Daylight Simulation Research Articles

An Evaluation of Useful Daylight Illuminance in an Office Room with a Light Shelf and Translucent Ceiling at 51° N

The present study investigates the issue of computer-aided daylight evaluation in an office room with a light shelf and dropped translucent ceiling. In this type of room, daylight is admitted from two sources: (i) a standard window in the wall and (ii) via a light shelf and clerestory window, which illuminate the plenum located above the working space. The light from the plenum is transmitted through the translucent ceiling into the office room. The present study is based on data obtained through a computer-aided daylight simulation by DeLuminæ (DL-Light, ver. 11.0.9, and DL-Instant, ver. 6.1.4) software using the Radiance engine and real weather data for Wroclaw, Poland, at 51st lat. N. An office room of 12 × 6 m with different shading and daylight distribution scenarios was simulated (Variants 1–5). Next, the useful daylight illuminance (UDI (%)) for the range of 300–3000 lx and daylight glare probability (DGP) were calculated. To further optimize the daylighting scenarios, an adaptive shading system was simulated, which was activated when the illuminance value dropped below 300 lx. In the final variant, Variant 6, mean UDI300–3000 values were recorded to be above 80% for 95% of the area of the work plane. This allows the conclusion that a light shelf and translucent ceiling guide daylight deep into the room, improving uniformity and reducing glare when the standard window is covered by an adaptive shading system.

3D CITY MODELS FOR SUPPORTING SIMULATIONS IN CITY DENSIFICATIONS

Abstract. In order to meet the increasing needs of housing and services in urban areas, cities are densified. When densifying a city, it is important to provide good living conditions while maintaining a low environmental impact. To ensure this, the urban planning process should include simulations of e.g. noise and daylight conditions. In this paper we describe a newly started projected directed towards the need for quality-assured and harmonised input data to the simulations, in the form of 3D city models. The first part of the paper includes the background and research questions of the project and in the second part a tool for daylight simulations on neighbourhood level is introduced, a tool that will be utilized for evaluating the 3D city model design.

A metamodel based on intermediary features for daylight performance prediction of façade design

In order to obtain information about building daylighting performance earlier in the design stage, recent studies have begun to develop daylight prediction models using machine learning methods. Most studies have adopted design variation parameters as the input parameters for model training, but this method greatly limits the scope of application of the daylight model. By extending application to different design possibilities, this research proposes a novel daylight model, which includes a pre-processing procedure to convert the design model into “Intermediary features” as input parameters representing daylight penetration performance. By changing geometry of one kind of parametric façade and performing daylighting simulation, we were able to generate the data for training, including Intermediary features and sDA/ASE values. The daylight model was then trained using an artificial neural network. Finally, the proposed daylight model was tested by predicting the daylight performance of other kinds of façades. The results indicated that the value of DA and ASE hours per grid were well predicted and that the daylight distribution was reproduced even with different kinds of façades. The deviations of sDA and ASE from simulation results ranged from 1.7 to 6.1% and 0.3–2.1 h respectively. The reproducibility, the predictive capability, and most importantly the extension of model applicability were all demonstrated for the proposed model. Furthermore, comparing to the daylighting simulation, the method using the proposed daylight model is estimated to save 9/10 daylighting evaluation time. This is critical for implementing the evaluation in the early design stage.

Predictive models for daylight performance of general floorplans based on CNN and GAN: A proof-of-concept study

A daylight performance evaluation at the early design stage is essential for a building morphology design and optimization, having a tremendous influence on energy consumption and indoor environments. Considering the complicated input parameters, time and computational cost of the simulation tools, although proxy models based on various machine learning algorithms have been developed, they are limited to certain building forms described based on the selected parameters. In this study, proxy models of a daylight simulation for general floorplans are proposed based on convolutional neural network (CNN) and generative adversarial network (GAN). ResNet (CNN) and pix2pix (GAN) are applied to predict static and annual daylight metrics (uniformity, mean lux, success rate, sDA, and UDI) and illuminance distribution in space, respectively. Geometry information is embedded in the image structure, and a grid-based simulation are conducted as the ground truth. Two datasets composed of real floorplan cases and parametric rooms were tested in the experiments. ResNet obtains the best R2 of 0.959 and an MSE of 0.008 on the real case dataset for daylight uniformity. In addition, pix2pix generates visualization results close to the simulation with an SSIM of 0.90 in the test set within a period of 1 s and provides real-time intuitive feedback for designers. The results show the possibility of using deep neural networks to extract features from general building forms and build predictive models, which can be integrated into automatic form-finding and design optimization.

