To apply the regulation energy performance of residential buildings (REH), the Itecons offers a tool of calculus, applicable to both to new buildings as to existing buildings. This calculus sheet is prepared to do in an automatic way and always applicable, the verification of minimum energetic requirements, for the year 2013 and 2016. Even allows, likeness to the old versions, the analyze technical-economic of improvement measures. The sheet is organized to permit create, the expert report need to the energetic certification. It is even possible to garner descriptions of the constructive solutions in a data base and load, always needed, these descriptions directly in the calculus sheet. Available in: http://www.itecons.uc.pt/p3e.