Mixed-Mode Ventilation Based on Adjustable Air Velocity for Energy Benefits in Residential Buildings

Abstract

Energy efficiency and air quality in residential buildings have aroused intensive interest. Generally speaking, the heating, ventilation and air conditioning (HVAC) system is widely used to regulate indoor environmental spaces. Meanwhile, mixed-mode ventilation has been proven to reduce energy consumption and introduce fresh air effectively. This study aims to discuss the correlations between air velocity, temperature and indoor thermal comfort and establish corresponding statistical models based on the ASHRAE_db II database and the Predicted Mean Vote (PMV). On this basis, the air-velocity adjustment strategy, including determining adjustability and establishing adjustable intervals, is optimized based on support vector machine and envelope curve methods. The results show that the recognition accuracy of the adjustability determination model is over 98%, and the air-velocity adjustable interval in the envelope is increased, facilitating control of mixed-mode ventilation. The case shows that interval adjustment increases the sample points by 18.6% (18.1% above 20 °C and 4.5% above 28 °C). Therefore, further research can be supported on improving thermal comfort by air-velocity adjustment to take advantage of the mixed-mode ventilation mode, which is beneficial to building energy efficiency.