Guidebook No. 11 (5th edition)
Authors: Tobias Zimmer, Riccardo Romanò, Romano Alberto Basso, Alain Ginestet, Paolo Tronville, Christian Rossi, Amelia Saszowska
The 2026 edition of REHVA Guidebook 11 provides an updated overview of air filtration in HVAC systems, reflecting recent regulatory changes, standards, and research developments.
Context: why air filtration is evolving
Recent years have brought significant changes to how air filtration is approached in buildings, driven by:
- The WHO Air Quality Guidelines (2021), highlighting the health impact of air pollution
- The COVID-19 pandemic, which increased awareness of airborne transmission
These developments have reinforced the importance of effective filtration strategies in indoor environments.
Alignment with current standards
The guidebook reflects the transition towards:
- EN ISO 16890 for classifying particulate filters
- EN ISO 10121-3 for gas-phase filtration
- EN 16798-3:2025 for ventilation performance requirements
Together, these standards define a new framework for air filtration in HVAC systems.
Scope of the guidebook
REHVA Guidebook 11 addresses:
- Filtration of particulate matter (PM1, PM2.5, PM10)
- Removal of gaseous pollutants (e.g. NO₂, ozone, VOCs)
- Application of multi-stage filtration systems
- Hygienic and operational considerations
Air filtration and health
The guide also includes updated information on:
- The role of filtration in reducing airborne contaminants
- The importance of managing recirculated air
- Guidance from EN 16798-3 and related standards
These aspects are increasingly relevant for healthy and resilient building design.
Emerging technologies
In addition to conventional filtration, the guide reviews:
- Antimicrobial-treated filters
- Ultraviolet germicidal irradiation (UVGI)
It provides a balanced, evidence-based perspective on their application and limitations.
Further information
REHVA Guidebook 11 is intended for professionals seeking a structured and up-to-date reference on air filtration in HVAC systems.