Daylight Simulation Research Articles

Facade Photometry: Linking Annual Daylight Performance to Facade Design

This concept paper illustrates a new simulation method to assess how building facades distribute light into interior spaces and how data from simulation studies can inform design for better facade performance. Facade photometry, a term developed by the authors, uses annual simulations and localized weather data to create temporally based illuminance and luminance distributions. This photometric chart is a unique signature of a particular facade design measured at a specific point in a specific climate. By linking data from the daylight simulation to the facade, the areas of the facade that need to be adjusted for improved performance are highlighted. Facade photometry is intended to allow designers to easily compare the performance of complex building geometry and daylight control systems, thus becoming an efficient tool to further aid designers in creating highly energy-efficient, high-performance, and comfortable building facades.

Assessing the applicability of the European standard EN 17037:2018 for office spaces in a cold climate

There is a lack of methods and studies that evaluate the validity of daylight standards such as the EN 17037:2018 in specific local contexts as cold climates. Moreover, the probable adaptation of the EN 17037:2018 by European countries motivated the aim of this investigation: to study the applicability of the EN 17037:2018 in a certain cultural context through the comparison of the subjective perception of Estonian office users with the quantitative assessment defined by the EN 17037:2018, including the four aspects: solar access, view out, daylight provision, and glare protection. In order to study the applicability of the EN 17037:2018 for Estonian office spaces, we used a mixed-method approach based on semi-structured interviews, measurements, and daylight simulations. Poor view out is related with high obstruction levels of urban features, despite the presence of multiple layers in the view. The level of recommendations for good view out in Estonian office rooms might be lower than the thresholds recommended by the EN 17037:2018. Except during winter months, direct sunlight exposure is not appreciated in Estonian office spaces since it is strongly related to glare discomfort caused by sun in the field of view and on computer screens. Working under daylight conditions during the whole year and having an easy-to-use interior shading systems to block the direct sunlight is very valuable for Estonian office users. For daylight and glare protection, there is a good agreement between qualitative evaluations given by office users and quantitative assessments proposed by the EN 17037:2018.

Trees in Daylight Simulation – Measuring and Modelling Realistic Light Transmittance through Trees

ABSTRACT Trees influence daylight availability inside and outside buildings by attenuating, scattering, and transmitting light. They resemble a complex fenestration around buildings that change in form, materiality, and permeability based on species of trees, seasonal variations, and environmental or human interventions. The current practice of modeling trees in daylight simulations ignores this complexity and models tree crowns as cones, spheres, or cylinders with assumed reflectance or transmittance value. In this paper, the authors propose an open-source, low-cost method using photography and image processing to measure the on-site transmittance of a tree crown described as gap percentage. Gap percentage is used to generate a 3D primitive crown model that mimics the distribution of leaves and gaps. When used in daylight simulation platforms such as Radiance, the proposed model predicts vertical light transmittance and creates shadow patterns similar to the measured tree crown. The 3D crown model also predicts luminance and illuminance-based daylight metrics similar to a detailed morphological tree model. An open-source program is created and described to generate trees from measured gap percentage data based on this research.

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 sky spectra and sky models in daylighting simulations

Sky models in daylight simulations represent the luminance variation across the sky-dome for different locations, dates, times and weather conditions, but skies are typically modelled as colourless. Recent studies explore techniques for incorporating the spectral content of daylighting in simulations. This paper provides an evaluation of the existing spectral sky models in lighting simulation software. The comparisons are made between the available mathematical sky models and naturally occurring skies that were recorded using high dynamic range photography and spectrophotometric measurements. The results show that recently developed sky models present progress compared to colourless sky models, but further research is needed to accurately simulate daylight spectra.

A Tunable LED Daylight Luminaire for Textile and Printing Light Booth Application with Optimum LEDs

Color quality testing in the light booth is one of the essential requirements of manufacturing industries. Due to conventional daylight simulators incompetence, there is a need for improvise of light sources used in these booths. Also, solid-state lighting advancements has given a breakthrough for provisioning a light source that is energy efficient, long life, tunable, providing stable and modifiable illuminance. This research work focusses on the optimal design of a polychromatic LED luminaire, mimicking D50, D65 and D75 daylight spectrum with CRI > 90 and average illuminance 2000 lx. A multi-objective algorithmic approach towards LED selection has publicized daylight simulations feasibility with seven emitter combinations of red–green-blue-amber-lime-white (5070 K and 6570 K). The proximity of chromaticity coordinates of the test lamp with reference illuminant ascertains the quality of the designed luminaire. Further, the test lamps spectral fit and illumination consistency in the light booth ensure its suitability for color quality testing chambers.

