Ing. Marek Bálský, Ph.D.

Prague, the capital of the Czech Republic, through its representatives, decided on a conceptual and systematic approach to the management of the public lighting. On the basis of this decision, a set of documents was submitted for processing under the title Concept of Prague Public Lighting. This set of documents is intended to specify what the night image of the city should be, creating through public and architectural lighting. When determining the night appearance of the city, not only the safety of the traffic of people and property, but also the undesirable effects of lighting on the surrounding environment and the effect of lighting on the appearance of public spaces should be taken into account. An integral part of the Concept of Prague Public Lighting is also the plan for the renewal and modernization of the public lighting system for the purposes of the city's financial planning. Concept of Prague Public Lighting also contains standards of activity and devices that specify requirements for activities related to public lighting and for products that are part of the public lighting system.

Street lighting is usually designed to meet luminance (or illuminance) requirements of technical standards and recommendations with minimum possible lighting installation power consumption. However, with the expansion of street lighting in growing cities caused by increasing traffic intensity, the disturbing effects of street lighting on the surroundings are often neglected in the design of lighting systems. Light emitted outside the area to be lit (spill light) causes an increase in complaints from residents and an increase in lighting installation power consumption. Therefore, this paper proposes an analysis of the effect of spill light on the energy efficiency of the street lighting systems.

Currently, the issue of undesirable effects of artificial outdoor lighting on the surrounding environment is a very widely discussed topic. In individual countries, there is an effort to solve this issue within the framework of documents that take different forms, from recommendations to technical standards to legal regulations. Most of these documents are based on the international recommendations of the CIE, which relate to limiting the undesirable effects of so-called obtrusive light on the surrounding environment. In practice, this concept is not widespread among the general public, and is often referred to as light pollution. In spite of the considerable efforts made to address this issue, there is no simple visible consensus in practice on how to deal with it. There are probably several possible reasons. The primary and fundamental one is the issue of terminology and definitions. In practice, one term is used to refer to a number of different phenomena, and at the same time, several terms are used for one phenomenon. Already in current documents, obtrusive light refers to phenomena that are not, by definition, obtrusive light. Clarity and consistency in the use of terms and adherence to their definitions is a prerequisite for mutual understanding when dealing with a particular issue. If definitions are not respected and terminological discipline is not observed, it is very difficult to deal with the issues related to the terms and definitions. The following paper also deals with other possible causes of the mentioned situation.

An integral part of the design and operation of lighting systems is the evaluation and control of lighting parameters at the beginning and during their operation. At present, this evaluation is in most cases narrowed down only to the measurement of illuminance or luminance on the established reference planes. However, the lighting requirements set out in the technical standards are more complex and some parameters are not controlled at all in practice. The paper describes the design of an operational luminance measurement procedure displaying a luminance meter as part of a comprehensive evaluation of lighting systems.

The issue of light pollution, which is partly caused by public lighting, is a frequent topic of professional discussions. The influence of the luminous flux emitted by the lighting system above the horizon, on the facades of houses in the area or into the nature is often discussed. This study therefore deals with the analysis of the distribution of luminous flux from public lighting in urban environments.

With the advent of modern LED light sources on the market in the last decade, great expectations have been placed on their use in public lighting. LED technology, fundamentally different from all existing light sources, was expected to completely change the characteristics of street lighting, especially in terms of the distribution of light flux from the light source to users.

The topic of the obtrusive effects of outdoor lighting on the surrounding environment has gradually permeated public debate and public space, and compared to the recent past, it is one of the most frequently discussed topics. Due to the growing attention and seriousness, this issue is also included in the newly prepared legal regulations in the field of building law, ie the Building Act and subsequent implementing regulations. The newly emerging legislation was one of the main reasons for the establishment of a new technical standardization commission (TNK) within the Czech Agency for Standardization under the name Light pollution - disturbing light.

The paper deals with the measurement of the integral reflectance of diffuse surfaces, which is one of the main input parameters in lighting engineering calculations of indoor and, in some application areas, outdoor lighting systems. Due to the absence of a simple measuring instrument that would allow the measurement of the above parameter, a prototype instrument for measuring the reflectance was designed and an approximate calibration was performed on the reflectance standards in the laboratory of radiometry and photometry of the Czech Metrology Institute.

Increasing the efficiency of lighting systems can be achieved not only by increasing the luminous efficacy of the light sources, but also by reducing the useless luminous flux, which is referred to as the light trespass. The luminous flux is in artificial lighting systems generated from electrical power and therefore the light trespass means the loss of electrical power. The paper deals with the possibilities of increasing the efficiency of street lighting by optimizing the luminous flux distribution of luminaires and its influence on the light trespass.

