Ventilation Performance Assessment of an Educational Building in a Hot and Humid Climate

Abstract

Air Handling Units in mechanical ventilation system possess a high degree of potential to circulate contaminants within occupied spaces of a building which often results in sick building syndrome (SBS), building related illness (BRI) and other indoor air quality (IAQ) related issues. This happens despite the expected role of ventilation systems to create a balance of thermal comfort and indoor air quality to the building occupants as well as the stored components. In the hot and humid climate mechanical ventilation systems play an important role of controlling the indoor hygrothermal conditions. Inadequate performance of the mechanical ventilation systems result in several issues ranging from human occupants discomfort, mechanical damages to archival materials and mould problem amongst others. This study presents the measurement and analysis of the mechanical ventilation systems' performance and its effect on various indoor spaces in an academic building in Malaysia. Measurement of airflow, thermal and hygric conditions of the facility together with the aero-biological sampling were executed. The ventilation performance assessment revealed that the AHU fails in its cooling and dehumidification capacities as most of the occupied zones witnessed elevated humidity and low temperature and hence poor hygrothermal performance. On the other hand, results of bio-aerosol assessment indicates that the AHU performs well in its decontamination capacities by reducing the microbial level between the AHU and the occupied zones. The dominant species of mould in the assessed spaces are Penicillium sp., Yeast, Cladosporium sp., and Chaetomium sp. with 100 % occurrence in all the assessed space. On the other hand, Black Mold, Syntalidium sp., and zygomycetes are the least species in spaces with 25 % occurrence. The presence of black mould portends a great danger to the occupants' health and therefore requires urgent attention.

Hygrothermal Performance of Building Envelopes in the Tropics Under Operative Conditions: Condensation and Mould Growth Risk Appraisal

“…In the hot and humid climate, evidence exists of linking condensation problems with the practice of running some part of the microenvironment under cooling mode while adjacent spaces are either not in operations -24hrs vs 8hrs [8,19,20] or rather being ventilated with unconditioned air by MSEF system [21]. Nevertheless, insufficient evidence exists on the building envelope thermal quality and the operative conditions over moisture related problems.…”

Moisture condensation on building envelopes in differential ventilated spaces in the tropics: quantitative assessment of influencing factors

“…This results presented in this study is part of a series of interdisciplinary research on mould growth in tropical climate building. Interested readers are directed to other companion studies for further information [32,[35][36][37][38]. Figure 1 shows a schematic of the case-studied room with the measurement locations.…”

“…Measurement positions include supply and exhaust outlets, ceiling plenum, room ambient, and corridor spaces. Further details of the air distribution systems, measuring equipment accuracy and measurement protocols are described in earlier studies by the authors [32,36,38].…”

“…Differential ventilation is adopted where building spaces are conditioned under varying profiles: some systems operate on 24-hrs basis, some on 8-hrs while others are either naturally ventilated or served with mechanical supply-exhaust fan systems with nonconditioned outdoor air. Evidence exists on linking condensation problems with the practice of running some part of the microenvironment under cooling mode while adjacent spaces are either not in operations -24hrs vs. 8hrs [29][30][31] or rather ventilated with mechanical supplyexhaust systems with unconditioned air [32] From the foregoing, there appears to be a synergistic relationship between HVAC energy consumption, building energy efficiency, insulation and above all moisture condensation problem. Although optimising insulation thickness is found to be an efficient way of providing energy savings [5,6,33], limited methods exist in the synergistic combination of insulation location (interior or exterior), insulation thickness, energy conservation and hygrothermal (moisture condensation, mould growth, etc.)…”