more information that would serve useful in years to come. 6
Scott Barber
MODERN DEVELOPMENTS In various adaptations and improvements
that were made to these designs, double
Since the twentieth century, there has glazing, windows that could be opened,
been a great variety of fairly modern and ventilating fans were used to maintain
passive solar developments. Though the comfort. Unfortunately, there was a
deliberate practice of using solar energy slight break in research and development
for heating within buildings was apparently concerning solar energy during World War
forgotten outside of agricultural, the II, even though there were still companies
1930s reintroduced this practice in the practicing these methods.
relatively colder climate of Minnesota[1]. After World War II, despite the revival
The sudden increase in the application of interest regarding solar heating, most
of and interest in passive solar energy people were focused more on active
was a result of sealed, insulating windows systems for solar energy and therefore
becoming available at a much more passive solar heating was largely neglected.
reasonable cost. Due to the necessity of The American Society of Heating,
windows within the application of many Refrigeration, and Air-Conditioning
passive solar techniques, easily available Engineers (ASHRAE), however, continued
windows allowed passive solar methods to research the gain of solar heat through
to appear in residential architecture just window placement, which has provided
before World War II[9]. The Keck brothers foundational information for today’s
in Chicago were forerunners within the strategies for determining solar heat gain
new appearances of passive solar energy, through windows, and has resulted in
providing prefabricated buildings in the multiple direct gain passive solar houses in
1940s. These buildings used large, south- New Mexico[9].
facing windows with overhangs to admit These homes implemented newer
sunshine in the winter but block it in the technology which improved them
summer months. They also included flat significantly from their fairly inefficient
roofs that were made to be flooded during predecessors built in the 1930s and 1940s.
the summer to decrease the amount of For example fairly consistent temperatures
solar heat gain[9]. were gained through concrete or adobe
Though these and similar houses were floors which absorb heat. Also, movable
being designed and constructed, they insulation protected the house in times of
lacked the full potential and were less exceptionally cold weather or when there
effective, mainly because the common were extended days where clouds blocked
heating and cooling systems were readily the sun[9]. The improvements in these
available at a much lower cost. Another structures significantly increased their
notable progression within solar energy practicality and effectiveness.
use in homes was the book entitled Your In the decades following, there were
Solar House, funded by Libbey-Owens- continued discoveries and inventions
Ford Glass Company. This book included regarding solar energy. In 1954 photovoltaic
forty-eight designs for homes to utilize technology was first revealed, as Daryl
direct gain solar energy, one design for Chapin, Calvin Fuller, and Gerald Pearson
each state within the United States at that invented the first solar cell that converted
time[9]. Again, these designs were not ideal energy from the sun to provide electrical
applications of solar energy, primarily power. The following year, Western
because there was no consistent way to Electric began selling licenses for silicon
control temperature within the buildings. photovoltaic technologies. It was during
7Explorations | Biology and Biotechnology
this time that architect Frank Bridgers monitoring, and rewarding sustainable
designed the first commercial office building. In 1985, Austin Energy, located
building that used solar water heating and in Austin, Texas, was the first residential
other passive solar designs[13]. It is worth energy efficiency program[6]. In 1991, this
noting that these passive solar systems are organization further developed and became
still in operation within this building today, known as Austin Energy Green Building®.
and this office building has been recognized Since that time, many more programs
in the National Historic Register as the have begun, such as the Advanced Energy
world’s first solar heated office building. Corporation located in Raleigh, NC, the
Since these improvements, the most Southface Energy Institute in Atlanta,
noteworthy addition to passive solar GA, and the Solar Living Institute in
energy is the Trombe wall. Developed by Hopland, CA. In 1995, the United States
Frenchman Felix Trombe, based on the Environmental Protection Agency began
work of Edward Morse in the 1880s, this the Energy Star program, which evaluates
wall faces the sun and essentially absorbs the energy use and efficiency of buildings.
the sun’s heat and releases it inside the Since the Energy Star program is limited to
building at night[9]. Aside from slight energy, the United States Green Building
alterations, most passive solar techniques Council (USGBC) was founded in 1993 and
have remained the same and have only within that, the Leadership in Energy and
varied in regards to application. Figure 4 Environmental Design (LEED) program
shows a modified Trombe wall that utilizes was founded in 1998[6]. These programs
a glazing material to collect solar heat and have proved a key role in encouraging and
vents to provide air flow and distribute the rewarding sustainable design, including
heat to the interior room. This type of passive solar energy practices.
Trombe wall is a very efficient way to take
advantage of passive solar energy. PASSIVE SOLAR APPROACHES
Although there are many different
aspects of passive solar energy as well as
the three pillars for producing sustainable
passive solar energy, there are five basic
approaches to forming these types of
passive systems: direct gain, thermal storage
walls, solar greenhouses, roof ponds, or
convection loops. These techniques can be
either direct gain, indirect gain, or isolated
gain, based on how they collect, store, and
transmit thermal energy [9]. These methods
are a result of the extensive research and
advancements throughout many centuries,
bringing us to the understanding we have
Fig. 4. Modified Trombe wall using today, allowing us to use the sun’s energy
exterior glazing and air vents for air flow. efficiently and responsibly.
