Overview
ISO 16000-8:2007 - Indoor air, Part 8 - defines procedures using a single tracer gas to determine the local mean age of air as an indicator of ventilation conditions in buildings. The standard describes practical tracer-gas measurement strategies (concentration decay and homogeneous constant emission) intended for indoor air quality (IAQ) studies. It applies in principle to all indoor spaces and ventilation types without disturbing prevailing ventilation, but it does not specify analytical laboratory methods for tracer-gas analysis.
Key Topics and Requirements
- Measurement principles: Use tracer-gas techniques to differentiate between existing indoor air and incoming ventilation air; determine local mean age of air and its inverse, the local effective air change rate.
- Methods covered:
- Concentration decay (decay method) - marking existing air and monitoring concentration drop;
- Homogeneous constant emission - continuous, spatially uniform tracer release (active or passive) and monitoring distribution.
- Planning and setup: Identification of the ventilated system and zones, selection of measurement points, and choice of appropriate tracer and feeding/sampling equipment.
- Zones and definitions: Clarifies terms such as zone, ventilated system, zone mean age of air and local mean age of air. Zones should have concentration differences within ~20% to be considered well mixed.
- Instrumentation: Guidance on tracer selection, concentration standards, tracer feeding equipment, sampling strategies and concentration determination (analytical details are excluded).
- Data use and reporting: Procedures for applying results to assess ventilation, estimate source strengths and prepare a test report. Annexes cover uncertainty estimation and worked examples.
Applications
ISO 16000-8:2007 is practical for:
- Checking whether building ventilation meets regulatory or design requirements
- Diagnosing inadequate ventilation in buildings with IAQ complaints (residential, offices, schools, healthcare)
- Characterizing the distribution and strength of indoor emission sources and helping estimate contaminant concentrations tied to air age
- Supporting ventilation design verification, retrofits, and forensic IAQ investigations
Relevant keywords: indoor air, ventilation measurement, tracer gas, local mean age of air, air change rate, IAQ assessment.
Who Should Use This Standard
- HVAC and ventilation engineers
- Indoor air quality (IAQ) consultants and industrial hygienists
- Building scientists and researchers
- Facility managers, building owners, and regulators involved in ventilation compliance and IAQ investigations
Related Standards
- ISO 12569 - Tracer gas dilution method for air change in buildings (complementary methods for single-zone air change)
- Guide to the expression of uncertainty in measurement (GUM) - for uncertainty estimation used in Annex C of ISO 16000-8
- Other parts of the ISO 16000 series addressing sampling strategies and VOC/formaldehyde measurement for comprehensive IAQ assessment
This standard helps link ventilation measurement (local mean age of air) directly to practical IAQ decision-making and ventilation performance verification.
