Passive solar systems are self-sufficient buildings which rely on natural
principles insted of mechanical systems to provide a non-polluting
source of heating and cooling.
 

Introduction
 

Passive energy is more sustainable than active energy systems because passive
systems use far fewer natural resources to build and maintain.  They do not rely so
heavily upon gas for heating or coolants for air conditioning.  Passive systems are
designed so that they can take natural energy from the sun to heat a building and
use specific design principles to cool a building.  Passive energy systems are also cheaper than
active systems because they are less susceptible to malfunction since they rely completely
upon nature, rather than using mechanical equipment to produce energy.  In order
to create a home that will maximize the effects of passive solar heating, a designer
must take many different variables into account.  Two major ideas crucial to creating
effective passive solar housing are orientation and materials. Passive solar buildings
should be oriented to receive as much southern sun as possible.  In the summer,
the hot sun can be blocked by using overhangs or through landscaping like large
foliated trees. In the winter, sun should help heat the house because the sun angle
is lower in the sky allowing more sun to hit the glazing more directly.  Thought
should also be given to the specifications of the windows for maximum solar gains
and heat loss.  By using the right building materials such as masonry or concrete and
combining them with effective insulation, solar energy can be contained in the
house allowing it to be comfortable year round (Desbarats 1980, 232).
 

Building Orientation

Building orientation is crucial to maximizing energy production in a passive solar
home.  Because passive solar homes rely on natural sunlight to power the building's
utilities, the building should be oriented on the site in a way that will allow it to
maximize the amount of sunlight.  The best way to achieve this is to orient the house
on the east-west axis and concentrate most of the house's glazing on the south
wall.  This allows the home to receive the most direct sunlight for the longest period
of time (Hibshman 1983, 261).  Heat travels through windows very easily, however heat
does not exit as easily.  Once the heat passes through the window, it breaks up and it
takes much longer for that heat to exit (Button 1993, 129).  This allows heat that enters a
building to stay in the building for a long time.  This is a helpful principal for heating
a building in the winter and is the reason why windows should receive as much light
as possible in the winter.  However, in the summer, the hot sun can become an
uncomfortable problem.  To alleviate some of this heat, passive solar homes should
be designed with attic fans or some sort of operable clerestory windows which can
be opened to release some of the hot air when it rises.  Glazing should be greatly
reduced on the east and west walls and should be virtually eliminated on the north
side of the home because most cold winds in winter come from the north and
west (Desbarats 1980, 56).  Because the house needs as much protection from these
winds as possible, and glazing cannot provide this protection, windows should be
eliminated. (Desbarats 1980, 28).
 
 

Glass

    The amount as well as type of glass windows used in a house are very important
considerations in terms of thermal comfort, cost and efficiency.  There are many
different types of windows available: single, double and triple paned (Button 1993, 164)
A single pane is simply one pane of glass.  These are generally the worst types of windows
to use.  Although they are the cheapest windows available, they are not energy efficient
and they allow more heat gain in summer and heat loss in winter than either the double
or triple paned windows do.  Double pane windows are much more energy efficient.
The reason is the cold winter air passes through the first pane but then must pass
through a gap of either air or Argon gas before it reaches the second pane.  The reason
this is helpful is because air or Argon gas provide excellent insulation and do not allow
the cold to penetrate nearly as much as it would if there were only one pane.  Triple
paned windows work on the same principal as double paned but they are even more
energy efficient because there is even an additional layer of insulation (Button 1993, 166).  It is
also possible to get windows with coatings such as low emissivity coatings (low-E)
which help to block the suns harmful rays but still allow visible light to pass through
(Button 1993, 173).
 

(Hibshman 1983, 29)
             R-Values for Different Types of Glass
 

Thermal Mass

    Thermal mass is another important concept to keep in mind when dealing with energy
efficient housing.  It is important for these types of homes to be built with materials
that have a large amount of thermal mass (Hibshman, 1983, p.48).  Such materials are brick,
stone and concrete.  These materials are ideal because materials with a large thermal mass
absorb much of the energy they receive from the sun.  These materials absorb and release energy
completely, but slowly.  Because it takes a long time for the energy to be released
after it is absorbed, a phenomenon known as lag, warm sunlight that is absorbed
during the day is finally released over time at night.  This is another natural phenomenon
which proves helpful because it provides warmth at night when the house is the coldest and
heat is necessary.  Because all of the heat is released at night the floor is then cool for the
next day and consequently this helps to cool the rest of the house.  It is also important leave
the concrete floors on the south side of the house exposed.  If they are carpeted, they lose most
all of their thermal mass properties.  However, carpeting would be acceptable on the
north side of the house because there should be almost no windows there anyway (Hibshman, 1983, p.32).
 
 

(Hibshman, 1983, p.32)
                    How Thermal Mass Works
 

Affordability in Sustainability Using Passive Solar Heating

Cost is a very important factor for designing sustainable architecture.  Aside from creating
enviornmentally friendly architecture, sustainable architecture allows lower building and
maintenance costs.  Affordability goes hand in hand with sustainablity and is something which
we, as designers, should concentrate on when designing the housing in East St. Louis.  One way
to create affordable homes is by using everyday, affordable materials to replace expensive and
wasteful mechanical ones.  One way this can be achieved is by using 55-gallon drums filled with
water to create thermal mass, a very necessary element for passive solar heating.  By placing these
drums in direct sunlight, they will absorb the sun's energy and, because lag also occurs in water,
they will have the same effect on the house that materials like concrete or masonry would, but
without the cost (Hibshman, 1983, p.50).  Another, affordable solution is to use these drums
filled with water to replace water heaters.  They can be placed in the roof or any other place
where they will receive a lot of direct sunlight (see figure on "Sustainable Design" page).
The owner can then use that water which has been naturally heated for bathing or cooking,
replacing a mechanical hot water heater and greatly reducing cost (Hibshman, 1983, p.53).
Another way to create affordable yet sustainable architecture is by using unconventional
building techniques.  One way is to use post-and-beam units instead of conventional stick
framing.  The posts are then anchored into the concrete. This creates a very stable framing
system and also reduces costs because no 2"x4" studs are used and therefore, less wood is
used.  However, the most important money saving factor in this construction is the use of
prefabricated wall systems.  These systems are cut into 4'x8' sheets and can then
be placed right in between the posts on the construction site with no wated materials used
(Hibshman, 1983, p.71).  This is also a faster method of construction so the labor costs
will also be reduced.  While these are just a few ideas more specific examples using these
techniques can be found in the sited material.

Diagram showing good passive solar design
(Hibshman, 1983, p.71) 
 

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