I thought it was time to upload and show this image taken back in Feb 2015. This is an 80 degree wall with 4 kinds of lettuce growing in it, Butter (Bib), Red Oak, Green Oak and Romain at the far end.
The wall is 16 feet long and 7 feet high with 8" x 8" plant spacing in vertical ducts, NFT style, 10 plants per row, 24 rows (columns).
Oliver