DG Set Acoustic Enclosures in India: CPCB Compliance & Costs

Understanding CPCB Noise Norms for DG Sets

As per the latest CPCB guidelines, the maximum permissible sound pressure level for new diesel generator sets with up to 1000 KVA capacity is 75 dB(A) measured at a distance of 1 meter from the enclosure surface.

To drop the noise from a raw engine output of 105 dB down to 75 dB requires a massive 30 dB insertion loss, which can only be achieved using heavy-gauge steel, high-density acoustic insulation, and specialized ventilation baffles.

The Anatomy of a DG Set Enclosure

A compliant acoustic enclosure is constructed using 1.6mm to 2mm thick CRCA (Cold Rolled Close Annealed) steel sheets. The inner cavity is packed with 50mm to 100mm thick Rockwool (minimum 96 kg/m³ density) or fiberglass, wrapped in acoustic tissue, and protected by an inner layer of perforated galvanized steel sheet.

To prevent the heavy mechanical vibration of the engine from transferring to the ground (which causes structural flanking noise), the engine and alternator are mounted on heavy-duty anti-vibration mounts (AVMs) or ribbed neoprene pads.

Acoustic Louvers and Exhaust Silencers

The biggest challenge in enclosing a generator is cooling. A DG set requires massive amounts of fresh air for combustion and radiator cooling. You cannot simply seal it in a steel box, or the engine will melt.

To allow air in while keeping noise out, enclosures use 'Acoustic Louvers' or splitters—aerodynamically designed baffles lined with Rockwool that force sound waves to bounce and dissipate while air flows freely. Furthermore, a hospital-grade exhaust silencer (muffler) must be installed on the exhaust pipe to mitigate low-frequency exhaust booming.

2026 Costs for DG Set Enclosures in India

The cost of a custom acoustic enclosure depends heavily on the KVA rating of the generator (which dictates the physical size of the canopy):

• Small DG Sets (15 KVA to 62.5 KVA): ₹60,000 to ₹1,20,000.

• Medium DG Sets (125 KVA to 250 KVA): ₹1,50,000 to ₹2,80,000.

• Large Commercial DG Sets (500 KVA to 1000 KVA): ₹4,00,000 to ₹8,50,000+.

For DG sets placed in basements, specialized acoustic treatment of the entire generator room (using acoustic wall cladding and massive fresh-air intake attenuators) is required, typically costing ₹500 to ₹900 per sq. ft.

Frequently Asked Questions