Review of Parametric Studies for Optimizing Laboratory Ventilation

Yueyang He, Building Department, National University of Singapore
Daniel Jun Chung Hii, School of Design & Environment, National University of Singapore

In Singapore, according to the statistics of Building and Construction Authority (2018), office buildings consume 140 to 420 kWh/m2/year and laboratories can achieve up to 100 times more energy usage. This is because typical offices require fresh air of around 1 air change per hour (ACH) while laboratories often require 100% outdoor air at 6 to 12 ACH. Even worse, many local laboratories arbitrarily set outdoor air to 15 to 25 ACH. It is understandable that sufficient ventilation is absolutely critical for ensuring the safety of laboratories with toxic chemicals. However, without understanding the potential effects of influential parameters on laboratory ventilation, high ACH may tremendously waste energy and yet remove pollutants inefficiently. For instance, according to previous studies, after 12 ACH, there is lack of impact according to Klein et al., 2009 while Yale research indicates the range of 6-8 ACH show significant impact. Another issue is regarding the minimum requirements of face velocity of fume hood. It is reported that a face velocity of 0.41 m/s is sufficient when occupancy is high and experimental activities require movement while 0.31 m/s is enough for unoccupied periods. This means a fixed high ACH value for all laboratories is not practical.

This review aims to collect the technical standards related to laboratory ventilation; then it aims to summarize the key findings of parameters studies for optimizing the laboratories ventilation; furthermore, this review aims to provide experience to develop appropriate laboratory ventilation strategies in Singapore by considering both energy efficiency and user safety. There are many parameters that affect the flow pattern and ventilation rate in the indoor laboratory environments. Based on the study objects, these parameters can be roughly classified into four groups, namely, parameters of general ventilation system, local ventilation system, heat source/s, and pollutant source/s. Initial findings are summarized as following: 1) the current laboratory ventilation standards tends to withdraw those unified minimum requirements and encourage laboratories to implement ventilation strategies on a case-by-case basis; 2) ACH significantly affects laboratory ventilation, but their correlations are not linear; and 3) flow pattern can be a key determinant factor for ventilation conditions, especially when the local ventilation system is complex. In other words, the relative positions among diffusers, exhausts, pollutant sources, and occupants are crucial for optimizing the laboratory ventilation. The study will eventually help prioritize which parameter/s will impact the ventilation rate the most and yet maintain the acceptable exposure risk.

Learning Objectives

  • This study aims to collect the technical standards related to laboratory ventilation;
  • This study aims to summarize the key findings of parameters studies for optimizing the laboratories ventilation;
  • This study aims to help prioritize which parameter/s will impact the ventilation rate the most and yet maintain the acceptable exposure risk; and
  • This study aims to provide experience to develop appropriate laboratory ventilation strategies in Singapore by considering both energy efficiency and user safety.

Biographies:

Yueyang He is a doctoral researcher at Department of Building, National University of Singapore (NUS). His research interests cover both indoor and outdoor computational fluid dynamics (CFD) simulations. Currently, he is involved in a research project, which attempts to explore the optimum lab ventilation rate for energy efficiency and chemical contaminant exposure risk in NUS.

Daniel Hii is a graduate of School of Design & Environment, National University of Singapore, with the research interest in harnessing environmental simulation and 3D visualization to solve issues related to the urban and built environment. These pertinent issues involved heat and air pollutants and thermal comfort. All these issues become more critical as we face a future with more ageing population and increasingly hotter climate. He also did extensive indoor and outdoor site measurements.

 

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