Millions wasted in office lighting each year!

The lighting industry has been self congratulatory for years now on the increasing efficiency of lighting within offices. And in many respects this self congratulation is warranted. The development of high efficacy fluorescent lamps, electronic control gear with very low losses and lighting control systems are all hardware elements that have certainly had a dramatic and significant effect in slowing the rate of energy used for the lighting of offices.

Similarly, the introduction of government measures such as the Building Regulations, Parts L1 and L2 Conservation of fuel and power, have also encouraged energy efficient lighting design within the office environment.

However, despite these welcome efforts, the fact remains that millions of pounds are wasted each year on energy for unnecessary lighting of offices. And of course as every pound sterling wasted on energy converts to approximately 5-6kg of unnecessary CO2 emission into the environment - the resultant numbers are frightening.

With in excess of 70 million square metres of office space in the UK consuming lighting energy at the rate of between 25 KWhr/m2/annum and 100 KWhr/m2/annum (depending upon office type and lighting controls) the magnitude of lighting energy consumed is probably in excess of a massive 4.5 GWhrs per annum. This consumption represents some £250-£300 million expenditure per annum, probably more! "So how do we save on this consumption and expenditure when we already use 'best practice' and high efficiency systems", you can hear the lighting industry cry. Well do we actually use 'best practice' and high efficiency systems?

It could be reasonably argued that over 90% of all office space has been designed to deliver a prescribed illuminance (300-750 lux) across the whole of a reference plane extending from wall to wall with a uniformity of greater than 0.7. The justification for this over design being that it allows the end user freedom of location of working plane within. What a luxury!

With the actual working plane in an office representing at maximum no more than 30% of the net lettable area, it means that vast quantities of energy are pumped into the carpet or floor covering, never to emerge again as light that will ever reach the working plane, or probably any other plane. Add to this that most offices only ever have 70% occupancy actually at their workstation and the true wastefulness of energy for lighting of offices becomes apparent.

If an open plan office utilising lighting energy at a density of 12.5 watts per square metre of floor area (500 lux) switched to lighting the actual working plane (task lighting) and considered the remaining areas with 'background' lighting at 200 lux, the overall load density would reduce to approx. 7.1 watts per square metre of floor area. Imagine the savings both in costs and CO2 emissions if all offices were designed in this manner - millions and millions of pounds saved and millions of tonnes of CO2 emission eliminated. (12.5 watts per square metre would represent current 'best practice' - many typical offices have lighting energy densities significantly greater than this, up to 35 watts per square metre).

And of course these savings are direct energy consumption savings. If one adds into this the potential embedded energy savings created by reducing the number of luminaires at point of utilisation the total energy savings increase significantly - and end users would also further benefit financially as the WEEE Directive is implemented.

This innovative thinking is beginning to happen in the office environment. BDP have recently implemented such solutions in their London Office and Philips, one of the world's largest lamp and luminaire manufacturers, also implemented such an innovative solution in their new corporate Guildford offices. In justifying this current situation, many designers will point out that there are no real alternatives for the lighting of the speculative office development. That as the work station layout is unknown at the time of the design; they have to provide this 'blanket' cover. Whether this has ever been true is open to argument, but it is certainly no longer true. 'Shell and Core' is a developer's option - this was the situation negotiated by BDP London, allowing a bespoke, yet flexible and adaptable solution to be installed.

The 'Shell and Core' philosophy obviously imposes limitations in the letting of buildings, however the need to have real energy saving lighting systems fitted into speculative office space should not be a problem. Better lighting controls are required providing both 'global' and 'local' control facilities. We have better control systems in our own homes than we do in offices.

Perhaps some of the perceived problems are who pays the capital costs and who reaps the financial rewards, but of course this is an 'ostrich' dilemma that can be resolved by first removing the head from the sand.

We must continue to applaud manufacturers for the significant developments in office lighting lamps, control gear, control systems and luminaires, and encourage them further in these developments. To expand the relationships that exist between Government Agencies and Departments, Energy Associations, Resources Research Departments within Universities, Professional Practice Institutions and of Office Developers - but at the end of the day it comes down to the mind set of the individual lighting designers.

They have to change the ways in which they deal with intellectual design. Follow my leader can no longer be an excuse. The millions and millions of pounds that could be saved each year are of great relevance. These are bottom line savings, going straight back into the coffers of the corporations occupying these offices. True, the financial equations need to be addressed, who gets what, when and why. But of far greater value is the savings to the environment - an enormous contribution into achieving the goals that UK entered into with the Kyoto Treaty. After all what would be achieved is better lighting for the office end user, not worse, at lower capital and operational costs and with significant reductions of CO2 emissions into the environment. Not a bad exchange for global responsibility.

This article is one of a series sponsored by the Lighting Industry Federation, the voice of authority on lighting. If you wish to know more about what the LIF can do for your practice, visit: www.lif.co.uk/affiliate