Tan­moy Kr. Choudary, R&D and tech­ni­cal man­ager at Maico Gulf, talks about good In­door Air Qual­ity prac­tices


When ex­plor­ing some of the In­door Air Qual­ity (IAQ) con­cerns in re­la­tion to HVAC sys­tems, Tan­moy Kr. Choudary, R&D and tech­ni­cal man­ager at Maico Gulf, says that we should first work with build­ing own­ers or con­sul­tants to es­tab­lish the project re­quire­ments with re­spect to IAQ re­quire­ments, such as if ASHRAE/ANSI Stan­dard 62.1-210 has enough in­for­ma­tion re­lated to IAQ.

Choudary says: “Many HVAC sys­tems are equipped with ei­ther an en­thalpy wheel or plate heat ex­changer, but the ideal sce­nario is to have ‘zero’ ex­haust air trans­fer ra­tio (EATR), which is pos­si­ble with an en­thalpy wheel through a purge sec­tor or with an in­crease in dif­fer­en­tial pres­sures be­tween sup­ply air & ex­haust air.” He lists down four ma­jor as­pects to come up with con­crete so­lu­tions for ac­cept­able IAQ:

• Var­i­ous IAQ-re­lated fac­tors can in­ter­act with other fac­tors, for ex­am­ple, re­turn air per­cent­age, out­door air qual­ity, cli­mate con­di­tion through­out the year, num­ber of oc­cu­pants etc.

• How the ven­ti­la­tion air is mixed with the cool­ing/heat­ing air? Other HVAC de­sign is­sues that may af­fect many other sys­tems in­clud­ing build­ing pres­suri­sa­tion & hu­mid­ity.

• Com­mis­sion­ing the build­ing us­ing ASHRAE guide­lines 0-2005. It should be an IAQqual­ity fo­cused process.

• For con­tin­u­ous im­prove­ments, it is rec­om­mended to have an IAQ au­dit at reg­u­lar in­ter­vals with a project to in­clude an as­sess­ment of pos­si­bil­i­ties.

He adds: “Most of the FAHU/ERV man­u­fac­turer fol­lows Eurovent EN1886 stan­dards for best leak­age and fil­ter by­pass fac­tor with Eurovent/AHRI-cer­ti­fied HRW/PHE (heat ex­changer); how­ever, with poor main­te­nance the cross con­tam­i­na­tion in­creases dras­ti­cally with an un­ac­cept­able IAQ sit­u­a­tion.

“Also, ERV/FAHUs should work si­mul­ta­ne­ously with the cool­ing/heat­ing sys­tem to han­dle de­hu­mid­i­fi­ca­tion de­sign con­di­tions, as mois­ture ac­cu­mu­la­tion in cer­tain spa­ces within the build­ing is some­times in­evitable.”

But are HVAC sys­tems op­ti­mised to strike the bal­ance be­tween pro­mot­ing good IAQ and manag­ing en­ergy costs? Choudary says that

with mul­ti­ple renowned cer­ti­fi­ca­tion au­thor­ity (Eurovent/AHRI) it is very easy to get a heat ex­changer with best ef­fec­tive­ness for re­quested sizes. The chal­lenge is to get the best IKW through the in­stalled mo­tor, which is only pos­si­ble with lower in­ter­nal pres­sure drop and op­ti­mised ex­ter­nal duct re­sis­tance. With ef­fec­tive sup­ply air and re­turn air duct lay­out we can eas­ily achieve the best op­ti­mum en­ergy con­sump­tion. But the main chal­lenge is to com­bine the MEP con­trac­tor’s de­sign with the equip­ment man­u­fac­turer’s best ap­pli­ca­ble prod­ucts.

Also, op­er­a­tion and main­te­nance train­ing must be a pri­or­ity to en­sure good health of a build­ing. He says: “Pro­vid­ing ex­tra space within the HVAC sys­tems for en­hanced fil­tra­tion usu­ally can be achieved at a very low cost and will re­sult in bet­ter IAQ and lower ROI (re­turn of in­vest­ment) and op­er­at­ing cost.”

