Lighting audit for companies – scope and measurements

A lighting audit in a company should answer far more questions than simply how many luminaires there are and what their wattage is. An inventory can describe the installation, but it does not yet show whether the lighting matches the actual visual tasks, whether illumination is uniform, how long the system actually operates, how much energy it uses, or whether the greatest improvement potential lies in replacing luminaires, improving controls, reorganising zones or simply correcting the existing installation.

A reliable lighting audit therefore combines a technical inventory, photometric measurements, an analysis of how the facility is used and an energy assessment. Only on this basis can different measures be compared and a decision made as to whether a full upgrade, replacement of selected luminaires, automation, changes to the layout or merely improved operating practices are required.

What should a good lighting audit deliver?

A good audit should provide the owner or facility manager with reliable answers to four groups of questions:

whether the installation provides appropriate visual conditions in specific zones and at workstations;
how the lighting is actually used – when it is on, in which modes and which circuits operate at the same time;
how much energy the lighting actually consumes and which elements account for that consumption;
which measures make technical and economic sense, and which would merely replace serviceable equipment with newer equipment.

In practice, this means that an audit should not end with a list of luminaires and a note saying “replace with LED”. It should be a document that supports an investment decision and later makes it possible to verify whether the assumptions were correct.

From an auditor’s perspective, the key is to separate two issues: the condition of the installation and the potential for modernisation. An older installation does not automatically need to be replaced in full. Conversely, the fact that a facility already uses LED luminaires does not necessarily mean that the lighting performs well or efficiently.

Why is counting luminaires and their wattage not a complete audit?

Two installations with the same number of luminaires and the same installed power can have completely different energy consumption and lighting quality.

The differences may result, among other things, from:

the actual operating time of individual zones;
shift patterns and seasonality;
access to daylight;
manual or automatic control;
how luminaires are grouped into circuits;
soiling of luminaires and light-reflecting surfaces;
mounting height and room geometry;
changes in the arrangement of racks, production lines or workstations;
the optics used;
the quality of light sources and power-supply components;
local under-lighting or over-lighting.

If an audit ends with the statement that “the facility has 300 luminaires rated at 100 W each”, we know the nominal installed power, but we still do not know whether and when those 30 kW are actually being used, or whether the installation provides the required conditions on the surfaces where people work.

Scope of a lighting audit – what data should be collected?

1. Dividing the facility into zones and identifying their actual functions

The first substantive step should be to understand what actually happens in a given space. A production hall is not a single zone merely because it is under one roof.

It is worth assessing separately, for example:

production lines;
quality-control workstations;
assembly zones;
traffic and circulation routes;
high-bay storage;
order-picking zones;
loading docks and loading areas;
technical rooms;
offices and staff facilities;
car parks, yards and outdoor areas.

For each zone, the type of activity, operating hours, typical staffing, the importance of daylight and the control method should be identified. Only then can the correct assessment criteria be selected.

2. Inventory of luminaires, light sources and power supplies

The inventory remains the foundation of the audit, but it must be more detailed than simply counting lighting points.

Depending on the purpose of the analysis, it is worth collecting:

the luminaire type and model, where identifiable;
the type of light source;
the number of luminaires in the zone;
rated power and – where justified – the actual power drawn;
the type of driver or ballast;
the mounting method and height;
optics and light distribution direction;
technical condition, soiling and visible damage;
information on the age of the installation and previous replacements;
available photometric files and manufacturer documentation;
assignment of luminaires to circuits and distribution boards.

Photographic documentation and a layout plan are particularly useful in large halls and warehouses, as they allow later measurements to be linked to specific areas.

3. Lighting control method

The audit should establish who or what determines when the luminaires are switched on.

Among other things, it should be checked:

whether the whole room is switched on with a single button;
whether the installation is divided into zones;
whether zones near skylights or windows can be controlled separately;
whether occupancy or motion sensors are installed;
whether daylight sensing is used;
whether the installation supports dimming;
whether a control system such as DALI is used;
whether schedules reflect actual operating hours;
whether users override the automation because it has been configured incorrectly.

Even highly efficient luminaires may operate inefficiently if lighting remains on in an empty part of a warehouse or runs at full output despite a high contribution from daylight.

More about the use of controls is covered in our article when lighting automation is worth using.

4. Actual operating time

This is one of the elements most often oversimplified in analyses.

It should not automatically be assumed that lighting operates for as many hours as the plant itself. In a three-shift facility, some zones may be used around the clock, others only during one shift, and others only occasionally.

Operating time can be determined from several sources:

shift schedules;
interviews with operators and maintenance staff;
BMS or automation-system data;
records of switching states;
energy meters for dedicated circuits;
observations during the site visit;
production or logistics data, where they accurately reflect how the zones are used.

The greater the share of lighting costs in the facility, the stronger the case for replacing assumptions with measurements or recorded data.

5. Measurements of illuminance and uniformity

Measurements with a lux meter should be planned to represent the actual visual-task area. A single reading taken “in the middle of the hall” is not sufficient to assess the entire installation.

In practice, the following must be established:

the surface or plane on which the lighting is assessed;
the measurement-point grid;
the operating conditions of the installation during measurement;
the contribution of daylight;
the condition of the luminaires;
the control mode;
the location of workstations and obstacles that may cause shading.

In addition to average illuminance, uniformity is important. CIE defines illuminance uniformity as the ratio of the minimum value to the average value over the assessed surface. A good average is therefore not sufficient if clearly under-lit areas occur within part of the zone.

For example, if five points give readings of 700, 680, 660, 650 and 200 lx, the average is 578 lx, but the minimum is only 200 lx and the uniformity is approximately 0,35. Reporting only “an average of 578 lx” would therefore conceal a significant local lighting problem.

6. Requirements for workstations and zones

There is no single illuminance value that is appropriate for an entire production hall, office or warehouse.

As of 8 August 2026, Poland’s general occupational health and safety regulations require daylight to be suited to the type and precision of the work, while the parameters of electric lighting must comply with Polish Standards. For indoor workplaces, PKN currently identifies PN-EN 12464-1:2022-01, and for outdoor workplaces PN-EN 12464-2:2025-04.

The Polish regulations also contain a specific requirement for transitions between adjacent rooms used for internal circulation: under § 27(1), the ratio of their average illuminance levels should not exceed 5:1. This is not, however, a general uniformity threshold for a workstation – it concerns the relationship between those rooms.

An audit should therefore first identify the type of workstation or area and only then assign the relevant requirements. This applies not only to illuminance but also to other lighting-quality characteristics.

The legal requirement governing workplace lighting in Poland is set out in §§ 26–28a of the Regulation on general occupational health and safety provisions.

7. Lighting quality – more than just lux

A proper assessment of the installation should also consider light quality. Depending on the type of facility and task, the following may be relevant:

glare limitation;
colour rendering;
luminance distribution within the field of view;
contrasts and shadows;
colour temperature and colour consistency;
flicker and the stroboscopic effect;
reflections on screens, machinery or work surfaces;
visibility of moving parts;
vertical or cylindrical illuminance where relevant to the task.

CIE emphasises that good lighting requires simultaneous assessment of the quantity and quality of light – an adequate illuminance level alone does not guarantee comfort or good visibility.

In halls with rotating or fast-moving parts, or in areas where cameras are used, particular attention should be paid to temporal light modulation. Flicker and the stroboscopic effect are measurable phenomena, not merely subjective complaints from users.

8. Installed power and actual energy consumption

The rated power of luminaires is necessary information, but it should not be the sole basis of the energy balance.

If the result is to support a reliable energy analysis, the following should be established:

the actual power of operating circuits or representative luminaires;
the number of operating hours in each mode;
the degree of power reduction when dimming;
switch-off periods;
operation of zones in daylight conditions;
seasonal changes in hours of use.

In a simple facility, a well-documented balance of power and operating time may be sufficient. In a larger plant, circuit measurements or temporary logging may be justified. The most important point is that the result can be reproduced from the data and assumptions recorded in the report.

