Comparative study of purifications technologies and their application to HVAC systems

Nowadays, there is a growing demand to guarantee indoor air quality in buildings. This study presents a solution that combines hygrothermal control and purification of the air supplied to occupied spaces, in which the control and purification system is integrated into the air distribution ductwork. Among all the air purification technologies, not all of them are suitable to be used in the residential and tertiary sector along with already installed HVAC systems. In this study, a review of the state of the art of technologies is made and the major purification techniques are analysed and compared, i.e., negative ionization, ozone, ultraviolet light, photocatalytic oxidation, and high-efficiency filtration. The comparison is focused on key aspects such as the use with occupation, whether there is a biocide or not, whether it can be used with HVAC units, costs, and maintenance. Finally, an effective and viable purification solution for HVAC systems is presented. It consists of a compact device based on the ionization technology. An ionizer device is placed in the air in-take of ducted HVAC units that is capable of remotely controlling the main operating parameters of the HVAC equipment (switching on and off, operating mode, fan speed, and setpoint temperature) while reducing the suspension time of fine particles in the air. Various studies carried out in Airzone laboratories have empirically shown that the use of this device results in a 47% reduction in the maximum concentration of particulate matter of 2.5 µm or PM2.5 and up to a 55% reduction of the time these particles are suspended in the air