Climate-based Daylighting Metrics Research Articles

Fast annual daylighting simulation and high dynamic range image processing using NumPy

Annual daylighting and point-in-time glare calculations depend on manipulating large matrices representing annual light levels and image pixels, respectively. Advances in computation speed have allowed modern green building standards like LEED, WELL, and EN 17037 to require annual daylighting calculations at a fine resolution across a building’s floorplate. As parallel ray tracing speeds become faster and cameras increase in resolution, matrix manipulation itself has emerged as a bottleneck to delivering fast simulation results. This paper describes a how vectorized computation methods can be applied to annual daylighting simulation and high dynamic range (HDR) image processing. Vectorization allows a computer to perform simple operations on large amounts of data simultaneously. We use the NumPy library in Python to vectorize multiple steps in the calculation of spatial daylight autonomy and annual renderings for glare as example climate-based daylighting metrics, achieving a speedup of two orders of magnitude. We also show that NumPy can manipulate large HDR images with speedups for individual operations up to six orders of magnitude.

Light-responsive kinetic façade system inspired by the Gazania flower: A biomimetic approach in parametric design for daylighting

Through a multidisciplinary approach, this research proposes a design solution for a light-responsive kinetic biomimetic system, inspired by the functional principles of the Gazania flower. The adaptive movements of the Gazania flower were studied through a morphological-functional analysis and then used in the abstraction phase for the design of the biomimetic system, through parametric modelling. Climate-based daylight metrics and luminance metrics were evaluated for the different kinetic alternatives developed. The results of the parametric simulations, carried out for different occupant positions in an office building in a temperate Mediterranean climate show that the biomimetic kinetic system is well suited to provide the office space with variable natural daylight between 87,5 % and 100 %, promoting energy efficiency and user comfort. The results correspond to the optimal ranges of climate-related daylight metrics that prevent glare and overheating by shielding direct sunlight. The study also highlights the importance of further research, including material's prototyping, to validate and improve the proposed design and its translation into technology. Overall, this study demonstrates the potential of combining principles from biology, materials science and architecture to develop adaptable and sustainable design solutions that address sunlight and indoor comfort challenges.

Determination of Climate-Based Daylight Metrics under 15 CIE (International Commission on Illumination) Standard Skies and Three Representative Skies

Daylighting serves as a crucial sustainable strategy in assessing the built environment. Climate-based daylight metrics (CBDMs) have been widely employed to evaluate the dynamic performance of daylight. However, conventional CBDM calculations heavily rely on time-consuming full-scale computer simulations. In addition, the CBDMs need representative annual daylight data that are essential for CBDM analysis, and can pose challenges in many locations. Even when suitable daylight data are available, they may not accurately reflect current trends and conditions. This study aims to determine the various CBDMs using both the 15 CIE Standard Skies and the three representative skies specific to Hong Kong. All data were simulated from a software named RADIANCE (version 5.3). The R2s of the CBDMs under both the 15 CIE Standard Skies and the three representative skies were more than 0.89, and the MBEs and RMSEs were not more than 5.4% and 9.1%, respectively, when the outdoor illuminance measured in 2004 was employed. The findings could be adopted for other locations where the required daylight parameters were not systematically recorded.

Simple mathematical models to link climate-based daylight metrics with daylight factor metrics and daylighting design implications

Determination of interior daylight illuminance is the key step in daylighting schemes. Recently, climate-based daylight metrics (CBDMs) which considers the real climatic data for the location has been adopted to evaluate the dynamic daylight performance. However, the usual method to calculate the CBDMs is full scale computer simulations which are quite time demanding and designated skills are required. Architects and building practitioners prefer simple methods to assess daylight performance particularly during initial design process when various building schemes and concepts are being appraised. Daylight factor (DF) is the traditional daylight metric and it has a strong relationship with room parameters which can be simply modified to fit the design criteria. This paper puts forward a series of simple mathematical expressions to correlate the CBDMs with DF metrics (DFMs). The vertical outdoor illuminance at the window center point and the 49 interior points were simulated via the RADIANCE software. The results showed that there are strong correlations between these daylight metrics. The proposed approach would be useful to building professionals conducted in visual comfort, fenestration and daylighting design and evaluation in the preliminary design phase.

