Enter the house volume, air flow, or air changes per hour into the calculator to determine the missing value.
- All Construction Calculators
- Air Flow Calculator
- Room Volume Calculator
- CFM to ACH Converter
- CFM from Differential Pressure Calculator
- CFM to Static Pressure Calculator
Blower Door Calculator Formula
The following equations are used to calculate the missing parameter in the Blower Door Calculator.
ACH = (CFM * 60) / HV (if calculating ACH) HV = (CFM * 60) / ACH (if calculating House Volume) CFM = (HV * ACH) / 60 (if calculating Air Flow)
- Where ACH is the air changes per hour (1/hr)
- HV is the house volume (ft³)
- CFM is the air flow (cubic feet per minute)
To calculate the missing parameter, leave its corresponding field empty and provide the other two values.
What is a Blower Door Calculator?
Definition:
A blower door calculator is a tool used to determine one of the key parameters in a blower door test by computing the missing value from the provided inputs, helping assess a building’s airtightness and energy efficiency.
How to Use the Blower Door Calculator?
Example Problem:
The following example outlines the steps and information needed to calculate the missing parameter.
First, determine the house volume. In this example, the house volume is 20,000 ft³.
Next, determine the desired air changes per hour. In this example, the air changes per hour is set to 5.
Finally, calculate the air flow using the formula above:
CFM = (HV * ACH) / 60
CFM = (20000 * 5) / 60
CFM = 100000 / 60
CFM ≈ 1666.67 CFM
FAQ
What is a blower door test?
A blower door test assesses a building’s airtightness by measuring the amount of air leakage, which helps in evaluating energy efficiency and overall building performance.
How does the blower door calculator work?
The calculator computes the missing parameter—house volume, air flow, or air changes per hour—by applying the relevant formula when one field is left empty.
Why is measuring airtightness important?
Measuring airtightness is crucial for determining energy efficiency, as it can identify potential heat loss, improve indoor air quality, and guide improvements to a building’s insulation and sealing.