How much cfm per square foot

In the midwest this is a good rule of thumb. If you are in southern California, or in the arctic circle, this rule of thumb is not so helpful. If you need to quickly determine how much cfm you need to deliver to a space, this is a great place to start. In spaces that are more density populated, like conference rooms, gymnasiums or auditoriums, the space may require closer to 2 cfm per sq ft or sometimes more! Register now to receive HVAC design and application tips that are not brand specific, delivered approximately twice per month.

Author Recent Posts. Connect on:. Brad Telker. Brad was born and raised in St Louis Missouri, where he spent the first 18 years of his life. Once you understand the volume or your space, it is time to understand the amount of air exchange that is required. This will vary from space to space, but here are some general air exchanges for a few residential and commercial applications Once you have the air exchange numbers, it is simple to calculate the CFM.

Divide the total air volume by the exchange rate to achieve the required CFM. The CFM will be higher for those applications that require a quicker air exchange in order to keep the indoor air quality at optimal levels. If we use the same dimensions from our previous example 10 x 10 x 15 ft for our 1, square foot room, we would expect to need the following CFM:.

This is the average air quantity required for a room or an entire building. This number is based upon an averaged heat load calculation for comfort cooling. There is an assumption of an 8-ft ceiling, no unusual window areas, and average insulation. Furthermore, how many CFM do I need for square feet?

As a practical example, if your room has a square footage of square feet with three windows and two inhabitants, you need 18, BUT to cool the room. When divided by 30, the result indicates you need an air conditioner capable of CFM. Then we calculate the volume of the room by multiplying the room height times the width times the length. Then we simply divide the CFH by the volume of the room.

The rule of thumb is that you need at least 1 CFM per square foot of room area. To determine the square footage of your bathroom, multiply the length times the width. For example, if your bathroom is 6 feet wide and 9 feet long, its square footage is Therefore, it should have a fan rated for at least 54?

What size ceiling fan do I need for a 12x12 room? How many CFM is a 3 ton? The airflow is measured in cubic feet per minute CFM. For example, if you are checking a 3 ton system, the air flow required is between and CFM. How do you calculate duct size for a room? Multiply that number by the amount of cubic feet of airflow per minute CFM your type of furnace produces.