Comparing daylight brightness perception in real and immersive virtual environments using perceptual light maps

While Immersive Virtual Environments (IVEs) are essential for pre-construction investigation of daylight perception in buildings, current daylight studies show limitations in achieving adequate immersion and interaction levels in IVEs, driven by the speed constraints of traditional light simulation tools. Therefore, it is necessary to examine whether using new real-time simulation tools can offer better interaction while maintaining accurate daylight perception. This study validates the accuracy of an interactive method to investigate daylight brightness perception in IVEs, through comparing collective perception visualizations (introduced as Perceptual Light Maps) across reality and an identical IVE based on real-time rendering in a game engine software. The results show strong consistency between perceptions in reality and IVE. The findings accentuate the adequacy of the proposed method as a surrogate to real environments in investigating brightness perception in daylit spaces. Furthermore, they encourage further investigation towards adopting game engines as a validated daylight simulation tool.

Optimization of the light‐emitting diode daylight simulator based on the CIE metamerism index method

AbstractBy using spectral loss simulation, it was found that six spectral bands are needed to produce a daylight simulator with good performance. The optimization model for both Commission Internationale de l'Eclairage metamerism index and luminous efficacy (LE) of light‐emitting diode (LED) daylight simulator (LDS) was developed. The optimal LDSs with AA grade for D50, D55, D65, and D75 illuminants should consist of the violet LEDs with violet phosphor excited by an ultraviolet chip, and the white LEDs with green, yellow, and red phosphors excited by a blue chip. Their limit luminous efficacies under the ideal case could reach 179 to 204 lm/W. And finally, a scheme for a spectrally tunable LDS with AA grade was presented.

Numerical investigation of a smart window system with thermotropic Parallel Slat Transparent Insulation Material for building energy conservation and daylight autonomy

Smart window designs have emerged as a means of providing dynamic regulation of solar energy and daylight, enhancing indoor comfort, and achieving building energy conservation. We evaluated a novel window design that integrated a thermotropic (TT) material and Transparent Insulation Material (TIM) and present the investigation in this paper. The Parallel Slat TIM (PS-TIM) structure contained within the window unit provides extra thermal resistance and helps to redirect daylight. The TT material, which is applied to the slats, provides automatic daylight and solar adjustment. Firstly, the TT PS-TIM window system has been characterised thermally and optically. Then, a comprehensive approach including both building energy and daylight simulation packages was used to predict building performance. The effects of geometry (i.e. slat spacing and slat tilt angle) and thermotropic features (i.e. transition temperature and optical properties) on building performance were investigated. The simulation results show that use of TT PS-TIM window system with carefully selected features can simultaneously improve building energy efficiency (up to 22% saving when compared with a conventional double-glazed (DG) window) and attain homogenous daylight distribution with an average Useful Daylight Illuminance, UDI 500–2000 lux, of 52.2%. It was also found that both the geometric configurations and thermotropic features of a TT PS-TIM have significant influence on energy and daylight performance. TT PS-TIM with horizontally placed slats performs better than the unit with tilted slats, in terms of balance between energy efficiency and daylight availability. This research provides design guidance and material development suggestions for integration of this novel window system in buildings.

