School ventilation design touches more regulations than almost any other building type. Between BB101, CIBSE guides, Building Regulations, and DfE guidance, it's easy to miss something. Here's a clear breakdown of what you need and when.
The essential standards
| Standard | Why you need it | Key section |
|---|---|---|
| BB101 (2018) | THE ventilation standard for schools — sets minimum fresh air rates, CO₂ limits (1000 ppm average, 1500 ppm max), thermal comfort criteria, overheating limits | Sections 3–5 |
| CIBSE Guide A (2015) | Environmental design fundamentals — internal design conditions, ventilation rates per person, overheating criteria (TM52 method) | §1 (ventilation), §5 (thermal) |
| Approved Document Part F (2022) | Legal minimum ventilation rates for new buildings — extract rates for kitchens, WCs, and minimum outdoor air rates | Tables 5.1–5.3 |
| Approved Document Part L (2021) | Energy performance — sets SFP limits for ventilation systems, U-value targets affecting heat loss calcs | §6 (SFP limits) |
| CIBSE TM52 (2013) | Overheating assessment methodology — required by BB101 for school projects. Defines the 3 overheating criteria | Full document |
| HTM 03-01 | If designing ventilation for school science labs or any healthcare-adjacent spaces, this covers specialist ventilation | Sections on fume cupboards |
Recommended supporting standards
| Standard | When you need it |
|---|---|
| CIBSE Guide B2 (2016) | Ventilation and ductwork system design — detailed guidance on duct sizing, air distribution |
| DW144 | Ductwork specification — standard duct sizes, construction requirements |
| BSRIA BG 30/2007 | Calculation methodology — if your practice follows BSRIA methodology for calcs |
| CIBSE Guide C (2007) | Reference data — pipe/duct sizing data, fluid properties |
| Part E (acoustics) | Noise from ventilation systems in teaching spaces — cross-reference with BB93 |
Common design pitfalls
BB101's CO₂ limits are tighter than Part F's general ventilation rates. You must meet both — and in practice, BB101 almost always governs for teaching spaces. Don't assume that meeting Part F alone is sufficient for a school project.
Not checking TM52 overheating early enough is one of the most common mistakes on school projects. The overheating assessment can force fundamental changes to the ventilation strategy — from natural ventilation to mixed-mode or full mechanical — and discovering this at Stage 4 is expensive.
Assuming natural ventilation will work without doing the overheating assessment first is a related trap. Natural ventilation is often the preferred approach for schools, but TM52 compliance depends on orientation, glazing ratios, internal gains, and local climate data. Run the assessment early.
Finally, don't overlook SFP limits in Part L. A well-designed duct system can fail compliance if the fan selection pushes specific fan power above 1.6 W/(L/s). Keeping duct velocities reasonable and minimising pressure drop through fittings is the most effective way to stay within the limit.
Quick reference — key values
Fresh air rate: 8 L/s per person (BB101 minimum for teaching spaces)
CO₂ limit: 1000 ppm time-weighted average during occupied hours
Max CO₂: 1500 ppm at any point during occupied hours
SFP limit: 1.6 W/(L/s) for central mechanical ventilation (Part L)
Overheating: TM52 criteria 1, 2, and 3 must all be assessed