## 3 Results and Discussion
### Heatwaves and Power Peaks  
In July 2024, Southern Europe was hit by an intense and prolonged heatwave. In Croatia, daytime temperatures exceeded 30 \({}^{\circ}\)C and the peak tourist season exacerbated the already high electricity consumption. New record peak loads were set multiple times throughout the month, with an all-time record of 3381 MW occurring on 17 July 2024, at 19:30 h. Historically, peak loads in Croatia were recorded in the winter months [53]. However, starting with 2015, peak loads became more frequent in the summer months. In the last 10 years (2015-2024), the maximum annual peak load occurred in the summer (July or August) on nine instances. Figure 3 compares the daily peak load with the average daily temperature during the cooling season in Croatia, for 2015, 2019, and 2024. It can be seen that daily peak loads exhibit increasingly steeper trends over the years. In the short-term, this is a consequence of the increased demand for thermal comfort in the expanding residential and touristic sectors. In the long-term, this effect could be further aggravated by the impact of climate change, especially with longer and hotter summers.  
For ambient temperatures between 10 \({}^{\circ}\)C and 20 \({}^{\circ}\)C, the difference in daily peak loads between 2024 and 2019 is negligible. However, for ambient temperatures below 10 \({}^{\circ}\)C, which corresponds to the heating season, daily peak loads are showing an increasing trend towards lower ambient temperatures, similar to what is seen in the cooling season. Future load profiles are obtained multiplying present load patterns with a load increment factor \(F_{\text{P}}\), which is a function of the average daily temperature, as follows:  
\[P_{2030}=P_{2024}\cdot F_{\text{P}}(t_{\text{amb}}) \tag{12}\]  
\[F_{\text{P}}=0.000270962\cdot{t_{\text{amb}}}^{2}-0.00691833\cdot t_{\text{amb }}+1.05063 \tag{13}\]  
Figure 3: Relationship between daily peak loads and average daily air temperature in Croatia.  
The load increment factor \(F_{\text{P}}\) in Equation (13) is obtained by dividing the daily peak loads in 2024 with those from 2019, and for the same ambient temperatures. The load pattern obtained using Equations (12) and (13) corresponds to a near future scenario, say in 2030, when the load demand increases in the winter and summer months but remains unvaried in the intermediate seasons. For an average daily temperature of \(-10\)\({}^{\circ}\)C or \(+35\)\({}^{\circ}\)C, the load increase would be 14% in 2030, relative to 2024. Most certainly, this approach is crude and cannot capture the relationship between future load patterns and all the impacting factors. In addition to daily air temperature, future load patterns could be correlated to other weather variables (solar irradiation, air humidity, and wind speed), the day in the week, the socioeconomic activity, the population growth and urbanization rate, the electrification in the industry and transport, and climate policies and regulations. Nevertheless, the obtained load patterns can be considered as a stress test for the power system in Croatia, which will be exposed to hotter summer and the expanding building sector and will have to adapt to the increasing share of variable renewable energy.