Energy savings: how much does intelligent lighting control bring in?

The savings from intelligent lighting with detection rest on a simple principle: consume only the light that is actually useful. Between switching to LED, presence detection, dimming and making use of daylight, the gains add up. But what orders of magnitude can really be expected, and how is the return on investment (ROI) calculated? Here is a cautious, quantified approach, without exaggerated promises.

Where do the savings come from?

Three levers are superimposed in a controlled installation, and it is important not to confuse them:

• Replacement with high-performance LEDs: for equivalent illuminance, an LED with high luminous efficacy (up to 200 lm/W in the best ranges) consumes a fraction of the energy of an old source. This is the basic gain, independent of control.
• Presence detection: switching off or lowering the illuminance of unoccupied areas eliminates unnecessary consumption, especially in rooms with intermittent use.
• Dimming and daylight management: modulating the flux to maintain a stable setpoint in lux, taking into account the contribution of the sun, avoids over-lighting.

These levers rely on a suitable control system. We detail the protocols in our article on DALI and KNX control systems.

Realistic orders of magnitude

There is no single figure: the gain depends on the starting situation, the uses and the contribution of daylight. The ranges commonly observed and documented by players in the sector nevertheless give cautious benchmarks:

• Presence detection alone: installing luminaires with detection makes it possible to reduce consumption considerably, by around half in rooms with intermittent occupancy, compared with lighting left on permanently.
• Daylight management: near glazed façades, a light sensor can greatly reduce the artificial share during the brightest hours; gains can be very high in the areas concerned.
• Dimming and remote control: in outdoor and public lighting, power reduction typically adds 20 % to 30 % of additional savings to those already obtained by switching to LED.

By combining high-performance LEDs and intelligent management, the most complete lighting management systems claim up to 80 % reduction compared with an old, uncontrolled installation. This high figure assumes an unfavourable starting situation and a use well suited to detection: it should be considered a ceiling, not an average.

No value can be guaranteed without a study: the real saving depends on the existing installation, the hours of occupancy, the architecture of the building and the contribution of daylight. It is precisely the role of a photometric study to quantify it.

Calculating the ROI: the method

The return on investment of an intelligent lighting project is assessed on the total cost of ownership, not on the purchase price alone. The approach comes down to five steps:

1. Measure current consumption: installed power, annual operating hours, consumption in kWh.
2. Estimate target consumption: new LED power, then application of the reduction factors linked to detection and dimming by zone.
3. Value the annual gain: difference in kWh multiplied by the cost of energy, to which is added the maintenance saving (longer lifetime, fewer replacements).
4. Include the available aid: Energy Savings Certificates (CEE) and support schemes can lighten the initial investment.
5. Divide the investment by the annual gain to obtain the payback time.

A better-performing luminaire and well-sized control represent an extra initial cost, but generally offer a better return on investment in the long term thanks to cumulative savings and reduced maintenance.

Examples by type of site

Car park

A car park is a textbook case: very intermittent occupancy, often permanent operation in the absence of control. Presence detection, combined with a reduced standby level, generates significant savings there while maintaining safety. Discover our car parks range. A municipal sports hall or gymnasium, occupied by time slots, follows the same logic: detection by zones and dimming greatly reduce the bill between two bookings.

Office and open space

In commercial buildings, the combination of dimming and daylight management is the most profitable, because workstations near the windows benefit from a strong natural contribution. Absence detection takes over at the end of the day. See our offices and open space range.

Logistics warehouse

In a warehouse with aisles, detection by aisle avoids lighting the whole volume permanently. Combined with high-efficacy luminaires, it greatly reduces the bill over large areas and great heights.

The efficacy of the luminaire remains the foundation

No control compensates for a mediocre luminaire: savings start with the luminous efficacy of the source. The more lumens per watt a luminaire produces, the less it consumes for the same illuminance, and the more control amplifies the gain. That is why we recommend starting from high-efficacy ranges, as explained in our article on luminous efficacy at 200 lm/W. The GALAXY HP linear luminaire at 170 lm/W is a representative example.

FAQ

What realistic savings can be expected from intelligent lighting?

It depends on the site. Detection alone often halves consumption in rooms with intermittent occupancy; by combining LED, detection and daylight management, gains can reach up to 80 % compared with an old installation. Only a study can quantify your precise case.

How long does it take to recoup the investment?

The payback time depends on initial consumption, the cost of energy, the aid obtained (CEE) and the operating hours. The more energy-hungry the current installation and the longer it is used, the faster the ROI.

Does detection reduce the lifetime of LEDs?

No. Modern LEDs withstand a large number of switching cycles. Conversely, dimming reduces heating and tends to preserve the useful life (L70/L80) of the luminaires.

Can a percentage of savings be guaranteed in advance?

No percentage can be guaranteed without an audit. A photometric and energy study models your installation to provide a reliable estimate, zone by zone.

Need a photometric study? Quantifying your savings and your return on investment is the work of a lighting design office: we recommend the expertise of the Luminance Consulting agency, the lighting design office that contributes to developing our ranges of luminaires based on an in-depth analysis of the needs of the most demanding customers. Rexylum supplies you with the prescribed luminaires and intelligent lighting solutions: contact us.