Sustainability

"The frog does not drink up the pond in which it lives."
— Chinese Proverb

The Cheyenne Botanic Gardens opened its doors in November of 1977. It was then the nations largest passively solar heated greenhouse. In 1997 the project added a photovoltaic system to help power the greenhouse/conservatory. Since then the project has added more solar electricity, a solar heated solar electric and wind turbine powered classroom/lab at the Paul Smith Children's Village and many sustainable landscapes.

Sustainability has been part of the DNA of the Cheyenne Botanic Gardens for many decades and long before the word sustainability was popularized. The Cheyenne Botanic Gardens philosophy of sustainability extends to people through inclusion of senior, youth at risk, and handicapped volunteers, believing that people are an important part of how sustainability should be viewed. In addition, we employ many non-toxic strategies for pest control, natural fertilizers and extensive composting in our operation.

Let's look at some of the specifics of our renewable energy system:

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 greenhouse/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.

See more views inside our solar conservatory and offices.

* Click here to learn about
our solar electric system

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.

Temperatures. On cold, sunny Winter days, our high temperatures can be up into the 80s. On cold, cloudy Winter days the high temperature reaches to the 50s and 60s.

The night temperatures are in the 40s to 50s. When we experience extreme cold and high winds (down in the minus double digits). We can get down to as low as 34 degrees but it is usually for only a brief amount of time.

While the temperatures are not always ideal even tropical plants seem to thrive in this environment. In addition, we have developed specialized growing schedules that optimize our yields for growth in a passive solar heated greenhouse. Similar growing schedules can be found in the book "Greenhouse Gardener's Companion."