At the end of November, the budget decision request arrives and the available costing fits on one line: the unit price of a luminaire multiplied by the number of points counted on a plan. The budget is voted on this basis, and the following spring the first contractor quote arrives with items nobody had anticipated.
The project is then postponed by a financial year, or cut by half its zones. A lighting renovation costing is built differently, by listing from the start everything that will be invoiced.
The items a lighting costing often forgets
Supply is the easiest part to obtain and the most visible in an offer, which explains why it serves as a proxy for the whole project. Yet a renovation on an occupied site ties up resources and hours that have nothing to do with the equipment.
Item | What it covers | What makes it slip |
|---|---|---|
Supply | Luminaires, drivers, fixing accessories, control equipment | Optics finally different, forgotten accessories |
Removal and disposal | Dismantling, sorting, treatment route for the old luminaires | Sources containing mercury, sorting to be done on site |
Access equipment | Aerial platform, scaffolding, platform, qualifications | Height, congestion, floor unable to bear the load |
Electrical rework | Circuits, protective devices, controls, control bus | Non-compliant existing installation discovered during the works |
Coordination | Work outside production, co-activity, prevention plan | Shortened time slots, overtime premiums |
Supply, installation, removal and disposal of the old luminaires
Removal is not the reverse of installation. It involves dismantling equipment often fixed for decades, sometimes on weakened supports, and immediately managing what happens to the equipment removed.
Luminaires and sources fall under the waste electrical and electronic equipment stream, with specific collection rules. Fluorescent tubes contain mercury and are hazardous waste, to be kept apart from the rest and entrusted to an approved stream, with traceability.
It should be noted in passing that the placing on the market of T5 and T8 fluorescent tubes has ended under the European regulation on hazardous substances. An installation still fitted with these sources is therefore renovated in a context where the resupply of parts is no longer assured over time.
Access equipment: aerial platform, scaffolding, work at height
This is the item that most often surprises management. In a high industrial hall, the cost of access to each point can weigh as much as the luminaire itself, and it depends on very concrete parameters.
The height dictates the type of machine, the nature of the floor dictates its ability to move when loaded, and the congestion of racks or machines dictates the set-up time. An aerial platform that must be repositioned at each luminaire in a narrow aisle does not produce the same output as a platform that handles an entire bay from a single position.
Added to this are the obligations linked to work at height: operating authorisation, inspection of the machine, harnesses, cordoning off the area. These elements are costed, and forgetting them distorts the budget as much as an error in quantities.
Reworking the circuits, controls and supports
Replacing luminaires often brings to light the real condition of the electrical installation. Saturated cable trays, undersized conductors, unsuitable protective devices, inaccessible junction boxes: these discoveries are made during the works if they have not been looked for beforehand.
Controls deserve a separate examination. Moving from a simple switch to bus control involves running a control line, powering the bus, addressing each luminaire and configuring the scenes, which represents an intervention time separate from installation.
Finally, supports are not systematically reused. A suspension designed for an old luminaire, an existing track or a sealed mounting plate may or may not be kept, and this check is done on site, not on plan.
Coordination with operations and work outside production
Few sites accept stopping a production area during the day. Work then moves to nights, weekends or technical shutdown periods, with the corresponding overtime premiums and lower productivity per time slot.
Co-activity, for its part, requires a prevention plan and an access protocol, as well as coordination with the other companies present. A project divided into short time slots multiplies set-ups and pack-ups, which lengthens the total duration.
This parameter is dealt with at the costing stage, by explicitly weighing hourly cost against the impact on production. Fixing it too late amounts to letting the contractor choose instead of the project owner.
What the audit makes it possible to secure in the budget
Most overruns come from unknowns that a visit removes in a few hours: real count of points, mounting heights, accessibility of each zone, condition of supports and circuits, operating constraints, presence of zones requiring special treatment.
A lighting audit carried out on site produces this inventory, and the accompanying study fixes the quantities and references before the tender. At Luminance, the visit, measurements, simulation and costed report are carried out free of charge for the project owner, which makes it possible to have a substantiated costing even before the budget decision.
The exercise is usefully completed by a reading over the operating life, such as the one set out in our analysis of the real cost of LED lighting over ten years. The study items, for their part, are detailed on our page dedicated to the price of a photometric study.
Building a costing that can be defended before management
A file that goes to a budget decision fits in a few documents: a works budget detailed item by item, an explained contingency, a schedule compatible with operations, and the written list of assumptions used.
The financing side is handled with the same caution. The order of 23 February 2026 abolished the energy savings certificate sheets BAR-EQ-110, BAT-EQ-127 and IND-BA-116, and only sheet RES-EC-104, relating to outdoor lighting, remains. A financing plan built on an abolished grant will not survive the first check.
Finally, the expected savings are presented with their assumptions visible: recorded operating hours, installed power before and after, maintenance interval. The chosen ranges, whether industrial luminaires or linear battens, are cited with their references so that the costing remains verifiable.
To have a survey and a full costing before your budget decision, schedule a site visit.
