What condition is indicative of a system requiring make-up air installation?

A system requiring make-up air installation is typically indicated by the intermittent operation of exhaust systems. Exhaust systems are designed to remove stale or contaminated air from a building, which can create negative pressure inside the space. When the exhaust systems operate, they can draw in air from outside the building; however, if there isn't enough supply air to replace the exhausted air, this can lead to undesirable conditions.

The need for make-up air arises because the lack of properly balanced air can make it difficult for heating and cooling systems to maintain desired indoor conditions. The installation of make-up air systems ensures that there is always a sufficient supply of fresh air entering the space, thereby promoting healthy air quality and improving overall system efficiency.

In contrast, factors such as low humidity levels, high energy bills, or consistent air leakage do not directly signify the requirement for make-up air. Low humidity levels can occur due to various reasons not necessarily tied to air balance, while high energy bills could result from a variety of inefficiencies not limited to air supply issues. Consistent air leakage can indicate other problems within the building envelope that may need addressing, but does not automatically imply a need for make-up air installation.