Lighting design and calculation procedual methods

An adequate lighting installation which fulfils photometric requirements for work place lighting, e.g. according to the standard EN 12464-1 and complies with legislation, regulations and directives concerning occupational health and safety can be determined in various ways.

One possibility is the consideration of a standard arrangement in a standard geometry.

Many existing room systems feature e.g. square lay-in luminaires in system ceilings with axis dimensions of 600 mm or 625 mm. Systems of this kind were often equipped with 3 or 4 T8 fluorescent lamps at 18 watts nominal lamp wattage. Due to luminaire defects or inefficient high energy consumption, most of these luminaires are due to be replaced.

For such situations, replacement luminaires for one-to-one substitution are commonly found on the market today. Some examples for this are presented in "licht.wissen" issue no. 9 on licht.de, which is available to download for free. The luminaires to be used must be selected in a way that achieves the required quality criteria for the lighting installation concerning light distribution and luminous flux after substitution.

Often, a simple exchange of luminaires when renewing the lighting wastes the opportunity of a carefully planned refurbishment. The following misjudgements often occur:

• The distribution of the new luminaires is narrower than before. The lighting is less uniform than it used to be.

• The luminaires’ luminous flux is too low. The required illuminance is not achieved.

• The luminaires’ luminous flux is unnecessarily high. The consequence is an unnecessarily high energy consumption, which could have been drastically reduced by means of a detailed design task analysis.

• The luminaires could have been arranged according to work zones based on the lighting standard effective today (EN 12464-1), which had not been applicable at the time of construction. Reduced energy consumption, improved glare-reduction and visual ambience as well as savings in terms of luminaire and installation costs would have been possible.

• The possibilities of modern light management are not utilised.

• Further aspects of modern lighting such as Human Centric Lighting are usually disregarded.

All this considered, it is often profitable to perform a closer inspection. Tools for this purpose include:

• the efficiency method described in standard EN 13032-2 (see also chapter "Luminous flux classification of luminaires and efficiency methods"),

• rapid calculation programs for approximate determination of the required luminaire quantity – and the corresponding connected load – such as e.g. the lighting calculator in the TRILUX online catalogue,

• photometric design programs such as DIALux and Relux for exact lighting design. These programs also show the specific connected load and hence the energy required for achieving the targeted lighting solution.

• Programs for comparative economic consideration of lighting installations such as the TRILUX efficiency calculator. They allow for the inclusion of  potential energy savings using light management for economic considerations.

• Photometric simulation programmes (3D rendering) as featured in DIALux, DIALux-evo or Relux. They provide an impression of the effects and visual ambience of a lighting solution in a room.

• High-quality calculations in terms of technical design results as well as 3D rendering can be achieved by experts or with the support of luminaire manufacturers on a case-by-case basis.