Zumtobel and Fraunhofer Institute Study Brings User Preferences to Light

With a global user study on perceived lighting quality in offices, which the Austrian luminaire manufacturer Zumtobel is conducting together with the Fraunhofer Institute for Industrial Engineering (IAO) in Stuttgart, the company is making an important contribution to basic research.

The luminaires flood the room precisely over a wide-area. Accents come from indirect lighting of the rear wall (left). Same room, similar lighting effect – but with brighter basic lighting and without emphasizing the left and rear walls (right)

In the planning and implementation of lighting in office environments, user preferences have hardly been taken into account to date. The focus is placed primarily on standards and threshold values for illuminance, luminance, color temperature and certain ergonomic criteria. Since the end of 2013, office workers from around the world are interviewed online. An interim analysis (of the data for Europe) of the ongoing study, which runs until the end of 2014, is now available.

Almost a third of those questioned find fault with the orientation of their desks

With these results, from roughly 2,150 participants thus far, architects and lighting designers as well as facility managers gain a secured data basis with which to improve the actual perceived lighting quality beyond the current standards, because it is precisely this act of going “beyond the norm” that makes the difference between appropriate and those that are needs-oriented – and not least because this has impact as a relevant value-added factor. For years, people have been at the center of diverse office concepts in which, of course, the lighting of the workspace is also given great importance, but even so, there is a marked difference between the status quo and user preferences.

Moving forward, Zumtobel wants to increasingly take these individual user preferences, task-related requirements and the subjective well-being of office workers into account. The idea is to learn what is best suited for whom and when, and then to resolutely adapt the company’s product development to match. So-called user-focused processes have already yielded such developments as LIGHT FIELDS and SEQUENCE. All of this is about nothing less than the future of innovative lighting solutions for offices of all kinds.

It is not that designs were made frivolously or “wrong” in the past, but users have usually remained anonymous as their work environments were brought into being. Additionally, in the course of use, errors creep in that are eventually regarded as given, even though they have nothing to do with the original design intent. It may be hard to believe, but among other things, almost a third of those questioned find fault with the orientation of their desks in relation to the windows. This flaw could be remedied rather quickly and easily, but an overall improvement of the actual lighting quality can rarely be achieved in so doing. Quality is complex, especially with regard to light. So the quality assessment is concerned with an array of criteria and diverse quality characteristics that are important for people’s individual well-being.

The color temperature alone makes the difference here – and it varies the character of the space enormously

In the group of questions concerning light sources, LEDs performed best overall

A key criterion is the lighting situation, with its components of direct and/or indirect light. Over 80 per cent of the people surveyed would like a combined lighting solution, but only about 40 per cent have one at their workplace. This 40 per cent of the participants also attach greater significance to their own well-being than do those who, for instance, work exclusively under direct light. Participants express the most satisfaction with a floor lamp in the workplace. But at only 15 per cent, these employees represent a minority.

The evaluation of lighting quality and well-being also depends heavily on a person’s ability to adjust the office lighting to match their individual preferences or needs. If there is no possibility to do so directly, at least 56 per cent of those questioned feel uncomfortable and as a consequence, they judge the lighting quality as being suboptimal.

In the group of questions concerning light sources, LEDs performed best overall. That is particularly interesting because up thus far, only about 10 per cent of offices are equipped with LED lighting. Apparently tubular fluorescent lamps – which represent 80 per cent of all office lighting, making them the most widely used light source – are not convincing, and word has spread about the quality of LED light. And the preferred lighting intensity also presents a surprise. Whereas the relevant standards for computer workstations specify 500 lux at desk level, which 40 per cent of the study participants also consider pleasant, the other 60 per cent want 800 lux and more. This hunger for light is most clearly pronounced in the group of people up to age 35, who comprise nearly 70 per cent of their group.

In this comparison, the varied proportions of direct and indirect light and the positions of the luminaires are primarily responsible for the respective moods

As the office size increases, the preference for cold light apparently grows

In the preference for a certain color temperature, a less distinct picture emerges. Although the majority of users feel most comfortable at 4,000–5,000 Kelvin, the spread begins at 3,000 and does not end until reaching 7,000 Kelvin. For general office use, however, these “runaway values” do not seem relevant. It also turned out that as the office size increases (individual office to large open-plan office), the preference for cold light apparently grows, but warm-toned light is generally perceived as more pleasant. These needs are also perfectly addressed by LED lights, whose color temperature can be continuously adjusted.

Other facts describe the overall situation: More than two-thirds of the study participants spend 16 to 20 days each month in an office, and nearly 20 per cent spend 11 to 15 days there. Sixty per cent of all office work takes place on a computer screen. Freestanding individual desks and blocks of two and four desks account for almost three-quarters of all workstations, but people feel most comfortable in an individual office near a window. At the same time, the greatest challenges for responsible lighting design come about with open-space environments. The lighting situations most commonly encountered there, however, are characterized by solely direct or indirect radiant light from louver or pendant luminaires with tubular fluorescent lamps. In other words, all of that has, strictly speaking, little to do with what the participants of the study want. And they want it for more than just the dark months of the year: one third of the participants also work under artificial light in the summer because their workplaces receive too little daylight.

The need for good artificial lighting is as great as the necessity for optimally combining it with available daylight – alone due to the potential energy savings of, for example, a daylight-controlled lighting solution using LED technology. To put it simply: A consistently good assessment of lighting quality, with the added benefit of positive well-being, would be favored by an individually adjustable, direct/indirect floor luminaire, fitted with LEDs, that provides an illuminance of 500 to over 800 lux with a color temperature of 4,000–5,000 kelvins. That is because future lighting solutions for offices must be able to be adapted, simply and reliably, to all kinds of activities and their vision needs.

Even in larger spaces with a balanced proportion of direct and indirect light, the color temperature dominates the general mood – from cool to cozy

What does this mean for architects and lighting designers?

On the one hand, existing buildings hold an enormous potential for improvement in terms of their wellness factor, which can be positively influenced by adding to and retrofitting the lighting equipment, and for new buildings, on the other hand, the much cited center of focus – people – must actually play a considerably more important role from the outset. Modern lighting design depends upon an opulent set of rules and standards, and yet Zumtobel’s long-term study on a global scale reveals a picture of office lighting solutions that are implemented largely without regard to the users.

Of course standards are important and helpful, but they are not the last word. The well-being of employees is not ultimately an attitude; on the contrary, it directly affects people’s performance and is therefore an efficiency factor. The task lighting and general room lighting are not solely responsible for this well-being. A room’s enclosing surfaces, its furnishings, and the quality of its air and indoor climate are likewise important, but even so, it is light that reigns above all. And in this role, lighting that is perceived as “wrong” has a negative impact on the whole; the user cannot see past this flaw, as might be possible with an annoyance like a “needle in a seat cushion” or a momentary exposure to loud noise.

This study gives rise to the hope that in a few years, the office world will be able to see in quite a new light.



Schreibe einen Kommentar

Deine E-Mail-Adresse wird nicht veröffentlicht. Erforderliche Felder sind mit * markiert.