: Heating, ventilation, and air conditioning (HVAC) systems account for 40-50% of total energy consumptioninresidentialandcommercial buildings, with conventional systems operating at fixed setpoints regardless of dynamic environmental conditions.Thisinefficiency leads to excessive energy use and increased carbon emissions. This paper presents a novel smart temperatureregulationsystem that combines Phase Change Materials (PCMs) for thermal energy storage with an Arduino-based IoT controller foradaptiveclimate control. Focusing on residential buildings and classroom environments, our system integrates microencapsulatedbio-basedPCMswithin building materials, coupled with real-time environmental sensors and machine learning algorithms for predictivethermalmanagement. The prototype demonstrates a 35-45% reduction in HVAC energy consumption while maintaining optimal thermal comfort,verified through experimental testing in controlled chamber environments. The system's modular design allows for seamlessintegrationwith existing HVAC infrastructure, offering a cost-effective pathway toward sustainable building operations. Keywords: Smart Regulation, PCM, Arduino, Energy Efficiency, Temperature Sensor, HVAC Alternative