What ventilation do I need?
Part F: what ventilation do I need?
A quick reference for Approved Document F, Volume 1 (2021 edition). A dwelling needs both of the below — worked out independently.
Continuous background ventilation, sized for the dwelling as a whole — including make-up air for wet room extract.
→ Section 1required
Continuous mechanical extract in each kitchen, bathroom, utility and WC — sized on its own, isolated from the supply figure.
→ Section 21. Whole-dwelling supply
Continuous supply air, sized for the whole dwelling. Supply units (FLUXO / AUREN) are installed in habitable rooms — bedrooms, living rooms.
Step 1 — work out the target. Use whichever number below is higher.
| Bedrooms in dwelling | Whole-dwelling rate |
|---|---|
| 1 bed | 19 L/s |
| 2 bed | 25 L/s |
| 3 bed | 31 L/s |
| 4 bed | 37 L/s |
| 5 bed | 43 L/s |
Or work it out this way: total internal floor area (m²) × 0.3 L/s.
Whichever of the two figures is bigger is the target you design to.
Step 2 — choose units and work out how many
| Unit | Max output | Notes |
|---|---|---|
| FLUXO 100 | 8 L/s | Basic, wall switch |
| FLUXO 150 | 17 L/s | Basic, wall switch |
| AUREN 160 | 17 L/s | Quieter, remote control, filtration options |
Number of units = target L/s ÷ unit output, rounded up.
Step 3 — position and spread
Install units as high as practically possible. Keep them no more than 400mm below the ceiling, and leave room to reach them for maintenance.
Spread units across the habitable rooms. One per bedroom or living room is typical best practice — though Part F doesn't require it.
Try it yourself — calculate your dwelling
2. Wet room extract
A separate requirement, on top of Section 1 — kitchen, bathroom, en-suite, utility and WC each need their own continuous mechanical extract.
| Room type | Required rate (continuous) | VENTI unit |
|---|---|---|
| Kitchen | 13 L/s | ARIA 100 or 150 |
| Bathroom | 8 L/s | ARIA 100 |
| Utility room | 8 L/s | ARIA 100 |
| WC only (no bath/shower) | 6 L/s | ARIA 100 |
Fit one unit per wet room. Note: ADF(1) doesn't have a separate “en-suite” category — treat an en-suite as a bathroom.