AirScape Engineer's Blog

We just launched our Bathroom Ventilation Calculator and Visualizer.

Users enter the room dimensions and then adjust airflow. As the CFM is raised, a ventilation quality meter and the ‘fog level’  change.  These indicators  allow the user to visualize the level of ventilation.

OK, first the boring defintion. A CFM stands for cubic foot per minute. This term is used as a measurement of airflow rate for ventilation systems. The cubic foot refers to a (mythical) cube of air 1 foot x 1 foot x 1 foot. CFM becomes a flow rate since we measure how many cubic feet are flowing by per minute.

Now, let’s get some perspective on what a cubic foot and CFM represent:

• It takes about13.5 cubic feet of air to weigh one pound. A 2,000 square foot house will contain 16,000 cubic feet of air. The weight of all that air is only 1,185 pounds.
• Warming or cooling air is “low calorie”. To warm all that air in your house up from 50 degrees F to 70 degrees F takes about 5,688 BTU’s . The smallest house furnace puts out 40,000 BTU’s per hour. So how come it takes so long to heat up the house on a cold morning?
• An unsealed door jamb, leaking 50 CFM would over the course of 24 hours, leak out 72,000 cubic feet of air – not “low calorie”