Determining the Effective Parameters in Dynamic Daylighting Case study: A Muti-Purpose Living Space in Tehran

Space geometry design is the first stage of proper daylight design. The basic ideas of form and space design should provide the best conditions for daylight. This article investigates the effect of living room proportions on the amount of interior lighting received in Tehran's residential buildings. In the first step, the information from literature related to daylight was studied. In the second step, a checklist has been compiled to examine the space based on daylight from the classification and summarization of the information obtained from the research background. Based on this theoretical framework, one of the houses in Tehran with a common plan was selected as a case study according to daylight design indexes to achieve the goal. In the third step, the problem was determined, and then the solution was provided by simulating using applied models and software. The modeling process and changing the geometric variables were performed parametrically with Grasshopper software, and daylight simulation was performed by Radiance and Daysim software. Thus, the intensity of annual illumination is examined in the current situation to optimize the illumination conditions; the window of this space is optimized by maintaining the optimum ratio of this window, the optimum space proportions obtained. The survey has shown that in optimal condition, the ratio of length to depth in the living room is 1.54 to 1.91, and the WFR ratio is 9% to 22%. Thus with the values obtained, the living room will have the best thermal and lighting performance during the year. In addition, with the optimal percentage of the window to the floor, appropriate shading device, and optimal dimensions of the room, this space can provide suitable light for various daily activities in a multi-purpose living space.

Daylight in buildings based on tubular light guides

Tubular light guides (TLGs) represent a solution for energy efficient performance of light during a day based on the daylight transport into building interiors. While daylight from windows sufficiently illuminates rooms close to building envelopes the light guides improve visual environment and perception of architectural space in deeper parts of interiors. The main aim of this study is focussed on the evaluation of efficiency of two selected TLG systems experimentally tested in temperate climatic conditions. Firstly, daylight illuminance measurements under the light guide installations were performed for one year period with documentation of the typical daily illuminance courses. The measurement results show differences between daylight efficiency of these systems. Secondly, spectral reflectance of the light guide tubes was measured and analysed to find out material influence on light transport effectiveness. Finally, daylight simulations were carried out applying software HOLIGILM for determination of daylight illuminance under the TLG of various dimensions. The study gives general overview about potentials of daylighting applications for straight light pipe systems.

Developing a parametric morphable annual daylight prediction model with improved generalization capability for the early stages of office building design

Building form and fenestration design decisions made in the early stages of design have considerable impact on the annual daylight performance of office buildings. Annual daylight performance needs to be evaluated at the conceptual design stage to support the building form and fenestration design decision-making process. However, the simulation modeling and ray-trace calculation required for annual daylight prediction are extremely time consuming, with an adverse impact on its feasibility in the early design stages. Machine learning-based models have received much attention to reduce the daylight simulation time; however, the generalization capability of these models is limited. This study develops an artificial neural network-based modeling approach to predict annual daylight performance in the early stages of the design process. A workflow to develop an annual daylight prediction model with higher generalization capability is proposed, through feature selection, feature engineering, and hyperparameter optimization, with an accompanying tool to integrate the machine learning model into the early design environment. The developed prediction model was validated against Radiance simulation results with a high accuracy setting and attained R2 scores of 0.988 and 0.996, MAE scores of 1.58 and 1.37, MAPE scores of 2.10% and 2.36% for UDI and DA300, respectively, while being 250 times faster. The proposed modeling approach can be extended by adding more types of parametric room modules.

An Evaluation of Annual Luminous Exposure from Daylight in a Museum Room with a Translucent Ceiling

The current study investigates the issue of computer-aided daylight evaluation in a museum room with a dropped translucent ceiling. In this type of room, daylight is admitted through classic windows located in the facade and then distributed in the plenum, which is located above the exhibition space and transmitted through the translucent ceiling into the museum room. This illumination method enables guiding daylight deep into the room, excluding the impact of direct solar radiation. The presented study is based on data obtained through computer-aided daylight simulation by DeLuminæ (DL-Light, ver. 11.0.9) software using the Radiance software for all calculations and real weather data for Wroclaw, Poland. A museum room of 12 × 12 m with three different heights of the plenums was simulated to establish an optimal relation of the width to height plenum ratio. Next, the annual exposure in K lx·h/year was calculated, as sensitive works of art may be subjected to damage caused by light exposure. To further reduce illumination, the simulation of an automatic shading system in the form of horizontal louvers was performed. The system was activated when certain illumination values were detected by the sensor on the building’s roof.

