It's seven o'clock in the morning, and residents of Cartesius are starting their day. With their well-insulated and ventilated homes, they enjoy a peaceful night's rest before showering, making coffee, and turning on the lights, which creates a high demand for energy. To meet this demand, much of the electricity comes from neighborhood and home batteries, which store self-generated solar energy from the previous day. Additionally, the wind turbines on the North Sea provide energy, thanks to a brisk breeze. Meanwhile, the batteries in the shared cars are charged gradually overnight, with energy tailored to each user’s needs. This system reflects Cartesius’ commitment to sustainable energy and smart grid solutions, ensuring a clean, efficient energy supply for residents while reducing reliance on traditional power sources.

As the afternoon arrives, the wind has died down and the sun breaks through, providing a surge of solar energy. In Cartesius, not only are the roofs and facades part of the local power plant, but the sound walls throughout the area also play a role in harvesting solar energy. This energy is then stored in the batteries of cars and homes, or fed back into the grid to ensure efficient distribution. One resident, feeling cold due to a heat pump malfunction, finds that the issue is automatically detected and reported. A service technician is already on their way, and within four hours, the problem is resolved. Best of all, the resident doesn’t need to pay for the service because everyone in Cartesius has a service contract with an "energy as a service" company, involved since the area’s development. This system ensures both sustainability and peace of mind for residents, providing seamless service and support.

As the sun sets, the LED lights and induction cooktops in Cartesius homes illuminate, and elevators are used sparingly. To manage the peak in consumption, batteries are employed to neutralize the demand, while any excess energy is stored for later use. As the evening progresses, energy consumption decreases, and it’s clear that sustainable energy has been used throughout the day. Much of the energy was generated from solar power within the area, ensuring minimal reliance on external sources. Notably, the gas power plants haven’t been needed, as the community’s smart energy system is running efficiently. Residents can easily view this sustainable energy usage through the app, which provides an overview of the day’s energy consumption and highlights the success of the renewable energy model.

The lifespan of a new building is crucial, as significant resources—materials and energy—are invested in construction. Once a building is completed, making adjustments can be challenging. Therefore, creating a pleasant indoor climate is essential, ensuring that people enjoy spending time in these spaces. During the use phase, it’s equally important to minimize energy consumption, and the energy infrastructure must be designed to support a future where all energy needs are met sustainably. One key aspect of this vision is ensuring that renewable energy generated within the neighborhood is used locally, minimizing external reliance. The temporary storage of energy will play a critical role in achieving this goal, helping Cartesius become completely energy-neutral over time. By efficiently storing energy, the district can ensure that sustainable energy is used to its full potential.