Most often people think the solution to solving a building's heat problem is to add more roof exhaust fans. The logic being that to draw more heat out of the building, the building needs more fans. To really solve a ventilation problem though, it is a bit more complex.

When it is hot inside the building, the issue isn't just about removing heat from the building but also about bringing incool air from outside. The part of the ventilation equation that is often missed is supply air.

Adequate supply air is often over-looked in industrial ventilation applications. In a high percentage of preexisting facilities, improving supply air is the best solution. Supply air is air that enters the building, generally at ground level. This is the opposite of the exhaust point that help move air out of the building via roof fans or vents.

Supply air means that warm air is not just leaving the building, but rather it is being pushed out by cooler, fresh air that is entering the building. The incoming air helps the hot air flow out of the building more consistently and at a faster rate. Improving supply air is often the best solution in retrofit situations.

Supply air is more effective at cooling workers and staff inside the building than exhaust fans. Since exhaust fans blow out, no breeze is created and the workers don't get the evaporative cooling effect in the building. In fact, since fans only have a reach equal to the diameter of its fan blade, most of the air movement from the fan isn't even felt on the floor at all.

By changing those fans to supply fans, and putting them at ground level, this creates a cooling effect right by the workers where it can make the most difference. These fans, sometimes even similar models to ones installed on the roof, have a greater effect when they are installed at wall level.

Having wall fans close to ground level means they are significantly easier to install and maintain as well. It is much easier to climb to the top of a ladder and fix something on the wall than it is to go up to the roof top.

Also, because these fans bring in cool, clean air, they don't need to be maintained as often because they don't get as dirty or wear out as quickly as roof fans. Hot dirty air can really take its toll on mechanisms leading to rust and other issues. Wall fans do not experience the same wear and tear because they don't have to move the polluted air. This means they require maintenance less often, saving time and money.

No matter how many roof fans are added to a building, if adequate and evenly distributed supply air is not introduced into the space then ventilation improvements will not be achieved. When considering improvements to a industrial ventilation system, Moffitt Corporation reminds you to consider supply air as well as roof exhaust fans.

Learn more about improving supply air, and a building's complete ventilation system, in our ventilation design section.