CIBSE Guide B2: Ventilation and Ductwork (2016)
Practical Guidance for Ventilation System Design, Ductwork Specification and Performance Verification
LEVCentral Expert Commentary
CIBSE Guide B2 remains one of the UK’s most widely recognised references for the design, installation and commissioning of ventilation and ductwork systems. Whilst the document is focused primarily on general building ventilation, many of the engineering principles are directly applicable to LEV systems and workplace contaminant control.
The guide provides valuable guidance on airflow design, ductwork construction, pressure losses, leakage control, filtration, commissioning and system verification. For LEV professionals, it reinforces the importance of considering the entire airflow system rather than focusing solely on extraction equipment or airflow rates.
Of particular relevance are the sections covering ductwork leakage, commissioning and performance verification. These are common areas where both comfort ventilation and LEV systems fail to achieve their design intent. Effective ventilation depends not only on good design but also on proper installation, testing and ongoing maintenance.
For designers, occupational hygienists and LEV engineers, Guide B2 provides a useful reference for understanding the wider ventilation principles that underpin effective airborne contaminant control.
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Source Document
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Source: CIBSE
Document Type: Technical Design Guide
Status: Current 2016
Last reviewed by LEVCentral: June 2026
Key Learning Points
- Ventilation effectiveness depends on more than airflow quantity alone.
- Ductwork design has a significant impact on system performance and energy consumption.
- Air leakage can reduce system effectiveness and increase operating costs.
- Commissioning is essential to demonstrate that design objectives have been achieved.
- Maintenance and inspection requirements should be considered during design.
- Many ventilation design principles are directly applicable to LEV systems.
Further Resources
- HSG258 – Controlling Airborne Contaminants at Work
- BESA DW144 – Specification for Sheet Metal Ductwork
- BESA TR19® – Internal Cleanliness of Ventilation Systems
- CIBSE Guide A – Environmental Design
Recommended Learning
- P602 LEV System Design Principles
- P604 Commissioning and Performance Verification
- P601 Thorough Examination and Testing (TExT)
- P600 Methods for Testing Performance of LEV
Thought Leadership
Effective ventilation is not achieved when the design calculations are completed.
It is achieved when the installed system delivers the intended performance under real operating conditions.
Guide B2 reinforces the importance of commissioning, verification and ongoing performance management—principles that are equally relevant to comfort ventilation and LEV systems.
