Are those efficient office lighting schemes you read about in magazines like Lux really achievable in the real world? Yes, says lighting economist Dave Tilley, with some caveats

Are the hyper-efficient office lighting installations you read about in Lux simply one-off commissions for high-profile clients? Is return on investment (ROI) important in these circumstances, and can the installations be duplicated for the general commercial office sector?

There is little doubt that there is plenty of potential in the commercial office sector to achieve significant energy and maintenance efficiency. In most cases, energy consumption can be cut by more than 60 per cent; but acceptable ROI, of say two to three years, is often difficult to demonstrate.

Do nothing or use bad practice

Is the answer to do nothing or simply adopt bad practice? I believe directors and shareholders will expect a different approach.

To start the evaluation I have taken a number of typical office areas equipped with efficient luminaires and compared their energy consumption to that of the same areas using conventional lighting technology.

The energy-saving potential is more than 45 per cent, with commensurate financial savings. With those savings, it is informative to examine the ROI.

The projected ROIs will not, as you would expect, excite many finance directors. So how can the ROI figures be improved without the use of smoke and mirrors? There are three principal ways to improve them:

  • lighting design,
  • intelligent lighting controls, and
  • new technology.

Before exploring the potential of this holistic approach to lighting management, it is important to appreciate that although a sophisticated approach will optimise energy efficiency, there is a price to pay, and this will affect the ROI.

Good design

Good lighting design can significantly improve energy efficiency and the overall quality of the working environment. Designers working in offices in the 1970s had a limited range of technologies to choose from, and by today’s standards they were inefficient.

With the benefit of improved light output ratios (LOR) and the potential to reduce light levels, it is realistic to suggest that energy savings of more than 30 per cent are possible.

Also, there are a number of applications in which the need for lighting uniformity is minimal. Meeting rooms, for example, can be illuminated at the point of use, the meeting table. The remainder of the space will make use of reflected and ‘borrowed’ light.

The potential to save energy through application design can be impressive.

Intelligent controls

Intelligent lighting controls can have a significant impact on the energy efficiency of commercial offices where there is an abundance of daylight. Daylight linking can cut energy use. But human nature must be factored in – how many times have you seen offices with blinds down and the lights on?

Occupancy sensors should be considered carefully for the particular application. If a space is used regularly, albeit for short periods, the switching cycle may affect lamp life, which drives up maintenance costs. I think we have established that maintenance costs outweigh energy savings.

New technology

Technology, particularly LED, gives us an opportunity to invest in infrastructure. LED technology commands a relatively high price but it is energy and maintenance efficient, so whole-life costs and sustainability criteria are fulfilled.

The table demonstrates, in simple terms, how the functions of design and control can improve efficiency and, ultimately, ROI. It also highlights another question: when is LED technology the appropriate option?

I have always stressed that although saving energy – as part of a long-term lighting plan – is important, maintenance efficiency generates the greatest savings.

Assuming that the option to do nothing has been rejected and the organisation does not have the budget to invest significantly in new lighting equipment, what is the way forward?

The answer is a strategic lighting plan that specifies the luminaires, light sources and controls, together with lux levels and switching policy, all of which is built into the organisation’s financial and operational plan.

The lighting strategy should focus on those areas that have the potential to demonstrate the highest efficiency, with ROI that appeals to the finance director. As the energy and maintenance savings accrue, investment in the medium and long-term projects can start.


Is there a verdict? If the commercial office sector does not invest in infrastructure, operational costs and fines, taxes and levies will place an unacceptable burden on financial performance.
Ultimately this will have a significant impact on business performance – and that will surely be an issue for directors and shareholders.
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