Rakesh Ranjan, Director, Zamil Air Conditioners, shares his insights on designing, installing and maintenance of HVAC system in commercial buildings

An HVAC system leads the building’s energy requirements and it consumes as much as 40% of the total energy requirement. A building should be designed with an orientation that will limit its solar gain to the minimum. Other solutions are a glass façade on the north-south face; walls with hollow fly ash blocks of autoclaved aerated; low U factors for roofs, roof thermal insulation (under or over deck with EPS), cool roof strategies, etc.

Green buildings certified by IGBC, GRIHA etc. have become differentiators for projects. High awareness of indoor air quality, PM 2.5 levels, sustainable buildings, ozone-friendly refrigerants, efficient building envelope etc. are the need of the hour. The Bureau of Energy Efficiency, Ministry of Power, GOI has been active since 2007 towards this goal and released a Energy Conservation Building code 2017 applicable for building services engineers and architects.

Rakesh Ranjan
For any building that an architect imagines and creates, there has to be a clear understanding of application, diversity of usage, and identification of areas to be air conditioned and ventilated, along with fire exigency services

Rakesh Ranjan

For designing a green building, use of IE3 motors, VFDs, efficient fans etc. as per ASHRAE 90.1 standard is prevalent in the industry. Newer energy-efficient HVAC systems like radiant cooling and displacement ventilation are slowly seeing the light of day.

For a commercial building’s HVAC, the general recommendation is with central plant and either screw or centrifugal chiller machines, depending upon capacities and energy efficiency. Biggest motors in the system are chiller machines, so, a high coefficient of performance (COPs) chillers should be selected.

A developer offers a building shell and a core air conditioning system for the tenant area. Common areas like lobbies, corridors, toilets, service areas etc. are provided with a complete HVAC system, and scope for fire emergency, for lift well, lobby, basement, and staircases, in line with the latest NBC codes and local statutory compliances. Basements are also ventilated for car parking purpose as per NBC codes. Tenants are provided air handling units but further fit-outs will be as per the interior works they want.


We need to emphasize that well-engineered layouts provide adequate access for service and maintenance of equipments. The site team must realize the importance of keeping a clean ducted system during execution by covering the duct opening. The system’s water and air balancing are key to a proper air conditioning of the building as per its design intent.

A properly maintained HVAC system by HVAC professionals will reduce stress on the system, else it can result in mechanical failures, electrical faults, and inefficient operation, all of which burn a hole in the pocket as there will be more power consumption. Regular preventive maintenance will increase the life of the equipment. Cleaning of filters is also mandatory for maintaining the desired IAQ levels of the space. However, good the HVAC system may be, if it is not properly maintained, the building owner’s investment will go to waste.