As part of a project to make lighting more efficient the National Trust wanted to switch from power-hungry 70w CDMT lighting to a new energy efficient LED solution.

The project was a retrofit using an existing CDMT track lighting system, and Liet Bar LEDs fitted within a surface mounted fluorescent tube system.

The project objectives were to achieve 600lux in the entranceways and create a relaxing ambience in the café and breakout areas, whilst achieve a significant reduction in energy, lamp and FM costs.

Our lighting designers produced the lighting schemes to include Liet D-Series, as the best LED for this application. We worked closely with the National Trust to ensure that beam angle, colour temperature and lighting control matched the incumbent CDMT technology.


Project images


The new LED lamps retro-fitted perfectly with existing luminaires and offered a long-lasting alternative to the legacy CDMT technology. As well as consulting in the early planning stages, Lietcorp offered a full LED lighting package including support and training to the client’s electrical installer.

No49, 70w CDMT lamps and No44 38w 4ft T8 tubes were replaced by the following LED light engines:

  • Liet D35: 18w, 4,000k, 36 degree, 90,000hour L70 life
  • Liet Bar: 6w, 4,000k, 160 degree, 90,000hour L70 life

Energy savings

  • Annual operating cost (electricity, bulb & FM) before LED: £4,151
  • Annual operating cost (electricity, bulb & FM) after LED: £679
  • Annual cost saving on retail store lighting: £3,472
  • Carbon reduction: 11 tonnes per year
  • CAP EX Required: £10,000
  • Payback (after ECA): 2.3 years

Note: all payback and saving calculations exclude: 1) any facilities management savings associated with call-out charges to change lamps 2) air conditioning savings associated with the low heat of Lietcorp’s LED lighting

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