Roundhouse with Siberian Chum Roof (click to enlarge)
Specifications: 16′ interior diameter with 201 sq. ft. interior, sleeping loft, half bath, Footprint: 19′ x 19′
Description: Here’s a compact design ideal for extremely cold climates. The basic concept comes from the Siberian Chum (tent). There are two chum roofs or conical shaped roofs made of poles with insulation between. Virtually all materials are made from small diameter wood poles, which are often abundant in northern forests – roof poles, bond beam, lintels, loft joists, wood shakes and woodchip insulation. Tilt-down stairs lead to a sleeping loft. Only a very small wood stove is needed for heating. It would be quite easy to build debt-free by gradually adding extra roundhouses as time and resources allow. A small cluster of these roundhouses would be real cozy.
Roundhouse with Siberian Chum Roof (click to enlarge)
Earthbag House Plans 
This is a great little house. Would love to live in a community of them!
Would you recommend this design over something like the Peace Dome (perhaps with a metal roof) for climate zone 5b (Placerville, CO.)? Can you explain more about the chum roof? What are the advantages of the roundhouse/chum roof versus earthbag dome in cold climates? Thank you.
You definitely want a roof. Domes are for deserts and often have water problems in wetter climates, so if you build a dome make a rainscreen covering or (better) build a roofed dome.
You can use any number of roof building systems. I explain numerous options on our Natural Building Blog. Search our blog and see if you find something that fits your needs. http://www.naturalbuildingblog.com/ One good option is the double pole roof: http://www.motherearthnews.com/green-homes/double-pole-roofs.aspx#axzz2i3XOcCvK
The chum roof is another option. Use what looks best to you.
Consider