The recent introduction of a building-energy efficiency code in Mexico limiting the heat gain through a building's envelope has created an opportunity for transforming existing construction schemes and reduce-energy consumption in air-conditioned buildings. In this work, an exhaustive discussion of this code is presented, including a discussion of the possible motivation for the code's requirements from a third-party perspective and a critical analysis of the possible impact of the norm. A comparison with the building-envelope part of the 2001 California Energy Standards is conducted and some conclusions are presented. Fields of opportunities for future amendments are discussed, including the necessity of limiting the cooling/heating load due to infiltration. (C) 2003 Elsevier Ltd. All rights reserved.