An engineer wishing to design a quieter or more efficient fan may be interested in developing a model in which 'open-ness' is a factor, but as a user, I am prim

An engineer wishing to design a quieter or more efficient fan may be interested in developing a model in which 'open-ness' is a factor, but as a user, I am primarily interested in firstly creating the required airflow quietly, and secondly efficiently. For my concerns, direct measurements are more valuable than indirect ones. The author did not compare the grills at specific airflows, but the information is still useful.