Step 1 - Lighting Audit

Before investing, audit what you have. Walk through every area and record: existing fixture type and wattage, burning hours per day per zone, measured lux levels (vs recommended levels from IS 3646), presence of daylighting (windows, skylights) that are currently unused. A proper audit typically reveals 3 types of waste: lights burning in unused areas, over-lit areas (e.g., 600 lux where 200 is sufficient), and inefficient lamp types (fluorescent, metal halide, sodium) that can be replaced with LEDs at 50–65% lower wattage.

Step 2 - LED Upgrade

Replace all fluorescent tubes with LED tubes (same fitting, direct replacement in most cases). Replace all metal halide and high-bay fixtures with LED highbay. Replace all sodium flood lights with LED flood lights. Expected energy saving: fluorescent to LED tube: 30–40% saving. Metal halide to LED highbay: 50–60% saving. Sodium flood to LED flood: 50–65% saving. For a factory running 10 hours/day, 300 days/year with 200 × 250W metal halide highbays: saving = 200 × 150W × 10h × 300 = 90,000 units/year = ₹6.3 lakh/year at ₹7/unit.

Step 3 - Occupancy and Daylight Sensors

Occupancy sensors in non-production areas: toilets, corridors, storerooms, server rooms - these areas are often lit 24/7 unnecessarily. Installing PIR sensors that dim or switch off lights after 10 minutes of no occupancy saves 30–60% in those zones. Daylight sensors near windows/skylights: dimming lights near windows when natural light is sufficient is called daylight harvesting. Modern dimmable LED drivers support 0–10V or DALI dimming. A factory with good skylights can save an additional 15–25% energy with daylight sensors.

Step 4 - Zone-Based Scheduling

Different factory zones have different operating hours. Implement zone-based switching: Production floor (main line): 6am–10pm. Loading bay: 6am–8pm. Security perimeter: dusk to dawn (solar lights recommended here). Parking: dusk to 10pm + dawn, with motion sensors. This alone can reduce lighting energy by 15–20% compared to lighting everything uniformly on a single main switch.

PAT Scheme Compliance for Large Industries

Industries covered under the Perform, Achieve and Trade (PAT) scheme under BEE (Bureau of Energy Efficiency) must meet specific energy intensity reduction targets. Lighting upgrades are one of the most cost-effective ways to earn energy savings certificates (ESCerts). Large industrial units (above 45,000 TOE - Tonnes of Oil Equivalent) should document all lighting upgrades and submit to their designated energy auditor for ESCert credit.