Louver Free Area Calculator
Why it matters is simple. A louver free area calculator tells you how much open space a louver really has. It uses…
Why it matters is simple. A louver free area calculator tells you how much open space a louver really has. It uses a small number called the free area factor. You enter the gross opening size. Then you enter the louver’s free area factor. The tool will give you the actual flow area.
It will help you size ducts, fans, and vents. It will keep systems working well. It will help you follow codes and avoid noisy fans.
When to calculate louver free area
When you install or check vents. An engineer is teaching a team on a rooftop now. She points at a wall opening. She says the gross opening is 1.2 m². She shows a louver spec that has a free area factor of 0.35. She asks her learner to work out the free area. They use a calculator to be quick.
They must pick a fan that can push air through that free area. If they do not check, the fan will strain. The project will waste time and money.
Calculate louver free area — step by step
First, know the simple rule. Free Area = Gross Area × Free Area Factor.
Second, note values we use in class. Gross opening = 1.2 m². Free area factor = 0.35.
Third, do the math. Multiply 1.2 by 0.35.
1.2 × 0.35 = 0.42 m².
So the louver gives 0.42 square meters of free flow area.
Fourth, check the fan. If the fan must deliver 300 L/s, divide flow by area to get velocity. Convert units carefully. This step will tell you if pressure rise is too high. If velocity is high, you will pick a stronger fan or a larger louver.
Practical notes:
- You should always use the manufacturer’s free area factor.
- You must convert inches to meters if needed.
- You can round reasonably for field checks.
Trick
A quick trick is to tape a sheet over the opening and measure the covered area. Then multiply by the louver’s free area factor. That gives you the free flow area fast by hand. Still, a calculator will speed the job and cut errors. It will save time and help you pick the right fan or damper.
FAQs
Q: What is a free area factor?
A: It is a number that tells how much of the louver is open. Multiply it by gross area.
Q: Can I use the same factor for all louvers?
A: No. Each louver type will have its own factor from the maker.
Q: Do I need the free area to size fans?
A: Yes. You must know free area to estimate pressure and velocity.
