On average, Dutchmen spend 80 to 90% of their time indoors, be it at home or at the office. So it is of paramount importance that the interior climate of buildings is of sufficient quality that everyone using the building feels healthy and comfortable.
This site provides more information on the importance of a proper interior climate in the workplace. It also diwscusses the causes of some of the more common temperature and humidity-related complaints, and what can be done to remedy them. In addition, the site lists information on office floorage, the layout of rooms and lecture halls, and the use and placement of printers and other equipment as they relate to interior climate.
A large number of other aspects determine whether people feel comfortable in a room or not. The primary aspects are:
A. Individual-related aspects
- the nature of the work;
- general health;
- being easily influenced or not.
B. Environmental aspects
- air temperature and humidity;
- any air currents (draught);
- any heat radiated by lamps and other heat sources;
- air quality (inflow of fresh air and existence of air pollutants in the room).
People working in office environments often complain about the air quality. Complaints include the air being stale, musty or too dry. On this page, we will discuss the causes of a number of common complaints, as well as the means to do something about them.
1. DRY AIR (HUMIDITY)
Air contains moisture to some extent. The absolute amount of moisture the air may hold (the 'humidity') mainly depends on the temperature. The higher the temperature, the larger the absolute amount of moisture the air may hold as water vapour.
Low humidity in practice only occurs in winter. It is caused by cold air being brought in from the outside and heated up. As cold air cannot contain high amounts of moisture, the absolute humidity of the air is low. As the air heats up, it becomes able to hold a much larger amount of moisture. So, if the absolute humidity remains the same, the relative humidity will decrease. For relative humidity is the ratio of the absolute amount of water vapour in the air and the maximum amount of water vapour this air may hold at any given temperature at that time.
The Working Conditions Information Sheet 24, Interior Environment (SDU, 2013) states that no connections exists between complaints of air being too dry and relative humidity for the usual humidity values in winter. Only when the humidity is extremely low, as is the case in airplanes, is there a possibility that low humidity may cause irritation to the bronchi and a sensation of the air being too dry. Humidity is considered to be extremely low when it is less than 15%. This percentage is hardly ever to never reached in Dutch offices, as the Dutch winter is not terribly cold and the building itself and the people working in it constantly emit (a lot) of moisture.
People are generally unable to accurately estimate relative humidity. The complaints related to low humidity are generally not caused by the low humidity itself, but by irritants in the air, like dust and pollutants (e.g. as emitted by equipment and printers). In particular when the temperature is high and little fresh air flows in, they may cause complaints and irritation to the mucosa.
When temperatures are higher, the dust present in the room (in chair coverings, on desks and in closets, etc.) is easily released up into the air, leading to eye and throat irritation.
2. STALE AIR
Research by Fang and Fanger, 1997, indicated that air of a high temperature and humidity has a high energy density and, consequently, is experienced as being much more stale and stuffy than air of a low temperature and humidity.
For example: If clean outside air with a temperature of 18 °C and a relative humidity of 30% is heated up to a temperature of 28 °C and has its relative humidity raised to 70%, the percentage of people not satisfied with the air quality will rise from 8 to 60, while nothing has changed about the composition of the air!
In addition, higher temperatures and humidity cause increased emission by fittings and furnishings. This may in turn cause irritation to the mucosa.
3. ACTIONS TOO TAKE WHEN THE AIR IS TOO DRY
As has become apparent, the climate here in the Netherlands generally does not require humidification of inside air. When the air is experienced as being too dry, the solution generally is not to be found in humidifying the air, as most of the complaints are caused by insufficient air quality. What's more, humidification can itself cause further complaints. Improper maintenance of air humidification systems will result in microbiological organisms developing in the water, which may lead to various health problems. Such pollution by microbes is least likely to appear when humidification systems are based on steam.
Humidification may only be required for some particular work, like in labs or printing offices, for work-related reasons.
Humidity-related complaints can be prevented by ensuring a proper inflow of fresh air, limiting the accumulation of dust and maintaining relatively low temperatures (< 21 ºC).
