According to an online questionnaire sent to over a hundred designers, this is one of them:
“Ecofont is a program that adds holes to a font. The software takes Arial, Verdana, Times New Roman and prints them as if they had been attacked by moths.
The plus side: In 2010 Ecofont won a European Environmental Design Award. The downside: a study at the University of Wisconsin claimed that some Ecofont fonts, such as Ecofont Vera Sans, actually use more ink and toner than lighter regular fonts such as Century Gothic (although one could, of course, always print Century Gothic using Ecofont software).”