The electromagnetic disturbance of individual LED luminaires and the requirements of technical standards to limit it are well known. This paper focuses on the analysis of electromagnetic disturbance of entire industrial LED lighting systems with a high number of luminaires and hence high power consumption. In such large industrial lighting systems, the effects of electromagnetic disturbance may be very different from the electromagnetic disturbance of individual luminaires.

The paper is focused on the parameters of light field description used to evaluate spatial properties of lighting. These parameters include the vector illuminance, mean illuminance values (spherical, cylindrical, cubic), shape factor and other derived quantities. Their use is mainly for evaluating the quality of lighting systems in terms of subjective perception of sufficient space illumination, but also in terms of visual perception of three-dimensional objects. Based on the theoretical analysis, a prototype sensor was designed for the measurement of mean cylindrical illuminance, which would allow measurement and evaluation of vector properties of light field and derived scalar quantities. The article builds on long-term research in the field of measurement of spatial illuminance characteristics at the Department of Electrical Power Engineering CTU FEE.

Due to continuous development, LED lamps are gradually becoming the dominant light source on the market, and with some exceptions in certain specific applications, LED technology today accounts for most of the lighting manufacturers' portfolio and sales. However, new technologies bring new technical problems and challenges that need to be addressed. One of the specifics of LED technology compared to conventional technologies is another design solution and the associated different light distribution in the luminaire. This paper therefore aims to analyze whether and how the design of LED luminaires affects the spatial distribution of the light emitted spectrum. The aim of the paper is also to verify theoretical hypotheses by measuring spatial spectral characteristics of LED luminaires.

The paper describes the influence of diffuser materials used in LED luminaires on properties of light passing through them. It focuses mainly on efficiency and changes in color properties of light and correlated color temperature (CCT) of light passing through diffuser materials.

The article deals with the possibilities of using the Arduino platform in lighting and photometry. The simplicity and wide range of libraries, expanding modules and sensors of this platform opens up new possibilities for simple modelling of the light field, its properties and for modelling the principle of photometric devices.

The aim of paper is biodynamic lighting, which is artificial lighting that should best simulate the spectrum and the daily course of natural daylight. Biodynamic lighting can be achieved by controlling luminaires with several different light sources with different correlated color temperatures, nowadays especially with the use of LEDs. This paper deals with analysis of spectral composition and other photometric parameters of light of industrially used LED samples and their effects on biodynamic lighting.

The paper describes the modernization of the goniophotometer in the laboratory of photometry at the Department of Electrical Power Engineering of the Faculty of Electrical Engineering of the CTU in Prague. The primary aim of the adjustment of the measuring system was to simplify the time-consuming measurement process with the new control software that would allow both the goniophotometer periphery to be controlled and the measured Eulumdat data directly exported. The secondary goal of the software was to create a platform that would allow the future change of the control hardware and / or the luxmeter device.

The paper deals with biodynamic artificial lighting, which should follow the spectral composition and the daily course of natural daylight. Biodynamic lighting can be achieved by controlling luminaires with several different light sources with different CCT, nowadays especially using LEDs. This paper deals with analysis of spectral composition and other photometric parameters of light of industrially used LED samples and their effects on biodynamic lighting.

The paper deals with the analysis of lighting system of real room with external window blinds, including comparison of artificial lighting and daylighting measurement and calculation in conditions of overcast and clear sky and several setting of external window blinds. Mathematic model of the lighting system of the room was simulated simultaneously using Dialux software to compare results and accuracy of the model calculations and real measurement.

The paper describes a new methodology for the selection of lighting classes in the newly translated standard ČSN CEN / TR 13201-1. It addresses the possibility of creating a new national methodology for the selection of lighting classes based on the administrative division of the roads defined in the national legislation.

The paper describes a new methodology for the selection of lighting classes in the newly translated standard ČSN CEN / TR 13201-1. It addresses the possibility of creating a new national methodology for the selection of lighting classes based on the administrative division of the roads defined in the national legislation.

The paper describes calculation of uncertainty of measurement of luminous intensity distribution of large luminaires at goniophotometer of type 2 with short photometric distance (near field photometry). The short photometric distance causes non-perpendicular incidence of the light coming from the edges of the luminaire onto the photocell of the goniophotometer and thus the measured luminous intensity values could be smaller, than values measured with goniophotometer with adequate photometric distance. The paper should highlight such measurement complication and enlighten operators of goniophotometer of type 2 how to correct measured values of luminous intensity and calculated values of luminous flux of the luminaire.

