The debate between LED and fluorescent lighting in commercial buildings has been settled by the data for some time, but many London offices are still running T8 or T5 fluorescent tubes installed a decade or more ago. In this guide we break down the key differences across every dimension that matters to a business owner or facilities manager: energy consumption, lamp life, maintenance cost, light quality, upfront investment, return on investment and environmental impact.
By the end of this post you will have the numbers you need to build a straightforward business case for an LED retrofit in any London commercial building.
Energy Consumption: LED Wins by a Large Margin
This is the most straightforward comparison. A standard T8 fluorescent tube rated at 36W produces around 2,850 lumens at the lamp. A direct LED replacement produces the same 2,850 lumens at 16W to 18W. That is a saving of roughly 50% per fitting, before accounting for the ballast or driver losses.
Modern LED panels are even more efficient. A 40W LED panel replacing a twin-tube 2x36W (72W) fluorescent fitting produces the same or better lux output at the workplane while drawing 44% less power. UK commercial electricity averaged 28p per kWh in 2024 (Ofgem, 2024). Across a 100-fitting London office running 2,500 hours per year, switching from 72W fluorescent panels to 40W LED panels saves approximately £8,400 per year in electricity alone.
The Ballast Factor
Fluorescent fittings include a ballast (magnetic or electronic) that consumes additional power beyond the lamp wattage. Magnetic ballasts add 10% to 20% to the nominal lamp wattage; even electronic ballasts add 5% to 10%. LED drivers are more efficient, adding only 5% to 8% to nominal LED wattage. This means the real-world saving from switching to LED is often slightly greater than the lamp wattage comparison suggests.
Lamp Life and Replacement Frequency
Fluorescent Lamp Life
A standard T8 fluorescent tube is rated at 10,000 to 15,000 hours under ideal conditions. In practice, frequent switching reduces this figure. An office where lights are switched on and off multiple times daily may see lamp life fall to 8,000 to 10,000 hours. At 2,500 operating hours per year, tubes need replacing every three to four years.
LED Lamp Life
Commercial-grade LED panels and tubes are rated at 40,000 to 60,000 hours. At 2,500 hours per year, that is 16 to 24 years of expected service before the first replacement. For most businesses this effectively means the LED fittings outlast any reasonable planning horizon for the current fit-out.
For a 100-fitting office, switching from fluorescent to LED eliminates approximately four rounds of full lamp replacement over a 20-year period. At a current cost of £8 per tube plus contractor time, the saving on lamp purchases and installation labour alone is significant.
Maintenance Costs
The True Cost of Fluorescent Maintenance
Maintenance costs for fluorescent systems are often underestimated because they are spread over time. A typical London office with 100 twin-tube fittings (200 tubes) will replace around 40 to 60 tubes per year as they fail individually. At an average cost of £8 per tube plus a conservative £25 per visit for a contractor to swap and dispose of the waste, annual lamp maintenance runs to between £1,500 and £2,500 per year for a mid-size office.
Add in the cost of fluorescent tube disposal (mercury-containing lamps are hazardous waste requiring a licensed waste contractor) and the real annual maintenance cost is closer to £2,000 to £3,000 per year for an office of that size.
LED Maintenance
For the first 10 to 15 years of LED operation, maintenance requirements are effectively zero beyond cleaning. LED drivers occasionally fail before the LED array itself; a quality LED panel driver costs £12 to £25 and takes 10 minutes to replace. For a 100-fitting office the expected maintenance spend on LED over 10 years is under £500 in total.
Light Quality
Fluorescent Light Quality
Fluorescent lamps operate by exciting mercury vapour, which produces ultraviolet light that in turn excites a phosphor coating to produce visible light. The resulting spectrum has peaks and gaps rather than the smooth continuous spectrum of daylight. Most fluorescent lamps achieve a CRI of 75 to 80, which means colours appear slightly inaccurate under them compared with natural light.
Fluorescent lamps also flicker at 50Hz (or 100Hz for high-frequency ballasts). While 100Hz flicker is imperceptible to most people, it contributes to visual fatigue in sensitive individuals. Studies of office workers found that switching from flickering fluorescent to flicker-free LED reduced reported eye strain by 37% and headache frequency by 23% (CIBSE, 2022).
LED Light Quality
Modern commercial LED panels achieve a CRI of 85 to 95 as standard, with premium fittings reaching Ra95+. LED fittings operate at very high frequency with no perceptible flicker when correctly specified. They are also available in a precise range of colour temperatures from 2700K warm white to 6500K cool daylight, allowing the scheme to be matched exactly to the requirements of the space and the preferences of the users.
Tunable white LED systems allow colour temperature to change automatically across the working day, supporting circadian rhythm and improving alertness. This option is simply not available with fluorescent technology.
Upfront Cost vs Return on Investment
Initial Investment
LED retrofits cost more upfront than a like-for-like fluorescent lamp replacement. For a 100-fitting London office, a full LED retrofit including supply, installation and certification typically costs between £8,000 and £18,000 depending on fitting type, ceiling access and control requirements. Fluorescent lamp replacements cost a fraction of that per unit.
Payback Period
With an annual energy saving of £8,400 and a maintenance saving of approximately £2,000 per year, the total annual saving for the example 100-fitting office is around £10,400. On a £14,000 installation, the simple payback period is approximately 16 months. After payback, the savings continue for the remaining 18-plus years of the LED fitting's service life.
The Carbon Trust (2023) reports that the average payback period for commercial LED retrofits in UK office buildings is 18 to 36 months, with larger sites and higher-usage premises achieving payback in under 18 months.
Environmental Impact
LED fittings contain no mercury, making disposal straightforward. Fluorescent tubes require treatment as hazardous waste under the Waste Electrical and Electronic Equipment (WEEE) Directive and the Hazardous Waste Regulations 2005. Every fluorescent tube contains between 3mg and 5mg of mercury; across a 200-tube office replaced over its lifetime that is a meaningful volume of hazardous material removed from the waste stream by switching to LED.
The energy saving from a 100-fitting LED retrofit is equivalent to removing approximately 15 to 20 tonnes of CO2 per year from the grid, depending on the electricity mix (Carbon Trust, 2023).
Conclusion
On every measure that matters to a London business, LED outperforms fluorescent. The energy saving is real and immediate. The maintenance saving compounds over years. The light quality is demonstrably better for the people working under it. The upfront cost is recovered within 18 to 36 months, after which the business keeps the saving for the remaining life of the fitting.
If your office, warehouse or retail space is still running fluorescent, our free site survey will give you a site-specific savings projection within 48 hours of our visit. Call us on 0800 000 0000 or use the contact form to book yours.