Commercial lighting: design, control, save

Three texts govern your commercial lighting project, and each sets a threshold that we read as a functional ceiling, not as a uniform floor.

• Lighting renovation: installed power less than or equal to 2.8 W/m² per 100 lux band of average illuminance to be maintained, according to Filière 3e; 500 lux on computer workstations, 750 lux only on precision tasks (CAD, plan reading, quality control), 300 lux in circulation areas, CRI above 80 and UGR below 19.
• Occupational health regulatory framework (article R4223-4) and NF X35-103: lighting sufficient to preserve visual health, documented lighting ergonomics.
• BACS order of 7 April 2023: building management system mandatory above 290 kW of installed power, with presence detection and daylight harvesting.

On the energy side, average commercial lighting consumption stands at around 25 kWh/m²/year, which we bring below 10 kWh/m²/year with controlled LEDs. A reduction trajectory documented annually on the dedicated platform then applies to the tertiary buildings concerned.

In practice at Kytom, the standard allows strong modulation: 300 lux in collaboration areas, 200 lux in circulation, 500 lux strictly on workstations, 750 lux only where the task justifies it. This differentiated reading frees up 25 to 35% of installed power without degrading a single comfort indicator.

Commercial lighting is no longer designed as a regular grid of luminaires. For the interior architect and the lighting designer who work with us, the challenge has shifted from photometric calculation to functional zoning and architectural integration.

• Lighting hierarchy rather than uniformity: the applicable regulatory framework requires an Emin/Eavg ratio above 0.6 on the task area, but tolerates marked variation between zones. An open space can alternate 500 lux on workstations, 300 lux in collaboration areas, 200 lux in circulation, without any regulatory breach. This modulation appreciably reduces installed power while restoring spatial legibility to the architecture.
• Colour temperature and circadian rhythm: 2700 K in reception areas and phone booths, 4000 K in open spaces, 5000 to 6500 K in creativity rooms or morning periods. DALI-2 control enables automatic drift aligned with sunset.
• Integration with fit-out works: linear luminaires recessed in suspended ceilings, suspensions over islands, indirect lighting on acoustic wall panels. Coordination with the partitions, ceilings and HVAC packages is settled at the detailed design stage, not during execution.

On projects where the lighting designer is involved from the concept stage, employee lighting satisfaction is markedly higher than that observed on projects where they only step in at the detailed design phase. The budget trade-off is decided upstream.

The LED + DALI-2 renovations we manage generate significant energy savings on lighting, with a return on investment generally between 3 and 5 years depending on the prevailing electricity tariff.

On a standard-sized floor plate, the switch to LED + DALI-2 generates significant annual savings on the electricity bill and reduces the carbon footprint in line with the regulatory obligations of the tertiary decree.

Three cases where we steer you towards a lighter solution, rather than selling you a disproportionate system.

• Floor plate below 250 m² or recent LED stock: full DALI-2 deployment with commissioning is generally not justified. A simple driver replacement with standalone presence detection is enough, for a much lower investment.
• Lease expiring in less than 36 months: full controlled renovation is counterproductive. We recommend renting standard LED luminaires, amortised over the remaining lease term.
• Site already compliant with regulatory illuminance levels and stable in its layout: there is no point in reconfiguring controls if flexibility is not an issue.

Conversely, as soon as you reorganise your floor plates more than 4 times a year, fixed KNX wiring penalises flexibility and zone-by-zone DALI-2 control becomes essential. This technical honesty is part of our contractual commitment: we first cost the relevance, then the service.

1. Photometric audit
   We measure your existing installation with a luxmeter, model the floor plates in DIALux evo and map zone by zone (open space, rooms, phone booths, circulation) the gaps against the illuminance levels required for each commercial use. Deliverable: a costed report identifying over-illumination, superfluous installed power and the savings potential. Timeframe 2 to 3 weeks depending on the area.
2. Lighting design
   We select LED luminaires above 130 lm/W, adjustable colour temperature 2700 K to 6500 K, UGR below 19, CRI above 90 in collaborative spaces. The layout plan takes into account functional zoning, ceiling sections and fit-out works. Validation at the detailed design meeting with your architect and your lighting designer.
3. Scenography and control
   We integrate a DALI-2 or KNX protocol depending on the intended flexibility, program the usage scenarios (arrival, focus, meeting, cleaning), deploy the presence and brightness sensors, and deliver a web and mobile interface for your Office Managers. Circadian coverage aligned with the sun’s course.
4. Commissioning and handover
   We measure compliance across 100% of the delivered zones, train your internal contacts, hand over the digital as-built file and activate the ten-year warranty. Operational monitoring over 24 to 36 months, with quarterly readings and adjustment of scenarios according to the usage actually observed on your floor plates.