Human health risk assessment and heating, ventilation and air conditioning (HVAC) systems hygiene

• Main Author: Foo, Yongjun
• Other Authors: Chang Wei-Chung
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Environmental engineering
• Online Access: http://hdl.handle.net/10356/61165
• Institution: Nanyang Technological University

The Heating, Ventilation and Air Conditioning (HVAC) system is widely used in many industrial buildings, office buildings, schools and in residential homes. The HVAC system controls the temperature inside the building and space, which affects the physical and mental well-being of the occupants. A clean and well-maintained HVAC system is essential in providing a high standard of Indoor Air Quality (IAQ), which has a positive impact on the human health and work productivity. This report focuses on investigating the amount of dust deposition and/or indication of any mold growth in the air duct component of the HVAC system. Dust and/or mold are harmful to the human body and since there are no existing data available, this study intends to find out and collect physical evidence of dust and/or mold in the air ducts located in Nanyang Technological University (NTU). Different locations in NTU were selected and primary investigations were carried out to obtain visual evidence and determine the current conditions of the air duct. At each location, a surveillance camera attached to a monitor was inserted into the air duct via the outlet diffuser, and images were captured showing the degree of dirtiness inside the air duct. Also, to obtain further physical evidence, Magic Clean Wipes were swiped against the air ducts in a consistent approach. Thereafter, the locations were narrowed down where secondary investigations were carried out. The Air Handling Unit (AHU) or Fan Coil Unit (FCU) was inspected for any signs of dust and/or mold, where samples were collected from the Supply Air Duct (SAD), Return Air Duct (RAD) and from the air filters. Results obtained showed no concrete evidence of mold growth in the air ducts. However, the dust deposited varies at different locations. 6 parameters that may affect the amount of dust deposited are discussed and explained, to make a comparison and obtain a relationship. An important finding from this study is that the parameters affect the amount of dust deposited to different extents, and it is difficult to determine which parameter is the most important. Saying that, it is evident that there is dust deposited in the air ducts, which will only increase as time progresses, unless duct cleaning is carried out at the locations. The dust degrades the IAQ standards and has an adverse effect on the human health of the building occupants.