9. Maintenance condition of the installation and environmental conditions

In industrial plants, deterioration in performance does not always result solely from the age of the light sources.

The audit should pay attention to:

soiling of diffusers, reflectors and luminaires;
dust in the rooms;
high or low temperatures;
humidity;
aggressive atmospheres;
vibration;
frequent overvoltages or failures;
soiling of walls and ceilings affecting reflections;
difficult maintenance access.

An installation may have been correctly designed originally but may no longer achieve the required parameters because of operating conditions or changes in how the hall is used.

How should illuminance measurements be carried out correctly?

A correct measurement requires more than simply switching on a lux meter.

Measure a representative surface, not a random point

The points should represent the task surface or assessed area. In a warehouse, this may be a different plane from that used for quality control, while on a traffic route it may differ from the plane used at an assembly bench.

Record the measurement conditions

The report should make clear:

which luminaires were switched on;
which mode the control system was operating in;
whether daylight entered the room;
whether the measurement was taken at full or partial occupancy;
what the hall configuration was;
whether the installation was in its typical operating condition;
which instrument was used for the measurement (model / identifier) and its current calibration or metrological-control status.

Without this information, the result cannot later be compared reliably with post-completion measurements. In measurement practice, especially when a result is close to a criterion value, a difference of only a few lux should not automatically be treated as “pass / fail” without considering measurement uncertainty, instrument characteristics and measurement conditions. This is a principle of good measurement practice, not an additional statutory threshold.

Separate the effect of daylight

If the purpose is to assess the electric lighting installation itself, daylight can distort the result. Depending on the facility, measurements are taken under conditions with limited daylight contribution, or its contribution is documented and the assessment is performed under several conditions.

This is particularly important in halls with skylights and extensive glazing. Lighting near skylights may require a completely different control strategy from lighting in the middle of the hall.

Do not stop at the average

Results should be analysed at least in terms of average values, minimum values and uniformity where applicable. If the issue is glare, colour, flicker or the visibility of vertical surfaces, a lux meter alone will not answer every question.

How should the audit result be interpreted?

The most important step is to connect the technical results with the cause of the problem.

Correct illuminance and good uniformity, but very long lighting hours primarily suggest analysing controls and schedules.

A good average but poor uniformity may indicate incorrect luminaire spacing, unsuitable optics, obstructions or a changed workstation layout.

Excessively high values in many zones are not an argument for leaving the installation unchanged. They may indicate oversizing and the possibility of reducing power, provided that all other required parameters are still met.

Values that are too low only locally do not necessarily justify replacing the entire hall installation. It may be more rational to correct a few points, change optics, add task lighting or reposition luminaires.

Correct parameters with older luminaires do not by themselves prove that replacement is economically justified. Potential energy savings, maintenance costs, spare-parts availability, failure risk and investment cost must be considered together.

Lighting controls – potential that is not visible from luminaire wattage alone

In many facilities, the more important question than “which luminaire should we buy?” is “when does this luminaire actually need to operate at full output?”.

The audit should assess the possibility of:

dividing a large hall into smaller zones;
separately controlling rows near skylights and windows;
using occupancy sensors in warehouses and ancillary rooms;
introducing schedules;
reducing output during periods of lower activity;
controlling illuminance in response to daylight;
central monitoring of operating states and faults.

This does not mean that automation is always cost-effective. If a zone operates continuously throughout a shift and receives no daylight, an extensive control system may deliver little benefit. That is precisely why it should be assessed in the audit rather than added to the design by default.

Which options should an audit compare?

An audit should not assume a single solution in advance. It makes sense to compare options with different levels of intervention, for example:

operational option – adjusting schedules, zoning, cleaning, repair or regulation;
control option – retaining existing luminaires and adding automation;
partial-replacement option – upgrading only the zones with the highest consumption, poorest quality or highest failure rate;
full-modernisation option – a new luminaire and control layout;
design option – changing luminaire positions where the problem is primarily caused by geometry or a new workstation arrangement.

When can an audit show that full lighting replacement is not necessary?

