Lighting Comfort Research Articles

Study of preferred background luminance in watching computer screen in children

Background In recent years, computers have been intensively used at home. In contrast to paper-based books and documents, computer screen is self-illuminated with larger screen-background luminance difference, which greatly induces visual discomfort. To compensate for that, one effective solution is to offer an additional background luminance. In this study, we investigated whether and to what extent additional background lighting is needed in looking at a computer display comfortably. Methods In this study, 60 healthy children aged from 9 to 12 years and 58 adults aged from 21 to 39 years participated in the experiments. They were asked to choose their most preferred background luminance intensities at three screen luminance levels. The data were analyzed by Matlab (R2012b) and SPSS 20.0. Results Both children and adult participants selected a non-dark background as their comfortable lighting condition when watching a computer display (children: t (59)=22.0, P <0.01, adults: t (57)=15.5, P <0.01). Comparatively, children preferred brighter background in general (F (1,116)=7.0, P <0.01). More importantly, participants’ preferred background luminance levels were linearly correlated with screen luminance intensities (children: slope=0.97, R2 =0.98; adults: slope=0.38, R2 =1.00). Conclusion These results indicate that varying background luminance to maintain screen-background luminance ratio is beneficial to human visual comfort.

Measurements of indoor environmental conditions in Italian classrooms and their impact on children’s comfort

This study evaluates the indoor environmental conditions and children’s comfort levels in 8 classrooms in three Italian primary schools. It is a development of a pilot study previously carried out by the authors in other educational buildings. Spot and long-term measurements were made to evaluate microclimatic conditions (i.e. air temperature, relative humidity, CO2 concentration, and illuminance). A questionnaire, distributed three times, investigated the students’ perception of thermal and lighting comfort, their satisfaction with building-related factors, and their interactions with the environment. Predicted mean vote and predicted percentage dissatisfied indexes were calculated and an adaptive approach was also applied, but their results did not correspond to the students’ subjective evaluation of thermal comfort. An innovative multivariate ranking method was developed as a possible tool to assess building stocks in order to establish priorities for repair, maintenance, and refurbishment. The problem which the students complained about the most was the thermal comfort in the hot season and solar penetration. Moreover, the school with the worst microclimatic conditions was also judged the worst for building-related and psychological factors.

Real-time smart lighting control using human motion tracking from depth camera

A smart lighting system provides automatic control of lighting illumination and color temperature for high quality of life as well as energy savings in smart cities. A real-time activity understanding system with accurate human location estimation under varying illumination is required for smart lighting control, since comfortable lighting conditions vary according to human activities. This paper presents a real-time smart lighting control system using human location estimation based on inverse-perspective mapping of depth map images and activity estimation from location, heading direction, and height estimation of the moving person from multiple depth cameras. Lighting control based on estimated proximity to the specific activity area, distance to the target lighting area, and heading direction of the person provides an automatic activity-dependent lighting environment as well as energy savings. We implemented several activity modes such as study mode, dialog mode, and watching TV mode, and applied the proposed lighting control system to a living room lighting control with known furniture, electronics, and lighting locations using multiple Kinect depth cameras. The proposed model is based on localized proximity-based lighting control and can be extended to a more general lighting control by combining with global lighting control schemes.

Simulation of Artificial Lighting Comfort of Cab for High-Speed Train

The artificial lighting level and visual comfort of drivers for a high-speed train cab are evaluated by using computer simulation technology. The simulation model is established first, and then some lighting quality indexes, such as illuminance, illuminance uniformity and glare, are analyzed based on related design standards. Considering the effects of environmental lighting on drivers physiology and psychology, the analysis on environmental psychology for driver of the cab are conducted also. The evaluation method proposed in the paper is significant for improving artificial lighting design of high-speed train cab.

Daylight perceptive lighting and data fusion with artificial neutral network

The basic concept of daylight perceptive is that the artificial light automatically dims to the appropriate level to keep constant indoor illumination when sufficient daylight is not available. Energy efficient character of daylight perceptive lighting was analyzed and a method to evaluate energy saving was present; according to the presentation, the more energy is saved if the longer Tlast—duration of indoor illumination being is less than threshold. A daylight perceptive controller was developed and the output power of LED light source under different PWM was measured, according to the measurement, work current and output power of LED is proportional to duty cycle. With two sensors, a data fusion method was put forward to exclude interference and improve lighting comfort. With more than two sensors, data fusion based on neutral network was discussed.

