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Blessed Be a Sunny House
By Thomas Hirsch
In the good
old days when life was simpler, building a house was also simpler.
With our feet planted on the earth, we looked around for available
materials. We knew about the
movement of the heavenly bodies, particularly the sun and the moon.
We knew that we wanted and needed to let the sun shine into our
dwellings during the winter months for heat and to shield from it during
the summer. It was a matter
of practicality. The
history of solar architecture is really a history of indigenous
architecture. “The solar
orientation of buildings was discussed by Socrates, Aristotle, Vitruvius
and others. Solar building
was employed in ancient Greece, China, Asia Minor and by the Anasazi and
Sinagua Indians in America.”1
The
Industrial Revolution preempted our wise ways in favor of something
“modern”.
Today, as we look to stretch our dollars, our energy and our
environment, we can often look to our ancestors for answers.
Since the Arab oil embargo of the 1970’s, there has been renewed
interest in solar energy.
When
we think of solar energy in our culture, what comes to mind are solar
cells or photovoltaics that convert sunlight into electricity or solar
panels that create heat transfer through the movement of fluids.
These are called active solar systems.
Passive solar systems on the other hand, allow the sun to penetrate
the building directly without mechanical means and provide some additional
heat. “Passive
systems are simple in concept and use, have few moving parts and require
little or no maintenance.
These systems do not generate thermal pollution, since they require
little or no external energy input and produce no physical by-products or
waste. Since
solar energy is conveniently distributed to to all parts of the globe,
expensive transportation and distribution networks of energy are also
eliminated.”2
Recall
what it feels like to enter a greenhouse or a closed up automobile on a
sunny day.
It is warm or even hot.
Solar radiation passes through glass as short-wave radiation or
light, but when it is absorbed by the interior surfaces, the light is
changed to thermal energy, also known as infrared radiation, thermal
radiation or heat.
The reason why the greenhouse, the automobile or a poorly designed
home will overheat on a sunny day is because the interior air and
surrounding surfaces have little ability to absorb and store the heat.
Reducing the temperature swing to create a more even temperature is
a function of good design.
After
consideration of the landscape and climatic conditions, a buildings’
design orients the solar collecting windows facing true south (in the
Northern Hemisphere) or within 15 degrees of true south.
Understanding the seasonal movements of the sun and the angle in
which sunlight passes through the atmosphere will allow you to maximize
heat gain during the winter months and provide appropriate shading devices
via overhangs, louvers or vegetation to reduce unwanted heat gain in the
summer. Sun
path diagrams included in most passive solar design books illustrate this
clearly.
Once
inside the building the solar radiation is best utilized when absorbed by
thermal mass materials in floors and walls.
The most commonly used heat storage materials like stone, brick,
concrete, adobe, earth and water have the ability to absorb considerable
amounts of heat and re-radiate it back into the structure when the
temperature warrants.
Good
passive solar design takes into account all aspects of heat loss/gain
factors.
Energy and heat conservation practices are necessary to make
efficient use of that precious solar energy.
For example, window glazing must by accompanied by an insulated and
tight fitting curtain, quilt or shutter system.
Without it, the energy gained by the sun during the day will
quickly be lost through the glass at night, resulting in a net heat loss.
This is a critical component often overlooked and sited by solar
naysayers.
Speaking of naysayers, I recall an incident recently where a window
salesperson was chiding me for specifying so much southern glass in our
work. She
was complaining about faded fabrics, carpets and furniture.
Of course, these issues become part of design schemes that minimize
the impacts like this.
In
a cold, cloudy climate such as ours, most people do not even consider
solar energy as an option.
While we cannot expect to achieve a cost effective, 100% solar
heated house here, we can greatly reduce our external heating requirements
with thorough planning.
It has been my experience that a well designed, insulated and
maintained passive solar home needs little external heat input during the
swing months of spring and fall.
During the depths of a cloudy winter is when the home needs some
added heat.
I've been in homes where only 6 cords of wood or less per year were
used in a back up wood stove to maintain a comfortable temperature.
When constructing passive solar homes this time of year, I have
been pleasantly surprised to find how toasty a space can become on a sunny
day and how comfortable it is the next morning.
These experiences have been in unfinished, uninhabited dwellings
without back up heat or window coverings.
As
with all things, we have many choices available to us.
Reducing our demand on the earth’s limited resources can fuel the
desire to create buildings that reflect these principles.
Someday maybe we will develop tax incentives, mortgage rates and
building codes that support this thinking.
Perhaps the struggle over Arab oil and our gasping for good air and
water will help us choose a solar-wise future. .
Let the sun shine in: it is a gift.
As we emerge from the season of long nights, let’s be grateful
for the return of the light.
References:
1.
The Healthy House: Creating A Safe, Healthy and Environmentally
Friendly Home, Sydney and Joan Baggs, Harper Collins Publishers.
2.
The Passive Solar Energy Book, Edward Mazria, Rodale Press.
3.
Passive Solar Energy: The Homeowners Guide to Natural Heating
and Cooling 2nd Edition, Bruce Anderson and Malcolm Wells,
Birch House Publishing Company.
4.
The Passive Solar Construction Handbook, Steven Winter
Associates, Inc., Rodale Press.
5.
The Solar Greenhouse Book, Edited by James McCullagh, Rodale
Press.
6.
Other Homes and Garbage: Designs for Self-sufficient Living,
Jim Leckie, Gil Masters, Harry Whitehouse and Lily Young, Sierra Club
Books.
RAISE
HIGH THE SOLAR GREENHOUSE, CARPENTER
Place
your hand in the sun
Like
an oak length of beam,
Turn
your wrist until the roots of the pulp deliver muscle
And
sap to the garden roof.
Walk
the property line
Like
a child, swaggering and sure,
Marking
with your toe the axis
Which
is a flush as equator heat.
Raise
your arms overhead
Like
a sextant
Bringing
down the heavens in an arc
Making
an A with your hands
And
imagine what green will sprout
From
that blessed plot.
James
C. McCullagh
Harmony
Home Construction, LLC.
8122 Barney Road
Traverse City,
Michigan 49684
Ph: 1-877-45-GREEN Fx: 231-932-9193
info@harmonyhomeconstruction.com
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