Press release for fensterbau/frontale 2012

Light effect

"A house is habitable, when it is full of light and air." (Le Corbusier) The famous Swiss architect and painter recognised the effect of light on the human organism as vital as far back as 1923 and he significantly shaped the "Modern" age with his architecture.

Light is not just light

Light is a small part of the electromagnetic radiation emitted by the sun, which is visible to the human eye. Invisible ultraviolet radiation changes into visible violet radiation at a wavelength of 380 nm and continuously changes through blue, green and orange into red, where it is invisible for humans again from 780 nm. When solar radiation passes through glazing the light's spectral distribution and intensity is changed. The transmitted light has the ability, range and effect of changing colours, just as our circadian rhythm determines it. Previous construction objectives pursued with glazing are also based on this. This means allowing the maximum share of radiation to be transmitted at 550 nm, therefore positively stimulating the eye's sensitivity to brightness.

Blue light controls the biorhythm of living creatures

What Le Corbusier did not know yet is that our circadian system (from Latin Circa: approximately; dia: day) is not influenced by the wavelength ranges that ensure maximum brightness in rooms but only by the blue wave light components. The evidence that there is a direct nerve connection between the retina and hypothalamus was only found three and a half decades ago with the discovery of the retinohypothalamic tract (RHT). Non image forming receptors sit at one end of the nerve connection (NIF: non image forming). The spectral sensitivity of these receptors lies in the range of blue wave light (between 380 and 580 nm) and reaches the maximum of roughly 460 nm. They have the function of forwarding light/dark signals. These signals reach the area, which is anatomically considered to be the organism's "biological clock". The impulses received there influence many vegetative and hormonal functions in the human body and are therefore incredibly important for our natural biorhythm. The melatonin metabolism is crucially influenced by this, which is in turn significant for the sleep/wake cycle.

"We know that light does not just have a direct influence on our inner clock but that it also has a direct stimulating effect on the brain. This means, activation happens within seconds, which means you are more alert, have improved concentration and a better attention span." (Dr. Dieter Kunz, sleep researcher at Charité Berlin, in a manuscript for rbb Fernsehen Berlin in cooperation with the Fraunhofer Institute for Industrial Engineering, Engineering Systems - Visual Technologies / LightFusion Lab)

"Good light" in terms of well-being and human health can therefore not just be based on colour rendering and brightness. By summarising the latest scientific findings about the influence of natural light radiation, the following statements can be made (Mark S. Rea, Ph.D. Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA 12180):

• Light can alleviate seasonal affective disorder
• Light can increase the length, depth and quality of sleep.
• Light can regulate the sleep/wake cycle of Alzheimer's patients.
• Light can increase the performance of night shift workers.
• Light can improve the weight gain of premature babies.
• The activation of the circadian system by light is influenced by a recently discovered perception system of the eye.
• Light positively regulates the melatonin levels and can therefore reduce the growth of breast cancer.
• Light has a direct influence on the cerebral cortex activity.

The studies listed only illustrate a few of the important research results, which demand an answer to the question: "How can we provide healthy light in our apartments, schools and offices?"

The challenge: low Ug values lead to lower translucency

The development towards every increasing lower U_g values requires concessions of glazing light transmittance. This contradicts the above mentioned requirements. Balancing out too little light and/or poor light quality through artificial light from treatment lights also conflicts with the aim of reducing energy consumption in our buildings. Currently a double-pane insulated glass with U_g = 1.0 W/m²K as per EN 410 has a light transmittance t_v  of roughly 71%, in relation to the human eye's sensitivity to brightness. The light transmittance important for the circadian rhythm is just 68% with a visible radiation of 460 nm (t_{v,c (460)}) with this insulated glass. A triple-pane insulated glass with standard function layers reaches t_v = 70%, or t_{v,c (460)} = 66%.

A new development together with the Fraunhofer Institute

UNIGLAS GmbH & Co. KG has risen to the challenge and developed an innovative glass together with the Fraunhofer Institute for Silica Research in Würzburg, which specifically transmits the bioactive blue light wavelengths thanks to its special transparency. Not only is a superb anti-reflective effect produced using a special coating, which in itself already clearly transmits more natural light through the window glazing.

"But rather the new coating is designed so that it makes the panes particularly transparent for blue wave light. The natural light incidence is therefore improved with regards to its biological effect," explains Walther Glaubitt from Fraunhofer ISC, who developed the coating with his team. Its aim is to improve the light conditions in rooms without additional treatment lamps so that people feel as good as it they were outside in the fresh air. "Relevant studies indicate that people, who spend a lot of time in closed rooms, therefore all of us really, are more effective, feel fitter and are sick less often under the influence of blue wave light. How wonderful that we can contribute to this with UNIGLAS^® | VITAL." The focus is not just on glazing for offices, but also for hospitals, old people's homes, schools and nurseries.

With the new UNIGLAS^® | VITAL - Wellnessglass, UNIGLAS GmbH & Co. KG is now launching a triple insulated glass on the market, where the spectral light transmittance is significantly raised over the entire range from 380 to 580 nm. The light transmittance already achieves 79% at 460 nm with this glass.

No loss of thermal properties

With UNIGLAS^® | VITAL - Wellnessglass light conditions can therefore be created with triple glazing, which roughly correspond to that of single glazing. There are no concessions made here with the heat transmittance coefficient and the g value. The heat transmittance coefficient is U_g = 0.7 W/m²K. This means that significantly better light conditions are also created in interior rooms with triple glazing than with double glazing (U_g = 1.1 W/m²K).

Press contact:

UNIGLAS GmbH & Co. KG
Yvonne Kuhlmann, Head of Marketing & Communication
Robert-Bosch-Straße 10
D-56410 Montabaur

Telephone:    +49 (0)2602 94929 100
Mobile:         +49 (0)176 24 340 346
Fax:             +49 (0)2602 94929 299
E-mail:          kuhlmann@uniglas.de
Web:            www.uniglas.de