Rule-based Design Analysis and Structural Rationalization Study of Ralph Symonds Laminated Timber Arches

ABSTRACT As the demand for steel increased to supply military construction during World War II, Australian engineers began to push timber capacity for long-span structures, one of which led to the emerging use of glue-laminated timber-bending in the post-war period. This article analyses the laminated timber arches of three Ralph Symonds factories in Sydney, the ground-breaking laminated timber projects in Australia between the 1940s and 1960s. The study interprets the design reasoning behind timber-arch application and the structural reasoning behind timber bending using daylight simulation, structural simulation, and rule-based design analysis. The method used to formulate the rules is outlined and demonstrated. The study clarifies that Symonds’s timber-arch designs evolved not only to accommodate space for medium to large-scale manufacturing activities but also to optimize economic, climatic, and structural constraints. The rule-based analysis reveals a consistent design logic applied across different factories, foregrounding Ralph Symonds’s signature design language in laminated-timber arches.

Machine learning-based real-time daylight analysis in buildings

Daylight analysis is essential in building design to ensure indoor environment quality, including health and thermal comfort vis-à-vis energy. It is a repeating and time-consuming process of design options. Several studies conducted machine learning models to accurately predict daylight performance in particular design situations. Therefore, developing an AI-based real-time daylight analysis platform becomes more promising. However, buildings can be designed with arbitrary shapes, creating a real challenge for the AI to recognize any building layout. From that perspective, the idea of finding the design variables that characterize all the building layouts becomes the key solution. To unlock this challenge, we promote a novel method of creating design variables and building a machine learning model that can efficiently forecast daylight performance with different building layouts. The daylight metric was Useful Daylight Illuminance with four ranges, and the case studies were assumed medium-sized buildings located in Ho Chi Minh City, Vietnam. All the data for training and predicting were created by the simulation DIVA tool. Obtained results showed the excellent performance of the proposed approach, which brings more promising in developing a data-driven machine learning platform for real-time daylight validation. Moreover, the present framework can adapt to any specific machine learning model or daylight simulation tool and daylight metrics.

Modeling the Shading Effect of Vancouver’s Urban Tree Canopy in Relation to Neighborhood Variations

Background: Cities consume a disproportionate amount of energy for internal temperature regulation. Being able to reduce cities’ cooling load on hot summer days can decrease energy consumption while improving occupants’ thermal comfort. The urban canopy is an effective shading agent, adding cooling benefits to existing buildings and streets while providing other ecological and physiological values. Yet the building and street shading dynamic is a highly complex system that involves micro-level building components and macro-level variables. Introducing urban canopy to such a complex system creates another challenge, as urban canopy variables can also interact with buildings at both micro- and macro-levels. In order to accurately represent the urban canopy shading effect, it is necessary to account for the interactions among buildings, streets, and urban canopies. Methods: This study simulates the shading effect of urban canopy measured by aerial laser scanning (ALS) in the City of Vancouver, Canada, through the integration of a Radiance daylight simulation engine and geographic information system (GIS) data. All trees detected by ALS were included in the analysis. Results: The results indicate that street surfaces receive more solar irradiance reduction than building roofs and façades (i.e., exterior walls). Neighborhoods with less density and lower buildings were shaded noticeably better than areas with higher density and taller buildings. Among Vancouver’s 22 neighborhoods, 2 neighborhoods, Kitsilano and the West End, demonstrated a promising sign where both building density/height and urban canopies are maintained. There was evidence of high canopy shading and high-density urban morphologies. Conclusion: Overall, this work provided an authentic canopy assessment from single building to city scale, creating opportunities to investigate intracity urban canopy variations, equality, and the balance between urban greening and urban densification.

