Code of Practice on Workplace Well-being: what does Book III mean for your office layout?

The Code of Practice on Workplace Well-being is a lengthy document that most employers only refer to when an inspection is coming. That is understandable but unfortunate, as Book III contains something you won’t find anywhere in Dutch legislation: concrete numbers that you can simply use to check your office against.

This article does not repeat the Codex. It translates Book III into what you physically need to arrange in your office — with the numbers included, so you can check what is and isn’t compliant.

What Book III is about

The Code consists of ten books. Book III is titled “Workplaces” and its Title 1, “Basic Requirements Concerning Workplaces,” is the section that pertains to your building: dimensions, light, air, temperature, and social facilities. It is the transposition of a European directive and applies to every place in your company where people work.

The main rule is stated in Article III.1-2: regardless of what follows from the risk analysis, as an employer, you must take the necessary measures to ensure that workstations at all times comply with this title. You must first seek advice from the Committee.

Pay attention to the phrase “at all times”. It’s not a one-time delivery but a continuous condition — and that’s exactly why most deficiencies creep in unnoticed, for example because a department grows within the same square meters.

Space: the numbers you need to know

Article III.1-6 is the article you want to memorize. The surface area, height, and air volume of workspaces must be such that employees can perform their work without risk to their well-being. And then it gets concrete:

These are absolute minimums, not targets. An office with a height of 3 meters and workstations of 4 m² is well above the standard; a converted attic with a height of 2.3 meters falls short, no matter how nice it is.

When you may deviate

The Codex allows for deviations, but under four simultaneous conditions: it is technically and objectively impossible or unreasonable to demand, the risk analysis shows that safety and health are not endangered or remain guaranteed through alternative measures, those alternative measures are actually implemented, and the competent prevention advisor has provided prior advice and the Committee has given prior approval.

This last condition is often forgotten. Without a written procedure, the deviation is not covered.

How to calculate this for a specific floor plan is explained in square meters per workstation.

Air: the requirement most frequently violated

Article III.1-34, since the amendment of 2019, is the most strictly worded article in Book III and simultaneously the article where most offices fail to comply.

You conduct a risk assessment of indoor air quality, examining the airflow rate of supplied air and potential pollution sources: presence and physical activity of people, building materials, flooring, furniture, plants, technical equipment, maintenance and cleaning, and the operation of the ventilation system.

And then the strict requirement. You take technical or organizational measures so that:

• the CO₂ concentration is usually lower than 900 ppm, or
• a minimum ventilation rate of 40 m³ per hour per person present is respected.

There is an exception regime with 1200 ppm or 25 m³/h, but only if you can demonstrate, based on the risk analysis, that employees enjoy an equivalent or better level of protection because pollution sources have been eliminated or significantly reduced — for example, through low-emission materials — and you have consulted the prevention advisor and the Committee in advance.

“Generally lower than” is defined: the concentration remains below the value for 95% of the usage time, calculated over a maximum of 8 hours, assuming an outdoor concentration of 400 ppm.

What this means in practice

For buildings with a building permit after January 1, 2020, you simply need to comply. For older buildings that do not meet the requirements, an alternative applies: you draft an action plan in consultation with the prevention advisor and the Committee, including measures for the short, medium, and long term, plus a timeline. This action plan and the risk analysis are included in the overall prevention plan.

In other words: not meeting standards is allowed, but doing nothing is not.

A CO₂ meter costs forty euros and provides an answer within a day. That is the cheapest compliance check available.

And the installation itself

Article III.1-36 sets requirements for ventilation systems. Two of these are directly relevant for office comfort: the system must distribute fresh air evenly across the workspaces, and employees should not be bothered by temperature fluctuations, drafts, noise or vibrations.

The latter is a point of reference that few employers are aware of. A noisy ventilation system is not something to get used to; it is a shortcoming in relation to the Codex. Additionally, for humidification or dehumidification systems, the average relative humidity over a workday must be between 40% and 60%, or between 35% and 70% if you can demonstrate that the air does not contain hazardous agents.

Lighting: 500 lux for desk work

Article III.1-31 requires sufficient daylight, and adequate artificial lighting if that is not possible. Article III.1-32 then offers you two options: apply the standards NBN EN 12464-1 and -2 and you are considered compliant, or follow the minimum requirements outlined in Annex III.1-2.

From that appendix, measured at the work surface or, if absent, at a height of 0.85 meters:

The appendix contains three additional provisions that are relevant in practice: lighting must be evenly distributed without sudden and sharp transitions, lamps must not flicker or exhibit stroboscopic effects, and lamps for the work surface must have a color rendering index of 80 or higher. Also explicitly stated: if more light is needed due to eye conditions or age, adjust the lighting intensity accordingly.

Social facilities: the list that is often incomplete

Article III.1-39 lists what you are obliged to provide. Four categories:

1. Sanitary facilities — lockers, sinks, showers, and toilets
2. A canteen
3. A rest room
4. A local space for pregnant employees and employees who are breastfeeding

The location, layout, and equipment are determined after advice from the prevention advisor-occupational physician and the Committee. The rooms must be sufficiently spacious, ventilated, lit, and heated according to their purpose, and cleaned at least once per day.

Toilets

At least 1 individual toilet per 15 male employees and 1 per 15 female employees working simultaneously. Urinals may replace toilets for men, provided there is at least 1 toilet per 25 male employees. For every four toilets or urinals, there is one sink. Toilets are fully separated for men and women and must not open directly onto the workshop, the canteen, or the locker rooms.

