Energy expert Ivica Jakić warns that climate change demands a completely different approach to building design, and external brise-soleil can lower indoor temperatures by as much as eight degrees.
The increasingly frequent and intense heatwaves that have been hitting Europe, including Croatia, in recent years are no longer an exception but are becoming the new summer norm. Energy expert Ivica Jakić explained to N1 how this shift fundamentally changes the way we think about housing, with cooling soon to become more important than heating.
"Air conditioning will no longer be a matter of comfort but a necessity. In the next 20 to 30 years, cooling will be more important than heating," Jakić told N1.
Jakić points out that Europe's housing stock has been designed for decades with a focus on retaining heat during winter, while in Croatia, generally less has been invested in the energy efficiency of buildings. Western Europe, which he knows well, has spent the last 40 years directing most of its resources precisely into temperature preservation, i.e., heating buildings. "Now the technology is changing, and there is a growing demand for protection against overheating, that is, ways to prevent heat from outside from entering the space at all. The trend of so-called passive houses is growing," he explained.
The key difference from the previous approach lies in the fact that heating a space is easier than cooling it. "That's why the issue of cooling will become extremely important. You can heat more easily, but cooling is much harder," Jakić added.
Jakić demonstrated how effective sun protection can be using a project he worked on. A building with six large glass walls facing west was nearly impossible to cool when the sun shone directly on the glass in the afternoon. "We first tested internal blinds and brise-soleil, but the temperature reduction was minimal. The sun simply had to be prevented from directly entering the space," he recounted.
The solution came in the form of external rotating brise-soleil. Before installing these elements, an air conditioning unit of approximately 10 kW had to run continuously to bring the temperature down to a comfortable 26 degrees. After installing high-quality external brise-soleil, the temperature immediately dropped by eight degrees. "A passive house means you have to prevent heat from entering from the outside. You can't constantly fight from the inside against heat that has already entered. Once solar energy penetrates the glass, the space heats up, and it's very difficult to reduce that afterward," Jakić explained.
Among the solutions increasingly being applied in Europe, Jakić highlights several key trends. "Recently in Europe, so-called bioclimatic pergolas are being developed. These are pergolas placed next to houses so people can spend time outside in summer, made of high-quality materials like aluminum. They have adjustable slats that allow for regulation of shade and airflow," he said.
He also sees great potential in reflective light-colored roofs that reduce the heating of buildings, especially on upper floors where temperatures are always higher. "Light-colored roofs reflect the sun's rays and reduce the heating of the building. Another trend is green roofs, but I'm a bit cautious there because they require a lot of irrigation," he added. He also emphasizes the advantage of external blinds over shutters because they allow air circulation between the outside temperature and the glass surface, thus preventing the glass from heating up.
Jakić, who has lived in Austria for 40 years, witnesses how even countries that never needed air conditioning are now facing new challenges. "I've been living in Austria for 40 years, and air conditioners practically didn't exist there because there was no need for them. The problem is that Austrian regulations do not allow the simple installation of air conditioning units on residential buildings. You can't just put one on a window or facade," he explained. He sees district cooling systems as a solution for large residential buildings, similar to how district heating exists today.
The growing need for cooling also brings challenges in electricity supply, especially during warm nights when there is no production from solar power plants. "That's why it will be necessary to increase the capacity of battery storage for electricity. They don't create new energy, but they allow it to be shifted over time," Jakić emphasized.
When asked whether Croatia is lagging behind in adaptation, Jakić replied: "I wouldn't say Croatia is lagging. The question is how quickly permits are obtained and how long it takes to secure all the necessary documentation to start construction." He added that Croatian designers work at a world-class level, as seen in new office buildings and production halls. Nevertheless, he stresses that everything depends on the investor. "If a financially strong company is behind the project, top-tier technological solutions are applied. If the investors are citizens who lack sufficient funds, they can turn to the Environmental Protection and Energy Efficiency Fund," he concluded.