Investigation into the daylight performance of expanded-metal shading through parametric design and multi-objective optimisation in Japan

This paper presents a parametric and Multi-Objective Optimisation approach to investigate daylight performance of the expanded-metal shading depicting the sky conditions in Kitakyushu, Japan. The study is an initial design method utilising a robust computational calculation aiming to verify expanded metal as an environmentally friendly building material concerning its function as a shading device. The proposed platform generatively iterates the logic of expanded metal as dynamic design variables, such as Bond, Strand, Length, Height and Angle, to achieve the optimisation goals of minimising Annual Sunlight Exposure (ASE) while simultaneously maximising Spatial Daylight Autonomy, Useful Daylight Illuminance (UDI) and the openness of the expanded-metal profile. Ladybug and Honeybee were utilised in a parametric platform, Grasshopper, to perform daylight simulation, while Octopus was employed to optimise the results. A thorough analysis was conducted to determine the significance of each expanded-metal parameter in achieving the daylight and View objectives. The results showed that adopting the proposed framework successfully fulfilled the LEED v4.1 daylight requirements by reducing ASE by 100% and improving UDI by approximately 50% over the baseline model. Furthermore, the iteration process revealed a wide range of aesthetic patterns, providing another factor for designers to consider during the design decision-making process.

Simulation of daylight in buildings with curved facades for rational use of solar energy

Simulation of daylight conditions in buildings with curved facades was carried out to show the possibility of more efficient use of solar energy with a constant change in the azimuth of the windows orientation. To optimize daylighting, a smart window with optical filter is proposed having an angular selectivity of light transmission due to two surface gratings with alternating transmissive and chromogenic parallel strips. Unlike conventional smart windows, the entire area of which is covered with chromogenic layers, a grating filter weakens or completely blocks direct solar radiation by allowing diffused sky light and reflected light to pass through. Methods for calculating the geometric parameters of the gratings are presented and the optimal slope angles of the filter gratings for windows with different azimuths of a building with round facade and the temporal characteristics of the light transmission of these windows are calculated. The results substantiate the advisability of using smart windows with grating filters in buildings with curved facades to improve the comfort of daylighting and insolation, to protect against direct rays when passing diffuse sky light and albedo by adapting the light transmission of windows to a change in the position of the sun relative to them.

Daylight simulation workflows incorporating measured bidirectional scattering distribution functions

Daylight predictions of architectural spaces depend on good estimates of light transfer through skylights, windows and other fenestration systems. For clear glazing and painted surfaces, parametric transmission and reflection models have proven adequate, but there are many cases where light-scattering, semi-specular shading and daylighting materials defy simple characterization. Something as commonplace as fabric roller shades and venetian blinds may turn daylight prediction into guesswork, and numerous advanced systems on the market tuned specifically to enhance daylight are not sufficiently characterized to distinguish their performance. In this paper, we describe new tools available to handle novel and specialized fabrics, materials, and devices using data-driven modelling of bi-directional scattering distribution functions (BSDFs). These representations are usually tabulated at constant or adjustable angular resolution for efficient point-in-time and annual daylight simulations. We describe a variety of BSDF simulation workflows, including some of the tools and methods that make advanced analysis possible, and highlight some of the current challenges. We conclude with a discussion of future work and how such data might be created and shared worldwide.

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.

Indoor Optimal Design of Building Renovation Environment Space Layout Based on Genetic Algorithm

The design of the buildings should not only meet the requirements of structural safety and functional applicability, but also ensure that the stress of the structural system is reasonable and the amount of materials is as small as possible. And the reasonable and optimal allocation of resources should be realized. The research and application of optimization algorithms for building structures are still relatively scarce. It is difficult to obtain the optimal solution based on genetic algorithm because of the large amount of time-consuming calculation of indoor environment and the complex optimization process of indoor design. In order to realize the optimization design of parametric design combined with architectural physics and structural performance, we must use the current powerful computer platform optimization algorithm, mainly genetic algorithm. Firstly, this paper explores the implementation process of genetic algorithm in parametric design platform and the characteristics of optimization calculation. The experimental model is established based on genetic algorithm, combined with computer intelligent operation platform and modeling software. Combined with EnergyPlus energy consumption simulation engine and daysim daylighting simulation engine, the optimization design process of genetic algorithm optimization is realized through Pareto intelligent solution programming. The optimization design method can quantitatively calculate and evaluate the spatial layout, and provide visual, more accurate and intuitive output results.

