# 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
#### 3.3.2. Proposed Update of Climate Zones for Peninsular Spain  
Once the WCS and SCS of the 7967 localities for the period 2015-2018 and the RCP 4.8 and 8.5 scenarios have been obtained, based on Table 1, the new climate zones of the 7967 localities of peninsular Spain have been obtained. Figure 6 shows the geographical distribution of the CTE climate zones for 2015-2018 and the RCP 4.5 and 8.5 scenarios. To analyze the variation of the climate rating observed concerning the CTE, Table 3 shows the percentage of cities that vary this rating, while Table 4 shows the percentage of climate zones in the CTE in the period 2015-2018 and the RCP 4.5 and 8.5 scenarios. The results obtained are discussed below. Proposed Update of Climate Zones for Peninsular Spain for the Period 2015-2018  
Concerning the CTE in 2015-2018 (Table 3), more than 80% of the cities have already changed their climate zone (winter + summer). Moreover, this change has meant that the number of climate zones in the country has increased from the 12 contemplated in the CTE to 19, with seven new zones appearing that were not previously re-categorized (\(\alpha\)3, \(\alpha\)4, B1, B2, D4, E1, and E2) (Table 4). The appearance of zones \(\alpha\)3 and \(\alpha\)4 should be highlighted, highlighting the trend, in areas such as the Mediterranean, towards climates more characteristic of subtropical zones. In the case of winter, approximately half of the cities have changed their winter climate zone to a warmer zone compared to the CTE (Table 3), although the most significant changes occur in the south and on the Mediterranean coast, while the climate zones in the north, northwest, southwest, and eastern part of Andalusia remain unchanged (Figure 6a,b). The winter climate zone D (Table 4) stands out, present in 49% of the localities, making it the predominant one. This result shows a rise in winter temperatures in almost half of the territory concerning what is contemplated in the current regulations. The average increase in temperatures is causing a decrease in the energy demand for heating but implies that the limits of parameters such as transmittance are compromised. In summer climate zones, more drastic changes are observed, especially on the Mediterranean coast (Figure 6a,b), due to the intense summer warming of the Mediterranean inland waters in recent years [59]. Thus for 2015-2018, 72% of cities have changed their summer CZs to warmer ones than those reported in the CTE (Table 3). Specifically, 58.7% and 12.2% of localities have changed their summer CZ to 1 and 2 warmer ratings, respectively. Climate zones 3 and 4 are the most predominant present in 38.21% and 29.35% of the localities (Table 4). Proposed Climate Zones for Peninsular Spain for the RCP 4.5 Scenario Projections  
Under the RCP 4.5 scenario (Table 3) for 2055 and 2085, 98% of the cities will see their climate zone (winter + summer) change concerning the CTE. Furthermore, Figure 6c,d shows how the geographical distribution of climate zones for 2085 resembles the resulting distribution for 2055. These climate zone changes are a consequence of the closeness of absolute values of WCS and SCS to the limiting value of climate zone delimitation (Table 1) so that a minimal change of the index can lead to a change of climate zone for a locality. This result is a limiting factor in the zoning of the existing CTE, reinterpreting the need for a significant improvement in the development and methodology of the current regulations in force. As shown in Figure 6c,d, by 2055 and 2085, half of the Mediterranean coastal localities will fall into climate zone A4. These regions will be characterized by hotter summers and warmer winters, while the northern coastal cities will have a greater variety of climate zones over the century, with mild summer temperatures and colder winters. The same occurs in the peninsula's interior, where a heterogeneous distribution is observed due to the complexity of the relief and the diversity of mesoclimatic and microclimatic zones.