The evaluation and results of a thermal balance is presented for a building located at latitude 18° N, in an intercultural university community in the “Sierra de los Tuxtlas” (Tuxtlas Mountains), southeast of Mexico. The case study corresponds to the main building of the Intercultural University of Veracruz "Las Selvas" which is able to house the library, a center for learning native languages and a computing. In order to maintain thermal comfort conditions in this space, the use of an air conditioning system is required, which works at its maximum capacity, implying high consumption of electrical energy, as well as important maintenance expenses. The objective of this work was to evaluate the thermal load of the building considering the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) methodology in order to reduce the consumption of the electric energy required for the use of air conditioning, which is of vital importance in this tropical zone. In the first stage of evaluation, the following assumptions were considered: (a) the loads related to the glazed enclosures (radiation, conduction and infiltration of air), (b) the effect of the surface of the windows of the different orientations of the building and, (c) the use of solar control films to decrease heat gains. Special care was taken not to make alterations on the infrastructure of the physical space and to not compromise the external environment. In the building that was under evaluation it was found that by reducing the enveloped area of the north and south sections, heat can be minimized and the transmitted visible light required for the development of the occupants’ activities is not affected. However, if the enveloped area on the west side is modified, visible light would be compromised. The use of solar control films provides significant benefits because the heat gained by radiation can be minimized by more than 60 %, this is achieved without obstruction the view to the outside nor the visible light required by the occupants to maintain an adequate performance in the development of their activities. If these strategies are implemented, the consumption of electrical energy can be reduced considerably.