Economic considerations play a key role in planning new installations or refurbishments of existing lighting installations. On a macroeconomic scale, only small energy savings can be achieved through reducing the energy consumption of lighting. However, in office buildings and work places with long operating hours for artificial lighting, particularly with shift work, the energy demand for lighting is significantly increased, which means energy-saving lighting installations pay back rapidly. With modern lighting installations, energy costs can be reduced significantly.
In refurbishment cases, the savings resulting from energy cost comparisons often make up for the required investments for the new installation. In such cases, the total costs for a lighting installation can be lowered if the existing equipment is replaced with light sources of increased luminous efficacy and luminaires with increased efficiency or more suitable light distribution.
Regarding installation costs, however, it is important to consider not only the costs for new luminaires and, as the case may be, lamps and their installation, but also possible costs for disassembly of old luminaires and their appropriate disposal. Furthermore, lighting refurbishments may also require additional adjustments in electric installations. These factors usually differ vastly depending on the object. For a profitability analysis, they should therefore be determined individually and not generalised. When it comes to the costs of the old installation, an item for repair costs as a necessary investment for its continued operation should be considered case by case.
In the case of a comparison of alternatives for a new installation, disassembly and repair costs are inapplicable. However, maintenance costs may differ significantly and, in unfavourable cases, considerably raise the total costs. Particularly modern lighting installations with LED luminaires are characterised by low maintenance efforts and a long useful service life.
In both cases – refurbishment as well as new installation – the aim of a profitability analysis is to compare the costs/financial benefits of alternative possibilities. A financial benefit is derived when the installation costs in terms of invested capital or additional capital investments plus incurred capital costs (interest) can be compensated by the achieved savings within the estimated useful life, meaning payback is achieved. From the point of payback, the more economic lighting installation generates a profit. The amount of profit is referred to as "total profit of ownership" (TPO).
The amount of savings in operating costs is the result of maintenance costs and energy costs. The former are only significant in exceptional cases; the latter – in addition to the energy rate – strongly depend on the operational utilisation data. These, just as the installation costs (see above), can be vastly different case by case. On the other hand, statistical values, which can be gathered from the standard DIN V 18599-10 (see chapter ), can provide a good guide to potential savings in typical "user profiles". These examples thus provide a certain universal validity. The refurbishment examples in the following sections show energy cost savings on this basis, assuming an energy rate of 23 ct/kWh.
The TPO (total profit of ownership) depends on the amount of yearly savings and the time period remaining from payback to the end of the useful life, during which profit can be generated. The time period up to the point of payback is mainly relevant since it shortens the period of profit generation. Consequently, a higher investment, due to its increased savings potential, can be the more economic solutions even with longer payback periods. Considerations of this nature can be executed using the TRILUX efficiency calculator (see chapter , figures ff.).