They are advising Century Gothic 11pt

See http://www.uwgb.edu/compserv/ehelp/office2007/fontchanges.htm for the suggestion to change the font size in Word and Excel. That's close to Arial 12 pt.

Taking an identical sample of text at *screen resolution*, the average colour of Arial 12 was 23.6/255 black, Century Gothic 11 was 22/255 black. So CG11 was 93.2% as dark as Arial12. Readability seemed comparable. If anyone wants to repeat as higher magnification they might get a closer approximation to the print ink savings.