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 IAQ-quality 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.
Maico Gulf is mainly into ventilation, airside 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.