This is one of the more important possible conclusions.

Full replacement may be unjustified when:

existing LED luminaires have good performance and are in suitable condition, but controls are lacking;
the problem affects only a few workstations;
part of the hall has already been modernised;
the installation is oversized and the output of existing luminaires can be reduced;
soiling is the main cause of poor performance;
the workstation layout changed after the original design was completed;
the greatest potential lies in reducing operating time rather than improving light-source efficiency;
the luminaires require changes to optics or positioning rather than complete replacement.

The opposite situation also occurs: an installation may use relatively little energy but fail to provide appropriate visual conditions. In that case, the purpose of the intervention is not to maximise savings but to bring the lighting up to the required performance.

The most common mistakes in simplified lighting audits

Assuming operating hours without verification

Using one number of operating hours for an entire facility can significantly distort the result, particularly in plants with many zones.

Basing the energy balance only on nameplate power

Rated power is a useful starting point, but in installations with different drivers, dimming or partial loading, it may not reflect actual operation.

A single lux-meter measurement

A single point does not allow uniformity or light distribution to be assessed.

A universal “500 lx” for the entire facility

Requirements depend on the type of task and zone. They should be selected according to the actual function of the area, not a general label such as “hall” or “warehouse”.

Ignoring light quality

A good illuminance level does not compensate for excessive glare, poor colour rendering, troublesome flicker or strong contrasts.

Comparing luminaires only by lumens or watts

Performance in the facility also depends on light distribution, geometry, mounting height, losses, reflecting surfaces and the control strategy.

“Savings” achieved at the expense of poorer lighting

Reducing power is not an improvement in efficiency if it results in inappropriate workplace lighting conditions.

No option that avoids full replacement

If every audit leads to the same answer – “replace everything” – it is difficult to regard it as an independent assessment of the available options.

Auditing a production hall, warehouse, office and outdoor area – what changes?

Production hall

The most important factors are the actual visual tasks, mounting height, process-related obstructions, soiling, changing workstation layouts and occupational safety. In selected processes, the stroboscopic effect, visibility of moving parts and colour rendering require particular attention.

Warehouse

Traffic routes, racking, picking areas, goods-receipt and dispatch zones, and areas used only occasionally should be distinguished. Occupancy-based control and zoning are often particularly important.

Office

In addition to illuminance, glare, screen reflections, uniformity and the relationship between daylight and electric lighting are important.

Specialist lighting

Emergency lighting, explosive-atmosphere zones, areas exposed to extreme temperatures and process lighting installations require additional criteria and should not be assessed solely using a standard checklist for production halls. PKN identifies separate standards for emergency lighting.

Outdoor areas and road lighting

For outdoor audits, additional factors include site geometry, the height and spacing of lighting points, the power-supply arrangement, night-time controls, impact on the surroundings and requirements specific to the relevant function. PN-EN 12464-2 applies to outdoor workplaces, while for road lighting PKN publishes the PN-EN 13201 series, including PN-EN 13201-2 performance requirements and PN-EN 13201-4 methods of measuring lighting performance.

If the assessed facility includes road lighting, it should be evaluated using criteria appropriate to roads and the specific function of the area; in this article, that scope is treated as supplementary to the main focus on lighting audits for companies and facilities.

Lighting audit vs lighting design – they are not the same thing

An audit primarily answers the question: what is the current condition, where are the problems and which options make sense.

A design answers a different question: how exactly should the target installation be designed – selecting luminaires, layout, optics, parameters and controls, and verifying the result by calculation.

Programs such as DIALux are very useful at the design stage and for checking alternatives, but a computer model does not replace a proper inventory and measurements. Its output depends on the input data: geometry, luminaire photometric data, reflection factors, operating assumptions and the maintenance factor.

Lighting audit vs energy efficiency audit and White Certificates

These are also two different documents.

A lighting audit can provide technical data, measurements and options required for further investment analysis. However, if the objective is to obtain energy efficiency certificates in Poland, a separate energy efficiency audit is required, prepared in accordance with the applicable Polish regulations and methodology.