Auricular Burns Associated With Operating Microscope Use During Otologic Surgery

To raise awareness of the potential hazard of auricular burns associated with operating microscope use during otologic surgery. Retrospective case series and summary of the Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience (MAUDE) database of voluntary adverse event reports pertaining to microscope related auricular thermal injuries. All patients who sustained auricular burns while using the operating microscope during otologic surgery at 2 tertiary academic referral centers. Surgical procedure, microscope model, intensity of illumination, length of procedure, focal length, location and severity of burn, and patient outcome. A total of 4 microscope-related auricular thermal injuries were identified from the authors' institutions. Additionally, 82 unique cases of soft tissue burns associated with the use of an operative microscope have been voluntarily reported to the FDA since 2004. A disproportionately large percent (∼ 30%) of these occurred within the field of otology, the majority of which were during tympanoplasty or tympanomastoidectomy procedures at focal length distances of 300 mm or less with xenon light source microscopes. Simultaneous advancements in light delivery technologies and lens optics have continued to improve the efficiency of the operating microscope; however, these improvements also increase the potential for thermal injuries. Although rare, a review of the FDA MAUDE database suggests that microscope-related soft tissue burns occur more frequently in otology than any other surgical specialty. A variety of factors may help explain this finding, including the unique anatomy of the external ear with thin skin and limited underlying adipose tissue. Preventative measures should be taken to decrease the risk of thermal injuries including use of the lowest comfortable light intensity, adjusting the aperture width to match the operative field, frequent wound irrigation, and covering exposed portions of the pinna with a moist surgical sponge.

The effect of architectural façade design on energy savings in the student dormitory

There are many reasons for adequate use of natural light inside students' dormitories. Intensity of light required for student activities and temperature inside the rooms are the major factors for an occupant's comfortable work and life. Design of building fa?ades has a significant impact both on the use of natural light and energy consumption. In this paper, a comparative analysis of student rooms with different orientations and different fa?ade designs was performed in order to investigate what type of refurbishment in the fa?ade is necessary. The goal of the refurbishment was generation of optimal thermal and lighting comfort for students' work with maximal energy saving for a new student dormitory in Nis, Serbia. An analysis of annual energy consumption of the newly designed student dormitory and proposed replacements on the exterior fa?ade was performed by using the software EnergyPlus. Based on the energy consumption analysis it could be concluded that significant energy savings would be possible by upgrading the shading devices across the width of the window. In other words, changing the fa?ade of the dorm could generally improve students' comfort, while the energy costs would be reduced.

The Preservation of the Solar Potential in Cities of Hispanic Trace. Analysis of the Current Situation, and Future Potential in Urban Areas of Argentina

To achieve urban sustainability, the access to solar radiation must be a guaranteed right in the cities. There is an urgent need to review designs, patterns and constructive technologies to obtain energy efficient buildings providing thermal and lighting comfort for their occupants through the maximum utilization of available renewable resources of energy.Although solar radiation is one of the most valuable resources of clean and renewable energy, the access to the same seldom constitutes a social right.When analyzing the viability of a bioclimatic design in a new building or in the recycling of an existing one, it is fundamental to know what the solar available potential is, especially in urban consolidated areas where the characteristics of the structure significantly determine the access and availability of the resources. This problem is present in all Latin American cities, emerging from a Spanish colonial grid layout.In order to reverse this tendency, it is necessary to ensure the future free utilization of solar power destined for central and water heating in urban surroundings regardless of their densities. However, the reality indicates that the legal existing frame in many countries of Latin America does not consider the renewable resources as appropriable.This paper presents the evaluation of the impact of regulations in medium scale Argentine cities, in relation to the solar potential of buildings located in consolidated areas. If the present patterns continue, the application of rules orientated toward the utilization of solar resources, will be viable only with great difficulty.

Study on Natural Lighting Modification of Existing Steel-Structure Plants in Cold Regions

This thesis takes it as an example that the steel-structure processing workshop of a machinery factory in Shandong province of cold areas, makes use of the software to simulate the factory’s natural lighting environment according to real conditions and objective analysis to its simulation result. Besides, it proposes feasible measures of optimizing and modifying lighting windows area and material selection for the purpose that creating a comfortable lighting environment for the steel-structure industrial plants in cold areas, and it also plays a role in rendering effective suggestions and reference.

Kenyamanan Visual Melalui Pencahayaan Alami Pada Kantor (Studi Kasus Gedung Dekanat Fakultas Teknik Universitas Brawijaya Malang)

Office as a work area requires an adequate level of comfort, so that users can carry out activities smoothly and has a good working productivity . Convenience is not only dependent on the temperature in the chamber , incoming solar radiation , air quality , and weather quality , but is also determined by the quality of the lighting. Indonesia with rich conditions year-round sunshine should put natural lighting as a priority in the design ; aside as environmental response efforts , utilization also can save energy consumption of building. research was designed to evaluate the visual comfort of the application of natural lighting in the office building, on case study Dekanat Fakultas Engineering University Brawijaya ( UB FT ) Malang. method descriptive and correlational research , seeks to combine the observations ( observations made in the form of illumination with luxmeter measurement , simulation contours of natural lighting , the identification of the elements that affect the natural lighting ) with the perception of the user to get an overview of visual comfort and design characteristics of natural lighting in buildings FT UB so as at a later stage can be given recommendations for the achievement of better visual comfort Keywords: office, visual comfort, natural lighting

