## 2 Materials and Methods
### HULC and CE3x Software  
The Spanish ministries of industry, energy and tourism, together with the Spanish Ministry of Development, has delegated the task of making available to the public valid methodologies for the energy efficiency rating of buildings to the Institute for the Diversification and Energy Saving (IDEA [16]). In consequence, to model buildings based on the result of the application of R.D. 235/2013, the following programs are currently recognized:  
* Lider Calener 2013 unified tool (HULC);
* CYPETHERM HE Plus by CYPE Ingenieros [17];
* SG SAVE;
* CE3x SOFTWARE [18];
* The CERMA computer program [19].  
The first one and the most recognized, is the Lider Calener unified tool [20] is a software developed by the Spanish Ministry of Industry, Energy and Tourism. It brings together in one application the Lider and Calener Vyp tools, which were previously developed by a research group from the department of Thermotechnology of the University of Seville belonging to the Andalusian Association for Research and Industrial Cooperation (AICIA, Sevilla, Spain). The tool complies with the provisions of article 4.1 of the Spanish R.D. 235/2013 [21] being the procedure for the energy efficiency rating of a building in Spain. It employs as calculation engine ESTO 2 based on DOE2 developed by the US Department of Energy as the calculation engine. This software was updated in accordance with the energy certification methodology in Spain and has incorporated the latest modifications to the technical building code in the field of energy demand (basic document HE0 [22]) and latest modifications of the regulation of thermal installations in buildings (RITE [23]).  
The Lider Calener unified tool is analogous to the CE3X software which was developed by Efinovatic and the Spanish National Centre for Renewable Energies (CENER [8]) and was validated by its own Ministry of Building. In particular, CE3X is another simplified energy rating procedure for existing and new construction buildings, but it presents a new advantage respect other existing software resources due to it generates an economical investment as output report. What is more, this is the more used Spanish software by architects due to the reduce time to introduce the information and get the simulation results.  
It is worth noting that this software approaches its simulations to the building objective of study by means of global dimensionless variables and a statistical adjustment [24] respect to buildings simulated previously with the old Calener Vyp, as it is represented in Figure 1. This fact supposes that the CE3X software does not analyze the dynamics of the target building but adjusts the dynamics of a simulated-type building in the provincial capitals with reference software.  
In order to use these tools to reach the objective of building energy analysis, an initial problem of entering input data were found. Particularly, in all of them, since modifying a single input parameter requires generating a new project before proceeding to start the calculation engine to analyze the results. To solve this problem, present study shows a new methodology based on modeling the building's energy consumption in spreadsheets using ISO 13790 after being validated by CE3X [25] software results.