Optimization of Daylighting Design Using Self-Shading Mechanism in Tropical School Classrooms with Bilateral Openings

Despite its potential, daylighting strategies in school classrooms in the tropical climate regions is little explored in the literature. The use of two-sided or bilateral daylight opening, as well as the self-shading mechanism using sloped walls, are currently seen as potential strategies to achieve good daylighting in tropical buildings. This study thus aims at exploring and optimizing self-shading design possibilities for creating daylight-friendly, tropical elementary school classrooms with bilateral openings, by means of sensitivity and uncertainty analyses. Design parameters such as façade orientation, window-to-wall ratio, window elevations, wall slopes, interior surface reflectance and glazing transmittance are considered in the model of a hypothetical, typical classroom without shading devices. Climate-based daylight metrics such as UDI250-750 lx, sDA300/50% and ASE1000,250 are utilized as the performance indicators. Computational modelling with Honeybee [+] in Rhinoceros/ Grasshopper platform is employed to conduct the annual daylight simulation. Multi-objective optimizations using genetic algorithms (GA) through Octopus with SPEA-2 algorithms are performed to determine the optimum design solutions following the sensitivity and uncertainty analysis. The slope and WWR of the wall that faces west, southwest, south, or southeast, has the strongest influence on the defined objective function that includes all daylight metrics. To achieve the optimum daylight performance, design of the opposing window façades of school classrooms with bilateral openings should not be identical.

Optical characterization of historical coloured stained glasses in winter gardens and their modelling in daylight availability simulations

Coloured stained glasses, with their peculiar light transmission properties, affect the perception of indoor spaces especially in winter gardens, where a great amount of coloured glazed surfaces can be easily found. This research aims at advancing the knowledge of coloured stained glasses in architecture and how they can be modelled in daylight simulation software tools. To this aim, the paper first proposes the measurement of light transmittance spectra for a series of coloured glazing tiles installed in a richly decorated Liberty style winter garden in Catania (Southern Italy). The measurements are performed in-place with a portable spectrophotometer, which does not imply dismantling the glazed tiles. A second novelty consists in the identification of the perceived chromaticity for the transmitted daylight, by means of the CIE Colour Space. This analysis reveals that, despite around 75% of the glazed elements are coloured, indoor light is still perceived as colour-neutral because of the wise location of clear panes.Then, the calculated integral transmittance values were used to model the winter garden in the Radiance-based ClimateStudio tool, and the reliability of two different degrees of simplifications in the model was also investigated. The comparison between simulated and measured indoor illuminance values demonstrates that the proposed simplified approach allows very good reliability in daylight modelling, with an average discrepancy below 11%, while also reducing time needed for the preparation of the model. Finally, the validated model is used to assess year-round daylight availability indoors by means of climate based daylight metrics.

EVALUATION OF DAYLIGHT PROVISION AND DAYLIGHT GLARE PROBABILITY FOR DIVERSE WORKSPACE CONFIGURATIONS

ABSTRACTS Office environments can be integrated with particular workspace configurations owing to diverse tasks encountered in these workspaces. This study attempts to discern how effective different office workstation configurations are on daylight performance and tries to quantify this effect by means of a dynamic daylight simulation based approach, depending on the criteria addressed in EN 17037:2018 Standard. The purpose of this study is to explore the impact of workstation configurations on daylight provision and glare protection in workspaces through several configuration setups. In this study, climate based daylight metrics are used for daylight performance determination and assessment of discomfort glare caused by daylighting is performed by Daylight Glare Probability (DGP) index. This study aims to contribute to the growing body of research in the scope of EN 17037:2018 for daylighting in office environments and the obtained results represent the significance of daylighting and visual comfort conditions for diverse workstation configurations.

EVALUATION OF DAYLIGHT PROVISION AND DAYLIGHT GLARE PROBABILITY FOR DIVERSE WORKSPACE CONFIGURATIONS

ABSTRACTS Office environments can be integrated with particular workspace configurations owing to diverse tasks encountered in these workspaces. This study attempts to discern how effective different office workstation configurations are on daylight performance and tries to quantify this effect by means of a dynamic daylight simulation based approach, depending on the criteria addressed in EN 17037:2018 Standard. The purpose of this study is to explore the impact of workstation configurations on daylight provision and glare protection in workspaces through several configuration setups. In this study, climate based daylight metrics are used for daylight performance determination and assessment of discomfort glare caused by daylighting is performed by Daylight Glare Probability (DGP) index. This study aims to contribute to the growing body of research in the scope of EN 17037:2018 for daylighting in office environments and the obtained results represent the significance of daylighting and visual comfort conditions for diverse workstation configurations.