Effects on different age levels of distinct lighting environment design

This research designed a suitable lighting environment to provide comfortable lighting surroundings to different age groups. Kruithof indicated that the human sense of sight can be directly affected by lighting equipment, meaning that human psychological sensations and perceptions can also be affected by varied lighting conditions. This study used five LED ceiling lamps, each exhibiting a different geometric shape, to create diverse lighting surroundings in a simulated living room at low color temperature and under low illumination. To obtain physiological data from participants of different age groups, we measured the galvanic skin response, heart rate, and skin temperature of the little finger of each participant. To obtain psychological data, we used subjective questionnaires to measure the feeling of the participants. Based on the results of this study, we found that the lighting environment projected by a linear geometrical shape is more suitable for elderly people than for younger groups. This finding can provide lighting manufacturers with a reference for improving product quality.

Case Study

An indoor environmental quality survey was conducted in a small private automotive repair shop during May 2009 (hot season) and February 2010 (cold season). It was established that the detached building, which is naturally ventilated and lit, had all the advantages of the temperate local climate. It provided a satisfactory microclimatic working environment, concerning the thermal and the lighting comfort, without excessive energy consumption for air-conditioning or lighting. Indoor number concentrations of particulate matter (PM) were monitored during both seasons. Their size distributions were strongly affected by the indoor activities and the air exchange rate of the building. During working hours, the average indoor/outdoor (I/O) number concentration ratio was 31 for PM0.3-1 in the hot season and 69 for the cold season. However I/O PM1-10 number concentration ratios were similar, 33 and 32 respectively, between the two seasons. The estimated indoor mass concentration of PM10 for the two seasons was on average 0.68 mg m−3 and 1.19 mg m−3, i.e., 22 and 36 times higher than outdoors, during the hot and the cold seasons, respectively. This is indicative that indoor air pollution may adversely affect mechanics’ health. Noise levels were highly variable and the average LEX, 8 h of 69.3 dB(A) was below the European Union exposure limit value 87db (A). Noise originated from the use of manual hammers, the revving up of engines, and the closing of car doors or hoods. Octave band analysis indicated that the prevailing noise frequencies were in the area of the maximum ear sensitivity.

Daylight Perceptive Lighting and Artificial Neutral Network

Energy efficient character of daylight perceptive lighting was analyzed and a method to evaluate energy saving was present, according to the presentation the longer duration of indoor illumination being less than threshold is, the more energy is saved. With two sensors, a data fusion method was put forward to exclude interference and improve lighting comfort. With more than two sensors, data fusion based on neutral network was discussed.

Enhancing Performance While Avoiding Damage: A Contribution of Macular Pigment

To compare action spectra for visual discomfort in the fovea and the parafovea and to determine the effect of macular pigment (MP). Visual discomfort thresholds to lights from 440 to 600 nm were obtained for six young (<35 y), visually normal subjects with a wide range of MP densities (0.10-0.71 at 30' eccentricity). Foveal and parafoveal conditions were assessed. Discomfort thresholds were also obtained for xenon-white light (partially absorbed by MP), and a broadband yellow (outside the absorption band of MP). MP was measured psychophysically using heterochromatic flicker photometry (HFP). For the parafovea, discomfort sensitivity (1/threshold) increased sharply with decreasing wavelength for all subjects. Commensurate with a subject's MP level, MP significantly reduced visual discomfort to short wavelengths (including xenon-white light) for central viewing. MP simultaneously reduces visual discomfort and protects from light damage at short wavelengths. As a result, MP increases the range of safe and comfortable light levels. Because higher light levels enable improved visual sensitivity for fine detail, these findings indicate that the spectral absorption properties and spatial distribution of MP combine to protect the retina while enhancing visual performance. The action spectrum for visual discomfort closely matches the risk for acute light damage to the retinal pigment epithelium, and it is consistent with a major influence from the intrinsically photosensitive retinal ganglion cells containing melanopsin. We suggest that MP interacts with nonimage-forming retinal input to achieve the dual outcomes of visual discomfort reduction and protection from light damage.

Design and Realization of Intelligent LED Fluorescent Lighting Control System

The intelligent LED daylight lamp lighting control system is designed. According to the external light intensity, the control system which uses the PWM light modulation technology, ST89C52 Single Chip Microcontroller as the control system core, can adjust brightness of the LED daylight lamp automatically and accurately, and can also manually adjust the brightness. A comfortable lighting environment can created through the system for controlling the illumination source, the purpose of energy saving can be achieved. The control system which can be used for a variety of lighting situations has strong application value.

