Alternatively, Parties may use national emission models or continuous emission measurement of CH₄ and N₂O. This is consistent with good practice, but in most cases continuous emission measurements are not justified because the high cost of the measurements.

It is good practice to use the most disaggregated technology-specific and country-specific emission factors available, particularly those derived from direct measurements for stationary combustion sources. Using a Tier 2 method, there are three possible types of emission factors:

• National emission factors
• Regional emission factors
• IPCC default emission factors, provided that a careful review of the applicability of these factors to the country’s conditions has been made. IPCC default factors may be used when no other information is available.