Relux Lighting Design: How Simulations Support Better Planning
A lighting calculation can show that enough lux reaches a work surface.
It can show how evenly light is distributed. Where glare could become critical. How daylight behaves within the model.
But it does not automatically answer another question: Is this actually the right lighting idea for the space?
Good lighting design does not begin with a calculation grid.
It begins with use, architecture, materials, viewing directions, daylight and the question of which areas of a space should receive visual priority in the first place.
Only then does simulation become genuinely interesting.
It makes assumptions measurable.
And sometimes its most valuable result is not confirmation, but the discovery that an idea does not yet work.
ReluxDesktop is professional software for planning and simulating artificial light, daylight and sensors.
Rooms, luminaires, geometries and calculation surfaces are built as a digital model. On this basis, lighting values can be calculated, alternatives compared and results documented.
Photometric data and room geometry form the basis for calculating artificial lighting.
Daylight can be examined together with openings, geometry and external obstructions.
Depending on the task, horizontal, vertical, cylindrical and other lighting metrics can become relevant.
Models and planning data can be integrated into digital architectural and BIM workflows.
- geometry
- luminaire positions
- photometric data
- reflection assumptions
- calculation surfaces
- defined boundary conditions
- viewing directions
- materials
- contrast
- faces
- reflections
- movement and use
A number displayed to several decimal places looks objective.
That does not necessarily mean the model describes reality correctly.
Ceiling heights, niches, built-ins and furniture influence the calculation and should not be simplified arbitrarily.
Light and dark surfaces return different amounts of light to the space. Material assumptions are therefore part of the calculation.
One luminaire family can create completely different results with different beam angles.
A value only makes sense if the calculation surface corresponds to the actual visual task and use.
A meeting table, exhibition, workplace and circulation zone do not have the same requirements.
Full output alone provides only a limited picture of a space with dimmable scenes and different uses.
Imagine an office.
The calculation surface on the desk reaches the desired value. Uniformity is correct. Technically, everything looks clean.
The room can still perform poorly.
The wall behind the monitor is very dark. Faces in video conferences are illuminated only from above. Reflections appear on screens. The room feels flat because every surface has a similar brightness.
Horizontal illuminance answers only one of several questions.
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Not every metric is equally important in every space.
In an office, glare may be decisive. In a gallery, vertical illumination may matter more. In a lobby, the relationship between floor, wall and faces may be critical.
Professional simulation therefore begins before the calculation – with selecting the right question.
False-colour representations are among the most useful tools in a lighting simulation.
Instead of making a space look as realistic as possible, they show very directly where illuminance rises or falls.
This can reveal issues that are easy to overlook in a photorealistic image:
Individual areas receive significantly more light than necessary and may attract unnecessary visual attention.
An average value may look good even though relevant edge areas receive significantly less light.
A highly uniform distribution may be functionally correct while removing every visual hierarchy from the space.
The simulation can reveal when light is falling where the actual use hardly needs it.
It comes from a complex sky, enters through windows, is shaded by geometry and reflected by surfaces.
A daylight simulation is therefore far more than simply drawing a window into a model.
Windows and skylights determine where daylight can enter the model in the first place.
Neighbouring buildings, overhangs and other geometries can shade or influence available daylight.
Materials and room geometry influence how incoming daylight is distributed throughout the building.
A room with large windows can behave completely differently in the morning than in the afternoon.
If a work or play area sits directly beside a window, it does not necessarily require the same artificial light output as an area deeper within the room.
Simulation can help make these differences visible and support the development of sensible luminaire and control zones.
The goal is not to overpower daylight with artificial light.
The goal is to understand when artificial light actually needs to add something.
A calculation can demonstrate that defined requirements have been achieved.
A dark floor behaves differently from a light one. Exposed concrete differently from white plasterboard. Polished metal differently from timber.
Reflection assumptions influence the calculation model.
At the same time, the complete effect of a material cannot be reduced to a single reflectance value.
Texture. Gloss. Colour. Viewing angle. Ageing. Actual surface quality.
This is why calculation, visualisation, material samples and – for critical details – mock-ups are not competing methods.
They answer different questions.
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It is based on geometry, photometric data, materials, calculation surfaces and defined boundary conditions. Its value lies in technical verification.
It helps communicate an idea and make spatial relationships easier to understand. The current Relux version also offers AI-assisted image generation.
One should never be read as proof of the other.
A convincing rendering can make a technically problematic concept look beautiful. And a sober false-colour image can precisely validate a very good concept.