Ac­cord­ing to Choudary, sev­eral stud­ies on Sick Build­ing Syn­drome (SBS) can be re­ferred to where we find that more than 75% of IAQ is­sues is re­lated to HVAC sys­tems.

Nu­mer­ous stud­ies place av­er­age pro­duc­tiv­ity loss due to poor IAQ be­tween 3% to 7% and in­di­vid­ual pro­duc­tiv­ity losses of 33%. The fol­low­ing check­list can be re­ferred to im­prove the prod­uct de­sign:

• In­cor­po­rate the best ef­fec­tive heat ex­changer in FAHU/ERV de­sign. A Eurovent/AHRI cer­ti­fied heat ex­changer can al­ways add value to the whole re­cov­ery per­cent­ages.

• The best fil­tra­tion stages, and lower pres­sure drop with higher ar­restance can def­i­nitely re­duce the mo­tor needs to over­come less re­sis­tance to de­liver the re­quired air­flow to the sys­tem, thereby re­duc­ing in­stalled KW (IKW) of the unit.

• The im­por­tant pa­ram­e­ter is to de­sign the low­est fil­ter leak­age fac­tor through the fil­ter frame; an ideal frame de­sign can re­duce the con­tam­i­na­tion per­cent­age dras­ti­cally.

• Unit con­struct should be re­ferred to a stan­dard, for ex­am­ple, EN1886 can be ap­plied for lower leak­age fac­tor through the cas­ing. and smoke vents prod­ucts.

Choudary says: “In ven­ti­la­tion we pro­duce the TA-HT range which is AMCA, EN12101-3 nd UL 705 listed. This is the best in FEI (fan

en­ergy in­dex) class in the re­gion.

“In air­side prod­ucts, DEV (ecol­ogy for com­mer­cial kitchen ex­haust) units are ETL listed as per UL 710, which we are the first in this re­gion to pro­mote safety stan­dards in such ap­pli­ca­tions. In smoke vents, we have two sep­a­rate range DSV (flap type) & DDSV (dou­ble door type) tested as per EN12101-2 by Ap­plus, Spain, which is DCD ap­proved. We of­fer mul­ti­ple se­lec­tions with PCA & alu­minum sheets for dif­fer­ent de­mand based ap­pli­ca­tions for cus­tomised sizes.”

Talk­ing about his com­pany’s ob­jec­tives, Choudary says: “Our en­deavor is to de­liver three new prod­ucts ev­ery year and im­prove our cur­rent prod­uct fam­i­lies with the best aero­dy­namic im­pellers, thanks to in-house CFX tools (ANSYS-CFD pack­age) that im­prove bKW of each prod­uct fam­ily, which in­di­rectly help us to re­duce the en­ergy cost of the sys­tem.”

Maico Gulf is ex­pect­ing to re­ceive an ISO/ IEC 17025 ac­cred­i­ta­tion soon. The firm is cur­rently in­volved in pro­mot­ing en­ergy-ef­fi­cient and AMCA-cer­ti­fied prod­ucts in the re­gion.

In ad­di­tion, the firm’s manag­ing di­rec­tor Amit Ahuja who cur­rently serves on the Board of Di­rec­tors AMCA In­ter­na­tional is set to be­come AMCA In­ter­na­tional’s Pres­i­dent in 2020.

Ob­jec­tives Maico Gulf is mainly into ven­ti­la­tion, air­side Pro­vid­ing ex­tra space within the HVAC sys­tems for en­hanced fil­tra­tion usu­ally can be achieved at a very low cost and will re­sult in bet­ter IAQ.″

Op­er­a­tion and main­te­nance train­ing must be a pri­or­ity to en­sure good build­ing health.

Tan­moy Kr. Choudary, R&D and tech­ni­cal man­ager at Maico Gulf.

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