LED Retrofit for Indoor Lighting

Replacing incandescent, halogen, fluorescent tubes and compact fluorescent lamps with LEDs (lamps or complete luminaires).

How does converting indoor lighting to LED work?

In an LED conversion, incandescent lamps, halogen spotlights, fluorescent tubes and compact fluorescent lamps are replaced by LED lamps or complete LED luminaires. The efficiency difference is substantial: luminous efficacy in lumens per watt (lm/W) indicates how much light is produced per unit of electrical power. Incandescent lamps achieve about 10 lm/W, T8 fluorescent tubes 60, T5 tubes 90 and LEDs 100 to 180 lm/W. For the same brightness, an LED therefore needs only a fraction of the power. Technically, there are two routes: in a retrofit, the luminaire stays in place and only the lamp is replaced, for example a 35 W GU10 halogen spot with a 5 W LED spot, or a T8 tube with an LED tube. In old tube luminaires with a conventional magnetic ballast, this must be removed or bypassed, or a ballast-compatible LED tube is used. Alternatively, complete LED luminaires such as panels are installed, often under a contracting model with a maintenance package.

Which buildings benefit from LED conversion?

The measure suits practically all indoor spaces, from offices and schools through retail areas to production halls. For a retrofit, a matching lamp holder is required; for tube replacement, the ballast question must be clarified. Only areas already fitted with LED are excluded. The longer the annual operating hours, the faster the replacement pays off: residential rooms are at 800 to 1,500 h/a, offices 2,500 to 3,500, retail areas 3,500 to 5,000 and 24-hour industry over 8,000 h/a. At workplaces, the illuminance requirements of EN 12464-1 must be met, which needs to be checked during planning.

What does LED conversion actually deliver?

Lighting electricity falls by 50 to 80 %. An office building with 200 tube luminaires saves around 26,900 kWh/a and 4.2 t CO2/a when switching to LED panels. Maintenance costs also fall, because LEDs last 25,000 to 50,000 hours instead of 1,000 hours for incandescent lamps. LED tubes cost €15 to €40 each, complete LED panels €60 to €200. Payback is 2 to 5 years with a service life of 12 years, which makes LED conversion a classic quick win.

Energy carrier

Strom → Strom

Savings potential

50-80 % Beleuchtungsstrom

Worked example

An office building is fitted with 200 louvre luminaires, each with four 18 W T8 fluorescent tubes. Including the losses of the conventional ballast, each luminaire draws 80 W. The lighting runs on working days from morning until evening, 2,800 hours per year in total. The operator replaces the louvre luminaires with LED panels with a connected load of 32 W that deliver the same illuminance at the workplace. The saving is calculated from the power difference, operating hours and number of luminaires: (80 − 32) × 2,800 × 200 / 1,000 = 26,880 kWh/a. Lighting electricity therefore falls by around 26,900 kWh/a, which at 0.156 kg CO2/kWh in the Austrian electricity mix avoids roughly 4.2 t CO2 per year. On top of that, tube replacements are no longer needed over the 12-year service life of the panels.

Investment & payback

LED-Tube Retrofit: 15-40 €/Stk; komplette LED-Panel: 60-200 €/Stk · Service life: 12 a · Payback: 2-5 a

Applicability

Requirements

Exclusion criteria

Typical buildings

Frequently asked questions

How much electricity does converting to LED save?

LED conversion reduces lighting electricity by 50 to 80 %. A 35 W halogen spot is replaced by a 5 W LED, an 80 W T8 louvre luminaire by a 32 W panel. In an office building with 200 luminaires and 2,800 h/a of operation, that comes to around 26,900 kWh/a. The higher the annual operating hours, the greater the saving.

How much does an LED conversion cost in an office?

LED tubes for retrofitting cost €15 to €40 each; complete LED panels €60 to €200 each plus installation. For 200 luminaires, the investment in panels is therefore roughly between €12,000 and €40,000. With savings on electricity and maintenance, the conversion pays back in 2 to 5 years, and the service life is 12 years.

What is the difference between an LED retrofit and a complete luminaire?

In a retrofit, the existing luminaire stays in place and only the lamp is replaced, for example a T8 tube with an LED tube. This is inexpensive but requires modifications where ballasts are present. A complete luminaire such as an LED panel replaces the whole fitting, offering better light distribution, higher efficiency and usually dimming or DALI capability for later control. For existing buildings with old louvre luminaires, the panel is often the more sustainable solution.

Does the ballast have to be removed when replacing fluorescent tubes?

In luminaires with a conventional magnetic ballast, it should be removed or bypassed, otherwise it continues to consume energy and the saving is reduced. Alternatively, there are LED tubes compatible with magnetic or electronic ballasts. Which option fits depends on the existing luminaire and must be checked before replacement. With electronic ballasts, compatibility needs particularly careful clarification.

What illuminance is required at the workplace?

EN 12464-1 specifies minimum illuminance levels for indoor workplaces, typically 500 lux for office workstations with writing and screen-based tasks. During LED conversion, it must be ensured that these values are met with the new luminaires, which should be demonstrated through lighting design and a measurement after installation. Conversely, over-sizing wastes saving potential.

Related measures

Standards & sources

Metering points in the EDM Toolbox

Stromzähler Beleuchtungskreis + Lux-Sensor an typischem Arbeitsplatz validiert sowohl Einsparung als auch Beleuchtungsqualität (EN 12464). Wichtig bei Audits.

All measures