To the best of my knowledge, "low volume" is a term coined by Malka Dubrawsky in an article written for the April/May 2009 issue of Quilting Arts Magazine.
In the intro, she says "...I’ve begun to explore the possibilities of crafting items exclusively out of fabrics that don’t rely on bright, saturated, or intense colors. I’ve come to call these fabrics “low volume.” They’re characterized by qualities such as simple, sometimes large-scale, graphic prints; the backgrounds are mostly white or paler shades with a variety of differently textured fibers. The initial inspiration for working with these fabrics came from several sources including the clean aesthetic of Japanese craft books, the art of minimalist painter Agnes Martin, and my desire to explore traditional quilt patterns in a way that felt fresh and modern."
The use of 'low volume' fabrics gives the design elements of line, shape, and texture much more focus than they get when the 'high volume' of intense color is claiming center stage. As a designer, I like that challenge.