*Emissions* [*gCO*2-*e*] = *Activity Data* × *Emission Factor*

The activity data may be the mass of material, consumptions or other methods to evaluate each item. Data have to be configured according to the use conditions, such as the chapter it affects, type of impact, units or year of calculation. It takes into account not only the GHGs emitted, but also the GHG sink effect—e.g., gas absorption due to own, promoted or managed forested areas by the university—when present.

However, the CF of a facility (building, school, hotel, etc.), service or product provides necessary but not sufficient information to determine the efficiency against GHG emissions. In an increasingly demanding society in terms of knowledge about the carbon footprint produced by services or products consumed and the impact this has on global warming, the education sector can be a driving force in responding to this demand. One of the objectives of this methodology is to define parameters of comparability, not only for an installation or product over time, but on a comparative level between similar ones in such a way that it facilitates decision-making on the choice of study centers as well as contributing to the reduction in these effects. The following activity rates are proposed for weighting CF, depending on the number of users, hours of use and surface area in order to facilitate the comprehension of the client's or user's contribution to GHG emissions: kgCO2-e/m2, kgCO2-e/student or kgCO2-e/student·hour [30–33]. The use of the kgCO2-e per student assessment is justified as it is an objective measure for comparison and will serve as a verification ratio of the improvements adopted.

BookFeel is structured on different levels for the scenario configuration:

• SCOPE STRUCTURE—this describes a hierarchical set of chapters that groups the different emission sources, according to each protocol, structured in three levels [28,34,35]: Scope 1, combustion direct emissions—changes in land use . . . ; Scope 2, indirect energy emissions—main electric power purchased;

Scope 3, other indirect emissions—footprint acquired with purchased products, services or waste generated by the activity.

Each chapter is associated with an algorithm that must be configured according to its scope of application.

• Analytic structure—in a corporate footprint, this could be constituted by the production centers, and these by sections or departments.

Table 1 give an example of BookFeel calculation factors, algorithms, conversion factors and sources. All data, factors and algorithms sources and URLs are explicitly referenced.

**Table 1.** Examples of algorithms and emission factors.