Evaluation of visual and non-visual effects of daylighting in healthcare patient rooms using climate-based daylight metrics and melanopic metrics

Daylight access in healthcare facilities is essential for creating comfortable ambiance conditions for the patients during their accommodation in a hospital. The aim of this paper is to investigate how the window size, the location (Paralimni in Cyprus and Brussels in Belgium), the room orientation and patients’ gaze direction have an impact on visual and non-visual effects. This research focuses on hospitals’ most typical patient room: the double room (3.50m * 5.50m). The building parameters under study arc eight orientations and three window sizes. Moreover, other parameters are the timing (season and hour in a day), the patient placement inside the room, and the patient gaze directions. For this study, computer simulations are used for daylight assessment using climatc-bascd daylight metrics and CIE S026 melanopic metrics for non-visual effects. Research findings show that it is possible to examine design options through a comprehensive investigation of climatc-bascd daylight metrics and CIE S 026 melanopic metrics for optimised performance for visual and non-visual effects.

Evaluating the visual comfort of Orosi windows in hot and semi-arid climates through climate-based daylight metrics: a quantitative study

ABSTRACT Proper design and appropriate configuration of daylight systems, as the primary means of controlling and distributing daylight, greatly improve the visual comfort and reduce energy consumption. Daylight systems are widely used around the world, controlling the light distribution in interior spaces; in residential buildings, vertical windows are the most common ones. Iranian architecture has been using a traditional daylight system for over centuries: the Orosi window. This research investigates how the Orosi elements affect visual comfort, based on climate-based daylight metrics. Results show that the tinted glasses have the potential to control the quality of the light that is transmitted into the interior space. Besides, frames have the potential to increase the UDI while keeping the overall illuminance of the space within the specific range. Furthermore, glass shapes, and consequently frame shapes, and the way they are scattered on the surface have the potential to control the way that light enters the interior space; therefore, they homogenize it by decreasing the illuminance differences between central, frontal, and side zones of the space.

A Survey on Daylighting Education in Italian Universities. Knowledge of Standards, Metrics and Simulation Tools

Daylighting is a strategic topic to achieve sustainable buildings, so it is more and more imperative that it is implemented in architecture curricula to prepare a new generation of daylighting-oriented practitioners. In this frame, the DAYKE project (Daylight Knowledge in Europe) was set up to explore the level of knowledge about daylighting among European professionals and students. DAYKE-Europe was replicated as DAYKE-Italy to study the knowledge of daylight standards, metrics and software among Italian architecture students, and to compare it to that observed within DAYKE-Europe. A sample of 542 questionnaires were collected in five universities. Primary outcomes were: (i) a general low level of knowledge on daylighting was observed; the most cited metrics were the average daylight factor and the geometrical window-to-floor ratio, while climate-based daylight metrics were rarely mentioned; (ii) master science M.Sc. students reported more knowledge on daylight metrics and regulations than bachelor B.Sc. students, while the implementation of daylight metrics and strategies in projects was mainly deficient among B.Sc. students; (iii) compared to European students (DAYKE-Europe), Italian students showed a higher knowledge of daylight metrics and software (especially as for M.Sc. students), while the opposite was observed for standards, regulations and protocols. Based on the results, a reconsideration of daylight education in architecture curricula is recommended.

Evaluations of long-term lighting qualities for computer labs in Singapore

This paper presents a study that investigates lighting qualities within three computer labs from a long-term perspective. Subjective assessments from 173 participants were collected. Accurately calibrated simulation models of three computer labs were generated to simulate annual lighting quantities based on horizontal illuminance (Eh), vertical illuminance (Ev) and monitor illuminance (Em). Gender, eyewear and access to exterior views have impacts on subjective long-term lighting assessments. Due to the low daylighting distributions, climate-based daylight metrics (CBDM) with the thresholds over 300 lx, including daylight autonomy (DA) 300 lx and 500 lx, Useful Daylight Illuminances (UDI) autonomous (UDI300–3000 lx), UDI-exceeded (UID>3000 lx) and Annual Sunlight Exposure (ASE) over 1000 lx (ASE1000 lx), are inapplicable in the context of this study. UDI-fell-short (UDI <100 lx) and UDI-supplementary (UDI100–300 lx) associated with Ev outperform other CBDMs in terms of predicting subjective satisfaction with annual access to daylight. In addition to Eh- and Ev-based annual lighting predictors, Em-based ones are practically correlated with subjective lighting assessments. However, contradictory correlations and logistic regression models between Em-based lighting predictors and subjective lighting assessments are found across the daylit computer lab and electrically lit computer labs, which emphasizes the importance of differentiating Em-based lighting predictors according to monitor type, lighting sources and classroom arrangement.

