Peter Hanuliak

The Influence of Internal Coloured Surfaces on the Circadian Efficiency of Indoor Daylight

The discovery of circadian stimulation by daylight has changed our understanding of the important effect the daylight has on our health and wellbeing. The new medical facts that emerged during the last decade have proven that a long-term absence of circadian light stimulation may be associated with sleep disturbance, tiredness and increased incidence of chronic depression, bipolar disorder, and seasonal affective disorder. The reason is the difference between the visual and biological (circadian) response to light and how it is being perceived by human beings: while the visual perception represented by the luminous efficiency function peaks at the wavelength of 555 nm, the circadian photoreception curve peaks in the blue light spectrum at ~450 nm. The primary circadian stimulation by daylight depends on the properties of light impinging on the retina. An experimental study was designed to quantify the effect of internal coloured surfaces on our circadian stimulation by daylight. Four identical models of a standard office were manufactured, equipped by wallpapers of different colours, and exposed to daylight. Illuminance and spectral distribution of light were measured at different positions along the room and the potential circadian stimulation was evaluated by an established model. The measurements have proven that although the visual comfort may be satisfactory, circadian stimulation may be inhibited, especially when room´s surfaces are yellow. Thus, proper choice of internal surfaces´ colours is important to prevent the potential negative health consequences.

The influence of indoor lighting with low blue light dose on urine 6-sulphatoxymelatonin concentrations and sleep efficiency of healthy volunteers

Light, especially its blue component, is the main synchronizer of circadian rhythms. We investigated effects of suppressed blue band of the spectrum on melatonin production and sleep efficiency in 18 young volunteers. During control days, participants lived in their home environment, and next five days in a room lit only by daylight with windows equipped with a filter blocking the blue band of the light spectrum. Light intensity, circadian stimulus and light irradiance were monitored. No significant changes in the daily pattern and total urinary 6-sulphatoxymelatonin excretion were found between control and experimental conditions. Parameters of sleep efficiency measured by wrist actigraphy were not worsened, but neutral chronotypes exhibited shortened sleep duration under light-modified conditions. We conclude that young healthy people can compensate for negative effects of transitory-worsened lighting conditions on their daily rhythms, but chronotypes and other personal characteristics may modify biological responses and should be considered.

Daylighting for Buildings: Influence of the Solar Eclipse on its Spectral Characteristics

Extraordinary occurrence of the solar eclipse offers opportunity to evaluate spectral characteristic changes and intensities of daylighting during its various phases. Changes of the daylight spectrum in positions: zenith and 45° above horizon with orientation of sensors opposite to sun position were measured. Changes of horizontal illuminance and luminance as well as changes of the correlated colour temperature in the range of the Planck curve were measured in Bratislava and evaluated. Paper presents results of experimental measurements and discusses in point of view of sunlight characteristic’s changes as source of daylighting.

The Effect of Colored Surfaces and Tinted Window Glazing on Daylight Spectral Characteristics and Illuminance Levels in Deep Space Rooms and its Evaluation for Human Visual and Biological Response

Examination, design and control of internal light conditions in permanently occupied spaces belong to important actual architectural issues. Especially in offices, workplaces can be often situated far from window. As the new medical facts were emerging during last decade, the significance of the non-visual human response on light, also known as circadian efficiency of light has been rising [1]. Biological stimulation of light depends on quantitative and qualitative properties of light, which penetrates directly into the human eye in contrast to visual stimulation depending more on the amount of the light reflected from the observed surfaces. Inappropriate selection of spectral filter in windows or internal coloured surfaces may significantly decrease potential light biological stimulation and may reflects in higher rate of Sick Building Syndrome (SBS) occurrence, which is connected to Seasonal Affective Disorders (SAD). The paper describes two experiments done in real conditions, focused on the effect of internal coloured surfaces and the influence of tinted glazing on daylight spectral characteristics in three deep space model rooms exposed only to natural daylight. Deeper positions with sensor`s orientation toward window and side wall were selected. The position of sensor representing the eye of sitting person and especially its orientation regarding to window proved noticeable different rate of biological stimulation`s efficiency in comparison with same level of horizontal illuminance on working area.

