ISO 11771:2010

Overview - What ISO 11771:2010 covers

ISO 11771:2010, "Air quality - Determination of time‑averaged mass emissions and emission factors - General approach", defines a generic, measurement‑based method for deriving time‑averaged mass emissions and emission factors for stationary sources. The standard specifies how to plan and execute measurement programmes, combine time‑series data, estimate uncertainties (including expanded uncertainty), and report results so that emission factors and mass emission rates are reproducible and of known quality. It is applicable to greenhouse gases and air pollutants (including fine particulate matter) and is intended for cases where calculation from fuel/raw material is not practical.

Key technical topics and requirements

• Measurement‑based approach: Requires use of standardized manual or automatic methods to measure concentration and gas flow simultaneously to determine mass emission rates.
• Measurement plan: Minimum planning requirements for data collection methodology, sampling selection, data processing and quality controls.
• Time‑series handling: Methods to generate time‑averaged mass emission rates from series of mass emission values, to fill gaps, and to combine datasets numerically to represent defined periods (e.g., a calendar year).
• Emission factors: Procedures to calculate time‑averaged emission factors for a specific installation or a family of installations, with documented operational conditions.
• Uncertainty estimation: Quantification of measurement uncertainty, variability in time‑series, and calculation of expanded uncertainty for averages and factors.
• Quality management: Requirements to support inventory quality assurance and verification through a documented quality management system.
• Scope limits: Not intended for compliance monitoring under emission control regulations; does not prescribe detailed measurement procedures in referenced standards nor provide guidance on generating activity statistics.

Practical applications and who uses it

ISO 11771:2010 is useful for:

• Environmental managers and facility operators developing site‑specific emission estimates and inventories.
• Emissions measurement laboratories planning source testing and uncertainty analysis.
• Inventory compilers and consultants producing emission factors for national or industry inventories, air quality modelling, and control strategy development.
• Stakeholders assessing greenhouse gas and air pollutant releases where direct measurement data are available.

Note: Although vehicular, area or fugitive sources are not specifically covered, the standard can be applied when reliable measurement data for those sources exist.

Related standards

• ISO 14064‑1 and ISO 14064‑3 - ISO 11771:2010 is compatible with these greenhouse gas accounting and verification standards.
• Referenced measurement standards (not fully reproduced in ISO 11771) provide detailed sampling and instrumentation methods.

Keywords: ISO 11771:2010, emission factors, time‑averaged mass emissions, air quality, measurement plan, uncertainty estimation, emission inventory, stationary sources, greenhouse gases, particulate matter.