Integrating Daylighting with Task-Ambient Lighting for Enhanced Energy Savings in Office Spaces

Daylighting has been widely studied as a fundamental aspect of spatial illumination and energy efficient façade design. Effective installation and control of shading devices diminishes the adverse effects of prevailing climatic conditions on building envelope performance and reduces resultant lighting and cooling energy consumption. Task-ambient lighting as a free-standing approach has also been proven to reduce lighting energy consumption compared with typical general ambient lighting. This study estimates the energy saving potential of integrating daylighting through fixed external horizontal shading slats with task lighting. Spot measurements were taken in a test room to validate a daylight calculation program. Full year indoor work plane daylight simulations were performed for office spaces of different floor areas and varying window to wall ratios. Indoor daylight quality was assessed using the Useful Daylight Illuminance metric and three different task lighting schemes explored. Lighting energy savings of 10% to 90% were estimated under the three schemes in comparison to similar office spaces with common unshaded heat reflective glazing.

Comparison between Radiance Daylight Simulation Software Results andMeasured on-Site Data

The paper focuses on comparing the popular daylight simulation softwareresults against the measured on-site data; it investigates softwareaccuracy and its limitations when used to calculate the daylight illuminance in clear sky conditions. The objective of the study is to examine the existence of any discrepancy and identify any systematic trend between actual and predicted results. Petrodar and NTC, both high-rise office buildings in Khartoum, were selected as case studies for the validation purposes. The study concluded that the diffuse daylight was simulated more accurately than the direct component. The variation between the measured values and simulated ones occurs at the points facing direct sunlight, and mostly when the sun comes at a low angle, this variation reached twice the measured in four cases. The study highlights the need for more refinement of the software when simulating direct component of daylight in clear sky conditions.

An analysis of daylighting performance of learning spaces in local government sector schools in Kandy

Natural lighting creates a pleasant environment, promotes healthier conditions and saves energy, and is an important factor in the design of education institutions. Many research indicates the positive impacts of better daylighting integration in educational spaces for student’s health and wellbeing. For this research, an in-depth lighting integration analysis was carried out in three typical classrooms in Berrewaerts college Kandy, Sri Lanka. A field study comprised of a questionnaire-based survey and measurement of illuminance was combined with daylight simulation using Autodesk Ecotect 2011 & Autodesk Revit. The study reveals that lack of awareness in integration of natural light with the design can either result in increasing the negative effects of excessive daylight exposure or lack of adequate daylighting. In upper levels and east facing classrooms the main problems were associated with high levels of daylight such as excessive shadow and light patches, uneven light distribution and color distribution and impede perception of objects and text. At ground floor level and south facing classrooms, when natural light is not properly integrated with the design resulted in uneven light distribution, non-uniformity of light resulted in difficulty in reading at work plane and impede the visual perception of objects and text.

Designing louvers toward optimum daylight performance in Indonesia: a parametric study

Architecture has a strong relationship with the daylight universe. It implicates further occupants’ behaviour toward visual comforts, healthiness, and energy consumption. The daylight simulation in the early phase of design benefits the architect in predicting the possibilities of daylight-related target goals during the design process. A shading system is one of the strategies in approaching passive design to prevent an excessive amount of undesirable daylight intensity. This paper investigates different sun louvers shading patterns and their relation to the Useful Daylight Illuminance (UDI) in the context of Indonesia, presented by incorporating the EPW file of Jakarta. Parametric and multi-objective optimization has been used to optimize, explore, and map the design possibilities based on the louver shading component as dynamic parameters. Rhinoceros and Grasshopper, as parametric-based modelling software, were used as the primary modelling platform, while the Honeybee and Ladybug plugin were used to undergo the daylight-related environmental analysis. The design exploration iterates 2.160 design solutions with a value of dynamic parameters and the targeted UDI value embedded in each. The results show that the solution founded from iteration process has more areas of illuminance within 300 lx to 500 lx by about 15%.