Whole dwelling ventilation verification against Approved Document F

Four dwellings, from a studio flat to a six-bedroom house, run through the same calculation the app uses and compared with the whole dwelling rates and extract rates printed in Approved Document F Volume 1.

Result: 11 of 11 checks pass
Cases: 4 worked examples
Version / published: v1.0 · 2026-09-28
Engine fingerprint: 9f46f99cf62e

Why we publish this

§1.20 sets two conditions and a dwelling must meet both: 0.3 L/s for every square metre of internal floor area, and the rate for its number of bedrooms from Table 1.3. The cases are chosen so each condition governs at least once, including the two notes under the table: the studio with one habitable room, and the house with more bedrooms than the table lists.

Editions

The 2026 edition of Volume 1 takes effect on 24 March 2027. Tables 1.2 and 1.3 print the same rates as the 2021 edition that applies until then, so every value here holds under both.

What is not compared, and why

The ASHRAE 62.2 setting. The calculator also offers ASHRAE 62.2-2025. It is checked in the regression suite against the §4.1.1 formula, and is not among the documents this page quotes from.

How to read the tables

Expected is the value printed in the standard, or a hand calculation from printed values. The working is shown under each quantity.
Tolerance is exact for tabulated values and selected sizes, and ±2 % for calculated quantities such as the floor-area rate and the rates beyond the printed rows.
Every check re-runs automatically whenever the calculation code changes, and this page is regenerated from those results. The engine fingerprint above identifies the calculation code the results came from.

Sources

Approved Document F, Volume 1: Dwellings, 2026 edition

Printed page numbers refer to the editions above.

Worked examples

WD-01

Three-bedroom house, 90 m²: the bedroom rate governs

Inputs

Three bedrooms, 90 m² internal floor area over both storeys
Kitchen, utility room, bathroom and WC on continuous extract

Checks for case WD-01
Quantity	Expected	Source	MEPCalc	Tolerance	Result
Rate by number of bedrooms (Table 1.3)	31l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	31l/s	exact	Pass
Rate by floor area, 0.3 L/s per m² 0.3 × 90 = 27 l/s	27l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	27l/s	±2 %	Pass
Minimum whole dwelling ventilation rate Both conditions must be met: the higher of 31 and 27 l/s.	31l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	31l/s	exact	Pass
Kitchen extract, minimum high rate	13l/s	Approved Document F, Volume 1: Dwellings, 2026 edition Table 1.2 (printed p9)	13l/s	exact	Pass
Utility room extract, minimum high rate	8l/s	Approved Document F, Volume 1: Dwellings, 2026 edition Table 1.2 (printed p9)	8l/s	exact	Pass
Bathroom extract, minimum high rate	8l/s	Approved Document F, Volume 1: Dwellings, 2026 edition Table 1.2 (printed p9)	8l/s	exact	Pass
Sanitary accommodation extract, minimum high rate	6l/s	Approved Document F, Volume 1: Dwellings, 2026 edition Table 1.2 (printed p9)	6l/s	exact	Pass

WD-02

Four-bedroom house, 150 m²: the floor-area rate governs

Inputs

Four bedrooms, 150 m² internal floor area

Checks for case WD-02
Quantity	Expected	Source	MEPCalc	Δ	Tolerance	Result
Rate by number of bedrooms (Table 1.3)	37l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	37l/s	0.00 %	exact	Pass
Minimum whole dwelling ventilation rate 0.3 × 150 = 45 l/s, higher than the 37 l/s bedroom rate.	45l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	45l/s	0.00 %	±2 %	Pass

WD-03

Six-bedroom house, 120 m²: beyond the last row of Table 1.3

Inputs

Six bedrooms, 120 m² internal floor area

Checks for case WD-03
Quantity	Expected	Source	MEPCalc	Δ	Tolerance	Result
Minimum whole dwelling ventilation rate Table 1.3 stops at five bedrooms, 43 l/s; Note 2 adds 6 l/s per extra bedroom: 49 l/s. The area rate, 0.3 × 120 = 36 l/s, is lower.	49l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	49l/s	0.00 %	±2 %	Pass

WD-04

Studio flat, 32 m²: one habitable room

Inputs

One habitable room and no separate bedroom, 32 m² internal floor area

Checks for case WD-04
Quantity	Expected	Source	MEPCalc	Δ	Tolerance	Result
Minimum whole dwelling ventilation rate Table 1.3 Note 1: a dwelling with only one habitable room uses 13 l/s. The area rate, 0.3 × 32 = 9.6 l/s, is lower.	13l/s	Approved Document F, Volume 1: Dwellings, 2026 edition §1.20 and Table 1.3 (printed p9)	13l/s	0.00 %	exact	Pass