Office lighting: targeting 500 lux, managing biorhythm and the tertiary decree. Kytom method, 3-4 year ROI, energy savings of up to 50%.
"The back of the floor is dark"
Uncontrolled artificial lighting accounts for 25 to 30% of the office electricity bill. Over 850 m², the excess consumption quickly reaches 4,500 euros per year. Added to this is the early replacement of inherited halogen or fluorescent sources, i.e. 8 to 12 euros per light point and per intervention.
Illuminance below 300 lux doubles cervical musculoskeletal disorders. <a href="https://www.actineo.fr/" rel="noopener" target="_blank">Actineo</a> 2023 measures that 42% of employees cite lighting as the leading source of discomfort in the office. The circadian biorhythm is desynchronised under constant cold light, with a notable drop in alertness after 2 PM.
The Labour Code (R4223-4) requires lighting adapted to the nature of the tasks. The Tertiary Energy Efficiency scheme requires a reduction in final energy consumption of at least 50% by 2040 compared with 2010, a significant share of which comes from the lighting category. A demanding environmental certification becomes unattainable without DALI control and calibrated brightness sensors.
Kytom approaches lighting as an integrated system, never as a separate lot. Our space planners first map solar gain hour by hour, then position concentration zones along the facade and circulation areas at the heart of the floor. The luminaire layout is set to an average of 500 lux at workstations and 300 lux in circulation areas, in line with the standards applicable to indoor workplaces. We specify adjustable colour temperatures (2700 K to 5000 K) to respect the circadian biorhythm and deploy DALI control with presence and brightness sensors. Across the 1,200+ projects delivered since 2006, this method reduces lighting consumption by 35 to 50% while improving measures of reported comfort.
Lux measurements at 3 times of day (morning, midday, afternoon) across the entire floor, mapping of solar gain by facade, audit of existing luminaires. Deliverable: thermal map of current illuminance and list of zones under 300 lux to be addressed as a priority.
Definition of usage scenarios by zone (concentration, collaboration, relaxation), selection of lux and colour temperature targets, budget trade-off between luminaire renovation and control. Deliverable: framing note with quantified energy assumptions and associated consumption reduction trajectory.
3D luminaire layout, Dialux simulation to validate 500 lux at workstations, selection of control protocols (DALI, KNX), integration of motorised blinds to manage glare. Deliverable: complete execution file with quantitative schedule and validated manufacturer technical sheets.
Installation coordinated with the technical trades, commissioning of the control system, sensor calibration, training of occupants on the scenarios. Deliverable: lux measurement report at handover and operational energy dashboard for the energy manager.
"Our staff on the north side complained every winter. After Kytom's intervention, the lux measurements are consistent and HR feedback on visual fatigue dropped significantly within a quarter."
In renovation, the installed power must remain less than or equal to 2.8 W/m² per 100 lux of average illuminance to be maintained. Kytom validates these thresholds through Dialux simulation, then by lux measurement at handover.
Yes, provided glare is managed with controlled motorised blinds and suitable glazing. Each metre gained in solar penetration reduces artificial lighting by 8 to 12% over the day.
DALI modulates each luminaire individually according to occupancy and external brightness. On our sites, energy savings reach 35 to 50% compared with conventional switched lighting, with an extended LED lifespan.
We deploy tunable white luminaires, 2700 K in the morning and at the end of the day, 5000 K in the middle of the day. This modulation supports alertness and limits sleep desynchronisation.
Yes, LED luminaire renovation with control falls under sheet BAT-EQ-127. Energy Savings Certificates generally cover 8 to 15% of the material cost, an amount that Kytom factors in from the budget framing stage.
Yes, we schedule removals and reinstallations in zones of 80 to 120 m², in the evening or in half-days. Across 1,200+ projects delivered, business continuity has been preserved in more than 90% of lighting renovations.