Illuminance, distribution, glare and vertical light components can be examined systematically.
With many luminaires, use zones and large distances, relationships quickly become difficult to understand from the floor plan alone.
Windows, skylights and shading can be included early in the planning process.
Different optics, positions or luminaire arrangements can be compared under equivalent conditions.
Reach, illuminance and unwanted light can be assessed before installation.
Regulatory requirements and defined escape or safety areas can be documented through calculations.
Detection zones can be examined in the digital model rather than discovering problematic gaps only after installation.
For refurbishment projects, a model helps compare existing geometry with new lighting solutions systematically.
Simulation should be part of an iterative process.
What actually needs to be tested? Illuminance, glare, daylight, a wall surface, a workplace or one specific option?
Model only the geometry and details relevant to the question – but model those correctly.
Materials, reflectance values, luminaires, usage profiles, calculation surfaces and scenes should all be set deliberately.
Do not evaluate results only through averages. Read the distribution, edge zones, viewing directions and unusual peaks.
Adjust position, optics, output or lighting strategy and test again. This is where simulation creates its real value.
Mock up critical details and, after completion, fine-tune aiming, dimming values and scenes in the built space.
Simulation is particularly powerful for questions that can be modelled and measured clearly.
It becomes more difficult where material, reflection, viewing angle and spatial impression interact very closely.
A glossy bar surface. A bespoke luminaire. A very low light source. A complex ceiling detail.
In these situations, a 1:1 test can provide a different kind of certainty.
The professional decision is therefore not simulation or mock-up.
It is: which method answers this particular question most reliably?
- illuminance levels
- light distributions
- defined glare criteria
- daylight conditions
- design options
- calculation surfaces
- sensor coverage
- regulatory requirements
- What should be seen first?
- Which surfaces can remain dark?
- How much contrast does the space need?
- Which light sources may remain visible?
- How should light respond to material?
- Which scene suits the use?
- How should lighting integrate with the architecture?
- What actually feels right in the built space?
This question comes up frequently when discussing lighting design software.
Both systems are used professionally for lighting calculations and provide extensive tools for different planning tasks.
In practice, the more important question is often not which software is theoretically “better”.
What matters is: Can the designer use the respective tool confidently? Are the required data available? Does it fit the CAD or BIM workflow? And are the results interpreted correctly?
Adding another luminaire on site is expensive.
Changing a beam angle in the digital model is not.
That is exactly why Relux should not be used only at the end to document an already completed design.
Its greater value emerges during the design process.
Calculate an option. Read the result. Question the assumption. Change the design. Calculate again.
Simulation then stops being merely proof of the design and becomes an active part of the thinking process.
Workplace, showroom and event space with different lighting requirements and programmable scenes.
View project →Daylight studies, different use zones and lighting design from the perspective of the actual users.
View project →Materiality, different lighting scenes and fine-tuning within a built hospitality project.
View project →Complex hospitality and event use with different lighting conditions and a 1:1 mock-up.
View project →ReluxDesktop is software for professional lighting and sensor planning. It can simulate artificial light, daylight and different lighting metrics, while supporting CAD- and BIM-based planning workflows.
Relux is used to verify lighting concepts through calculations, compare alternatives, analyse illuminance and light distribution, and document results. Depending on the project, daylight, glare, sensors or safety lighting may also be relevant.
The software can support calculations and simulations, but it does not automatically determine the design strategy. Deciding which areas should be emphasised, reduced or treated differently remains a design task.
Geometry, materials, reflectance assumptions, photometric luminaire data, calculation surfaces and use all need to be defined appropriately. A technically precise result is only as meaningful as the assumptions underlying the model.
Yes. ReluxDesktop supports daylight calculations. Windows, skylights, sky models as well as modelled external shading and reflections can be taken into account.
No. Illuminance is an important technical part of lighting design, but it does not fully describe contrast, material effect, spatial hierarchy, viewing directions, scenes or the actual use of a space.
Both programs are used professionally for lighting calculations. Which software is better suited depends on the workflow, required functions, available data and the designer's experience. Proper modelling and interpretation of the results remain decisive.
Not always. Simulations are very strong for measurable quantities and option comparisons. For critical materials, reflections, bespoke luminaires or unusual viewing angles, physical mock-ups can provide additional insights.
Studio De Schutter combines lighting technology with architectural thinking.
Develop concepts. Test assumptions. Compare options. Mock up critical details. Fine-tune the built space.
Calculation provides certainty. The decision about lighting quality remains part of the design.
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