Direct gain is the simplest application of
A noteworthy aspect of passive passive solar energy, and as such is the most
solar design is the many programs and popular. Direct gain is beneficial because it
organizations devoted to encouraging, is not only simple, but it also has a relatively
8Scott Barber
low cost. However, direct gain struggles could serve beneficial for both heating
because it cannot control temperature and cooling by adding or removing the
as effectively due to of a lack of thermal insulation during summer and winter, or
storage. Other potential problems that may day and night.
arise include undesirable lighting during The final approach for passive solar
the day such as glares, as well as discoloring techniques is the convective loop, which uses
of fabrics due to extensive ultraviolet a thermo siphon, a machine that circulates
rays[2]. water, to move heat from the collection
The second common approach to passive point to a storage area. Water heaters often
solar energy involves using a thermal storage use this idea, as it is very inexpensive and
wall, which essentially uses a material that reliable, more so than many other types
absorbs the sun’s heat after it has passed of water heaters commonly known. This
through the glazing. The wall may be system works well without needing pumps
black or another dark color to assist in its or controls[9]. Air convention loops often
absorbing, or it may even consist of water combine passive collection/storage with
held in masonry or other containers[2]. active distribution to provide a simple but
Regardless of the absorbing material, its effective system to provide temperature
purpose is to absorb the temperature and control for a building.
release it into the interior room. This assists Overall, these five types of applications of
in controlling temperature and reducing passive solar energy can be very beneficial
temperature extremes, as well as reducing to include in many different climates and
the negative effects of direct gain: glare or situations. When applying these ideas to
undesirable lighting and material damage buildings, it is important to be aware of the
due to the ultraviolet light. While direct strengths and weaknesses of each of these
gain can heat up a room much quicker, it applications. It also may be very feasible to
is much more difficult to control, which is combine a variety of these approaches in
a benefit of using a thermal storage wall. order to utilize their strengths and develop
Often, windows are included in this wall a well-rounded passive solar building.
to combine direct gain with the thermal The majority of all passive solar energy
storage to incorporate the benefits of techniques are applied during the planning
both[7]. and construction process of the buildings,
Using a roof pond is the third common because the most important aspect of
approach to passive solar techniques[2]. a building is its location and direction.
It may or may not include the physical However, there are a few options that
presence of water on the roof, but where provide heating from solar energy for
there is not water present, movable pre-existing buildings. By adding larger
insulation is required on the roof. windows or double-glazed, low-emittance
Essentially, this technique relies on windows on the south wall, passive solar
gathering solar heat through the roof, but energy can be utilized. The double-glazed,
with insulation that prevents too much heat low-emittance windows have the ability
from collecting during the hotter summer to allow heat to enter into the building
months [2]. There have also been studies but reduce the amount of heat lost to the
and research in New Mexico and Arizona, outside. Also, planting deciduous trees,
testing various active and passive systems trees that shed their leaves in the winter,
to control the amount of heat transferred on the south side of a home will provide
through the roof. This type of system shade from the sun during the summer but
would be used for a flat roof, ideally, and allow the sunlight to enter into the windows
9Explorations | Biology and Biotechnology
during the winter. Blocking in windows on solar for heating or cooling. However,
the north side of a home may also assist in pairing up passive solar aspects with a
solar heating, though doing so may not be back-up heating system, shading devices
aesthetically pleasing. or operable windows will greatly increase
the amount of control one has in regards
PASSIVE SOLAR ENERGY: IS IT to temperature[2]. Also, passive solar
WORTH IT? heating also maintains a warmer floor,
which is desirable. Most heating systems
While passive solar energy is growing in used today can lead to large floor-to-
popularity within the green movement and ceiling temperature differences, resulting
has improved significantly in the last few in discomfort at the floor level. On the
decades, there are still doubts surrounding contrary, passive solar systems use materials
its viability and effectiveness. The primary that absorb heat, and therefore the floor is
arguments that are made in favor of using warmer and more comfortable[2].
passive solar energy are divided into One of the greatest attractions of passive
economic, architectural, and comfort/ solar energy is the fact that it is very
health categories. In general, passive environmentally friendly; it is a renewable
solar energy is very beneficial because it is energy source and does no damage to the
inexpensive and has little, if any, impact on environment around it[6]. By using passive
the environment. solar energy rather than a common heating
When observing the economic aspects or cooling system, there is a great reduction
of passive solar design, it is important to in the consumption of fossil fuels and the
remember that each building is different, production greenhouse gases and other
depending on construction and materials pollutants[6]. Overall, passive solar energy
used. However, the benefit to passive solar has few disadvantages and its advantages
energy, as opposed to active solar energy are both economical and environmentally
or other types of renewable sources, is friendly.
that it requires no additional cost for
upkeep; the costs are the same as the FUTURE TRENDS
general maintenance costs of any building.
