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Safe guarding indoor air quality

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Perhaps no facility has as vast an indoor area used by as many people as an airport terminal is by travelers. Edward D’Souza, President, ServiceMASTER India and subject matter expert Prem Prakash write about how they track and safeguard Indoor Air Quality (IAQ) in large facilities like airports.

Monitoring IAQ

Smart sensors and AI for IAQ monitoring: We use different kinds of smart sensors to monitor real-time IAQ parameters, which are plotted with alerts through a mobile-based app for easy reference and awareness. This helps us plan early remedial actions to avoid adverse/prolonged effects of poor IAQ. Actions like auto start of exhaust fan, controlling fresh air requirements and maintaining the level of oxygen at working floors can all be configured through this IoT-based application.

Observing foul odour on the working floor under HVAC: The team is trained to detect these. Odours persistent for a longer period indicate some deterioration in air quality due to some biological presence.

Observing excessive biofilm generation over AHU coil surface: During routine checks and daily working inspection. This means the quality of air is being compromised and we need to control the source of dust.

Observing condition and cleanliness of Air Diffuser on working floor: If the team finds excessive dust deposition on the air diffuser and if it needs frequent cleaning, the IAQ is understood to be compromised.

Employee feedback on heavy air and respiratory discomfort at work: If there is common feedback about discomfort/fatigue while breathing, air quality needs to be checked.

Excessive dust on Furniture/Floor: If we observe this, it means the filter section of AHU or fresh air damper filter, or an Air curtain is underperforming.

Maintaining IAQ

 UVGI treatment

  • Installing UVGI coil at AHU between coil and blower, to disinfect the air at source.
  • Installing UVGI coil in HVAC duct to disinfect bacteria/viruses in the flowing air stream.
  • Upper Room UVGI in an occupied area/room: Above 7.5 feet height, to treat airborne contaminants; the air remains free of bacteria/viruses and other microorganisms.
  • By UVGI Mobile UV Tower for surface disinfection: Useful where normal spray, chemical, water etc cannot be used for disinfection, like in pantry and washrooms for frequent disinfection
  • UV wall mounted air disinfection: Disinfects the moving air stream through UV.

Ozone treatment

Ozone interferes with cell metabolism of microorganisms, disrupts their multiplication process and achieves total deactivation and hence, elimination. Being a very strong oxidant, ozone oxidizes almost all Volatile Organic Compounds (VOCs) and odour causing compounds. With ozone, the demand for fresh air reduces dramatically. It is very effective in disinfecting surfaces/ furniture/equipment etc.,  reducing chances of surface contamination.

Photo Hydro Ionization (PHIO)

Ozone and hydrogen-based oxidizers are created by exposing activated oxygen molecules to a hydrated catalyst containing four unique metals and 300 nm UV light (photon energy). These friendly oxidizers are Ozonide ions, Super Oxide ions, Hydro-peroxides and Hydroxides.

Night Purging

 Cools the inside environment by pushing early morning cold air in the premises. Removes the stale air with contaminants and purges indoor air, as per ASHRAE guidelines

Demand Control Ventilation

  •  Ensures ventilation norms are followed, as per ASHRAE guidelines
  • Intelligently control inoculation of fresh air.
  • Energy recovery by passing stale air through an energy exchanger.
  • Fresh air is infused through a separate chamber in the energy exchanger (recovering 70-89% of energy).

Challenges in maintaining HVAC system

  • Energy consumption: Almost 60-70% of the energy is consumed by the HVAC system while it operates to meet the required air cooling and working comfort level.
  • 100% up time: Almost 100% redundancy is not planned for an HVAC system; this becomes a reason for its criticality.
  • Water scarcity and water dependency: Continuous supply of water to maintain the cooling tower and HVAC operations, and recycling of used water to another area is a challenge.
  • High Maintenance Cost: Every person per hour cost of treated air is a cost to the company, which includes the cost of maintaining the HVAC equipment.
  • AHU filter cleaning and replacement: To maintain air quality standards, the air filter must always be kept clean and be replaced once beyond the scope of cleaning. If the filter is not cleaned, there will be development of negative pressure and the absence of air volume, which will add to the load on the blower and compressor to meet the air demand on the working floor.

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