Domes 101 - Understanding the Basics
Geodesic Domes offer the following advantages to traditional structures:
Most energy efficient structure available, maximizing the use of surface area for heating and cooling; vs. square structures.
Fewest materials required to enclose any space when compared to cube shaped structures
Fastest construction times
Streamlined shape aerodynamically deflects wind, rain and snow.
What is Geodesic Frequency? 2V, 3V, 4V....?
The Geodesic Frequency (v) refers to the amount of times that a sphere is subdivided by triangles. The higher the number before the “v” the more subdivisions, the more triangles and the rounder and closer the dome is to a perfect sphere. A 1V system is the simplest form of geodesic dome, and is the basis for all other domes. It does not look very much like a sphere. All the hubs in the system are the same pentagon configuration and utilize the same length strut to form the structure A 2V system is derived by subdividing each of the struts of a 1V to create a new vertex or hub location at the middle of each 1v strut, then connecting all the new vertices with new struts. There are pros and cons between high and low frequency domes. For instance, the higher the frequency, the higher the strength and the larger you can go. But in contrast, the higher the frequency, the higher the cost and the more materials involved. The choice of which frequency to use should be based on your needs and the application, such as how large it has to be and what type of environment will it be used in.
What are Truncations? 4/9ths, 5/9ths...?
A truncation is defined as shortening something by cutting off the top or end. In the case of geodesic domes, we are essentially cutting a sphere in order to have a flat surface to put on the ground. Think of cutting an onion in half so that it can be set on the cutting board and diced without rolling around. For even frequency domes a 1/2 truncation is almost always used. The math that lays out the struts works out such that there are struts at the half way point on the sphere. For odd frequency domes, there is never a horizontally running strut at the center of the sphere. So it is usually "cut" either above or below the center line, creating a 4/9ths (above center) or a 5/9ths (below center). The 4/9ths makes a great cap to a riser wall and a 5/9ths is great when extra height is desired.
General Dome Information Wikipedia: http://en.wikipedia.org/wiki/Geodesic_dome Buckminster Fuller Institute: http://www.bfi.org/ How Stuff Works: http://www.howstuffworks.com/engineering/structural/geodesic-dome.htm