Search results

An indoor office space should not only provide adequate illuminance on horizontal planes but also cater to the physiological and psychological requirements of the occupants. This paper aims to describe a lighting simulation-based work conducted in Kolkata, India which modeled an indoor office to investigate the effects of variation in room surface reflectance combinations on user perception, mean room surface exitance (MRSE), average horizontal illuminance and overall uniformity of horizontal illuminance.

A fluorescent illumination system–based office space was modeled and retrofitted with tubular LED lamps in DIALux. Simulations were conducted for 16 different room surface reflectance combinations and a five-point Likert scale-type survey questionnaire was formulated to conduct a survey with 32 test subjects to assess the subjective preferability of each resultant light scene.

Simulation results demonstrate that the relationship between average horizontal illuminance and MRSE as well as between average horizontal illuminance and overall uniformity of horizontal illuminance, was statistically significant (p < 0.001). In the conducted survey, the resultant light scene arising out of the reflectance combination of wall:ceiling:floor = 60%:90%:20% was the most well-received one with 187 convinced agreements (“agree” and “strongly agree” responses).

This work found strong linear correlation between average horizontal illuminance and MRSE and between average horizontal illuminance and overall uniformity. A five-point Likert scale-type survey questionnaire with seven questions was formulated and validated with 32 test subjects (Cronbach’s alpha > 0.9295), which showed that the wall:ceiling:floor reflectance combination of 60%:90%:20% was the most favored choice.

Daylight plays a crucial role in the attainment of building energy savings. Harnessing daylight in building designs will require the need for daylight illuminance data. However, daylight illuminance data are scarce due to few measuring stations. Aside from being sparse, illuminance measuring stations can be expensive to set up, thus making the luminous efficacy model a better alternative. Hence, this study attempted to model horizontal luminous efficacies under the 15 Commission internationale de l'éclairage (CIE) standard skies. Therefrom, daylight illuminance was estimated from a proposed vertical luminous efficacy model.

Measured solar irradiance, daylight illuminance and luminance distribution data were gathered from the local measuring station in Hong Kong. The luminance distribution data were used to classify the skies into the 15 CIE standard skies. Next, the solar irradiance and daylight data were used to derive the horizontal luminous efficacies under each standard sky. Furthermore, a vertical luminous efficacy model developed using the measured data was described, and this was used to predict vertical illuminance.

It was observed that Skies 1, 8 and 13 seem to be predominant in Hong Kong. Also, the result showed that constant luminous efficacies could be used for deriving illuminance data. Furthermore, horizontal luminous efficacy ranged from 40 to 190lm/W, indicating that daylight can provide sufficient visibility during working hours. The vertical luminous efficacy model proves to offer reasonable estimations of vertical illuminance data.

Further work needs to be done with more measured data to cover for spring seasons. The described model still needs to be fitted with different world climates to ascertain its universal applicability. The evaluations need to be done under obstructed sky conditions to cater for dense and clustered urban centres.

The discussed luminous efficacy model could be used to derive illuminance data in the absence of measured daylight illuminance data, especially in the subtropical region. Also, the comparative advantage of daylight over artificial lighting was highlighted in this study.

Unlike previous studies, this paper discusses the luminous efficacies of global, direct and diffuse components under the 15 CIE standard skies. Furthermore, the described luminous efficacy analysis provides an approach for deriving vertical and horizontal illuminance data. Such vertical data will be required for analysing building lighting requirements, sensible heat from electric lighting, and energy savings from daylighting controls. Also, the information on horizontal luminous efficacies will help evaluate solar roof and skylight designs.

Lighting in building sectors (consumes the highest energy in commercial buildings and the second highest in residential buildings in India) has very much potential for energy conservation in buildings. With the use of daylighting system, energy consumption in lighting can be lowered up to 30 to 40 per cent.

An experimental effort has been made in this paper to explore the internal wall coloring effect on the performance of tubular light pipe. Trace-pro software has been used and validated. With the help of this software, light pipe has been designed and simulated in a ray tracing mode. Assessment of four globally used prediction models has also been conducted to compare the performances in different seasons for light pipes in the composite climate of New Delhi.

