Having said this, it is not uncommon to hear users complain that they do not achieve the savings that the original design promised. This is surely the reason behind the recent interest in low-flow fume hoods. After falling short of the projected savings, the owner's question becomes, "Where did the savings go?" In this article, we will shed some light on the reasons why and suggest some remedies that those either operating or designing vav systems for research laboratories can use to translate the theoretical savings to reality.
The total volume of air required in a particular space is determined by three airflow drivers: air changes, heat load, and makeup air needs. (Figure 1)