PART III: QUANTIFYING YOUR EMISSIONS
CHAPTER 11: SIMPLIFIED ESTIMATION METHODS (SEMS)
The rules, methodologies and standards in the GRP are designed to support complete reporting of a Member’s total GHG emissions in North America. Members must quantify emissions using the Registry-approved methodologies described in Part III, Appendix D and any relevant sector-specific protocols.11 However, The Registry understands that Members may have difficulty applying these methods to every source within the organizational boundary—either because it is not possible or not efficient to use them.
The Registry, therefore accepts emissions estimated using simplified methods in certain cases.
11.1 Simplified Estimation Methods
Members are allowed to use rough, upper-bound, Simplified Estimation Methods (SEMs) for any combination of individual emission sources (e.g., individual electricity generators, vehicles, furnaces, etc.) and/or gases, provided that the emissions from these sources and/or gases are less than or equal to five percent of the sum of reported scope 1, scope 2 and direct biogenic emissions aggregated on a CO2e basis. Once estimated, these emissions must be included in the inventory.
Members must identify emissions that have been estimated using SEMs and maintain documentation of the source and application of the SEMs used to arrive at the estimated emission for verification.
Using SEMs
The Registry does not provide a list of SEMs for Members. No list would be comprehensive in accounting for all of the possible emissions sources. Instead, Members may develop and implement SEMs as necessary and appropriate. In developing SEMs, should always use upper-bound
assumptions following the principle of conservativeness (i.e. erring on the side of overestimating rather than underestimating emissions).
Once a Member has completed an emissions inventory including simplified, upper-bound emissions estimates for a set of emission sources and/or gases, the Member does not have to re-estimate the emissions for this set of sources/gases in subsequent years unless the initial assumptions change. Instead, Members may simply report estimated emissions for each emissions year. However, if initial assumptions change, Members must recalculate simplified emissions estimates using new
assumptions.
Furthermore, if a Member finds that recalculated emissions now exceed five percent of the total scope 1, scope 2 and direct biogenic emissions, or if total entity-wide emissions decline such that the
Member’s originally estimated emissions no longer represent five percent or less of the total, the
Member must re-select the sources and/or gases included in the simplified estimation calculations such that the resulting simplified estimates will once again sum to less than five percent of total entity
emissions.
Simplified Methods and Geographic Boundaries
The five percent threshold for using SEMs refers to the sum of a Member’s total reported scope 1, scope 2 and direct biogenic emissions from all sources in North America.
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If a Member is reporting worldwide emissions, this five percent threshold must also be met in regards to reported worldwide emissions (if the Member chooses to have worldwide emissions verified) or non- North American emissions (if the Member chooses to have a non-North American report verified). See Chapter 2 for information about reporting and verifying worldwide emissions.
Selecting Sources and Gases for the Application of Simplified Estimates
The sources and gases that may be estimated using SEMs will vary from Member to Member. For example, fugitive GHG emissions may fall under the five percent threshold for some Members, but will likely exceed five percent for Members involved in the transmission and distribution of natural gas. Similarly, some Members may choose to apply SEMs for their non-CO2 GHGs, if non-CO2 emissions are less than five percent of the Member’s total emissions.
Throughout the following chapters, sources that are commonly reported using SEMs have been identified. These include CH4 and N2O emissions from ground-based vehicles and, HFC and PFC emissions from refrigeration.
Members have some discretion in identifying which emissions to estimate using SEMs. Example 11.1 provides guidance on the kinds of upper-bound methods that should be used as simplified alternatives to Registry-approved methods.
Reporting Emissions Estimated Using Simplified Methods at the Facility-Level
Members have two options when reporting emissions estimated using SEMs:
1. Emissions can be included in the facilities where the emissions occurred, either as part of the facility total or as emitting activities within facilities, or
2. Members can choose to report aggregated SEMs across facilities at the state/province, national, North American or non-North American levels as long as these emissions are reported in
facilities made up exclusively of emissions estimated using SEMs within the appropriate
geographic boundary. Emissions reported in this way can use methodologies that aggregate or extrapolate activity data across multiple facilities.
Example 11.1. Estimating Emissions Using Simplified Methods
Meridian, a hotel chain with hotels located throughout the U.S. is planning to report its GHG emissions to The Registry. Using the Registry-approved methods in Part III, Meridian has already calculated its GHG emissions for most of its sources, including:
Indirect emissions from electricity purchases
Direct emissions from fuel used in stationary combustion units
Direct emissions from courtesy vans used at some of the hotels to shuttle customers to and from local airports
Direct emissions of HFCs from the hotels’ HVAC system.
Total emissions of all GHGs from these sources are calculated as 36,472 metric tons CO2e.
There is one emissions source remaining to be quantified—the lawnmowers that are used to maintain the grounds at the hotels. There are 50 such lawnmowers in use at 47 different locations. However, only five of the hotels have kept fuel purchase records for their lawnmowers. Because data on all 50 lawnmowers are lacking, and the lawnmowers as a whole are likely to represent a very small source (less than five percent) of emissions relative to the other sources, Meridian decides to quantify emissions for one lawnmower, and multiply the result by 50 to obtain a simplified estimate of emissions for all 50 lawnmowers. Recognizing the importance of developing a conservative emissions estimate, Meridian selects the lawnmower in use at its Miami, Florida location for three reasons. First, fuel consumption data is available for this lawnmower. Second, unlike the lawnmowers at its more northerly locations, this lawnmower is in use year round, and hence its emissions tend to be relatively high. And third, the grounds at the Miami hotel are extensive, and hence more fuel is required to mow the lawn at this hotel than at most of the other hotels owned by Meridian.
Meridian calculates the emissions of the Miami lawnmower to be 0.32 metric tons CO2e. Multiplying this result by 50, total lawnmower emissions for the chain as a whole are conservatively estimated as 16 metric tons CO2e. Adding this value to the total emissions estimate for all other sources yields 36,488 metric tons CO2e. The estimated lawnmower emissions represent less than 0.05 percent of this total—well below the five percent threshold for the use of SEMs. Therefore, Meridian’s use of the SEM is allowable in this situation, and the chain reports the resulting 16-metric ton value as its estimate of emissions from its lawnmowers.