Scope 5 GHG Resource Library Maintenance


Scope 5 makes available a broad range of resource libraries for use by Scope 5 users. In general, these libraries hold descriptions of various activities (and the units in which the corresponding activity data is expected) as well as various impacts and the conversion factors by which each impact is calculated. An important subset of these resource libraries concern Greenhouse Gas (GHG) impacts. These GHG libraries quantify GHG emissions (in the form of emissions factors) for a variety of activities.

The emissions factors provided in our GHG libraries are sourced from reputable authorities such as the GHG Protocol (a.k.a. WRI)  and The Climate Registry. Often, these authorities update their emissions factors, or recommend updates to global warming potentials (GWPs) that are incorporated into emissions factor calculations. (The following conversation discusses emissions factors but applies equally to GWPs).

A subset of Scope 5's standard GHG resource libraries is maintained by Scope 5. This means that we periodically update our libraries to reflect updates published by the authorities from which our libraries are sourced. As such, Scope 5 users can use Scope 5 to generate emissions inventories with the knowledge that the emissions factors are reputable and reasonably up-to-date. The purpose of this article is to explain our maintenance protocol and the consequences of using resources from maintained libraries.

The following table lists the standard GHG libraries that we maintain:

Scope 5 Name



Last Update from Authority


The Climate Registry


May 2019


The Greenhouse Gas Protocol/WRI


March, April 2017


Environmental Protection Agency


January 2020

WARM (v15)

Environmental Protection Agency


May 2019

ReCon (v5)

Environmental Protection Agency


October 2010

GHG Protocol GWPs

The Greenhouse Gas Protocol


June 2017

CBECS Office Buildings



CBECS: May 2016

eGRID: January 2020

TCR: May 2018

EPA Hub Tables 1-5 & 7-9

Environmental Protection Agency


March 2018  

The Last Update column indicates the date on which the source authority published their most recent update.

Please check back here at any time for status regarding maintained libraries and updates. If your organization would like to see additional resource libraries maintained by Scope 5, please contact us to discuss your needs. 

Maintenance Schedule

Scope 5's maintained libraries are updated in response to updates from the corresponding source authority. As a policy, Scope 5, reviews its libraries on a quarterly basis.  This review is two-fold; a technical review, and a review of ad-hoc communications and requests from our user community.

Our technical review amounts to monitoring communications from source authorities (EPA, WRI, etc.) and other industry leaders to identify updates. In addition, inquiries are sent periodically to the Scope 5 executive team, sales and marketing, and to Scope 5 account managers, asking for feedback from customers and other stakeholders to learn of any deficiencies or requests for new libraries. The Scope 5 library maintenance team works with Scope 5 management to decide when to add to our list of maintained libraries.

If a deficiency is found at any time, in any library, Scope 5 makes every effort to update and correct library emission factors. We strongly encourage feedback from the Scope 5 user community, as our partners in providing and maintaining a current and expansive library database.

Understanding Discrepancies

Our users benefit by using resources from our maintained libraries in that they do not need to track and update emissions factors themselves in order to produce defensible GHG emissions inventories. However, users choosing to do so must be aware of the following caveats.

The world of emissions factors is dynamic - various authorities source their emissions factors from other authorities which in turn source emissions factors from yet other authorities. Some of these authorities pick up updates from some but not all of their sources. There is no perfectly correct set of emissions factors. Our goal is to provide defensible emissions factors. Above all, we aim to be transparent regarding our emissions factors.

This means that on any given day a subset of emissions factors in the Scope 5 libraries may differ from emissions factors in a certain authority's library. Our promise to our users is that our emissions factors are equivalent to or are reasonably derived from those published by the authority (or the authority from which it drew its emissions factors) on a reasonably recent date. In addition, we show the source(s) from which our emissions factors derive, in the application (and in downloaded CSVs of each maintained resource library). Further detail is provided in the articles corresponding to each resource library in this knowledge base.

Users should consider the following dates when producing any emissions inventory:

  1. Activity Date - the date on which the emitting activity occurs (for example, the date on which a certain volume of fuel was combusted or  certain amount of electricity as used).
  2. Effective Date - the earliest activity date for which a set of emissions factors should be applied. 
  3. Publication Date - the date on which the authority publishes a certain emissions factor or an update to that emissions factor.
  4. Current date - the date on which an emissions inventory is generated.

Consider the following example. In November of 2015 (the publication date), the EPA published an update to the eGrid electricity emissions factors. This update included emissions factors with an effective date of 2012. 

So - if a user were to generate an emissions report today (2/12/2016) for 2014 electricity activity, they would be applying the 2012 emissions factors. Had the report been generated in October of 2015 (just a few months ago), they would have applied the most recent emissions factors available at that time (with an effective date of 2010). As a result, the two emissions reports would produce different numbers.

This example illustrates an important point - when using maintained libraries, users may find that emissions resulting from the same activity, change based on when a report was run. While this can be disconcerting, it is readily explained and it generally reflects improved knowledge regarding emissions factors. 

Most often, users run emissions reports early in each year, for activity that occurred in the previous calendar year. In the example above, our 2014 emissions report would probably have been run prior to November 2015 and as a result, would have used the 2010 emissions factor set. Our 2015 emissions report would be run early in 2016 and would use the 2012 emissions factor set. There would be no discrepancy with which to be concerned because each of the two reports are for emissions resulting from activity in different years.

The problem occurs when users run multiple reports over time, that quantify emissions for multiple years (often including some base year). In this case, results for the same year can differ depending on when the report was run. Users must be aware of this eventuality when conducting audits or publishing reports to their stakeholders and should be prepared to explain differences that arise from updates to emissions factors. We recommend that whenever a user runs a report intended for external consumption, they should use the CSV download link (in the top right corner of each resource library page) to record the sets of emissions factors and sources that were used to generate the report.

Wolf Lichtenstein is the Principal of Lightstone Consulting, LLC and of Evergreen Carbon, an organization dedicated to promoting sustainable development through carbon offsets. With many years of auditing Greenhouse Gas inventories and carbon offset projects, Wolf has been a technical adviser to Scope 5 since 2010. Wolf can be reached at or at


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