or: Why the theme "Healthy light" not really interested.
While I'm here talking about the activating effect of light, better sleep and more performance, you'd be happy, if you properly could see everything at your workplace, without to dislocate or effort. Every spring comes the moment in which you ask yourself whether the light or your eyes have become worse again. Both probably. And now?
I will show you how to quickly find out, if you have enough light in the workplace and, as you are – if there is too little – make the correct small changes for a good result.
"Miriam Döhner, HCL expert at planlicht, recommends to remain always as close as possible to the natural curve and use no short-term"booster". Only in the morning help a higher proportion of blue than in the daylight, when the appropriate receptors in the eye of the most active and the discrepancy to the natural brightness is great: better higher light intensities than the 500 lux required in the workplace were over 10 000 lux outdoor – ideally about 1200 lux. […] The staff should have intervene according to Miriam Döhner, to feel not gegängelt. You need training, but to understand that a momentary activation can have negative consequences with blue light in the evening hours. Energetic reasons the individual will be always for only an hour effective projects."
Paramita Banerjee for "Light"
Our approach for human centric lighting is composed of current standards, our experience and results of light therapy.
Studies, recommendations and current standards to the theme of light in the Office and light in the workplace account rules for healthy architectural lighting design. It all starts from the perception of the people. Occupational safety and health regulations, when it comes to glare and eye safety.
Our experiences from projects such as the Office building of OMICRON in Vorarlberg include directly.
At what level is the light effect? How is it applied? What results are achieved? That is explored in the psychological treatment of light, so that the results can be included in our projects.
So, the question is always the same and sounds really really simply: "what do you recommend for now's Office or for the workplace?"
Here, the answer is not so simple. Because what I recommend must somehow also the reality be connected, isn't it?
Preferably it would be probably, myself and many others if daylight's Office were flooded, the roof terrace of our offices, but without the dazzling reflections on the monitor, no glare and no wind, here you go.
To build up with artificial light, we need 10. 000lx on covered days, from every direction, as under the open sky and still without glare. At Sun have a shot of directional light with higher intensities. Voila.
This won't do. So much light in the Interior would be not only really expensive but also exhausting. Because our eyes, must how out there not the same "spout" register with desk work outdoors, they rather focus on short-haul, which already tiring to the eye is enough. The light should offer as much relaxation as possible.
But how much light is enough or too little because now much? Herrjeh!
The standard requires 500 lux. This is a well lit Office.
And we have become accustomed to, so to read the standard as if it were a recommendations. These are a minimum requirement. Here only lower limits appear to us. Or ceilings. But just when the illuminance in the Office, the norm should not say "must 500 be at least lx", but rather make information, how "the illumination should be between 500-2000 lx lie". In the case, hardly anyone would decide lx for 500. Same rule, different wording. At the time, but exactly what happens: we make do with the lower bound.
So, what do we recommend for the Office? Well, first of all, that we all together stop with these planning of dregs of. Dear clients, are you really the minimum?
1. Adeui minimum. 500lx are (mostly) not enough
The last revision of the EN 12464 standard focused on energy efficiency and cost reduction. Cheaper light. We now have that and now the backlash follows: better light. That this better light at the end must be yet energy efficient, is out of the question.
According to recent recommendations, more light is required 1% per year over 32 years. In other words: at the age of 60, you need almost twice as much light, than the standard recommendation. At least 1000 lx.
2. Shared tasks: Customize lighting job
This not the whole room must be paved somehow with lights, to achieve the recommended illuminance in the medium everywhere. Zones with 150lx, 300lx, 500lx and 750lx be planned depending on the furnishing and work item. Energy saving lighting and partly area-related lighting through this workspace-related.
3. Wide-area lighting effect
"Studies show that 500 to 1500 Lux is sufficient if many receptors on the retina will be achieved by a wide-area lighting. The light is similar to the colour spectrum of daylight in addition and the color temperature varies according to dynamically distributed throughout the day so it is perceived by the people as pleasant and reaches its positive biological purpose."
