Design works

Lighting design should not be confused with the work of illumination engineers. The lighting designer’s responsibility extends beyond the mere provision of lighting and equipment, for today it must extend to creating effective environments. Space can be lit to enhance comfort, aid efficiency of people at work and ensure safety, but it takes more than the installation of a required number of luminaires.

Another factor that affects everyone concerned with lighting is the need to comply with legislative requirements that include safety, Building Regulations and even the disposal of lamps and tubes. A corollary of the quest for energy savings has also created greater corporate and social responsibility with organisations requiring greater efficiency and visible sustainability from their buildings. In truth, more and more companies want to be seen as green, but few recognise what that really entails when it comes to lighting.

Vested interest

In practicality, most lighting design is driven by the equipment manufacturers, who clearly have a vested interest in promoting their wares. Most of these companies have either a limited range of equipment or lack the resources to properly deliver a holistic design service appropriate to the needs of the installation. Hence, the role of the lighting designer, who can better integrate lighting into the overall requirements of the space being lit.

From the electrical contractor’s point of view, lighting design is one area that leads a project away from pure engineering and into the less tangible realms of ergonomics, aesthetics and creativity. While a qualified contractor is capable of installing anything, many struggle when it comes to designing with light. The plethora of types and styles of lighting is daunting and this is equally true for architects, interior designers and building services engineers.

Modern lighting design works on many layers and lighting is increasingly being provided from ceiling to floor. Understanding the need for light, the colours that best suit the environment being created and any requirements for controlling lighting schemes in accordance with changing needs are all considerations. Underlying this is the need to comply fully with health and safety and the challenging new Building Regulations.

Early decision making

Decisions over lighting control must be taken early in modern schemes, as these systems not only involve power cabling, but also communications cables. Control systems for lighting have become extremely sophisticated over the past decade, and the growth of multiple occupancy networks such as the Digital Addressable Lighting Interface (DALI), LONworks, C-Bus and others have steered lighting systems into the field of data networks.

The types of luminaires deployed are important. For example, in ceiling mountings, lighting can consist of concealed downlighters, reveal or trough lighting, along with pendant and surface mounted fittings. Used judiciously, all of these types provide flexible illumination without glare. Wall lighting can be surface mounted or flush fitted, and picture lights remain an easy way to direct specific stronger lighting to artwork or architectural features. A recent trend has been towards low level floor lighting, and it is here that LED technology has made the fastest inroads into space lighting. Floor or low level mounted LEDs provide pleasing effects, bathing lower walls in light and colour. They can also aid safety on stairways – a consideration for compliance with the Disability Discrimination Act.

Long term

One of the factors that WF’s lighting design team is able to address is the use of the lamps and tubes in a scheme. For example, while lamp manufacturers give life expectancy figures for their products, these are always based on averages with the lamps operating at their rated voltage. Hence, while a low voltage lamp may have a rated lifetime of 2000 hours at say, 12 V, even a voltage increase of 5 or 6% could halve that lifetime. Conversely, a 5 or 6% decrease in voltage could double the lamp life. WF’s designers consider such issues because they lead to lower maintenance costs and greater ability to organise the facilities management of a building.

Similarly, the use of soft starts can dramatically improve lamp life for cold filament lamps. Most lamps suffer high current surges of up to 20 times the running current when turned on and, while this lasts for just a fraction of a second, it dramatically affects the mortality of the lamp. How many times does a lamp fail when it’s switched on, compared with simply expiring while illuminated?

In short, the lighting scheme must be considered comprehensively if it is to succeed on every level.

This leads us into the field of legislative considerations. The Building Regulations have always addressed lighting efficiency, but until the introduction of Part L earlier this year, the requirements were dreadfully flawed. For example, in the past it was sufficient to select fittings from a given list of high efficacy lamps to comply with the Regulations. Now, under Part L2A covering commercial buildings, it is necessary to compute the figures and there is no waiver for the first 500 W of installed lighting load. There are a few notable exceptions, such as the lighting used on serving counters in restaurants, where such luminaires are considered display lighting. Other exceptions include certain outdoor lighting, but the exemptions are complicated and it is best to seek expert advice when making calculations under Part L2. Another factor under Part L2 is the need for manufacturers to give higher light output ratios to meet the need to reduce energy consumed.

The tangled web that is Part L2 and the way in which it relates to lighting requires detailed knowledge of the Building Regulations, expertise in designing adequate lighting while meeting them and knowledge of the latest products designed to give the best possible lighting solutions while aiding compliance. The problem with consulting lighting equipment manufacturers is that few, if any, have the breadth of range or necessary expertise to give truly impartial advice. This is why WF Electrical’s lighting design team is possibly unique in the industry.