It has been conducted based on three statistical indicators as mean bias error, root mean square error and R². Using regression, an empirical model for average internal illuminance has been developed as a function of light reflectance value (LRV) and solar altitude angle. Trace-pro results confirmed that maximum internal illuminance can be obtained with wall surfaces coated with high LRV color. Finally, by using of a single light pipe system for a test room with the artificial lighting system and applying continuous dimming control, the amount of electrical energy has been saved up to 38.5 per cent per year.

After going through the literature, it has been identified that there has been no paper published which explores the effect of colors of the internal walls on the performance of the light pipe. Along with this, the comparison between existing empirical performance models and find out which model gives the best result in different seasons has been carried out for New Delhi, India.

This paper presents the views of 16 fully sighted people who carried out typical office tasks under eight different lighting systems. This work is taken from a much larger study, primarily involved with the lighting of office tasks for visually impaired people. Non‐parametric statistical tests show there are significant differences of opinion about the different lighting systems in terms of adequacy and comfort. Whilst there is a general trend in the results which suggest that increasing task illuminance and wall illuminance is preferred by the test subjects, other issues are identified which can influence aspects of lighting quality.

The purpose of this research is to investigate natural illumination properties of one of the classrooms in the School of Architecture at Izmir Institute of Technology, located in Turkey, which is the northern hemisphere.

In this study, the definitions of the basic terms in daylighting, such as daylight factor, illuminance, glazing ratio, are given first. Then, a luxmeter and a lighting simulation software, Velux, are used in order to calculate variable lighting factors during daytime, at different storeys, at different directions, for the classes. Velux is a proprietary software and it enables natural lighting analysis practically.

Chosen classrooms are examined regarding their having sufficient natural illumination. The height of windows from the floor is changed, and the resultant effects on natural lighting in the classrooms are determined by using the lighting simulation program, Velux. The study shows that daylight factor and illumination near the window decreases as the height of the window above the floor increases. However, the illumination increases away from the window, giving greater uniformity to the lighting. At the same time, the usable depth of the classroom increases. The tall and narrow windows bring the daylight near themselves.

Practical window design decisions can help architects to provide effective and healthy natural lighting for interiors.

Adjustment of the dimensions of the windows is important in order to balance the energy consumption of buildings. This study investigates natural lighting depending on both experimental measurements and simulation software, Velux.

Good illumination creates an aesthetic environment that may positively influence patients’ well-being and provide comfort to the hospital staff. This study aims to focus on exploring the energy efficiency of lighting and subjective perception of the lit environment in a hospital ward to assess quality indicators of ambient lighting conditions.

The existing conventional tubular fluorescent lamp–based lighting system in the surveyed patients’ ward was retrofitted with light-emitting diode (LED) luminaires to explore illumination and energy parameters. Thereafter, a software lighting model was created, simulated and analyzed. A Web-based survey with five bipolar adjective pairs in a semantic differential scale was conducted with 48 participants to record and analyze their subjective responses pertaining to the variations in lamp types and surface reflectance combinations.

The findings imply that the LED tubular lamp–based illumination was deemed more adequate compared to other lamp types and the effects of variations in room surface reflectance combinations on the participants’ responses were statistically significant at α = 0.05 level. The simulated horizontal work plane average illuminance level varied from 131 to 171 lx, mean room surface exitance (MRSE) levels remained between 30 and 90 lm/m² and overall uniformity of illuminance remained between 0.5 and 0.7.

In a hospital ward illuminated by LED tubular lamps, variations in room surface reflectance combinations for a constant luminous flux package output from the lamps may affect the subjective perception of users and the correlation between horizontal work plane average illuminance and MRSE is found to be highly linear (coefficient of determination > 0.97).

Optimisation of daylight admission through window is crucial for alleviating glare while maintaining useful daylight levels in order to enhance occupants' health, visual comfort and moderating lighting energy consumption. Amongst various solutions, fixed external shade is an affordable solution for housing spaces that need to be sophisticatedly designed, especially during the period of increasing home spaces as working environments. In the humid subtropical region, daylight control plays an important role in indoor comfort, particularly with areas with a high window to wall ratio (WWR). Due to the insufficient amount of such study on non-office spaces in Australia, shading-related standards are not addressed in Australian building codes.

