I just added some more links to this post but here they are again:

farming statistics for a small hemp farm operation

Building with Hemp and Lime

Here are the expected yields per acre for industrial hemp according to the USDA. For hemp produced solely for fiber, the average yield is between 3-5 tons per acre. For the average size hempcrete family house, you'll need about 14 metric tons which can be grown on about 3-5 acres.