## 2 Methods
### Case Study  
The building 'IndUVa' (Figure 1), classified as a near-Zero Energy Building (nZEB) and situated in Valladolid, Spain (continental climate), has achieved a 5 GREEN LEAVES certification during its design phase. This represents the highest level of sustainability certification available in Spain. Furthermore, the project is aiming to secure LEED PLATINUM certification, a globally recognized standard for sustainable buildings. The IndUVa building (nZEB) encompasses a total built area of 5846 m\({}^{2}\) distributed across six floors, with a usable area of 5539.7 m\({}^{2}\). It operates year-round from Monday to Friday between 8:00 a.m. and 10:00 p.m., except during the summer months of July and August. This innovative structure integrates a hybrid approach combining passive and active technologies, renewable energy sources, advanced demand management strategies, and cutting-edge passive design solutions to optimize environmental performance. The architectural design minimizes the external surface area, thereby reducing thermal losses and enhancing solar energy utilization. Natural daylight is maximized through glazed facades on the northeast and southwest orientations, complemented by a Parans fiber-optic system that captures sunlight from the roof and channels it into interior spaces. High-efficiency LED lighting, controlled via DALI-based sensors, ensures optimal energy performance and uniform illumination throughout the building. A strategically designed high-performance building envelope significantly reduces energy consumption. The thermal transmittance coefficients for key elements are U = 0.16 W/m\({}^{2}\)K for facades, U = 0.15 W/m\({}^{2}\)K for green roofs, and U = 1.10 W/m\({}^{2}\)K for windows, incorporating low-emissivity and low-transmittance glazing to minimize energy demand. The building achieves substantial reductions in non-renewable primary energy consumption compared to the baseline requirements of the Spanish Building Technical Code (CTE), with savings of 90% for heating, 85% for cooling, and 75% for lighting. These efficiencies are further enhanced through renewable energy integration and advanced building management systems. Figure 1: IndUVa building. The IndUVa building incorporates a range of renewable energy systems to meet its energy demands while significantly reducing consumption and greenhouse gas emissions. One of the key systems implemented is geothermal energy through Earth-to-Air Heat Exchangers (EAHX). These exchangers contribute to the building's ventilation and air-conditioning needs, resulting in an annual reduction of 29,654 kWh in HVAC energy consumption. Specifically, this includes savings of 17,136 kWh for cooling and 12,518 kWh for heating, highlighting the system's efficiency in managing indoor climate control. Moreover, the building is connected to the University of Valladolid's biomass district heating network. This connection supplies an equivalent of 251,930 kWh of renewable thermal energy annually, providing a sustainable and reliable source of heating. The integration of this system supports the building's low-carbon objectives, and it also enhances its energy independence by leveraging locally available renewable resources. Photovoltaic technology is another cornerstone of the building's renewable energy strategy. The southeast facade features 272 vertically installed photovoltaic panels that collectively generate 12,997 kWh of electricity each year. This system contributes to a reduction in non-renewable primary energy consumption by more than 10%, aligning with global sustainability targets. The building employs sophisticated automation and monitoring technologies to optimize energy use. Each classroom is equipped with CO2 and temperature sensors to regulate ventilation demand dynamically. The SCADA (Supervisory Control and Data Acquisition) system integrates with the heat recovery units (EAHX) and the enthalpy rotary heat exchanger, automating ventilation processes while incorporating free cooling strategies.