Validity and reliability testing of a post-occupancy evaluation questionnaire on indoor environmental quality and occupants' satisfaction

A post-occupancy evaluation (POE) conceptual framework and questionnaire were developed and tested for occupant satisfaction in sustainable buildings. The purpose of this study was to test the POE questionnaire for validity and reliability and report the test results as well as those of a confirmatory case study analysis. An online, self-administered questionnaire was completed by 218 occupants of a sustainable office building in the Midwest. Statistical analysis for validity and reliability is reported. Additionally, several notable results were found in the case study: a) overall occupant satisfaction is significantly influenced by lighting/view conditions and furnishings conditions; b) occupant satisfaction with lighting/view conditions was significantly related to visual comfort of lighting; c) occupant satisfaction with furnishings conditions was significantly related to visual privacy. Finally, the questionnaire was found to be valid and reliable, which provides the industry with an instrument to learn more about occupant responses to sustainable buildings.

Homeostasis Lighting Control System Using a Sensor Agent Robot

In this study, “homeostasis”, the function by which living things keep their constancy, was emulated as a lighting control for a building space. The algorithm we developed mimics the mechanisms of the endocrine and immune systems. The endocrine system transmits information entirely, whereas the immune system transmits information with a concentration gradient. A lighting control system using the proposed algorithm was evaluated in a simulation and experiment using a sensor agent robot. In this algorithm, a robot recognizes a person’s behavior and uses it to decide his or her preference as to the illuminance. The results indicate that the algorithm can be used to realize a comfortable lighting control in several situations.

The Architecture Studio of Universiti Kebangsaan Malaysia (UKM): Has the Indoor Environmental Quality Standard Been Achieved?

Studio-based learning is a shared learning environment in which ambiguous problems are addressed. This paper primarily focused on the lightings at the Universiti Kebangsaan Malaysia (UKM)’s architecture studio and to find out whether it had achieved the Indoor Environmental Quality (IEQ). A good design, involving a space in a building, requires sufficient daylight in order to perform a task. This can be achieved by providing enough means to let in diffused light from the sky, yet keeping out direct light from the sun to prevent heat gain and glare. The purpose of this research was to identify the importance of the IEQ in creating conducive studio-based learning environment. The IEQ is crucial for a learning institution since indoor environment factors can actually affect human comfort, health and productivity. Lighting is most important to students as high-quality lighting will improve students’ moods, behavior, concentration, and consequently, their learning. However, the effectiveness of learning in a studio cannot be fully achieved if the IEQ is being overlooked. Presently, artificial lights are being used most of the time in the UKM architecture studios in order to optimize students’ vision and comfort. Using an equipment, named LM-8100, and supported by a questionnaire survey to gauge the lighting comfort level from the students’ perspective, a lighting reading was taken for a duration of 10-hours for three days in the UKM third year architecture studio. The finding showed that the lighting setting is not within the range of the Malaysian Code of Practice on Indoor Air Quality (IAQ). However, the students have perceived it as normal and thus, the situation does not hinder them to stay long inside their studio. This situation will affect the students’ ability to perceive visual stimuli in the short-term and health, in terms of students' vision, in the long run.

Indoor Environmental Quality for UKM Architecture Studio: An Analysis on Lighting Performance

Lighting can be efficiently used to maximize occupant comfort, and to conserve energy. This paper focuses on lighting in UKM architecture studio space in order to achieve better IEQ. Good design for building requires sufficient daylight for tasks performed within a space. This is achieved by providing enough means to let in diffused light from the sky, but keep out direct light from the sun to prevent heat gain and glare. Lighting is important to the student because high quality lighting improves student moods, behavior, concentration, and therefore their learning. The artificial light is used most of the time in UKM architecture studio to optimize student vision and comfort. The methodology of the lighting analysis is first by using the equipment named LM-8100, and second by a questionnaire in gauging the lighting comfort level from students’ perspective. Lighting measurement is taken for 11-hours in 2 days for UKM year 3 architecture studio. The finding shows that the lighting setting is not within the range of Malaysian Code of Practice on Indoor Air Quality, but the students perceived it as normal and this is do not hinder them to stay longer inside their studio. This situation will affect the student ability to perceive visual stimuli in short term and health in terms of students’ vision in the long run.

Study on Properties of Bast Fibers

Light weight , softness and comfort are becoming the development priority for the bast fabrics for apparel use. Therefore, some properties of the bast fabers related to these aspects become important. In this paper, the properties of bast fibers, including fiber length, fineness, tenacity, softness were tested and evaluated to determine which is better for developing fabrics pleased by the consumers by using optimal design theory. The results show that ramie fiber has high softness, great tenacity and is finest. It is the best material for the garments required light weight and comfort, hemp second, the next is flax and kenaf. Jute is the worst one.