How to Prepare a Room-by-Room Airflow Schedule
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List each room's length, width and ceiling height, compute volume, choose one basis (ACH target or sensible cooling load), compute CFM per room, then total. Keep ventilation-based and cooling-based schedules separate and note the ΔT or ACH used.
An airflow schedule is a simple table: one row per room, with the dimensions, the basis for its airflow and the resulting CFM. It makes assumptions visible and lets someone else check the arithmetic.
Run the numbers with the Room-by-Room CFM Planner.
Steps
- Name every conditioned room and measure inside dimensions.
- Compute volume = L × W × H in cubic feet.
- Decide the basis: an ACH target, or sensible loads from a Manual J report.
- Calculate per-room CFM with the matching formula.
- Total the column and record the assumptions (ACH or ΔT, altitude).
- Give the schedule to the designer for duct and register sizing.
Worked cooling schedule
Sensible loads from a load report; ΔT = 20 °F (divisor 21.6)
| Room | Volume (ft³) | Sensible load (BTU/h) | Supply CFM |
|---|---|---|---|
| Bedroom 1 | 1,344 | 4,000 | 185 |
| Bedroom 2 | 1,056 | 3,000 | 139 |
| Office | 720 | 2,000 | 93 |
| Total | 3,120 | 9,000 | 417 |
Common mistakes
- Mixing rooms calculated by ACH with rooms calculated by load in one total
- Leaving out closets or bathrooms that receive supply air
- Not recording ΔT, which makes the CFM impossible to check
Assumptions and limitations
A schedule is only as accurate as the loads or targets in it. It does not size ducts, select registers or verify that the blower can deliver the total at the system's static pressure.