The chosen methodology for the research is a quantitative data collection and analysis through field measurement and simulation simultaneously. The first step is a multi-objective optimisation of shading elements through a non-dominated sorting genetic algorithm (NSGA-II) on parametric modelling via Rhino3D CAD and simulation engines (DIVA and ClimateStudio). In the second phase, the Pareto front solutions are validated by experimental measurements within a room with a single north-facing window (the most probable for the daytime glare in Sydney) for the seven most common local window configurations.

Through the simulation of ten genes, 1,560 values and 2.4 × 1,019 of search space, this study found an optimum shade for each local common window layout, resulted in +22% in (UDI) and −16% in views with discomfort glare on average. Moreover, an all-purpose polygonal shade showed an average of 4.6% increase in UDI and a 5.83% decrease in the percentage of views with discomfort glare.

The findings are subject to the room dimensions, window dimensions and layouts, and orientation of windows for selected residential buildings in Sydney.

The study contributes to the development of highly accurate fixed external shading systems with rectangular and tapered-form external shapes. A real-time measurement by luminance-metre sensors and HQ cameras located at six eye levels is conducted to corroborate simulation results of the visual comfort.

The responsibilities of the employer/facilities manager in today′s “commercial” world are extensive when considering the wellbeing of staff and the economic working of the office/building. One element of this tangled web is lighting. The recent publication by the Chartered Institute of Building Services Engineers (the professional body), Lighting Guide No. LG7, Office Lighting (1993), is an invaluable compendium in guiding professional “lighters” and the non‐expert in design standards. The guide is particularly useful not only in considering good practice, but also in identifying subjects where the employer is possibly vulnerable with respect to recent EEC legislation and health and safety requirements for satisfactory VDU operations working; and emergency lighting, among others. Examines the contents of LG7, highlighting areas of particular interest and likely concerns to the inquisitive facilities manager.

The purpose of this paper is to improve the accuracy and signal-to-noise ratio (SN) of a crop nitrogen sensor.

The accuracy and wide adaptability of two spectral calibration methods for a crop nitrogen sensor based on standard reflectivity gray plates and standard detector, respectively, were compared.

The calibration method based on standard detector could significantly improve the measurement accuracy and the SN of this crop nitrogen sensor. When compared with the method based on standard gray plates, the measurement accuracy and the SN of the crop nitrogen sensor calibrated based on the standard detector method improved by 50 and 10 per cent, respectively.

This research analysed the calibration problems faced by the crop nitrogen sensor (type CGMD302) based on standard gray plates, and proposed a sensor calibration method based on a standard detector. Finally, the results of the two calibration methods were compared in terms of measurement accuracy and the SN of the crop nitrogen sensor.

The purpose of this paper is to determine the approximate window-to-wall ratio (WWR), window width-to-height ratio (WHR) and sill level for a room in Rasht–Gilan province and to present an optimal window in each of the WWR ranges providing the minimum energy consumption by integrating artificial lighting and thermal analyses, whilst maintaining internal comfort conditions using dynamic evaluation.

The process of modelling has four main steps: 1 – defining the building's features and requirements, 2 – validating input weather file data by on-site measurement, 3 – determining input parameters for the lighting and thermal analysis and 4 – clarifying variable parameters and fitness function for the optimization algorithm. Also, the survey study is performed in a daylit office room, in which 30 employees are employed to answer the questions in three different times of a day. In this process, the impact of daylight on their visual comfort is surveyed in 1,350 different illuminance levels which are manually recorded.

The range of useful daylight illuminance (UDI) values is determined as 200–1,000 lux. The optimum range of WWRs in the case study is 15%–25%. Also, due to the appropriate window height, electric lighting could be decreased by 40%.

Thermal and lighting performance in buildings is the relation of facade characteristics to environmental sustainability. Recent studies focussed on optimizing WWR and window characteristics considering thermal comfort and energy analyses. However, architects need freedom for designing façade and making decisions in their first sketches. Thus a guideline for optimum window conditions in each WWR is required. Also, considering occupants' behaviour in practical buildings, the visual comfort investigation is a gap in WWR optimization.