Passive Solar Heating at the
Cheyenne Botanic Gardens
Teaching a class on renewable energy?
Click here for a PDF file on our solar energy
system and energy conserving tips.
Click here for an explanation of how
Native American Indians used
passive solar heating.
Heating is expensive in greenhouses, but our conservatory is heated for free. The Cheyenne Botanic Gardens is a regional center for demonstrating renewable solar energy—both
passive solar heating and solar
electricity (click here to learn more about our electric system).
This technology is based upon many earlier designs of
Native American Indians.
The use of solar
energy in the Cheyenne Botanic Gardens is elegantly simple. A
passive solar heating system provides 100% of the heat to three
separate 30' x 50' greenhouse sections. The rest of the 6,800 square foot
building also receives a substantial amount of heat generated from the
solar greenhouses.
 
This is a sample of our triple thick Polycarbonate glazing. It
has two insulating air spaces to help hold in the heat.
Barrels full of water - are one component of a
passive solar greenhouse.
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A passive
solar energy system is one that has very few or no moving parts. Thus the
word "Passive." The solar heating is a result of the combined effects of the following:
South-oriented,
triple-thick polycarbonate glazing.
Instead of
glass we use a plastic material called polycarbonate. It lasts
approximately ten years before it begins to yellow. It is triple thick
which allows for two insulating air spaces. Dead air space insulates and
slows the cooling of the structure as well as helps to keep it cooler in
summer. The glazing faces south at an optimal 45° angle. It is strong and
is resistant to both hail and fire. This glazing is hail resistant which
is important in Cheyenne, Wyoming.
Insulation.
Both the east and west walls as well as the north roof
are heavily insulated. The perimeter of the foundation exterior is also
insulated into the earth with a two-inch sheet of Styrofoam along the
outside of the concrete foundation to a depth of two feet. This insulates
the ground inside the greenhouse from the cold ground outside the
greenhouse during winter.
Thermal mass .
The daytime sun heats the water-filled fiberglass tubes
and 55 gallon metal drums. The containers are located along the north and
south walls. The containers heat up to about 70° in the summer and 60°
in the winter but will never feel warm to the touch because our body
temperature is 98.6° and our skin temperature is usually warmer than the
water. These water-filled containers give-off heat because the night/day
difference in temperature is great enough to cause the warmer heat from
the containers to radiate into the colder greenhouse. In summer they help
to keep the greenhouse cooler because they are shaded most of the day.
Weatherized
structure. All
windows, doors, fans and vents are well weather-stripped to prevent leaks
and cold drafts.
Read more about home solar greenhouses at this site:
Greenhouse
Gardener's Companion |
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