The paper deals with possibilities of applications of luminaires with tunable correlated color temperature (CCT) and their influence on the perception of light scenes and on biological functions of human body. The first part starts with a description of human visual system, physiological effects of optical radiation and principle of perception. The second part shows the analysis of photometric parameters of the sample of tunable white luminaire with variable CCT.

The paper deals with the analysis of lighting system of real room with external window blinds, including comparison of artificial lighting and daylighting measurement and calculation in conditions of overcast and clear sky and several setting of external window blinds. Mathematic model of the lighting system of the room was simulated simultaneously using Dialux software to compare results and accuracy of the model calculations and real measurement.

The research deals with construction of solar concentrator with photovoltaic panels and thermal circuit. As a part of this research there is a design of solar tracking system for solar concentrators. The use of concentrator with solar tracking system shows the performance of combined generation of electrical power and heat from solar radiation. The results of electrical and thermal measurements show the electrical performance and power performance of heat circuit.

The paper deals with finding the regression function describing extraction of luminance values of the samples measured with luminance meter from digital images simultaneously taken by a digital camera using scientific computer algebra software.

The paper deals with the analysis of lighting system of real room with external window blinds, including comparison of artificial lighting and daylighting measurement and calculation in conditions of overcast and clear sky and several setting of external window blinds. Mathematic model of the lighting system of the room was simulated simultaneously using Dialux software to compare results and accuracy of the model calculations and real measurement.

The aim of this paper is to analyse possibilities of measurement of reflective properties of materials used in the interior and to propose methods of recording of measured reflective properties of materials for calculation of multiple reflections in light scenes. One of the basic assumptions for definition of the appropriate methods of recording of measured reflective properties of materials is the analysis of input data and methods used for the calculation of multiple light reflections in computer graphics and capabilities of these methods in the lighting calculations.

The paper deals with calculation of luminous efficacy and power losses of modern light sources. The energy efficacy dependence on the spectral distribution of light is described as well as the luminous efficacy dependence on total luminous flux. These two dependences are shown for frequently used light sources, such as fluorescent tubes and LEDs.

The aim of this paper is to analyse the current state of multiple light reflections solving and propose solutions to calculate the properties of light scenes characterized by the reflective properties of real materials. One of the basic assumptions of such calculations is to define appropriate methods of measuring and recording reflective properties of materials and their subsequent use in the calculation of multiple light reflections using methods available for the calculation of multiple light reflections in computer graphics.

Illuminance measurements in the mesh of control points is the most commonly used method for evaluation of parameters of interior lighting systems as national supervisory authorities (eg. The regional health stations) and private entities engaged in design activities in the field of lighting systems. Measurements can verify requirements for lighting systems of the Czech technical standards. The measurement of illuminance is still processed manually, ie. projecting a mesh of control points and then measuring the illuminance by illuminance meter in each of the control points. One of the ways to ensure a considerable acceleration of the lengthy process of illuminance measuring in the interior is the automation of the measurement process using robotic units, which would be able to project its own mesh of control points according to standards and at the same time ranging mesh of control points to measure illuminance in this mesh.

One of the basic methods of evaluating the quality of interior lighting systems is the measurement of the horizontal illuminance. It means a manual illuminance measuring in a uniform network of checkpoints. In practice, these measurings are often used to veryfy the lighting part of the projects or for the health stations. Such measurements are due to the large number of control points (measurement often takes place in multiple rooms of the reference object) time-consuming, taking their course in each control point repeats the same act. For this reason, it was in the context of inter-faculty study program Intelligent Building at CTU announced topic of the student project, whose aim is to describe the possibilities to automate this process to speed up the measurement.

Nowadays there are procedures to evaluate the energy performance of buildings, but in the field of lighting systems often only in terms of electrical power consumption. The obstacle of a comprehensive evaluation of a lighting system is the perception of the lighting quality demands and the energy performance as two separated opposing areas. The current evaluation of lighting energy performance of buildings, also including an evaluation through parameters such as the relative installed power, is misleading, is not related to the real lighting energy performance, has no direct binding dependencies to photometric parameters in the given building and can negatively influence photometric parameters and the environment of buildings. The basis of the comprehensive solution of lighting systems of buildings is a paramete, describing and evaluating the lighting. Such parameter is containing both the physiological aspect, related to the lighting environment and vision conditions, as well as the energy aspect, related to energy demands of the lighting. This approach makes it possible to work with any light source, to combine them and to rate their energy efficiency and at the same time to assess the relationship between the lighting quality demands and their energy performance. It directly links up the quality of the lighting with its energy performance, which is currently not obvious, is highly subjective and in the currently way of designing elusive.

The aim of this paper is to describe the reflective properties of materials and their specific use in calculating the parameters of lighting scenes. Computer programs commonly used for modeling parameters of lighting scenes to create a mathematical model of a scene primarily work with diffusely reflecting surfaces in the intended area where light can be employed to characterize the surface integral reflection coefficient. Numerical model of a scene containing only diffusely reflecting surface is mathematically less demanding than the model in the calculation of parameters including lighting scenes and actual generally reflecting surface. Structural elements of modern buildings are often made of materials with its reflective properties differ significantly from the ideal diffusely reflecting surfaces. If the modeling of lighting scenes is not taken into account the directional dependence of the reflection coefficient, the model of light scenes can contain considerable error.

The aim of this paper is to summarize the methods of mathematical description of reflective properties of materials and their use in calculating the parameters of lighting scenes. Computer programs commonly used for modeling parameters of lighting scenes currently use for mathematical model only diffuse reflecting of all surfaces in the intended area. Numerical model of a scene containing only diffusely reflecting surface is mathematically less demanding than the model including in the calculation real reflective parameters of lighting scenes and generally reflecting surfaces. Structural elements of modern buildings are often made of materials with its reflective properties differ significantly from the ideal diffusely reflecting surfaces. For correct modeling of lighting scenes containing non-diffuse elements is needed to better mathematically describe reflecting of generally reflective properties of the material.

In order to be able to measure direct and indirect solar radiation, a device referred to as Solar Tracker was developed. Values of direct and indirect solar radiation are important for efficient selection of technology, operation, control and policy mainly in the field of fotovoltaic power plants and are also important in other subject fields, such as the lighting systems in building industry.

Nowadays there are procedures to evaluate the energy performance of buildings, but there is no methodology to design buildings with optimized energy performance. It is impossible to effectively optimize the lighting systems of already designed buildings. The obstacle of a comprehensive evaluation of a lighting system is the perception of the lighting quality demands and the energy performance as two separated opposing areas. The current evaluation of lighting energy performance of buildings, also including an evaluation through parameters such as the relative installed power, is misleading, is not related to the real lighting energy performance, has no direct binding dependencies to photometric parameters in the given building and can negatively influence photometric parameters and the environment of buildings.

The paper describes the use of a solar concentrator for producing electrical energy. It deals with production of electrical energy using solar radiation. The principle of the device is based on concentration of solar energy into a given area and the use of photoelectric effect for transforming this solar energy into electrical energy. The first goal was to find the amounts of electrical power and waste heat from the solar concentrator. For the chosen design a mathematical model was proposed and solved by Wolfram Mathematica. The following physical quantities and processes were modelled: the total electric power (described by photoelectric phenomenon equations), the flow of oil used as coolant (Bernoulli equation), and heat transfer between the concentrator, the cooling medium and ambient environment (laws of heat transfer by convection, conduction and radiation). The device was built in the laboratory and the numerical model was consequently tested and improved using the measured data. To achieve a relatively optimal level of concentration, an aluminium sheet in the shape of the letter "U" was used. Focused solar rays were used for the electrical energy production in a solar cell located in the lowermost part of the device. Oil flowing through the pipes removes the heat from the solar cell and cooling of the semiconductor layer improves the efficiency of solar-electrical energy conversion. The influence of device positioning (azimuth and elevation angles) was also studied. The authors hope that future experiments will lead to better understanding of the roles of direct and diffusive radiation components.

The paper presents the comparison of luminous and electrical properties of modern LED-based luminaires with properties of the conventional luminaires with high pressure sodium lamp. It collects available product information of compared luminaires with measured luminous and electrical properties of them to allow a reader to take a view of mentioned luminaire properties. The most important values of the luminaire samples compared are the luminous efficacy, color rendering index, startup process characteristics, spectral distribution of the light sources, etc.

The book comprehensively describes the area of lighting technique and the individual chapters are devoted to the themes in this field. The first chapter summarizes the physical definition of physical values in lighting, then describes the function of the human eye and vision problems. The following section of the book provides an overview of currently used light sources and their properties in context with the properties of daylight. Based on the description of different types of lighting systems are listed calculation methods, measurement, control and economy of operation of lighting systems. Finally, the book describes the possibilities of using light in various applications.

The paper should describe the methods of solar power concentrator projecting. The main part is focused on calculation of multiple planar mirrors profile, which could be used as a concentrator for combined photovoltaic-thermal system. Multiple mirrors should concentrate the solar power from larger area to smaller photovoltaic panel with additional thermal unit. Therefore the irradiation of the active part of the system increases, which causes the higher power production of photovoltaic cells and higher heat production in a thermal part of the system.

The electrical power of photovoltaic systems depends on the power of solar radiation incident on the active parts of the system (photovoltaic panels). The incident solar radiation contains of direct and indirect component which is caused by actual weather conditions. Due to the receiving characteristics of the solar panels it could be more efficient to turn the panels directly to the sun while the direct component of solar radiation dominates. The solar concentrators for photovoltaics are based on concentrating the direct solar radiation. This paper should describe the ratio of direct and indirect component of solar radiation in different weather conditions.

The paper presents the comparison of luminous and electrical properties of modern LED-based luminaires with properties of the conventional luminaires with high pressure sodium lamp. It collects available product information of compared luminaires with measured luminous and electrical properties of them to allow a reader to take a view of mentioned luminaire properties. The most important values of the luminaire samples compared are the luminous efficacy, color rendering index, startup process characteristics, spectral distribution of the light sources, etc.

The paper discusses commonly used light sources employed in road lighting and new technologies of light sources coming to this field of application. It focuses on the most progressive recent light source, light emitting diodes (LEDs) and LED-based luminaires. In the main part of the paper luminous and electrical properties of LED luminaires are compared with properties of the commonly used luminaire with high pressure sodium lamp. The most important values of the luminaires compared are the luminous efficacy, color rendering index, startup process characteristics, spectral distribution of the light sources, etc.

This paper deals with frequently discussed problems of photovoltaic system applications in central Europe and countries with similar climate conditions. The climate and the latitude of given area are the main limiting factors of photovoltaic system effectivity. The capacity of photovoltaic systems couldn't be fully exploited in higher latitudes (such as in Czech Republic) due to lower solar irradiation of the surface and worse climatic conditions than closer to the equator. Consequently the economic return of photovoltaic systems is very long and the photovoltaic systems must be subsidized by the government to become profitable for their operator. The solution of mentioned problems could be to concentrate the solar power from larger area to small photovoltaic cell. A concentrator increases the irradiation of the photovoltaic cell, which causes the higher power production per photovoltaic cell area.

Software Gofosoft v2.1 previously used in the photometric laboratory at the CTU in Prague, FEE was programmed in LabVIEW environment which supported the A / D converter for digitizing data from luxmeters. LabVIEW software was not optimal for that purpose. The luxmeter was later directly connected via a serial interface to the computer and A / D converter was no longer needed. There was a new requirement to provide a practical simplified alternative measurement software for goniophotometer to measure luminous intensity diagrams. Designed and implemented applications Gofosoft4 provides the necessary user interface and automatic measurement of luminous intensity diagrams in the selected photometric planes. Application Gofosoft4, whose functions are described in this paper, was developed in the NetBeans IDE Java environment.

The article describes the modernization of goniophotometer in the laboratory of photometry at the Department of Electrical Power Engineering at Faculty of Electrical Engeneering, CTU in Prague. There is decribed a new method of arm propulsion with step motor driven by computer and automatical processing of measurement results. It also includes analysis of uncertainty of photometric measurement.

The paper should inform about a new possibilities of the laboratory goniophotometer at The Department of electrical power engineering at The Faculty of Electrical Engineering at Czech Technical University in Prague. The goniophotometer is used for measurements of luminous intensity distribution in laboratory practices and for independent measurements of luminous intensity distribution and calculations of luminous flux in commerce. Changing inconvenient manual control of this device to computer control increased accuracy of measurements and made measurements more user friendly. This enhanced quality of education of lighting engineering and provided compliance of measurements with new requirements of European Standards for lighting.

The paper describes possible sources of errors influencing inaccuracies of luminous intensity measurements on goniophotometer. Based on this analysis there are described calculations of partial uncertainties corresponding to each mentioned measurement error. Finally there is calculated composite extended uncertainty of luminous intensity measurements with concrete goniophotometer.

Articel is focused on research of obtrusive light and measurement of its light parameters. It shows a way how to measure the luminance of the night sky with following process of mathematical simulation and its validation using illuminance measurement and luminance integration. Finaly there is shown luminance measurement using digital camera.