Calculating LED energy savings vs T8 fluorescent in commercial refrigeration

The energy-savings case for LED versus T8 fluorescent is well-known but rarely properly calculated for refrigeration applications specifically. The headline numbers — "LED uses 50% less power" — undersell the actual savings, because they ignore the secondary refrigeration load that fluorescent fixtures impose. This article works through the maths for a single supermarket aisle.

Direct lighting energy: T8 vs LED

A standard 1200mm T8 fluorescent tube draws around 36W for the lamp itself, plus 5–8W for the magnetic ballast (older fixtures) or 2–4W for an electronic ballast. Total system draw per fixture: typically 40–44W.

A modern 1200mm LED bar at equivalent or higher light output draws around 9–14W depending on configuration. Take the CAPST SLK-VL/R 1500mm at 9.2W, or the SLK-VC 1500mm at 18.3W for higher-output configurations.

For a fair comparison, take a refrigerated multi-deck cabinet with 12 vertical fluorescent positions, each fitted with a 1200mm T8 and ballast:

• T8 fixture load: 12 × 42W = 504W per cabinet
• LED equivalent load (SLK-VL/R 9.2W): 12 × 9.2W = 110W per cabinet
• Direct savings: 504 − 110 = 394W per cabinet (78% reduction)

For a typical Bangkok supermarket with 24 multi-deck cabinets in the chilled aisle, that's 9.5kW continuously of installed lighting load eliminated.

Annualised energy savings

Refrigerated retail lighting runs effectively 24/7 — display cabinets stay lit during operating hours, and LED is left on overnight in many supermarket formats for security and stocking. Conservative annual operating hours: 16 × 365 = 5,840 hours.

Direct annual energy savings for the 24-cabinet aisle:

9.5 kW × 5,840 h = 55,480 kWh/year

At a Thai commercial electricity tariff of THB 4.20/kWh (mid-2025 reference), that's THB 233,000/year in direct lighting energy alone.

The secondary refrigeration saving — the bigger number

This is where most LED energy comparisons stop. The actual saving is larger, because every watt of waste heat from a fluorescent fixture inside a refrigerated cabinet has to be removed by the compressor.

Fluorescent fixtures convert roughly 80% of their input power into heat. LEDs convert about 40-50% to heat (and most of it is dissipated forward, away from the cabinet interior). The thermal load that the refrigeration system has to remove drops correspondingly.

For each watt of waste heat avoided inside a refrigerated cabinet, the refrigeration system saves roughly 0.3–0.4 watts of compressor work (the figure varies with cabinet temperature and ambient conditions; this is a conservative ratio).

Combined annual saving for the 24-cabinet aisle: THB 287,000/year — direct lighting plus secondary refrigeration.

Payback period

A typical retrofit cost for the same aisle (24 cabinets × 12 LED bars per cabinet = 288 bars, plus drivers and labour) runs in the THB 350,000 – 500,000 range depending on bar specification, optic grade (CRI 80 vs 90), and labour scope. With combined savings of THB 287,000/year:

• Low end (THB 350,000 retrofit): payback ≈ 1.2 years
• High end (THB 500,000 retrofit): payback ≈ 1.7 years

Beyond the payback, the LED installation continues to save THB 287,000+ annually for its lifetime — typically 50,000 hours, which at the operating profile above is 8.5 years of effectively free saving.

Other operational savings often missed

Two more savings rarely make it into the spreadsheet but show up in operating cost over time:

• Reduced lamp replacement labour. T8 tubes typically run 8,000–12,000 hours before replacement. LED bars run 50,000+ hours. Over an 8-year window, the same fixture position requires four to six fluorescent tube replacements versus zero LED replacements. Labour, parts, and operational disruption all drop accordingly.
• Reduced refrigeration system stress. Lower thermal load translates into fewer compressor cycles and less wear on the refrigeration system. Maintenance intervals lengthen; equipment lifetime improves.

Where the numbers can shift

The arithmetic above is a base case. Specific projects move along three axes:

• Operating hours. Stores running 24/7 (convenience formats) gain proportionally more; stores running 12 hours per day gain less.
• Tariff. Higher commercial rates (over THB 5/kWh in some districts) push the savings figure up; lower rates pull it down.
• Cabinet temperature. Freezer cabinets gain more from the secondary refrigeration saving than chillers — the COP of refrigeration drops at lower temperatures, so each watt of avoided heat saves more compressor work.

For a project-specific calculation tied to your actual cabinet count, operating hours, and electricity tariff, our specialists can put together a savings forecast as part of the quotation. Share your aisle count and we'll model the annual delta before you commit.