Current legislation and materials concerning energy efficiency certificates in Poland are published by the Polish Energy Regulatory Office (URE).

Likewise, under grant programmes, the required documentation depends on the specific call. The fact that a lighting audit has been carried out does not automatically mean that the programme requirements have been met or that funding will be awarded.

Lighting audit vs enterprise energy audit

Lighting is only one of the energy-consuming systems in a company. An enterprise energy audit examines a much broader energy balance which, depending on the organisation, may include processes, buildings, compressed air, refrigeration, heat sources, drives and transport.

A lighting audit can be an in-depth analysis of one of these areas, but it does not replace the enterprise-wide audit.

If you primarily want to see the sequence of stages in the auditor’s work, rather than the criteria used to assess the installation, a separate article explains how an energy audit of lighting is carried out.

What should a lighting audit report contain?

For a larger facility, the report should allow another person to reproduce the analysis. In practice, it should contain at least:

a description of the facility, zones and how they are used;
an inventory of the installation;
a plan or map of lighting points;
a description of the controls and actual operating hours;
the measurement methodology and results;
assignment of requirements to the assessed workstations and zones;
assessment of illuminance, uniformity and other relevant quality characteristics;
an installed-power and energy-consumption balance;
identification of the causes of the problems found;
alternative measures with clearly stated assumptions;
technical and economic assessment of the alternatives to the extent permitted by the available data;
photographic documentation;
a list of missing data or information requiring confirmation;
recommendations for post-completion measurements.

Such a report supports decision-making. A table containing only “current condition / LED replacement / savings” is closer to a modernisation proposal than to a complete audit.

How should a facility be prepared for an audit?

Before the site visit, it is worth collecting:

floor plans and facility layouts;
distribution-board and circuit diagrams, if available;
luminaire schedules and previous designs;
information on the operating hours of individual zones;
shift schedules;
BMS or control-system data;
bills and energy-consumption profiles if lighting represents a significant share;
documentation of previous modernisations;
information on employee complaints or visibility problems;
planned changes to the production, warehouse or workstation layout.

Missing some of the data does not always make an audit impossible, but the gaps should be described explicitly. It is better to identify an assumption and its impact on the result than to present an uncertain value as if it were a measurement.

FAQ – frequently asked questions about lighting audits

Does a lighting audit require measurements?

If the audit is intended to assess actual lighting quality and compliance of workplace conditions, measurements are a key element. Technical documentation alone does not show the current condition of an installation after years of operation.

Is measuring illuminance enough?

No. Illuminance is one of the basic parameters, but a full assessment may also require checking uniformity, glare, colour rendering, flicker, visual conditions and the control method.

Do measurements have to be taken at night?

Not always. It depends on the purpose. If the aim is to assess electric lighting alone in a facility with substantial daylight, the daylight contribution must either be limited or documented separately. When assessing daylight-linked control, measurements under different conditions may be required.

Does having LED luminaires mean that an audit is unnecessary?

No. An audit may reveal problems with controls, oversizing, poor uniformity, glare, incorrect positioning, changes in room use or the quality of the luminaires themselves.

Does an audit always end with a recommendation for full replacement?

No. A proper audit should allow for retaining part or all of the existing installation where this is the best technical and economic solution.

Is a lighting audit the same as a modernisation design?

No. An audit diagnoses the current condition and compares possible courses of action. A modernisation design defines the target solution in detail.

Key conclusion

A lighting audit should assess the installation as a system, not as a list of luminaires. It must combine actual use, measurements, workstation requirements, light quality, power, energy consumption and controls.

Only then can a responsible decision be made on whether to invest in full replacement, modernise selected zones, add automation, correct the design or leave the installation largely unchanged.

If you need an assessment of a lighting installation in a production hall, warehouse, office building or another larger facility, contact Energy Trend. The audit scope can be tailored to the purpose: technical assessment, a planned investment, measurements, energy analysis or preparation of data for a subsequent investment process.

Sources and technical basis

The key sources used to prepare and verify this article are: