# Dynamics of Changes in Climate Zones and Building Energy Demand. A Case Study in Spain
## 3 Results and Discussion
### Determination of the Dynamics of Changes in Climate Severity Indices  
Figures 3 and 4 show the results obtained from calculating the WCS and SCS indices for the years 2055 and 2085, under the RCP 4.5 and RCP 8.5 climate change scenarios at the 77 reference stations.  
For the RCP 4.5 scenario (Figure 3), it is observed that the WCS index values for 2055 range between \(-\)0.1 and 1.3, determined for the stations located in the Mediterranean coastal cities of Alicante, Barcelona, Cadiz, Castellon, Malaga, Murcia, and Valencia and the inland city of Soria, respectively. Thus, the projected emissions for this scenario mean that by mid-century, all the reference stations will be in regions with mild winters, which will lead to a drastic drop in heating consumption. It is observed that the SCS will be increasing in the first half of the 21 st century, with values ranging between 0.3 and 2.8 for the cities of Oviedo (station #49) and Cordoba (station #20). It will imply a significant increase in summer temperatures, which will drastically increase cooling consumption. However, by the climate trends projected for this scenario, a progressive stabilization of temperatures at all stations will be observed by 2085. Thus, by the end of the century, WCS values range between \(-\)0.1 and 1.3; SCS values range between 0.3 and 2.9.  
For the RCP 8.5 scenario (Figure 4), a more drastic change in WCS and SCS values is observed than in the previous scenario. Thus, the WCS index values for 2055 range from \(-\)0.1 to 1.4 and decrease until 2085, with values ranging from \(-\)0.1 to 1.1. In SCS, a progressive increase is observed until 2055, to increase dramatically until 2085, with values ranging between 0.2 and 3 and 0.5 and 3.7. It reflects by the end of the century and increases in cooling energy demands and an almost total decrease in heating energy demands in most cities of the reference seasons.  
3.1. Climate Severities for 2015-2018 and the Periods 2055 and 2085 of the RCP 4.5 and 8.5 Scenarios for 7967 Locations in Mainland Spain  
Figure 5 shows the average WCS and SCS values for 2015-2018 and 2055 and 2085 for RCP 4.5 and 8.5. Comparing the values obtained for the WCS indices with those for the 2015-2018 range (Figure 5a) shows that, for the RCP 4.5 scenario, the average value decreases considerably from 0.96 in 2015-2018 to 0.57 and 0.56 in 2055 and 2085, respectively. It is because emissions in this scenario peak around 2040 and then stabilize. In the RCP 8.5 scenario, the decrease is more significant, with average values of 0.43 and 0.28 for 2055 and 2085, respectively, due to the more abrupt character of this scenario, where the most significant changes are located to the end of the 21 st century. For both scenarios, there is a significant softening of winter temperatures [1].  
For the SCS indices, the comparison with the values obtained in the 2015-2018 interval (Figure 5b) shows that, for the RCP 4.5 scenario, the average value increases from 1.15 in 2015-2018 to 1.43 in 2055; it then stabilizes until 2085 with 1.45. In the RCP 8.5 scenario for 2055, compared to 2015-2018, a slight increase is observed with 1.43 before rising sharply to 1.93 by 2085. The most pessimistic climate change projection will lead to more noticeable temperature changes, with sweltering summers.  
Finally, it should be noted that it is not possible to compare these indices with current regulations since the CTE does not provide exact values, which leads to problems in the field of energy efficiency research and adaptation to climate change in buildings in Spain.