You are here: FoundationFootprint™ Help Centre > Miscellaneous > IPCC Tiers - Login

Tiers of Emission Factors and Activity Data

Following the 2006 IPCC guidelines, FoundationFootprint™ includes the ability to specify a "tier" to rate the reliability and methodological complexity of emission factors and activity data.

A tier represents a level of methodological complexity. Three tier's are described for categorizing both emissions factors and activity data. Tier 1 is the basic method, frequently utilizing IPCC-recommended country-level defaults, while Tier's 2 and 3 are each more demanding in terms of complexity and data requirements.

It is possible that a mixture of tier's will be needed to complete emissions inventory, reflecting the availability of information in different parts of a country or organisation. In some cases, calculation of emissions from a single source will require use of different tier's of activity data or different tier's of activity data and emission factors combined especially when calculating supply chain, project or product emissions.

It is good practice to report tier's for all emission sources included in the inventory. In some cases where aggregate reporting is a significant goal, Country/Regional Supplements may make this a mandatory requirement. In any case, organisations should strive to utilize the highest tier of data which is available.

In most cases, FoundationFootprint™ assigns the tiers for you. For example, the default emission factors are tiered. Activity data that enters the system from invoices from your supplier are automatically tiered.

Note: Some standards and regional environmental programs recommend or insist on the use of tier's in inventories. Nevertheless, tiering gives an organisation and their stakeholders more confidence in the accuracy and validity of their GHG Inventory.

Which Tier Should I Use?

In cases when you need to specify a tier for an emission factor or activity data, the following explains which to choose:

Tier 1 Emission Factors
Tier 1 emission factors are readily available national or international factors such as those provided by the IPCC and therefore should be feasible for all countries. The use of a Tier 1 emission estimate requires the following information:

• data on the amount of fuel combusted
• a default emission factor (e.g. provided by the IPCC).

Tier 2 Emission Factors
Tier 2 standards require an intermediate level of complexity and locally specific data. Generally the use of a Tier 2 approach requires:

• data on the amount of fuel combusted
• a country-specific emission factor for each gas.

Country-specific emission factors are developed by taking into account country-specific data, such as carbon content of the fuels used, carbon oxidation factors, fuel quality and (for non-CO2 gases in particular) the state of technological development.

Tier 3 Emission Factors

Tier 3 standards are the most complex and require the most specific data. A Tier 3 approach splits the fuel combustion statistics according to the following variables and uses emission factors that are dependent upon various combinations of each:

• data on the amount of fuel combusted
• a country-specific emission factor for each gas
• combustion technology
• operating conditions
• control technology
• quality of maintenance
• age of the equipment used to burn the fuel.

Tier 1 Activity Data
Tier 1 activity data is defined as activity data which is sufficient to approximate the scale of emissions from a particular source, but which will not accurately respond to local changes in use or behavior. Tier 1 activity data should be used only in cases where more accurate data is unavailable and where the source is secondary such as with some scope 3 emissions. Examples of Tier 1 data are:

• methane recovery system effectiveness estimates based on the assumption that the system meets regulatory guidelines
• national average fuel use per customer or supplier
• national average solid waste generation per customer or supplier

Tier 2 Activity Data
Tier 2 activity data is defined as activity data which is sufficient to approximate the scale of emissions from a particular source and which will accurately respond to local changes in use or behavior. While Tier 2 data is often based on estimates or models, it is important that the sources of data adhere to a professional standard for conducting such estimates. It is also important that, wherever possible, estimation methods comply with methods used elsewhere in the organisation's planning efforts. Examples of Tier 2 data are:

• engineering estimates of energy use based on system use and design
• estimates of heating fuel use based on known historical use modified based on population changes and variations in annual temperatures (heating degree days)
• fuel use estimated from distance traveled multiplied by average fuel efficiencies
• methane recovery system effectiveness estimates based on system design
• total customer or supplier distance traveled estimates based on systematic traffic counts and road segment lengths
• local change forecasts by an approved census body
• quantity of fuel used in a year based on known price paid times average fuel cost in that year

Tier 3 Activity Data
Tier 3 activity data is defined as activity data which is sufficient for regulatory or billing purposes and which will precisely respond to local changes in use or behavior. Examples of Tier 3 data are:
• metered energy use
• metered methane recovery
• quantity of solid waste as weighed at a transfer station

NOTE: Organisations seeking to comply with ISO14064-1 should note the requirement in that standard for an uncertainty assessment to be included in an analysis of emissions. The uncertainty of an emissions analysis will clearly be affected by the Tier selection as described here.

Copyright (c) Rev-ID International Ltd