It is possible to save money long-term While there has been a dramatic amount
simply by taking passive solar systems into of progress and development throughout
consideration for the design process[6]. history regarding passive solar energy, by
Changing the direction of the structure observing where technology is today, one
alone, in order to gain more heat from the can only wonder how much more progress
sun on the southern part of the building, can be made. While there certainly will be
can make a huge difference in collecting improvements in materials, it appears that
solar heat. Essentially, passive solar energy the techniques have currently reached a
only requires a slight increase in cost, if any plateau. However, when asked “What is it
increase at all, to incorporate these systems that we really require from scientists and
into the design and construction of the technologists?” economist E.F. Schumacher
building. provided guidance into the improvements
In terms of temperature within the of passive solar energy: “We need methods
building, some people may be hesitant and equipment which have the following
to use this technology, mainly because it characteristics: they are cheap enough
isn’t easy to control the temperature of so that they are accessible to virtually
a room which is dependent on passive everyone, they are suitable for small scale
10Scott Barber
applications, they are compatible with With this in mind, passive solar practices
man’s need for creativity, and they are not within sustainable design will become more
heavily dependent on natural resources”[10]. common, and industry leaders around the
Passive solar energy certainly has the world will incorporate sustainable practices.
potential for meeting these requirements. It is important for the future of passive
The design of passive solar buildings, solar design that those involved in the
based on the materials and technologies design and construction of buildings to be
available today, will remain consistent for certified in sustainable design, for resources
the next several decades. The strategies and products used to be sustainable, and
and techniques being used today will be as a result, the structures will be more
replicated in various ways depending on sustainable as well.
location and availability to maximize the
benefits of passive solar energy. One can CONCLUSION
assume that when new technologies arrive,
the design of passive solar buildings will Throughout history, mankind has
adapt to incorporate them to maximize benefited from and worked to harness
their efficiency. However, the specific the sun’s energy in order to create a more
design for buildings regarding passive solar enjoyable living space and save energy. Solar
energy has climaxed for the present time. energy has been used for centuries and has
The further development of passive solar only improved with time, as researchers
energy is reliant on new technologies and and scientists have developed processes
the development of more appropriate, and materials to improve the quality and
efficient resources. One of the newest effectiveness of solar energy. Using solar
developments that will continue to grow and energy, specifically passive solar energy, is a
improve passive solar use involves window very cost efficient way to take steps towards
glazing. Low-emittance coatings, known as sustainability, and as the green movement
low-E coatings, are metallic oxide films that continues to develop and expand, passive
are installed on windows to reduce from solar techniques will be utilized more and
within the building while still allowing solar more throughout the United States and
heat gain. These coatings do not affect the in nations around the world. It is helpful
visual aesthetics of the window, yet provide to realize the history in regards to passive
valuable benefits. There are also double- solar energy, and the benefits that can be
glazed windows filled with argon gas, which gained by applying passive solar energy.
provide the same benefits as the coatings on Overall, the various types of passive
the windows and can be used together to solar energy have unique strengths and
increase efficiency. As these technologies weaknesses. Direct gain, the simplest
continue to improve, passive solar energy application of passive solar energy, provides
will become more beneficial and effective. quick, economically friendly, inexpensive
It is also important, however, to recognize heating for a home. The main disadvantage
the role that green building programs will is its difficulty in providing adequate control
serve in the continuation and expansion of the environment. Indirect gain, a slightly
of passive solar practices. Certifications more complicated use of passive solar
and recognition within these programs energy, goes beyond direct gain and offers
are available for the buildings being a more stable environment with better heat
constructed, the professionals who design, control. However, indirect gain requires
build, and remodel those buildings, and the greater planning and also takes longer
products used for the buildings as well[6]. to heat up a room or home. The third
11Explorations | Biology and Biotechnology application, isolated gain, delivers even passive solar energy requires an evaluation more control and stability in controlling for each building in regards to feasibility the indoor environment. This, too, requires and usefulness. They can certainly be further planning and is more expensive to useful in many applications, and are worth construct. considering in the planning process. The five strategies used for passive solar Passive solar energy will continue to energy, direct gain, thermal storage, solar grow and change, providing inexpensive, greenhouses, roof ponds, and convection sustainable alternatives for common loops, all have their own advantages and heating and cooling systems. As technology disadvantages as well. The main drawback improves and awareness increases, passive to implementing these strategies into a solar energy will become more widely used building is a need for further planning and throughout the country and around the specific materials. However, this increased world. It is certainly a viable option for new initial cost only increases the long-term construction, and will continue to assist in savings for a building using passive solar saving energy for many. energy. The use of these approaches to 12
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