In the context of energy-efficient and sustainable building practices, decentralized ventilation units have become increasingly popular. These units offer fresh air supply while recovering heat from exhaust air, enhancing thermal comfort and reducing energy consumption. However, they are subjected to changing affecting forces caused by the pressure difference and wind. This influence is not deeply studied in existing research. This study focuses on pressure differences' influence on airflow, heat recovery efficiency, and acoustic performance of a decentralized ventilation device. Understanding this correlation is vital for occupant comfort and environmental sustainability. The research was conducted in a controlled climatic chamber, replicating external conditions. The main objectives included airflow, heat recovery efficiency, and acoustic performance. Findings showed airflow significantly affected by pressure differences, with extract cycle reductions up to 20 m³/h at Δ30 Pa. Supply cycle airflow moderately increased with pressure differences, maintaining balanced volumes. Heat recovery correlated directly with pressure difference, reaching approximately 96% efficiency at 0 Pa, which is similar to the one stated by the manufacturer, but declining to 76% at Δ30 Pa. The results show that such a ventilation system will serve mostly as an air supply at higher pressure differences and during wintertime in colder climates can lead to cold draught and complaints from users even leading to shutting off the devices This research contributes to improving ventilation device design for more effective and sustainable building practices.