## 2 Materials and Methods  
First, the MedZEB approach developed within the framework of the HAPPEN project should be explained. The MedZEB (Mediterranean Zero Energy Building) approach aims at stimulating the market uptake of energy deep and beyond retrofitting of existing buildings of the Mediterranean [18]. Its holistic nature implies the evaluation and integration of a range of relevant factors and the effective support to the retrofitting supply chain, also with the help of an ICT open platform [20]. The main features of the MedZEB approach are holistic, transparent, and adaptive, giving the possibility for a step-by-step renovation approach.  
This study calculates the total primary energy savings per year (MW/h) that could be obtained in Comunitat Valenciana region if the public residential building stock of Entitat Valenciana d'Habitatge i sol (EVha) was renovated applying Optimal Renovation Strategies through Life-Cycle Analysis. This methodology optimizes the performance of the building's envelope and its domestic hot water (DHW) and ventilation systems considering not only energy savings but also the investment and the operating costs [5].  
This methodology has been applied in four pilot buildings in Cyprus, Croatia, France, and Spain (Table 1) of four different Mediterranean countries representing the more frequent climates (W1S2, W2S2, W2S3, and W3S2) in the Mediterranean area as developed in the framework of the H2020 HAPPEN project.  
As a result, a set of 16 pre-evaluated Packages of Optimal Solutions (POS) with renovation measures were obtained, one per combination of building and climate. This set of 16 pre-evaluated POS have been called the preliminary POS (Table 2).  
It is important to clarify that each POS is defined as the whole set of solutions near to the optimal point with the minimum life cycle cost. To this end, the solutions with a LCC up to 5% higher than the minimum were determined. Then, the solutions with an increase of 5% of Primary Energy Consumption with regards to the optimal point were determined. Among these solutions, 12 were selected as the representative of the POS [5].  
Therefore, although all the solutions in the POS minimize the life cycle cost, one is the absolute minimum, and the rest are close to it. Thus, it was possible not to limit the renovation of the building to a unique set of measures, and to increase the flexibility and the degree of freedom on behalf of the architect or engineer involved in the refurbishment process.  
In order to increase the accuracy of these POS and increase their applicability, another set of 16 pre-evaluated POS have been obtained for the combination of the same climates and the buildings spinned 90\({}^{\circ}\), to have their main facades oriented in E-W instead of N-S orientations. These POS solutions have been called POSX spinned. Where the number X corresponds to the same number that the one in the Table 2 for the combination of a given building and climate.  
The 16 preliminary POS have been evaluated in 13 different climates and 42 reference buildings, providing a total of 546 cases where the POS have been proven to perform properly. In this matrix (Figure 1), each combination of reference building and representative climate is assigned with the POS that provides the best performance for the building. Therefore, each POS has been assigned with a specific colour to differentiate at a glance in the matrix the different POSs. As explained before, this is a result of the HAPPEN project developed by the authors of the article [5] and its use is explained in the case study section.  
This methodology has been implemented in an online tool [20] where the orientation of the building can be assimilated to a building with the main facades N-S or E-W oriented.