Blower Door Calculator Tool

CFM Formula:

\[ CFM = \text{Fan Speed} \times \text{Calibration Factor} \]

CFM Result:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Blower Door Calculator?

The Blower Door Calculator Tool calculates CFM (Cubic Feet per Minute) using fan speed and calibration factor measurements from blower door testing equipment. This measurement is essential for assessing building airtightness and ventilation requirements.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

\[ CFM = \text{Fan Speed} \times \text{Calibration Factor} \]

Where:

\( \text{Fan Speed} \) — Blower door fan rotation speed in RPM
\( \text{Calibration Factor} \) — Manufacturer-specific calibration value in CFM per RPM

Explanation: The equation converts fan rotation speed to airflow volume using the equipment-specific calibration factor.

3. Importance of CFM Calculation

Details: Accurate CFM measurement is crucial for determining building airtightness, calculating air exchange rates, identifying air leakage locations, and verifying compliance with building energy codes.

4. Using the Calculator

Tips: Enter fan speed in RPM and the calibration factor in CFM/RPM as provided by the blower door manufacturer. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a blower door test?
A: A blower door test is a diagnostic tool used to measure the airtightness of buildings and help identify air leakage locations.

Q2: Where can I find the calibration factor?
A: The calibration factor is specific to each blower door system and is typically provided by the manufacturer in the equipment manual or calibration certificate.

Q3: What are typical CFM values for residential buildings?
A: CFM values vary significantly based on building size, age, and construction quality. Newer, tighter homes might have CFM50 values below 1000, while older leakier homes might exceed 3000 CFM50.

Q4: Why is building airtightness important?
A: Proper airtightness improves energy efficiency, prevents moisture problems, enhances indoor air quality, and improves occupant comfort.

Q5: Can this calculator be used for commercial buildings?
A: Yes, the same calculation applies, though commercial buildings typically require larger blower door systems and may have much higher CFM values.