Lighting

Lighting is of critical importance in buildings. An adequate level and distribution of light is vital if visual tasks are to be carried out safely and effectively. Good lighting will also improve the internal environment and appearance of a building. Lighting should be used to supplement daylighting, which makes the design, planning, and functionality of lighting one of the most important elements when building. Lighting also needs to be efficient and cost effective. The use of efficient lamps, ballasts and luminaires with appropriate lighting controls, can provide the right visual environment, be energy efficient and cost effective, as the cost of electricity becomes more and more expensive. As with any design related project, the budget is central to the design. This is usually established by applying a certain percentage of the overall building budget towards the “architectural professional”. It used to be accepted that lighting should constitute approximately 2 to 3% of the total budget. However, all too often budgets allowed for lighting are extremely low and inadequate, again highlighting the need for proper planning. Today, the suggested budget for lighting should be in the region of 4 to 5%.

It is possible to save significant amounts of electricity over long periods of time with energy-saving lamps. Traditional light sources such as Compact fluorescent and tubular fluorescent lamps are rapidly being phased out in favour of solid state lighting (SSL) such as LED’s and OLEDs.

South Africa has adopted a policy framework designed to directly regulate for lighting products of higher energy-efficiency LED lighting and thereby removing incandescent, halogen and most integrally ballasted compact fluorescent lamps (CFLi) from the market. Although tubular fluorescent lamps are not yet regulated, these are voluntary being phased out through luminaire retro-fit programmes and are replaced with tubular LED lamps.

New compulsory specifications for general service lamps (GSLs)are being introduced and will become effective towards end 2022. These compulsory specifications set minimum energy performance standards (MEPS) for general service lamps, which will practically phase out lamps that contain mercury.

A few simple guidelines to help get your lighting right:-

  • Decide what the lighting is needed for, and then design your lighting scheme to position lights where they will be used. Use functional lighting and provide sufficient plug sockets for reading lamps.
  • Use only lamps appropriate to the luminaire (see lamps later in section).
  • Light for safety and security.
  • Light for effect. Reduced background lighting levels create more contrast in a room and can save energy.

Ballast/control gear
Apparatus to start and control the current through fluorescent and other discharge lamps.

Diffuser
A translucent screen used to shield a light source and at the same time, soften the light output and distribute it evenly.

Discharge Lamps
A lamp whose illumination is produced by an electric discharge through a gas (neon), or a metal vapour (mercury, sodium), or a mixture of gases and vapours.

Efficacy
A measure of the effectiveness of a light source(lamp) or luminaire in converting electrical power to light (lumens/watt).

Utilization
A measure of the effective application of light emitted from a luminaire on the visual task area. The task area for interior lighting depends on the type of activity.

Lumen
A unit of luminous flux used to describe the amount of light given off by a lamp.

Luminaire
The term for a light fitting. A luminaire distributes light from a lamp and includes all components for fixing, protecting the lamps and connecting them to the electricity supply.

Lux
Unit of illuminance, or amount of light on a surface (lumens/m2).

Lamp
Commonly known as a light bulb.

LED
Light-emitting diode.

LED Driver
An electronic device that regulates the power to an LED or a string of LEDs

LED Module
An array of LEDs arranged on a printed circuit board.

CFL
Compact fluorescent lamp.

Colour Rendering Index (CRI)
CRI is a comparison of a light source’s ability to accurately render the colour of an object to that of a standard reference light source. The CRI scale is from 0 to 100, with a value of 100 indicating excellent colour rendering. Sunlight and most incandescent lamps have CRI values of 100.

Colour Temperature (CCT)
Colour temperature is a way to compare the colour of light from different lamp types. It is often referenced as cool (slightly blue) or warm light (slightly orange). Incandescent lamps and candles give off warm colour temperatures, while sunlight and some fluorescent lamps emit cool colour temperatures. Units: K. Lamps with a high CCT, e.g. 6500K, produce blueish-white light, whereas those with a low CCT of 2700 produce light that is more yellowish-white.

Lighting Principles
When designing or planning lighting, ensure that light is directed to where it is needed. Heavy shadows can be avoided if the light is properly positioned and there is adequate contrast. Often, a whole room is lit to a bright level, or even the whole house is lit, and yet a person is working with barely enough light for the task at hand, e.g. reading, writing or preparing food. In general, lighting layouts should avoid creating a situation where all lighting has to be switched on to illuminate one part of a room, e.g. lights furthest from windows should be switched on independently from those closer to windows. Lighting equipment comprises a lamp, ballast, control gear or transformer if needed, and the luminaire (light fitting). Each element contributes to the overall efficiency. There is no sense in placing an efficient energy saving lamp in an inefficient luminaire, or an efficient combination of lamp and luminaire in an inefficient position. It is, therefore, imperative to choose the combination that is most efficient for the position and purpose.

