Air Pollution And Its Associated Impact Continue To Hit The Headlines As We Move From One Year To Another

Varun Pahwa, President, DRI ­ Pahwa GroupWith varied expertise in the domain, Varun looks for new ways to improve energy efficiency and bringing in new technology to effectively bring better changes in the environment

For all practical purposes to-day, there is no good news about air, especially in the NCR region as AQI swings between Unhealthy and Hazardous. PM2.5, PM10, VOCs, etc. have become common terminologies, even though not understood fully.

The very BREATH we take is loaded with pollutants. While we try and protect ourselves with masks, air purifiers, etc., outdoors or at home, we often do not have control over the air we breathe in the modern climate controlled interiors-offices, malls, hospitals as well as bus stations, airports where we spend more than 80 percent of their time.

Till a few years ago the main challenge was how to maintain the air inside a conditioned room as good as the fresh air outside. The realization that indoor air was probably 10 times more polluted than outdoor air, and that in the absence of fresh air being let into a building on a regular basis resulted in built up indoor pollutants, leading to "sick building syndrome", the IAQ standard mandated more fresh air.

Thus, the MANTRA then was" Solution to Pollution is Dilution". It was important that while more fresh air was brought indoors in conditioned spaces to flush out the pollution generated inside without raising the tonnage and thus the utility/power bills.

The challenge, then for the HVAC & R designer was out to keep utility bills low while bringing in more fresh air.
Treated" fresh air meant mainly energy recovery from the conditioned air being exhausted and using the recovered energy to pre-condition the fresh air being bought in without raising the tonnage and thus, the lowering the utility bills.

Unfortunately, such is not the case now as outdoor air is highly polluted and has to be "cleaned" before being brought into conditioned space.

Enclosed conditioned spaces such as office complexes, malls, hotels, restaurants, auditoriums, and various other buildings are dealing with not only contaminants/pollutants generated indoors but also has to ensure outdoor pollution like PM2.5, PM10, VOCs as well other gaseous contaminants is not brought inside conditioned spaces through conditioning systems.

It has also become comparatively easier to manage Indoor Air Quality given the increased awareness of reducing outdoor air pollution and the emergence of cutting edge technologies to manage air quality indoors

"Now, more than ever, it is imperative to monitor and improve indoor air quality.

However, it has also become comparatively easier to manage Indoor Air Quality given the in-creased awareness of reducing outdoor air pollution and the emergence of cutting edge technologies to manage air quality indoors.

With outdoor air as input, in-door air handling systems design needed to do more than merely cooling to heating, ventilation, and air conditioning. Often known by its acronym, HVAC, it is goes beyond providing thermal comfort to ensuring acceptable indoor air quality.

The Paradigm shift "Treated" fresh air which meant mainly energy recovery for fresh air in 1997 has expanded beyond energy recovery to include humidity control as well as particulate and gas phase filtration.

Desiccant based technologies for "Treated" fresh air incorporates concepts of "divide and conquer" in HVAC system designs:

DOAS/TFA for fresh air with de-humidification

AHU for internal sensible cooling only.

As outdoor air providing fresh air becomes more polluted than indoor air to be exhausted, the dilemma has led to "beginning of the tube solutions... new innovations / technologies" where the needed fresh air is available through energy recovery plus gas phase filtration.