Air Balance Report Template

An air balance report is the primary deliverable of a Testing, Adjusting, and Balancing (TAB) inspection. It documents the design airflow requirements for each terminal device in a building and records the actual measured airflow — confirming whether the system is delivering air as the mechanical design specifies.

What Is an Air Balance Report?

A TAB agent visits a building after HVAC installation is complete, measures the actual airflow at each supply diffuser, return grille, and exhaust register, then adjusts dampers and equipment to bring airflow into alignment with the mechanical design. The air balance report captures this process in tabular form.

The report typically includes:

• A system summary for each air handling unit (AHU) or rooftop unit (RTU)
• A line item for every measured terminal device (diffuser, grille, register)
• The design CFM for each device (from the mechanical drawings)
• The final measured CFM after adjustment
• The variance between design and measured airflow
• The TAB agent's certification signature and date

Report Table Structure

The core of an air balance report is a tabular summary of terminal devices. The columns below represent the standard fields found in most TAB reports.

Field Explanations

Room / Area

The name or number of the room or zone where the terminal device is located. This typically matches the room labels on the mechanical drawings (e.g., "Office 101", "Conference B", "Corridor 2").

System

The air handling unit, rooftop unit, or fan coil unit that serves this device. Useful when a building has multiple systems (e.g., "AHU-1", "RTU-3", "FCU-B4").

Design CFM

The airflow (in cubic feet per minute) specified by the mechanical engineer in the construction documents. This is the target — the amount of conditioned air this device is supposed to deliver. Source: mechanical drawings and airflow schedules.

Measured CFM

The actual airflow measured in the field by the TAB technician after adjustment. Measured using a flow hood (capture hood), pitot tube traverse, or other approved method per the applicable TAB standard.

Difference

The arithmetic difference between measured and design CFM. Calculated as: Measured CFM − Design CFM. A positive value indicates the device is delivering more than specified; negative means less.

Variance %

The percentage deviation from design. Calculated as: (Difference ÷ Design CFM) × 100. A commonly referenced tolerance in TAB standards is ±10%, meaning the measured flow should fall within 10% of the design value — but acceptable variance depends on project specifications and the applicable standard. Check project documents.

Notes

Free-text field for observations. Common entries include damper position, device condition, obstructions, ceiling tile status, duct issues noted, or items requiring follow-up.

Example Completed Row

The following is a sample completed row showing how measured results would be recorded for a single supply diffuser.

In the second row, the measured CFM is outside the commonly referenced ±10% tolerance band. The TAB technician has flagged this for correction (ceiling tile obstruction) before the report is finalized. Specific acceptance criteria depend on the project specifications — always verify with the applicable contract documents.

Use the CFM Variance Calculator to quickly compute difference and variance percentage for any device.