Testing the residential daylight score: Comparing climate-based daylighting metrics for 2444 individual dwelling units in temperate climates

Evaluation metrics using climate-based daylight modelling paradigms have become the de-facto standard in work environments but have only limited applicability in residential architecture. Qualities of daylight cited in the architectural design literature, such as daily and seasonal availability of daylight as well as access to direct sunlight, are simulated in detail but are usually overlooked in the commonly used evaluation metrics. In a recent paper, a new climate-based, annual daylight evaluation framework called the residential daylight score has been proposed for cold and temperate climates. It assesses daylight autonomy and access to direct light in 12 daily and seasonal bins and proposes targets for seasonal and diurnal daylight autonomy and duration of direct sunlight exposure. While the metric aims to capture essential characteristics of residential daylight, only a few reference cases exist in the literature to adequately judge its achievability and applicability. This paper aims to thoroughly test the residential daylight score and provide reference cases for 2444 apartments from a set of 18 multifamily buildings that compare the new metric with currently used climate-based metrics.

Long-term visual quality evaluations correlate with climate-based daylighting metrics in tropical offices – A field study

In this paper, we present a post-occupancy study of 326 participants in 10 daylit office buildings in Singapore and correlate the results with climate-based daylighting metrics and electric lighting simulations using calibrated simulation models of the 10 buildings. For the first time, this study tests the climate-based daylighting metrics which are used in building design against their impact on occupant perception within buildings. We find significant correlations between climate-based daylighting metrics and reported occupant satisfaction with access to daylight, view interest, perception of ‘too low’ lighting levels and visual comfort. Overall, climate-based daylighting metrics which account for lower illuminance thresholds such as continuous daylight autonomy and useful daylight illuminance combined (100–3000 lx) correlate more strongly with subjective results than do electric lighting sufficiency metrics such as daylight autonomy at 300 and 500 lx thresholds. Simple descriptive statistical representations of annual daylight distributions, mean and median annual daylight illuminance values, outperform climate-based daylighting metrics in correlation strength and p-value. Based upon these results, new metrics are proposed for occupant satisfaction with daylight access and views. In addition, increased daylight levels are shown to decrease reporting of lighting levels being ‘often too low’ even when adequate electric lighting is provided, and contrast is likely to be beneficial to space perception at non-glaring thresholds.

Interactive kinetic façade: Improving visual comfort based on dynamic daylight and occupant's positions by 2D and 3D shape changes

Applying active occupant engagement into a responsive façade concept leads us to a transition from the façade regulatory function to the interactive phase. The Interactive facade has the capacity for hierarchically filtering daylight and real-time control, and preventing daylight discomfort. This research applied the combination of qualitative and quantitative methods for studying innovative daylight guide systems functions, relation with building forms and development of kinetic façade forms as advanced real-time daylight control. Literature referred to the responsive modular elements which can be adapted to dynamic daylight by continuously changing façade configurations. In particular, parametric decentralized façade's apertures interact with sun radiation based on relationship between external environment, interior space and occupant position as well. In this study, we develop a kinetic interactive façade with the capability to be transformed based on dynamic daylight and occupant position (functional scenario based) in order to meet visual comfort. Also, daylight parametric simulation investigates visual comfort performance provided by the kinetic façade forms through climate based daylight metrics. The simulation results prove high performance of the kinetic interactive facades for improving visual comfort regarding the base case. In particular, the three dimensional shape changes façade provides more visual comfort improvement than the two dimensional shape changes one regarding UDI, Exceed UDI and DGP metrics. Also, the results refer to multifunctional aspects of the three dimensional shape changes façade, as an advanced interactive daylighting system, which has a capability to control solar radiation in the facade ambient environment for preventing thermal discomfort.

Daylight control and performance in office buildings using a novel ceramic louvre system

This study examined the design and daylight performance of a new louvre screen for office buildings. The screen was evaluated for three different material finishes: specular aluminium as a traditional material commonly used in louvres, and two types of ceramic finishes, with the intention to reduce the systems’ environmental impact. The new system was assessed taking an unshaded window, a window with a rod screen and a window with venetian blinds as references. Annual performance simulations for a full-scale room, using the lighting software Daysim, were conducted to assess the effect of the three material systems on indoor daylighting levels and distributions using both the traditional Daylight Factor and climate-based daylighting metrics (Daylight Autonomy DA and Useful Daylight Illuminance UDI). The results show that the proposed louvre system can provide satisfactory daylight levels and visual comfort within the room, while ceramics appear as a promising alternative material to be used in the production of advanced daylighting technologies.