Canteen

The minimum area depends on the maximum number of simultaneous users: up to 25 employees, 18.5 m²; from 26 to 74 employees, 18.5 m² plus 0.65 m² per employee above 25, and so on. The canteen is equipped with sufficient tables and seating with backrests, drinking water distribution, means to wash hands, facilities for storing and warming food, and covered waste bins.

You may dispense with a canteen with the Committee’s approval, and you may allow employees to eat in the same office space provided hygiene is guaranteed and the occupational health and safety advisor and the Committee have given prior approval.

Rest room

Mandatory when the risk analysis shows that employees need rest breaks. The Codex explicitly mentions several situations, including exposure to noise or vibrations, work that causes increased exposure to psychosocial risks, waiting duties, and a workday interrupted throughout the day. Also when the prevention advisor or the Committee deems it necessary.

The minimum area: 9 m² for up to ten employees, plus 2 m² per each subsequent group of ten. The rest area may be an annex of the canteen or located in a space with another purpose, provided it is protected from the nuisance that caused the need. See quiet space in the office for practical implementation.

Breastfeeding room

Article III.1-62 is clear: a discreet and enclosed room where pregnant employees can rest in a lying position under comfortable conditions, and where employees who breastfeed can feed and express and store milk in hygienic conditions. The room is equipped with a facility for washing hands.

This is the regulation most often missing in Belgian offices. What a good implementation looks like is explained under office breakout spaces.

What Book III does not regulate

Two things employers often look for.

Office acoustics. There is no specific Belgian standard for the acoustic quality of offices. What does exist: the requirement that ventilation systems must not cause noise disturbances, and the mandatory rest room provision in case of noise exposure. In practice, ISO 22955 (2021), the international standard for acoustic quality in open-plan offices, is used as a reference. Practical application: acoustic solutions.

A prayer room. It is not listed as a mandatory social facility. Setting it up is a free choice — see prayer room.

The checklist

• Rooms are at least 2.5 m high
• Every employee has at least 10 m³ of actual space and 2 m² of free surface area.
• An indoor air quality risk analysis has been conducted
• The CO₂ concentration remains generally below 900 ppm, or there is 40 m³/h per person, or there is an action plan in the global prevention plan
• The ventilation system does not cause discomfort due to drafts, noise, or vibrations
• Office workstations and meeting rooms achieve 500 lux
• There is sufficient daylight, or a justified explanation why not
• Sanitary facilities meet the required numbers: 1 toilet per 15 employees per gender, 1 sink per 4 toilets
• There is a canteen with the correct minimum area, or a documented agreement from the Committee
• There is a restroom if the risk assessment requires it, with a minimum of 9 m² per up to ten employees
• There is a discreet, enclosed room with laundry facilities for pregnant and breastfeeding employees
• All social facilities are cleaned at least once a day
• The Committee has advised on the measures from this title

Belgium versus the Netherlands

The contrast is sharp and worth noting if you operate in both countries. Belgium sets the numbers in law, while the Netherlands uses open standards and refers to NEN.

Where the Code prescribes 2 m², 10 m³, 2.5 m, 900 ppm, and 500 lux, the Dutch Arbobesluit states that the dimensions must be "such" and the lighting "sufficient and efficient." These numbers come from NEN standards, which are not laws themselves. The Dutch side is covered in Arbo Act workplace requirements: checklist for offices.

From compliance to practical

An office can comply with every provision of Book III and still be a place where no one can concentrate. The Code sets the minimum requirements: enough air, enough light, enough space. It says nothing about whether people enjoy working there.

That’s why we start with the people, not the standard. The impactscan surveys employees and translates the results into zones and numbers; then follows the design. The Codex is the starting point, not the destination.

How to request this without setting up a half research bureau is explained in employee survey on the workplace: 25 questions, seven minutes to complete.

Frequently asked questions about the Code and your office

How many m² does the Codex require per employee?

Article III.1-6 requires at least 2 m² of free surface area and 10 m³ of actual space per employee, in a room at least 2.5 meters high. These are absolute minimums. Deviations are only allowed under four simultaneous conditions, including prior advice from the prevention advisor and approval from the Committee.

What is the CO₂ limit in Belgian offices?

The CO₂ concentration should normally remain below 900 ppm, or at least 40 m³ of fresh air per hour per person present must be supplied. An exception regime of 1200 ppm or 25 m³/h is possible, but only with justification from the risk analysis and prior advice from the prevention advisor and Committee.

How many lux are required for office work?

At least 500 lux, measured at the work surface or, if that is absent, at a height of 0.85 meters. The same value applies to meeting rooms. For canteens and lockers, 200 lux is sufficient, and for corridors and stairs, 100 lux.

Is a lactation room mandatory according to the Codex?

Yes, as soon as the risk assessment shows that employees need rest breaks. The Code explicitly mentions, among other things, exposure to noise or vibrations, work with elevated psychosocial risks, on-call duties, and a workday that is broken up throughout the day. The minimum area is 9 m² for up to ten employees, plus 2 m² for each additional group of ten.

What if my building doesn’t meet the air quality requirements?

For buildings with a building permit application after January 1, 2020, you must simply comply. For older buildings that do not meet the requirements, you develop an action plan in consultation with the prevention advisor and the Committee, including measures for the short, medium, and long term, along with a timeline. This action plan is incorporated, together with the risk analysis, into the global prevention plan.

Last updated on 24 October 2026 by Stijn Belmans