Oliver Stefani in LightWork
Don't forget to vertical surfaces! For VDU workstations and desk, a ratio of 1:3 has proven (the wall has one-third of the brightness of the worktop). While we are talking about the luminance, i.e. the surfaces and materials also play a role. A ratio of 1:2 to 1:5 is still in acceptable.
Light on the walls and vertical surfaces (cabinets, etc.), ensures at the same time, that the lighting throughout the room is uniform, the space brighter overall effect and high illuminance levels are less than dazzling felt.
Many receptors on the retina can be reached via the large surfaces. The receptors for the biological, non-visual effects are lower in our eyes and on the periphery, so that a large bright area, such as the sky, you can enable well.

In practice
What really welfare illuminance is equivalent to? In one of our projects – an office building in Vorarlberg – we had the lucky opportunity to find out in a sampling. Pattern indoors, which we assemble so should that until 2000lx in the Middle were possible, the employee should test different lighting scenarios and find out what is good for them, the best.
We had coupled room lighting and wall lighting so Dim all luminaires have been together dark and the brightness ratio wall to Visual task remained the same. Employees were allowed to work here so a couple of weeks and try everything, adjust how they liked and decide at the end of the trial period, which could now be the lighting for the entire building. It came out that the favored light intensity, which is relaxed working read, lx was at 1350. not surprising, if you understand the norm only as the absolute lower limit.
An automatic daylight course activated in the morning with cool light and leads over the light in the evening in a golden hue. The employees feel this course as pleasantly natural and activating. The art lighting control system corresponds to the natural course of attention and concentration through the day.

Light therapy
"In the context of light therapy the patient consists of light of at least 2500 lux, better 10,000 lux, daily up to a week or longer, the best morning for 30 to 40 minutes." In our latitudes, a day walk offers a comparable supply of light and in addition exercise and fresh air but also on a cloudy winter day"
Drug Commission of the German medical profession (AkdÄ)
Now you need to go there just yet, this fresh air. For most workers, a winter workday looks but rather so: In the dark to the car from the car to the front door of the workplace, and in the evening in the dark the same back. We get daylight then only on weekends. Not a bad idea is to give to the light dose in the Office or on the bench. Because the dose is one (so very platt said: the number of photons that arrive in the eye), the lighting strength must out view of the light therapy also not 10,000 lx be and be administered in half an hour. 1250 lx in quadruple time serve the same purpose.
4. Contrast is glare
If there is a lower limit for light intensity, there is also an upper limit. When is there too much light in the workplace? Of course, if it hides.
Glare is often dependent on the contrast, so the background. Uniform illumination is dazzling perceived as less than high-contrast of very bright and very dark areas turns. High doses of light should be conveyed so be sure about evenly illuminated surfaces or of uniform light areas
To calculate this glare, there are the UGR (unified glare rating) process.
In DIN 5035 part 1 set sq cd / m as a maximum average luminance 500, used to limit glare a UGR value of 19.
"Contrary to many opinions, the UGR value is not pure property of a lamp. It here much more goes to the interaction» brightness level "of the illuminating surfaces of a light in relation to the» brightness level «The environment, the observer position and the direction of the observer."»
Klaus Baker Eckmann for DIAL
The checklist for free download:
How much light in the Office?
Bibliography:
Drug Commission of the German medical profession (AkdÄ) (2006): recommendations for the treatment of depression. 2. Edition. In: drug regulation in practice.
Pross, Achim; Stefani Oliver; Bossenmaier, Sebastian; Bues, Matthias: Study of LightWork.
Riemersma-van the Lek, Rixt F; Swaab, Dick F.; Twisk, Jos; HOL, Elly M.; Hoogendijk, Witte J. G.; Someren, Eus J. W. Van (2008): Effect of bright light and melatonin on cognitive and Noncognitive function in elderly residents of group care facilities: A randomized controlled trial. In: JAMA 299 (22), pp. 2642-2655. DOI: 10.1001/jama.299.22.2642.
Wessolowski, Nino (2014): Efficacy of dynamic lights in the classroom. Dissertation. University of Hamburg, Hamburg.
DIN 12464, DIN spec 60767, DIN spec 5031-100
This article first appeared in the architecture and construction forum.