I just found this, and this is exactly what I am planning to build. I was calling it an earth sheltered
greenhouse, I have never heard the term Wofati before. My modification would be a more traditional peaked roof with the southern half glazed, and the northern half under earth. I was thinking that on the northern side there would be clerestory windows for venting, and the southern wall would be fully walk-out. I am in the missouri Ozarks so I plan to use eastern red cedar logs "log cabin style" to form the stepped retaining walls. I was also figuring to line the back side of the cedar walls with old worn out barn tin to keep dirt from washing between the logs. I am hoping to achieve a totally passive freeze free
greenhouse. At worst I believe I will be able to raise hardy tems like lettuces and spinach etc through the winter.