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Dynamically Responsive Fan-filter Unit

Technology #15263

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Tech Offer 15263N Fan Filter [PDF]

Dynamically Responsive Fan-filter Unit 

-A Haze Resilient Technology that enhances Indoor Air Quality (IAQ)during haze 

Industry Problem

* The cyclical haze episodes  in Singapore has been in the limelight ever since 2013 when the PSI level skyrocketed and hit a record high of 401 

* Particular matters which are less than 2.5 µm( PM2.5) have significantly elevated during haze episodes in both outdoor and indoor environment and are related to adverse human health effects

* The current solutions  for resisting haze are using either air-conditioning or air cleaners; which the former has the disadvantages of high capital cost, high operating cost and high energy consumption; whereas the latter faces ventilation issues and continual worsening of thermal comfort conditionsSolution


  • * A fan filter unit (FFU) was invented for removing contaminants from outdoor air and to provide adequately filtered airflow into otherwise naturally ventilated indoor environments by achieving sufficient pressurization to inhibit outdoor particulate matter infiltration, requisite ventilation for indoor environmental quality, and thermal discomfort alleviation.
  • * The present invention relates to removing particulate matter (PM) and microorganisms to mitigate against high indoor contaminant levels during haze episodes (influx of biomass and peat fires impacted PM emissions) and chronic outdoor pollution (such as those related to traffic and industries). 
  • * Clean (filtered) and pressurized air is supplied into an enclosed, but otherwise naturally ventilated indoor environment; and therefore the present invention can be applied to a range of indoor environments including homes, schools, hostels and hospitals. 
  • * Two types of FFU are designed: 1) Draw through: one or more filters and associated housing are provided in the rear of the fan in the fan chamber; 2) Push through:  one or more filters and associated housing are provided at the front of the fan in the fan chamber. 

Figure 1. Schematic of Fan Filter Unit showing Draw Through FFU and component parts

Value Proposition

  • * Achieve desired volumetric flow rate without compromise to filtration efficiency
  • * Alleviating adverse degradation of thermal comfort conditions in enclosed premises
  • * Effective low energy solutions based on pressurization control, ventilation, effective filtration and heat and moisture removal


Applied to naturally ventilated residential premises, hospitals, classrooms, laboratories, hostels

For more information, contact: 

NUS Industry Liaison Office       :+65 6516 6279       :       :

PI’s contact:Assoc. Prof Tham Kok WaiEmail: