Lambros Doulos

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• Professor Associate
• Professor at Hellenic Open University

The indoor environmental quality is very significant as humans spend more than 90% in indoor space. Biophilic design of indoor spaces has become a popular approach in the design of indoor building spaces sector using green walls, especially in offices, leisure and hospitality facilities. So far there exist neither guidelines with the proper Spectra...

Despite the abundance of daylight in hot desert climates, deep-plan office buildings still lack the provision of sufficient daylight. Although tubular daylighting devices (TDDs) offer a potential solution, they may have visual and economic consequences. Therefore, the present study evaluated the visual comfort, overall energy consumption, and econo...

The objective of the present research is to determine those daylighting design strategies that may optimize the visual environment in preschool classrooms in the context of the climatic data of Greece, as well as to evaluate Climate Based Daylight Modeling metrics as an assessment tool during the daylighting design process. The research models a se...

While LEDs are now the most efficient light sources, their adoption in the road lighting design has been delayed due to a variety of reasons such as malpractice, huge number of inappropriate luminaires, missing technical information and ineffective policies. An example is the, low luminous efficacy values, which confuse the decision makers for nati...

The energy consumption for the artificial lighting in school buildings is one of the main consumers of electricity. In Greece, there is a large number of school buildings with quite old lighting systems using luminaires with T8 and sometimes T12 fluorescent lamps and degradated translucent diffusers. Due to the economic crisis, the public sector fa...

Στο παρόν άρθρο εξετάζονται συνθήκες φωτισμού που επικρατούσαν στην Αρχαία Ελλάδα υπό το φως του λύχνου, μέσα από τη συνδυαστική ανάλυση αρχαιολογικών δεδομένων, εικονογραφικών μαρτυριών, αρχαίων κειμένων, εργαστηριακών μετρήσεων, φωτομετρικών υπολογισμών και προσομοιώσεων φωτισμού. Από την έρευνα προκύπτει ότι ο λύχνος απέδιδε επαρκές φως για βασι...

The influence of light on human physiology, including its non-image forming effects, has been recognized for several decades. A significant breakthrough in understanding these non-visual effects came with the discovery of a new type of photoreceptor: intrinsically photosensitive retinal ganglion cells. The circadian effects of light include the reg...

Light pollution refers to the result of excessive and incorrectly targeted artificial lighting, which is observed in large cities and is mainly identified by the absence of starry skies. The purpose of this research is the interdisciplinary analysis of the effects of light pollution in various fields such as astronomy, ecology, environment, human h...

Compliance with standards and regulations is an important and integral part of lighting design projects. However, many lighting designers do not take always into consideration compliance with norms. A new Greek regulation concerning lighting, Technical Instructions of the Technical Chamber of Greece 20701-7/2021 as part of the new Greek Energy Buil...

Mosques, revered as sacred spaces, are distinguished by their sustainable architectural designs. A critical aspect of these designs is the implementation of daylighting strategies, essential for ensuring adequate light levels, particularly for reading the Holy Quran. Traditional daylighting typologies in mosques, such as multi-lateral lighting, cle...

Lighting in the built environment has evolved since the rapid uptake of solid-state lighting (SSL) devices [...]

Lighting has experienced dramatic developments in the last two decades. The simplest example to understand this is the fact that just twenty years ago, we suspected that humans had one more photoreceptor in addition to the apparently well-known rods and cones but did not know what it was. Since ipRGCs were identified as the photoreceptors initiatin...

Rapid urbanization across hot arid environments transforms local microclimates, yet linkages between density, layout, and outdoor thermal comfort remain inadequately characterized. This study investigates these correlations in the desert city of Biskra, Algeria. We conducted extensive in-situ measurement campaigns during peak summer and winter peri...

Nowadays, it is considered that lighting the facades of buildings, especially historic and heritage buildings, is a crucial and essential intervention in promoting the building as a landmark. This is a necessary part of any building restoration design study, since it can potentially qualitatively improve the environment in which it is located, or t...

Humans spend more than 80% in indoor spaces. For this reason, both human centric lighting and biophilic design of indoor spaces have become popular approaches in the design of indoor building areas using white tuning luminaires and green walls in order to imitate daylight and natural environment correspondingly. The effect of light on humans and it...

The effect of light on human physiology as well as its non-image forming effects have been known for several years. An important milestone in understanding the non-visual effects of light was the discovery of a new type of photoreceptor namely the intrinsically photosensitive retinal ganglion cells, or ipRGCs which play a vital role in the human ci...

The scope of this work is to analyse the methodology used for the official designation of the first International Dark-Sky Park in Greece which was Aenos National Park, designated in May 2023. The methodology was based on the official International Dark-Sky Park requirements of the International Dark-Sky Association with many differentiations due t...

The objectives of the ECOSLIGHT project are the identification of skills and competences required for the professionals operating in the lighting sector, the detection of training programs currently offered and the gaining of deep insights and an analysis of gaps. Due to these goals, 342 valid questionnaires were gathered, 40 stakeholder interviews...

This research looks at the optimisation of industrial buildings through the application of the principles of lean thinking and philosophy, with an emphasis on daylighting in the design of industrial buildings. With the use of multiparametric analysis tools, we provide a solution for the optimized design of a roof system for the provision of dayligh...

In our days, the urgent need for minimizing energy consumption, forces governments to take immediate actions in all directions. A review of the existing norms along with a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis has been conducted, with reference to façade and road lighting in the urban structure. This methodology was selec...

Light pollution is a phenomenon that affects both humans and the environment negatively. Currently there are no established means to calculate light pollution. This work proposes a method for calculating the levels of light pollution on the facades of buildings, specifically historical buildings, which are the most difficult to light, using simulat...

The new version of the European Standard of Interior Lighting (EN 12464-1) considers LED technology for energy saving and minimizing environmental impact by giving new criteria for quantitative and qualitative lighting, including those that concern the “non-image-forming effects” (NIF) of light. In addition, it takes into account normal aging as an...

The exterior lighting in hotel buildings has a significant impact on humans and the ambient environment of city centres. The case study is a small-sized Boutique hotel, located at the historic centre of Athens, as far as its façade lighting is concerned, in relation to the ambient environment and the lighting standards that the general area archite...

Outdoor lighting has a more significant environmental influence on flora and fauna than humans mainly because of the shortest time period that they may be spending outdoors. Yet, light trespass has an equally important influence on people since it may affect the living conditions in their everyday life, and consequently, their prosperity. The prese...

In general, for the last 150 years, linear economy dominates the society. A model in which products are made from raw materials recovered from the environment, used, repaired, and finally disposed of in landfills. The environmental impact of the linear economy gave rise to the concept of the circular economy. This paper aims to provide a literature...

Lighting is a hugely important aspect of the environmental building design. During the past decades the building industry has been primarily concerned with the illuminance and the energy efficiency part of the artificial lighting rather than the human health. Latest studies emphatically state that a proper lighting design and luminaire types should...

Apart from the visual effects, light can also affect the human non-visual system, which includes a wide range of functions such as hormone secretion, alertness, mood etc. The non-image forming effects occur because light affects melanopsin, a photosensitive protein present in the receptive domain of retinal ganglion cells. These cells are responsib...

The necessity of energy equilibrium in industrial building stock must be addressed at design level in order to optimise use of materials without jeopardising the functional outcome. To do so effectively, the designer should incorporate a light use vs availability balance that will harness as much natural light resources as possible without creating...

One word that characterizes the situation in the lighting industry during recent years is “change” [...]

The proliferation of contemporary technologies, as well as the need to cover specific topics on lighting, green, entrepreneurship and horizontal needs, have created serious training needs for lighting professionals. These professionals are typically working adults, already working in the lighting or neighboring sectors that have to be re-skilled or...

The advent of LEDs in street lighting applications and the corresponding technological evolution during the last decades has given the opportunity to societies to create a more sustainable lighting environment. However, in most cases, up to now, in upgrading the infrastructures of the national roads, the assessment of street lighting tenders is lim...

Lighting corresponds to a significant amount of a building’s total energy consumption, hence a variety of alternatives exist so as to minimize the energy consumption used for lighting such as the installation of energy efficient light sources and the exploitation of lighting controls and more significantly daylight harvesting. The position of an am...

Purpose Primary objective of present study is to introduce a contemporary methodology for the lighting standards update addressing both normophakic and pseudophakic patients. Methods For the sake of our study, we theoretically estimated the intraocular-to-crystalline lens iIluminance ratio (ICIR) and the intraocular lens (IOL) luminous efficiency...

Life Cycle Impact Assessment (LCIA) of lighting products is a methodology that analyses and evaluates environmental impacts throughout their total life cycle, from the extraction and processing of raw materials, design, construction, transportation, distribution, use, recycling and re-use of materials, and last their final disposal. According to th...

The use of municipal football fields by a large number of citizens and amateur athletes on a daily basis during evenings is a popular activity. Usually, the aiming of the pitch lighting, without taking into account the dense urban environment in the surroundings, causes light pollution. Obtrusive lighting in most cases is the rule and not the excep...

The objective of this research is the study of lighting the facades of historic buildings having as an orientation the reduction of dire effects of light pollution on the environment and humans. Lighting is an important way of underlining characteristics of historic buildings, such as beauty and identity, which form part of our cultural heritage. S...

This work describes the preparatory steps for the planning of a light pollution protected area in the form of an International Dark-Sky Park in Aenos National Park at the island of Kefalonia that refer to lighting and light pollution. In more detail, we identified and measured luminance, illuminance and spectrum of public lighting at the island of...

A daylighting control system that uses the closed loop proportional algorithm needs to be calibrated both during nighttime and daytime. The selection of the daytime calibration time can affect the behavior of the system and is usually performed when the ratio of the illuminance of the ceiling sensor (SD,tc) to the illuminance at a point on the work...

The present study includes a combined assessment of the energy efficiency and economic performance of energy measures in five-story existing and newly constructed office buildings in Greece. The building primary energy consumption and investment and operation & maintenance costs are calculated per Directive 2010/31/EU and EN 15459-1 standard. VRV h...

The necessity for energy saving in lighting leads to installation of new energy efficient light sources, especially LED luminaires. Although solid state lighting is considered the dominant lighting technology for the future there exist no concrete methods to evaluate LED luminaires and decide the optimal one for each lighting application. Multicrit...

This work investigates the real-time performance of Linux kernels and distributions with a PREEMPT_RT real-time patch on ARM-based embedded devices. Experimental measurements, which are mainly based on heuristic methods, provide novel insights into Linux real-time performance on ARM-based embedded devices (e.g., BeagleBoard and RaspberryPi). Evalua...

Nepal houses many traditional and cultural sites rich in historical cultural diversity. These sites are also economically important to the nation. These monuments show the culture and the living beliefs of the communities; hence, people from all over the world are attracted to such place to observe the beauty and to feel the spirit and the conserva...

The use of artificial lighting in the built environment can affect not only the visual perception and wellbeing of humans but also the environment. Light pollution is a type of pollution that climaxes in the cities, but occurs increasingly away from them, due to the increase of artificial lighting but also due to malpractices and improper lighting...

Daylight utilization significantly contributes to energy savings in office buildings. However, daylight integration requires careful design so as to include variations in daylight availability and maintain a balance between factors such as lighting quality and heat gain or loss. Designers with proper planning can not only improve the visual environ...

Because of the absence of lighting calculation tools at the initial stage of tunnel design, the lighting systems are usually over-dimensioned, leading to over illumination and increased energy consumption. For this reason, a fine-tuning method for switching lighting stages according to the traffic weighted L20 luminance is proposed at no additional...

Daylighting is the cornerstone of low energy building design. Therefore, the adoption of a daylight – harvesting lighting control system can substantially increase lighting energy savings. These are strongly depended on the determination of daylight zones (DZ) which in turn help to identify the lighting loads that must be controlled separately. The...

The aim of this work is to assess the impacts, both in terms of daylight efficiency and energy impacts, of an advanced daylighting system that utilizes a heliostatic configuration for sunlight redirection in a deep South oriented office room in two (2) different climate conditions. Conventional daylighting systems such as windows, and clerestories...

Light pollution is a type of pollution that climaxes in cities and occurs increasingly away from them, due to the increase of artificial lighting and inappropriate lighting design (selection of luminaires, aiming, illuminance/luminance levels, and spectral characteristics). Increasingly, light pollution also affects the countryside due to local lig...

The scope of this paper is to identify the benefits of lamp recycling from the domestic sector. Data related to the recycled lamps was obtained from two recycling companies and were compared to those related to the waste lamps from the domestic sector. This was achieved by a new methodology which uses two alternative approaches. The first one is de...

This research discusses the feasibility of replacing or supporting artificial lighting with Transgenic Bioluminescent Plants (TBP), as a means of minimizing light pollution, reducing electrical energy consumption and de-carbonizing urban and suburban outdoor environments, creating sustainable conditions and enriching the quality of life. Until now,...

With the advent of LED technology, lighting studies have gained a great interest, especially street lighting. Nowadays, these studies demonstrate the great energy savings achieved by replacing high pressure sodium lamps with LED. As LED technology is continuously improving, energy savings are increased and thus the payback time of the investment is...

Used properly, daylight can provide visual comfort, reduce energy consumption and improve health and safety at work. This paper investigates the influence that different roof types, (i.e., sawtooth roof, skylight and monitor), have on daylight levels, along with the construction cost in an industrial environment in Athens, Greece. Construction cost...

Office lighting planners are faced with two key objectives as their plans should meet customers’ needs and also be compliant with a range of policy guidelines targeted on a wide variety of lighting attributes. In the EU, the most recent relevant guidelines are led by the “2030 climate & energy framework” which among other targets calls for a more e...

Visual adaptation demands increased illuminance in the tunnel entrance, which results in an increased number of installed luminaires and power consumption of each luminaire. There are norms that define the required luminance in this entrance zone, which depends on the variability of the daylight on the surfaces that surround the entrance. In most e...

Although with the advent of the LEDs the energy consumption in buildings can be reduced by 50%, there exists a potential for energy savings due to lighting controls. Moreover, lighting controls can ensure that the near zero energy requirements by EU can be achieved for near zero energy buildings (nZEBs). For this reason, more sophisticated lighting...

Daylighting is a cornerstone strategy aiming at reducing a building's energy consumption. Daylight responsive dimming is a proven, mature technology, that significantly reduces lighting energy use, which in turn, affects both energy consumption and peak loads as well. Although in Energy Performance Building Directive (EPBD), the use of a daylightin...

Light shelves have been discussed in numerous studies as suitable solutions for controlling daylight in side-lit spaces. It is a system that can be easily modified, offering a range of design solutions. It can be easily mounted on the exterior and/or the interior of a vertical opening, it can come in various shapes from static flat forms to curved...

Used properly, daylight can have lots of benefits, not only in visual comfort but also in reduction in energy consumption as well as improving H&S at work. [L. Bellia et al,2013]. This paper identifies the effects of different roof types (i.e. saw tooth roof, skylight and monitor) and opening geometries to the overall ingress indices of natural lig...

The energy consumption for artificial lighting in school buildings is one of the main consumers of electricity. In Greece there is a huge number of school buildings that their artificial lighting system in classrooms is obsolete using luminaires with T8 and sometimes T12 florescent lamps with electromagnetic ballast and inappropriate cover. Scope o...

The energy consumption for artificial lighting in school buildings is one of the main consumers of electricity during the year. In Greece where daylight is adequate during the year there is a missing opportunity for energy savings. Scope of this paper is to examine the lost opportunities for optimizing the lighting system combining with daylight ha...

The objective of this study is to present the opinion of students for the visual comfort from the daylight in classroom via questionnaires and the confrontation of results with measurements of condition of daylight at the moment of completion of the questionnaires. The school buildings should not risk the health of students and teachers, provide a...

Nowadays, more human activities are developed in the urban area, throughout night time period. The effect of space on human behavior is often the subject of study and research, especially during the night hours, when the feeling of safety is diminished, and the need for light even more imperative. The aim of the research is to investigate the relat...

The existing road lighting installations in Greece, although many of these have been performed a few years before, present a lot of waste of energy. There are several options to redesign an efficient lighting system on an existing motorway to save energy. Egnatia Odos (E.O.) one of the largest national roads in Greece was selected as a case study....

In Greece, the household sector consumes21% of the total energy consumption that is based on the data provided by PPC S.A Hellas and 1.7% of this is consumed in lighting. Commonly used incandescent and halogen lamps, fluorescent lamps, and since 2012 and then we have a dynamic input of LED lamps reaches in 2016 30%. Fluorescent lamps contain a quan...

The aim of this study is to investigate the impact of the color temperature of artificial lighting in the visitor’s viewing experience of the artworks in display. More specifically, an experiment was designed to approach the role of the Correlated Color Temperature (CCT) of artificial light sources in highlighting the colors of artworks. The object...

While saving energy is one of main scopes for improving a lighting system, there are also other parameters that are crucial for lighting design of special applications such as a football stadium. This presentation analyses these parameters such as glare and vertical illuminance for football pitch lighting. Furthermore, presents two case studies: a)...

While the efficiency of the Lighting Emitting Diodes (LED) is increasing and new installations are being implemented, their control due to the adoption of daylight harvesting systems, hasn’t been sufficiently examined yet, although this can reduce further energy consumption. A crucial parameter for achieving improved performance is the proper match...

While daylight harvesting is one of the most energy efficient ways to minimize energy consumption in areas with adequate nature light inside buildings, Ambient Light Sensors (ALSs) are still not being widely installed. Many drawbacks on installation and commission of ALSs, are holding back their wide spread use in building sector. Most of the drawb...

This paper aims to investigate the feasibility of indoor nocturnal activities in houses of antiquity in terms of colour perception under the lighting conditions resulting from the use of lamps and the ability or discomfort for users when discriminating colours. A set of 3D simulations were performed in the Lighting Laboratory of the National Techni...

Working in a lighting laboratory means that every day we face various demands from either luminaire manufacturers or lighting designers, making us question some parts of the current standards. Many technical CIE committees are continuously trying to improve these standards, however, due to the extremely wide range of lighting applications and the r...

Over the past years, extensive research has been carried out in the creation of working environments that utilize natural light as their primary source of illumination. Transferring glare-free daylight into the core of the building can significantly increase lighting energy savings but it can increase cooling needs as well. Traditional daylighting...

While daylight harvesting is one of the most energy efficient ways to minimize energy consumption in areas with adequate nature light inside buildings, Ambient Light Sensors (ALSs) are still not being widely installed. Many drawbacks on installation and commission of ALSs, are holding back their wide spread use in building sector. Most of the drawb...

The lack of lighting planning for internal and external illumination of buildings contributes to wasting energy and to the issue of light pollution. This will be demonstrated with research from the ground and by analysis of images, taken with detectors on satellites, the International Space Station or planes. Besides large area floodlighting from a...

There exist a lot of alternatives to minimize energy consumption of artificial lighting systems. Daylight harvesting with the use of photosensorsis one of the most usual methods to achieve energy savings and maintain visual comfort. Wireless sensor networks are a prominent technology to monitor a variety of environments and have plenty of applicati...

With the advent of LED technology the importance of a proper dimming procedure of luminaires became crucial. The greater luminous efficacy of LEDs in comparison with other light sources in interior spaces can offer increased energy savings. Furthermore using lighting control technics such as daylight harvesting or lumen maintenance using photosenso...

The LighTin Phone project is a realistic and applicable attempt to explore the potentiality of light for the creation of expressive visual forms. The whole project, which has artistic premises, is based on the ideas of interhuman communication and friendship that are transformed into specific visual experiences through their embodiment into forms c...

Chronos nº 32-2015 doriNa moullou, lamBros t. doulos & fraNGiskos v. topalis 1 The assessment of the performance of ancient lighting devices may provide scholars with valuable information on the lighting conditions that existed in ancient houses, and on the level of optical comfort created by the use of those devices. Consequently, it also provides...

The lack of knowledge concerning the commissioning of a daylight responsive system constitutes a serious impediment to their widespread use. Furthermore, installation details and tools regarding their photosensor position and field of view (FOV) are insufficient. This paper presents a decision making method capable to estimate the best position of...

This paper presents the results of the evaluation of various LED in terms of their photometric and electric performance. These lamps are promoted as retrofit replacements of halogen reflector lamps with GU10 base. This type of lamp is widely used in commercial lighting. The tests and corresponding calculations were carried out according to the Euro...

Aim of this paper is the optimal selection of energy saving solutions implementing multicriteria analysis in order to reduce artificial lighting consumption in buildings. The method is applied to an educational building in which solutions such as luminaires with energy efficient lamps, occupancy sensors, photosensors and electronic ballasts are pro...

The objective of this paper is to assess the lighting conditions in houses of antiquity providing the necessary photometric basis and infrastructure for current and future studies on ancient lighting. Lighting in antiquity is a research area that has not yet engaged the attention of many scholars. One of the main reasons is the notable lack of inte...

Aim of this paper is to present a multicriteria decision methodology for choosing the appropriate luminaire for lighting provincial streets, which belong to various classes of EN 13201. To begin with, five different types of low wattage street luminaires (70-85W) are presented, each one representing a different lighting technology from the ones men...

Archaeological data- when properly recorded and published- give significant evidence for the activities that took place inside an ancient household/room and valuable information for the amount and the kind of lighting equipment used (MOULLOU 2010, passim). However, these data alone cannot supply the information needed in order to understand whether...