The Influence of Selected Type of Daylight Device on Horizontal and Vertical Internal Illuminance

Daylighting is one of the key parameters of internal environment generation in buildings. This parameter determines creation of suitable conditions for visual activities in internal spaces and contributes to human well-being and comfort. Daylight is also the primary stimulus for synchronizing the human circadian photobiological system. Traditional parameters and criterions based explicitly on photopic vision have been critically re-evaluated and basic principles of circadian photometry have been developed in theoretical level. Nevertheless daylighting has often been neglected or left out from the main design proposals, which are usually just focused on covering basic needs for vision tasks represented barely by the illumination limits on working plane. Because the amount of light entering the eye is the most important for circadian entrainment, the illuminance recorded on a vertical plane, at eye level, is more significant for human biological system. This paper deals with the comparison of internal horizontal and vertical illuminance recorded in 3 models of room, inserted in simulation program Radiance and illuminated by three types of lighting devices, i.e. window, light-pipes and permanent supplementary artificial lighting represented by the combination of window and light-pipes. Achieved data also express the influence of a workplace position on the amount of illuminance entering the eye according to the direction of the incoming daylight from windows in side-lit room.

The influence of photometric coating on spectral reflectance of artificial sky dome

The artificial sky has been in operation at the Institute of Constructions and Architecture of Slovak Academy of Sciences in Bratislava since 1970s. This artificial sky provides lighting simulations in conditions of overcast sky mainly for daylighting measurements in physical scaled models. It has been used for wide spectrum of photometric measurements ranging from scaled building interiors to light distribution using tubular light guides. The sky dome was made of reinforced concrete and is suspended to loadbearing structure of the surrounding building on steel ropes. It is hemispherically shaped with diameter of 8 meters. Thanks to support of grant scheme APVV the lighting system in artificial sky is undergoing the total reconstruction. The part of this reconstruction contains the renewal process of the domes surface through applying special photometrical coating, developed especially for this purpose in cooperation with company Chemolak a. s. Smolenice, Slovakia. The other part of reconstruction consists of new LED lamp installation in combination with the new electrical installations and new controlling and calibration programming system. This paper deals with comparison of spectral reflectance of domes surface before and after application of new photometrical coating to determine inputs for simulation of CIE Standard General Sky in laboratory conditions. The experimental results show the quite high rate reflectance values and uniform - spectrally neutral reflectance properties. The surface also meets the desired requirements regarding the diffuse light reflectance. The aim of lighting system reconstruction is to improve spectral rendering of new lighting system, to decrease consumption of electricity and enable to simulate of all 15 types of the CIE Standard General Sky, which are adopted by ISO and CIE in ISO 15409:2004/CIE S 011/E:2003.

Case Study of Light Pollution in Urbanized Area of Slovakia

This paper deals with the problem of light pollution and its potential impact on human body. Loss of darkness during the night has a negative effect on the environment, animals, plants and humans. Concerning humans, the light during the night can lead to desynchronization of circadian rhythms with subsequent lower production of sleeping hormone called melatonin. In addition to the negative impact on organisms, there is also economical effect of wastage of lighting during the night. Pollution caused by the occurrence of light during the night is relatively new term, which has been perceived very roughly so far. That is probably the reason, why Slovak legislation deals with this problem very roughly. Some limitation levels of illuminance of billboards were stated, but the legislation doesn ́t deal with the effect of the occurrence of higly influential light during the night on people at their homes.

Comparative Study of Window Glazing Systems Influence on Melatonin Secretion in Patients in the Hospital Wards

The interest in the research of non-visual effects on human health has risen during last decade rapidly. Daylight that has humans during our evolution adapted to is considered as healthy in its natural form. In reality, the daylight inside the buildings can be different in many parameters from the exterior one. Not only intensities and spatial distribution is altered, but also spectral composition can differ significantly. Daylight transmitted through transparent elements in buildings envelope and its shading devices is filtered and therefore can have different photobiological quality compared to the daylight in exterior. Effects of the altered light conditions can have negative impact on health mostly by people that spend time continually or permanently in those internal spaces, such as long term hospitalized patients in medical facilities. The aim of the research was to find out, whether the dramatic change in the transmittance of daylights blue component will evoke the change in melatonins secretion in patients urine samples. Despite great level of circadian disruption of observed subjects a typical changes in melatonin secretion were observed as a result of altered spectral transmittances due to different glazing systems.