Duct selection

Place the ducts in this image in order of efficiency, from most to least efficient:
I. Square
II. Round
III. Rectangular, long horizontal
IV. Rectangular, long vertical

A. III, IV, I, II
B. I, IV, III, II
C. II, III, IV, I
D. II, I, IV, III

AnswerD. The most efficient shape is one using the least perimeter length in relation to cross-sectional area and minimized friction loss to move a volume of air.

ARE 4.0 exam prep: BS