Quantitative Investigation Through Climate-based Daylight Metrics of Visual Comfort Due to Colorful Glass and Orosi Windows in Iranian Architecture

There are several alternatives to passive strategies in the early stages of the design process including orientation, window to wall ratio, shading device, material and colour that affect occupants’ visual comfort. However, applying simple traditional principles such as using colorful glasses for windows are effective in the optimizing of visual comfort at interior space. The main aim of the current research is investigating the appropriate colors to control direct sunlight for meeting visual comfort criteria based on climatic-luminance metrics. Which combination of them would be more effective for optimizing visual comfort in terms of daylight glare probability? In particular, how can combination of lattice frame and Iranian-Islamic pattern improve visual comfort based on aforementioned metrics? Quantitative approach for evaluating colorful glass daylight performance is relatively rare. Moreover, these studies applied laboratory measurements and numerical calculation for exploring colorful glass performance. However, parametric simulation provides an opportunity for investigating daylight performance of colored glass based on new perspectives. This research reintroduces the main application of colorful glass as a light controller in the window that considerably affects climatic-luminance based metrics containing daylight autonomy (DA), useful daylight illuminance (UDI), exceeded UDI and daylight glare probability (DGP). A combination of quantitative and qualitative research methods have been applied in order to generate hypotheses and then analyze them. Parametric simulation analysis proves that colored glass has the capability to improve occupant’s visual comfort during office time. Moreover, an appropriate combination of lattice frame and Iranian-Islamic patterns with colored glass in the Orosi window considerably depends on function, climate and occupant behaviour.

UAE heritage buildings converted into museums: Evaluation of daylighting effectiveness and potential risks on artifacts and visual comfort

This paper provides a comprehensive process that investigates daylighting performance with regards to museum lighting (adequate lux levels versus safe light exposure) and visual comfort requirements (no glare or sunlight) in the UAE traditional courtyard buildings that were converted into heritage museums. The study used several methods such as site visits, on-site measurements, surveying of architectural drawings, and statistical analysis of design data to examine existing case studies and extract information that helped identify building morphology configurations and define parameters to represent this building typology. The defined configurations helped develop the 3D geometry of the representative model in which the most dominant courtyard and exhibit room ranges were considered. Then, a comprehensive multi-scenario simulation process based on several climate-based daylight metrics under the UAE sky conditions was carried out to investigate lighting adequacy against potential risks on artifacts and visual comfort using several configurations of the developed model. The scenarios included different orientations with different window-to-wall ratios (WWR) of windows looking upon the courtyard using different configurations of the traditional verandah that helped shade the windows and reduce light exposure risks. The performance variables were analyzed against the recommended values/ranges by several international lighting standards. The study recommended several options to enhance the overall lighting environment and minimize risks on artifacts and visual comfort. This included better spatial arrangements, better designing and sizing of openings, and implementation of effective shading systems.

A critical review of daylighting metrics for residential architecture and a new metric for cold and temperate climates

Residential architecture constitutes one of the largest market segments in the construction sector. However, the attention that it is given in the field of daylight performance simulation is surprisingly low. This poses the question of whether existing daylighting metrics are well suited for residential design. Findings from 79 references are summarized, and a critical review of current climate-based daylighting metrics in the context of residential architecture is provided. It is found that existing workflows often overlook relevant aspects of daylight in residential spaces, such as diurnal and seasonal availability of daylight and access to direct sunlight. Hence, a concept for a new climate-based, annual evaluation framework that overcomes these shortcomings, called the residential daylight score, is introduced.

Influence of input reflectance values on climate-based daylight metrics using sensitivity analysis

The insertion of climate-based daylight metrics as a requirement in several design guidelines calls for a better understanding of their effectiveness. This paper draws attention to the sensitivity of annual daylight metrics to changes in input reflectance values. The uncertainties related to the choice of guidelines and of simulation techniques were also considered. Total Annual Illumination (TAI) showed the most consistent correlation and the highest sensitivity to variations in reflectance (up to ±60% from the benchmark), independently of the geometrical characteristics of the space. Other annual metrics were less sensitive, or showed a poorer correlation. The deviations among different simulation techniques varied with the chosen metric too ( for TAI), but all techniques were equally affected by variations in reflectance. The results highlighted the importance of selecting appropriate metrics for annual climate-based daylight evaluations.