APPROACH IN REGULAR SITUATIONS:
Measures that may help reduce humidity-related complaints:
- The ventilation system is to be in proper working order, so plenty of fresh air enters the room. When in doubt about the state of the ventilation system, report this at the building's service desk.
- If possible and permitted, ventilate the room as well as possible by opening windows. To prevent any consequential complaints of draught, open the windows during breaks.
- Preventing or reducing dust accumulation:
- Install sources of pollutants like photocopiers and printers outside the workspace.
- Make sure that floors, desks, windowsills and other horizontal surfaces can be easily reached for cleaning. This means:
- adopt a clean desk policy
- bind cables together and place computer cases underneath the desk.
- put books, folders and binders in closed closets.
- do not place anything on top of closets.
- do not put boxes on the floor.
- Regularly remove the dust from plants and throw away withered plants/flowers.
- Lower temperatures to 20-21 degrees.
- Do not attach water bowls to radiators. Only a very small amount of water evaporates into the air. At the same time, these bowls are the perfect breeding ground for mould and bacteria, which will actually worsen the complaints.
APPROACH IN EXTREME SITUATIONS (WINTER):
At times of low outside temperatures (long-term frost with daytime temperatures below freezing), inside air humidity may become extremely low (< 15%). This hardly ever occurs, but if it does, this low humidity may contribute to the air being experienced as being too dry. People wearing contact lenses are especially affected. People with asthma or other complaints of the airways or skin can be very sensitive to low humidity as well. In addition to the measures detailed above, the company doctor may advise that further measures need be taken. The company doctor may, for instance, advise the Facility Department to install a temporary mobile air humidifier.
- Working Conditions Information Sheet 24, Interior Environment, instructions for healthy and comfortable buildings. 3rd edition, 2013.
- Fang, L., Wyon, D.P., Fanger P.O. (2003) Sick building syndrome symptoms caused by low humidity. In: Proceedings of Healthy Buildings 2003, Vol. 3, pp. 1-6.
Printers and photocopiers
Toner is mainly used in laser printers, photocopiers and fax machines. Some of the powders released when using toner may cause irritation and, with exposure to extreme amounts, even constitute a health hazard. Research has proven, however, that low concentrations of the powder do not pose a health risk.
Toner powder is a mixture of a number of very fine particles:
- resin particles to melt the toner and bind it to the paper;
- carbon black;
- colour pigments;
- magnetizable metal oxides to generate an electrostatic charge.
Threshold limits (the so-called MAC values) have been determined for hazardous materials, defining the maximum allowable concentration of such substances in parts per million of air. Standards like the MAC values may not be exceeded. However, the MAC values of these substances could be exceeded through intensive use of badly maintained equipment or use of the equipment in small, poorly ventilated spaces. Maintenance and replacement of parts like internal filters reduce emissions and are therefore by regulation to take place regularly.
Hazardous materials include:
- nitrogen dioxide (NO2);
- toner powder (particulates, carbon blacks), which may include heavy metal particles (mercury, cobalt, nickel);
- chlorized carbon compounds;
- paper dust;
- volatile organic substances like benzene, styrene and toluene;
- ozone (O3): prevalent mainly in older equipment, less so in more modern machines.
RECOMMENDATIONS FOR THE PLACEMENT OF LASER PRINTERS AND PHOTOCOPIERS
Photocopiers, fax machines and laser printers are more of a health risk at the office when multiple machines are placed next to each other or if it concerns mid-to-high-volume machines.
Laser printers and photocopiers are classified as one of the following volume categories:
- low-volume: less than 5,000 print-outs per month;
- can be placed in a workroom, but place as far from the workplace as possible
- mid-volume: more than 5,000 but less than 50,000 print-outs per month;
- need to be placed in a separate space or well-ventilated hallway
- high-volume: more than 50,000 print-outs per month;
- need to be placed in a separate printing room with a dedicated exhaust
- Another possibility is to use an inkjet printer instead of a laser printer.
Recommendations for toner replacement
Current printer toners are almost fully closed systems (cartridges), resulting in a very slight chance of being exposed to toner powder when replacing the cartridge. However, this does not apply to toner containers for photocopiers and suchlike.
The following recommendations apply when replacing such containers:
- never replace the container with your bare hands. Wear disposable gloves and, preferably, a disposable industrial mask;
- wrap the toner container in a plastic bag and dispose of it as a hazardous material.
The minimum amount of space required for an office workstation is determined by the furniture required for the position, the control space and the circulation area of the workstation. Most companies have developed their own office room floorage standards, based on the number of employees and the available furniture. The NEN 1824 standard was developed on the basis of these standards. This is a Dutch standard for determining minimum office workstation floorage. The legal basis for this standard is formed by Section 3.19 of the Working Conditions Decree, which states: "The workstation dimensions and air volume are such that the employee can perform their work with no danger to their safety, health or well-being."
In addition to determining the floorage on the basis of the NEN 1824 standard, attention needs also be paid to light incidence, draught and suchlike. It may turn out to be necessary to adjust the amount of floorage accordingly.
- Basic workstation
A basic workstation per person is the starting principle. A basic workstation consists of: office chair, worktable, screen space, reading/writing desk, circulation and movement area. The point of entry to an office space forms part of its circulation area. The use of this point of entry (including any doors) may not infringe on the movement area. The dimensions of the basic workstation for one person are as follows:
- at least 6 m2 for a workstation with a flat panel display (LCD/TFT) or laptop;
- at least 7 m2 for a workstation with a classic cathode ray tube (CRT) screen.
Depending on the work to be performed, the minimally required floorage dimensions may be adjusted. The basic workstation minimum floorage dimensions adjustments are as follows:
- a table for laying out drawings: +2 m2
- a freestanding closet: +1 m2
- a (moveable) drawer unit: +0.5 m2
- a meeting area: +1.5 m2
- other furniture and equipment (printer and suchlike, filing cabinet): + actual dimensions + dimensions of use
The minimally required floorage for an office for three persons, all working with a flat panel display, with 3 freestanding closets and a printer amounts to:
3 basic workstations
3 freestanding closets
The basic workstation standard only applies to administrative workstations in use for the larger part of the day. workstations only in use for one or two hours a day, or for one day a week, do not have to meet these standards.
The UT has computer rooms available for students to perform their work. The Working Conditions Act applies to students as well. Students are to be able to perform their work in safety and good health. No defaults have been set as regard the floorage of computer room workplaces. In consultation with the Labour Inspectorate, the UT has decided on the following workplace floorage defaults: a desk of 1.20 x 1.0 m, in front of which 1 m of space for a chair and 0.5 m of space as a passageway/escape route between 2 rows of workplaces (so 0.25 m per row). In total, this amounts to at least 2.7 m2 per workplace per person.
In addition to the space required for the computer workplaces, the rooms are also to have space available for other required workplaces, equipment and tools. The floorage to be made available for equipment and tools amounts to the floorage of the tool concerned + the minimally necessary user space.
Naturally, when arranging the workplace layout, inside climate and climate perception requirements (e.g. fresh air supply per person and equipment heat emissions) should also be taken into account. In addition, attention needs also be paid to light incidence, draught and suchlike. It may turn out to be necessary to adjust the amount of floorage accordingly.
The Buildings Decree plays an important part in determining minimum required floorage and number and dimensions of the escape routes when workplaces are arranged in multiple rows. The below details the relevant information from the Buildings Decree: Section 7.13 on seat arrangements and Section 7.14 on aisles.
Section 7.13 Seat arrangement and additional layout
1. Rooms are laid out in such a way that:
- at least 0.25 m² of floorage is available to each person without a seat;
- at least 0.3 m² of floorage is available to each person with a seat, provided no fittings and furniture can be displaced or made to tip over due to crowding;
- at least 0.5 m² of floorage is available to each person with a seat, if fittings and furniture can be displaced or made to tip over due to crowding.
The amount of floorage available to each person is calculated by deducting the floorage taken up by the fittings and furniture from the total habitable space floorage.
2. In rooms containing more than 100 seats, the seats are to be connected to each other or the floor in such a way that they cannot be displaced or made to tip over due to crowding, insofar as the seats are arranged in more then 4 rows of more than 4 seats.
3. When seats are arranged in rows, an unobstructed space is to exist between 2 rows of no less than 0.4 m wide between the normals of the parts of the rows closest to one another.
4. If a table is placed in a row as referred to in the third paragraph, this table is not to occupy any part of the unobstructed space as referred to in that paragraph.
5. Any row of seats with access to an aisle or exit on only end is to consist of no more than eight seats.
6. Any row of seats with access to an aisle or exit on both ends is to consist of no more than:
- 16 seats if the unobstructed space referred to in the third paragraph is no wider than 0.45 m and the unobstructed passageway of the aisle or exit is at least 0.6 m wide;
- 32 seats if the unobstructed space referred to in the third paragraph is no wider than 0.45 m and the unobstructed passageway of the aisle or exit is at least 0.6 m wide;
- 50 seats if the unobstructed space referred to in the third paragraph is no wider than 0.45 m and the unobstructed passageway of the aisle or exit is at least 1,1 m wide.
Section 7.14 Aisles
- Aisles between stands, stalls, shelves, stages and such fixtures in publicly accessible spaces are to be at least 1.1 m wide.
- An unobstructed floor space is to exist in front of exits from a space as referred to in the first paragraph, which length and width are at least to equal the width of this exit.
General advice concerning summer heat
Account should be taken of the fact that everyone experiences heat differently. It is therefore difficult to draft 'rules' for this.
In general, however, the following practical rules of thumb are used to differentiate the activities performed at different ambient temperatures in order to take appropriate measures:
duration in hours/year
differentiation of maximum temperature by work activity
nature of the measures
office work (sitting)
other light work
intensive work, provided that there is a perceptible flow of air in the room
very intensive work, with a perceptible flow of air
ditto, without flow of air
> 35 oC 
At the maximum temperature of, for example, 30 oC office work (sitting), this means that the inside temperature is higher than 30 oC for more than 2 hours. There is in fact no risk associated with this maximum for healthy staff, although productivity is significantly reduced at such a temperature. Since these temperatures are clearly very uncomfortable, it is this wise to pay attention to this.
1. tackle the source:
- switch off heat-producing appliances as much as possible;
- switch off or reduce the lighting in the workspace;
- extract heat;
- consistent and correct use of blinds, exterior blinds are more effective than indoor blinds;
- increase ventilation (only if it is warmer inside than outside);
- install extra ventilation and/or fans. Exercise restraint with the installation of mobile air conditioners. These often cause drafts, make noise, can become microbiologically contaminated and use a lot of energy;
2. organizational measures
- work for shorter periods, work continuously as little as possible;
- take more breaks, if possible in cool rooms;
- adust work hours in hot weather conditions Many UT staff can work variable hours. It is cooler in the morning than in the afternoon; those who start earlier can also go home earlier.
3. the body
- adapted clothing;
- drink a lot, don't forget salts and minerals;
- no alcohol;
- outside: head cover and use sun cream;
- in the case of medical problems: ask for advice from the medical officer (see also under 4), telephone Working conditions service 088-2726312.
- deal flexibly with complaints and wishes of staff and students. Extra vigilance is required for persons who:
- have an illness, such as diabetes, heart or lung disease;
- after illness, are not yet quite 'themselves';
- suffer from high blood pressure;
- are pregnant;
- have problems with obesity;
- have a sensitive skin;
- use medication;
- general: are not in an optimal condition.
 activities in a workshop and transport, lifting and carrying, under extreme conditions.
 at average humidity