Dust accumulated fungi in air-conditioning system: Findings based on field and laboratory experiments

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Dust accumulated fungi in air-conditioning system: Findings based on field and laboratory experiments

1. Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, China 2. Faculty of Built Environment, University of New South Wales, NSW Sydney 2052, Australia 3. Institute of Building Environment and Energy, China Academy of Building Research, Beijing 100013, China

Abstract

Keywords

This study analyzes the growth and reproduction of dust accumulated fungi (DAF) in an air-

dust accumulated fungi,

conditioning system based on field measurement and molecular biology, laboratory experiment and prediction modelling. The field measurement was conducted to collect dust in filter screen,

high-throughput sequencing,

surface cooler and air supply duct of two air handling units (AHUs). The results indicate that dust

duct material,

volume and fungal number in two AHUs generally met the hygienic specification of public buildings,

orthogonal experiment,

but the cleansing did not fulfil requirements. High-throughput sequencing was conducted, revealing that the dominant fungal species were Alternaria_betae−kenyensis, Cladosporium_delicatulum, Aspergillus_sydowii, Verticillium_dahliae. Laboratory experiment was conducted to analyze the impact of several factors (e.g. growth time, temperature, relative humidity, duct material) and their combination on the DAF growth. The results indicate that fungal growth increased with time,

Research Article

Zhijian Liu1 (), Yuzhu Deng1, Shengyuan Ma1, Bao-Jie He2 (), Guoqing Cao3

air supply duct,

fungal growth prediction

Article History Received: 10 May 2020 Revised: 04 July 2020 Accepted: 16 July 2020

peaking at 4 days or 5 days. Higher relative humidity or temperature was conducive to fungal growth. The orthogonal experiment revealed that the condition of “antibacterial composite, 22 ± 1 °C and 45%–55% RH” had the strongest inhibiting impact on fungal growth. Logistic model,

© Tsinghua University Press and

Gompertz model and square-root model were further developed to predict the fungal growth under different conditions. The results show that the Logistic model had high feasibility and accuracy, the Gompertz model was feasible with lower accuracy and the square-root model was

part of Springer Nature 2020

Springer-Verlag GmbH Germany,

feasible with high accuracy. Overall, this study facilitates the understanding of the DAF growth in air-conditioning ducts, which is important for real-time prediction and timely control of the fungal contamination.

Introduction

The outbreak of coronavirus (COVID-19), as well as previous pandemic diseases (i.e. SARS, MERS), has resulted in the deadliest losses to human society. To cut off the virus transmission path, many countries have taken isolation or quarantine measures. Residents must stay the indoors and the creation of comfortable, healthy and livable indoor environments is essential. Air-conditioning (AC) system is important in optimizing indoor environments by regulating air temperature, humid