Building a Greenhouse

How to build a Greenhouse

Has your greenhouse been performing as expected or did you even get that far? Sure would love to hear success stories or any greenhouse gardening adventures to watch out for. We actually do learn by hearing the many trials and tribulations one has with building a successful growing greenhouse and what kind of growing experiences you have had.

building a greenhouse, building a polycarbonate Cross Country greenhouse, polycarbonate greenhouseWhy just yesterday a Colorado engineer called me to find out how do you keep a greenhouse from freezing throughout the winter months but yet maintain a sustainable R -factor on the roof? The roof design would either have a few large skylights or 5-wall polycarbonate panel sheathing or a glass roof.


These are critical questions that need to be dealt before starting a greenhouse project.



Greenhouse Designs

All of these roof options mentioned would have an R-factor of R-3.03 for his soon to be greenhouse project. So the question here is what is the best way to maintain a greenhouse with a minimum temperature of 50-55 degrees F, in the winter?

Good question..? So what is the exact definition of a greenhouse? For all intents and purposes, it’s a building with glass walls and a translucent roof for the cultivation of plants under controlled conditions. This is a very broad but accurate definition. For those who are solar enthusiasts and who want to harness the power of the sun, without the aid of purchased energy such as gas, or electricity there are ways to accomplish this.

  • When building, make sure your structure is as weather and air tight as possible, but always allow for ridge ventilation and cross ventilation.
  • 60% of all walls and roof should be insulated.
  • Your north wall should be solid and insulated as much as possible. If it’s a lean to, use the wall of an existing structure and use RFP (reinforced fiberglass panels) these are waterproof white panels for the interior walls.
  • Create a heat sink. For the sake of expediency we can say a heat sink can be a wall with painted black canisters or metal drums, filled with water and Ethylene glycol or an open water tank filled with water with the walls of the tank painted black to absorb heat both inside and outside the tank. A thick black rubber water tight membrane works the best.
  • A mixture of 60% ethylene glycol and 40% water does not freeze until temperatures below -45 C.
  • Diffused light as opposed to direct sunlight works best in a greenhouse setting
  • An underground heat exchanger loop that can capture or dissipate heat to or from the ground as well as warm air circulating from the top of the greenhouse through these same tubes.


Greenhouse Efficiency


These short and brief points are only the basics for maintaining a warm greenhouse throughout the winter without the use of purchased energy.

Note: In certain regions because winters can be frigid cold especially in the evenings the use of a small basic vented gas heater is not uncommon and in many cases very much a necessity.

While harnessing the power of solar, how to build a greenhouse coupled with the fact that you need a transparent medium to allow light and solar rays into your greenhouse, there is fine line you need to achieve to have that perfect balance of maintaining 55 degrees in the dead of the winter, 6 hours of minimum daylight and an R-factor of 3 to 11 between the walls and roof.

Here’s a nifty tool that allows you to covert Fahrenheit to Celsius, Miles to Kilometers, Feet to Meters, and vice-a-versa ……..Click Here

Barnes and Noble has a great selection on. How to Build Greenhouse books “search the title”….Click Here

AntiFreeze for your plants… Click Here


how to build a greenhouse, greenhouse building plans