Put lighting first

With much publicised rising crime figures in the UK, it is hardly surprising that organisations in both the private and public sectors are paying more attention and investing heavily in security and related safety measures. The noticeable rise in the installation of CCTV systems, the growing use of private security personnel as well as the greater emphasis on security alarms and protection measures, are all in response to this rise.

However, the major contribution that high quality lighting can make, both as a security measure in its own right and as a contributor to making other security systems more effective, is frequently overlooked when companies are considering new security measures. This is partly due to the fact that many security and safety initiatives have tended to be purely tactical. This is set to change with the advent of recent legislation and new initiatives.

Secured By Design
For instance, under section 17 of the Crime & Disorder Act 1998, all local police authorities have a duty to consider crime and disorder reduction whilst exercising any of their duties. Some legal experts believe that this Act, allied to the Human Rights Act 1998, could lead to actions by citizens against local authorities and organisations if appropriate security and crime reduction measures are not taken.

To assist there are a number of initiatives which have been designed to help encourage the planning of crime prevention, and the creation of more secure environments. One such scheme is 'Secured by Design' organised by the police and endorsed by the Association of Chief Police Officers with the backing of the Home Office. Security planning reflected by Secured by Design principles makes a distinction between reducing the opportunity for crime and the fear of crime. Good lighting can play an important role in both these areas.

The ability to see and be seen is an important factor in reducing both the opportunity and fear of crime. If we can see our surrounding environment clearly and visibly we can anticipate hazards and take the appropriate action. Equally, when we know 'we are seen' we tend to comply with social norms. Poor and inadequate lighting can, in certain environments, create the most difficult areas of all.

There are a number of guiding principles that installers can use in assessing lighting schemes.

While, in theory, sodium based light output is high, what is actually seen by the eye under its yellow light is comparatively low

• Consider the total area to be lit and how the lighting will integrate into adjoining developments.

• Assess specific high-risk areas e.g. walkways, steps, ramps, parking etc.

• Beware of crime hotspots, where the very nature of a building can influence crime and social behaviour.

• Think about the needs of the likely users of the space.

• Assess links and short cuts linking two or more popular places.

• Appraise the availability of suitable locations for light fittings.

• Look at the need for lighting controls and timing.

• Consider the environmental factors including energy efficiency and light pollution.

Finally, consider the lamp which will be used in the luminaires as this has a considerable impact on the quality and the colour of the light output. Remember, the human eye judges lighting subjectively. The latest research suggests that the old lumens/watt method of judging lamp efficiency is incorrect, since it is not the amount of light produced that is important, but how well the eye can see using that light, particularly when overall light levels are reduced.

In this situation our eyes' sensitivity to yellow and red light greatly reduces, while the response to blue and green light increases. Sodium based light produces most of its light output in the yellow spectrum so while, in theory, its light output is high, what is actually seen by the eye under its yellow light is comparatively low. Alternatively, while its lumen output is slightly lower, the white light of metal halide lamps is spread more evenly over the whole visual spectrum and helps to improve the accuracy of identification and reduces anonymity. Looking straight ahead the effective lumen output is 100 per cent higher for metal halide than for the HPS (High Pressure Sodium) lamps. For Peripheral vision, detection and reaction to visual stimuli is six times higher.

Colour identification is also improved under white light. The best light source is the sun, which is given a score of 100 using a measure known as the colour-rendering index (CRI). Other lamps are measured as a percentage against this benchmark.

High-pressure sodium lamps have a CRI of only 20, while metal halide lighting typically scores 70. Hence CCTV is far more effective when it is used in conjunction with the white light of metal halide or fluorescent lamps.

With the new holistic approach many authorities are now taking to safety and security, the role of lighting as a contributor to the greater efficiency of other measures, as well as a fundamental element in its own right, is set to grow along with the importance and adoption of white lighting.