An efficient HVAC system starts with louvers built for the task. Learn the three key factors to consider when choosing a louver for air performance.
A green, sustainable building is many things: efficient spaces, built with renewable materials, provides a comfortable atmosphere for its occupants, and uses the least amount of resources and materials possible. An efficient HVAC system can go a long way towards making an sustainable building work.
And the most efficient HVAC systems start with louvers built for the task.
Louvers designed for air performance can make the difference between an overtaxed system that wastes energy and an efficient system that saves you money over time. Let’s look at the first and last stage of every large-scale HVAC system: the intake and exhaust louvers on your building’s face.
As air moves, it must go through the spaces between the louver’s blades. The louver's blades allow air in and prevent foreign material – water, sand, dust, and other debris – from getting through to the duct work beyond. Different louvers will perform these two functions in different ways, even though they may look the same.
Exhaust applications work in reverse: the fan pushes air through the louver to the outside. The same concepts will apply.
It’s important to find a balance between these two functions. Your louvers may be required to block a certain amount of water, to withstand hurricane force winds, or to withstand impacts from wind-borne debris. If efficiency is your primary goal, then it is important to focus on the airflow aspect of the louver.
There are three things to consider when choosing a louver for air flow: the louver’s blade profile, the louver’s free area, and the louver’s pressure drop. Blade profile refers to the surface features of the louver’s blades.
These features play a key role in blocking unwanted elements, but they can also cause air resistance. As air passes over the blade profile, its features will catch the unwanted elements in the air stream before they enter through the louver. This air resistance is known as pressure drop, or the amount of air pressure lost as air passes from the face of the louver to the duct work. Pressure drop will increase as air velocity across the louver’s face increases or if the amount of louver free area decreases.
In other words, the more obstructions that are in the way of the airflow, the greater the loss in air pressure. If the louver has a high pressure drop, then intake fans will have to work harder to pull the necessary amount of airflow through the louver. Your entire system will feel the excess strain.
The key to efficiency is finding a balance between the louver's pressure drop and its ability to block rainwater. Learn more about air performance with this quick Condenser read: Air Performance and Keeping the Flow.
Chevron blades are shaped like an upside-down V. The middle section of the blade curves upward, creating a hill shape profile. As air enters the louver, it will move up the hill on the face side of the blade and then down the hill. This shape creates a natural flow that can block debris without sacrificing airflow.
Chevron blades often come with catches along the blade’s profile to capture moisture and smaller debris. This makes the chevron blade a nice balance between water protection and air performance.
If efficiency is your primary concern, then your best option is a louver with straight blades.
Larger louvers will have more square feet of free area than a smaller louver, but the percentage of total louver area will be the same across all sizes. A louver with more free area will have less pressure drop than a louver with less free area, since there is more space for air flow.
When choosing a louver for air performance, look for a model that provides the most free area for the size you need. These louvers will provide the most airflow through the louver with minimal pressure drop, allowing for the most efficient airflow through your HVAC system.
By choosing air performance, you end up minimizing the amount of power needed to drive air through intake and exhaust louvers. This saves power and money over time! Learn more about the pressures involved in efficient airflow with "Balanced Flow".
Your louvers will have more requirements than air performance. In areas with frequent severe weather, you may need a louver that can block wind driven rainfall. If your project is in a high velocity hurricane zone, your louver will need to resist hurricane-force winds, heavy rainfall, and impacts from wind-borne debris. In these cases, you may need to sacrifice air performance to meet these requirements. Your project’s requirements should always come first.
If you need a louver that provides efficient air flow, then consider a model with a high free area, low pressure drop, and a flat blade profile. These louvers will maximize airflow and increase efficiency in your HVAC system.
For more on louvers, read these Newsstand articles:
Every little bit counts when designing an efficient HVAC system. What do you look for when choosing a louver? What aspects stand out the most? Share your thoughts on louvers in the Comments section. We want to hear from you!
MCDLG offers free self-paced courses online through AEC Daily.
Our louver course, Louvers for Style and Aesthetics, goes over the basic stats, terms, and principles involved in choosing louvers for any application. You can also learn a few pointers for enhancing the style of your louvers.
This course provides continuing education credits for a variety of institutions, including AIA's LIUs. Learn the basics of louvers and earn credit, at your own pace. Visit the MCDLG course page on AECDaily.com today!
Do you have a question on something we haven't covered here? Or do you need help from industry experts? MCDLG can help. Contact us by clicking on the button below.