Influential factors on the energy efficiency of fresh air systems in nearly zero energy buildings

Abstract

Ensuring precise control of fresh air volume is crucial for minimizing energy usage in nearly zero energy buildings. Research shows that automatic pressure-independent dampers offer a promising solution for maintaining the desired fresh air volume. However, the energy performance of damper-controlled fresh air systems is influenced by multiple factors that have not been thoroughly investigated. This study focuses on examining the impact of influencing factors on the energy efficiency of fresh air systems. Laboratory experiments and field testing were conducted on a typical fresh air system. Subsequently, based on the experimental data, an energy saving model of the damper-controlled fresh air system was developed and validated. The main influencing factors were comprehensively investigated according to the energy-saving model. Results show that damper resistance is one of the main influencing factors on energy efficiency. Pressure-independent damper with a low resistance ratio of less than 48 % are recommended; When the average PM2.5 concentration increases by 1 µg/m3, the energy saving rate decreases by approximately 0.3 %, indicating that pressure-independent dampers are more suitable for use in regions with cleaner air; In the heating season, the energy saving rate increases by approximately 0.075 % when the dry bulb temperature decreases by 1 °C; In the cooling season, the energy saving rate increases by 1.19 % when the wet bulb temperature rises by 1 °C. This study contributes to the development of sustainable building practices by identifying key factors that influencing the energy usage of damper-controlled fresh air systems and further guiding the selection and utilization of pressure-independent dampers in nearly zero energy buildings.