Artificial lighting can be categorised in the following three groups:

  1. General, e.g. a central hanging light;
  2. Functional or task, e.g. wall mounted picture light or a table lamp; and
  3. Decorative, e.g. ornamental wall light or lighting used for effect.

The light must have the right illuminance, it must be uniform and glare-free, and it must have an excellent colour rendering to avoid fatigue and eye-strain e.g. a soft light that is not too bright is needed for a relaxing mood, while for reading you need luminaires that offer a small pool of bright light. Wardrobe and dressing tables can be attractively lit with dimmable LED light sources.

Illumination Levels

Standards and Regulations for Lighting

Lighting installations in new dwellings and buildings, to be served by artificial lighting, should comply with the lighting requirements of SANS 10114-1: Interior Lighting Part 1: Artificial Lighting of Interiors.

This part of SANS 10114 covers requirements for good lighting and also provides basic guidelines for and recommendations on the design of artificial lighting installations for general interior locations. It is primarily aimed at new installations in interior workplaces, but also applies in general to other interior locations.

The safety requirements for luminaires are also covered by compulsory specification VC8055, which refers to the requirements of the following standards:

SANS/IEC 60598-2 Series of Luminaire standards (Not all part 2’s are compulsory)

Some luminaire types are compulsory by reference as listed in SANS 10142-1: The wiring of premises. Part 1: Low-voltage installations, these are the following:

  • SANS 60570/IEC 60570: Electrical supply track systems for luminaires.
  • SANS 60598-2-18/IEC 60598-2-18 (SABS IEC 60598-2-18), Luminaires: Part 2: Particular requirements – Section 18: Luminaires for swimming pools and similar applications.
  • SANS 60598-2-23/IEC 60598-2-23 (SABS IEC 60598-2-23), Luminaires: Part 2-23: Particular requirements – Extra low voltage lighting systems for filament lamps.

With the introduction of the new compulsory specifications,

VC9109:  Compulsory specification for energy efficiency and functional performance requirements of general service lamps (GSLs), and

VC9110:  Compulsory specification for the safety requirements of general service lamps (GSLs)

The CFL lamps and the less efficient tungsten filament lamp (incandescent) lamps are being phased out with the final implementation of the above specifications.

LED lamps that are interchangeable and can be used in most standardized lampholders are readily available to replace the less efficient lamps. Important to note, that these replacements may change the photometric distribution of luminaires, and will in many instances change the utilization, uniformity and glare of the lighting installation.

Although LEDs are an alternative to most traditional light sources, they have different characteristics that users need to be aware of. Not all LED lamps are dimmable. Those that are dimmable, will be clearly marked on the packaging.

SON lamps have been the main choice for external lighting because of their very long lamp lives (typically 14 000 to 24 000 hours) and low electrical consumption. However, the lamps give a yellowish light, but the SON Deluxe lamps (improved SON lamps) have a golden white light.  These lamps are rapidly being phased out in favour of LEDs that have higher efficacy, better colour rendering and life expectancy of up to 50 000 hours, which makes them the preferred choice.

Metal halide lamps give excellent, crisp white light and have low energy consumption with a lamp life of about 6000 hours. Lamp replacement costs are therefore higher than for SON lamps. However, these lamps have better colour rendition than SON lamps and can be used indoors or outdoors. There are smaller wattage lamps that are useful for display lighting.

LED technology in lighting has come a long way in South Africa over the past few years, providing very low energy consumption. These lamps cost more to purchase but outlast conventional by a long way. They also save energy and, therefore, money. LEDs are now manufactured in different shapes to suit past installation, e.g. golf ball, candle, down lighters, spot lights.

Luminaire Types

The product range of luminaires per category is too vast to cover in this publication. Detail of product choice, range and specifications are contained in product literature available through manufacturers, distributors and luminaire merchants. A visit to an established lighting showroom will provide the reader with an indication of what products are available.

Lighting Design

For lighting installations in offices, shops, commercial buildings, factories etc., it is essential that lighting design specialists are appointed to ensure that the most efficient installation is developed, which addresses the particular visual tasks, illumination levels, energy considerations and maintenance of the installation.

Leading luminaire suppliers, will be able to supply or recommend such services.

Lighting Tips

For residential, domestic lighting where the photometric properties of luminaires are not critical, the following should be considered:

  • With multiple light sources, you can create pools of light and give structure to a room.
  • Indirect lighting adds height to a room.
  • Create different moods with different light sources. Recessed furniture light turns shelving and cabinets are real eye-catchers.
  • Avoid beam angles that are excessively narrow so people around the table are not in shadow (desk, dining etc.).
  • Luminaires integrated in furniture provide light precisely where it is needed.
  • You can create different lighting moods with dimmable luminaires.
  • Indirect light creates a pleasant glare-free atmosphere.
  • Provide adequate lighting over work surfaces and ensure the luminaires are positioned correctly to avoid working in your own shadow.
  • Lamps positioned to the left and right of a mirror prevent annoying shadows falling on your face.

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