A data-driven method to minimize sensor use for dynamic shading control

Dynamic facade systems are a promising strategy to balance the benefits and drawbacks of daylight penetration through the window in a built environment. A well-operated shading system should allow for sufficient daylight access while preventing glare in response to changing weather conditions. The dynamic shading system can also help with making use of daylight to reduce the lighting energy use when integrated with electric lighting control. This paper presented a data-driven approach to control the automated shading system. The control method allows the system to be responsive to outdoor weather conditions. With data from offline daylight simulation using typical meteorological year weather, three machine learning classification algorithms were applied to train predictive models for online shading control. The proposed method was validated using a climate-based simulation. It was found that all models had a satisfying prediction performance, with an accuracy of 0.85 to 0.92. The shading control could maintain the work plane illuminance for 97% to 99% of the time during the year. It was also associated with a potential of reducing electric lighting energy use by 40% to 43% compared to that of on/off lighting control.

Decision-making pathways to daylight efficiency for office buildings with balconies in the tropics

Daylight in the indoor environment is directly influenced by the building surroundings, envelope and its shading devices, such as balconies. Despite their potential in contributing to increase shaded periods and, at the same time, act as a daylight distribution system, balconies are not designed to their full potential when used in office buildings and the literature lack studies that investigate the effect of balconies on their luminous performance. This study aims to explore this niche: the integration of balconies to the design of office buildings in the tropics, in order to improve their daylight performance. The research method was based on a parametric design approach in combination with daylight simulations, while combining a systematic analysis with a data mining algorithm. The study revealed successful combinations of building design parameters as well as important cut-off points for design decision-making to achieve daylight efficiency in typical mixed-mode office buildings in the city of São Paulo , Brazil. Results provided multiple design routes to achieve successful performance targets showing that, if properly dimensioned, balconies could be an efficient shading device and daylight diffuser. As a key contribution, successful combinations of design parameters that allow deeper balconies to yield better Useful Daylight Illuminance levels were identified. Further details about when balconies stop influencing daylight performance results as well as when an increase in balcony depth becomes beneficial to performance were reported in attempt to develop design guidelines for the early design stages for office buildings in São Paulo. • Analysis of the role of balconies to improve daylight in office buildings. • Decision-making pathways to improve daylight whilst reducing cooling demand. • Cut-off points for design decision-making to achieve daylight efficiency.

Development of a Daylight Simulation Software for Early Design Stage: A Case Study of a Container House

Daylight simulation software play a significant role in decision-making during the architectural design process. These software enable architects to make informed decisions about daylight performance in the early phases of the project. Radiance as a simulation engine provides a physically accurate model of the lighting conditions in the scene, thus capable of achieving a high degree of accuracy and validity. However, with a command line interface, it requires a large number of input parameters, which complicates modelling and restricts flexibility. When integrated in the early design process, this approach becomes less efficient, or requires enormous computation time. This paper introduces a daylight simulation software named DaylightX that uses the backward raytracing algorithm implemented on the GPU to calculate the spatial distribution of daylight across the space. The tool aims to enhance the capabilities of the simulation environments through a user-friendly interface and thus allow for flexibility in the design process. An individual residential unit - a shipping container - was used as a base case for evaluation. The modular design of shipping containers allows for flexibility in window placement and orientation, but requires careful design and implementation from daylight performance perspective. The results of the study can serve to improve the daylight performance of container housing units.

Building Retrofitting through Coupling of Building Energy Simulation-Optimization Tool with CFD and Daylight Programs

Simultaneous satisfaction of both thermal and visual comfort in buildings may be a challenging task. Therefore, this paper suggests a comprehensive framework for the building energy optimization process integrating computational fluid dynamics (CFD) daylight simulations. A building energy simulation tool, IDA Indoor Climate and Energy (IDA-ICE), was coupled with three open-source tools including GenOpt, OpenFOAM, and Radiance. In the optimization phase, several design variables i.e., building envelope properties, fenestration parameters, and Heating, Ventilation and Air-Conditioning (HVAC) system set points, were selected to minimize the total building energy use and simultaneously improve thermal and visual comfort. Two different scenarios were investigated for retrofitting of a generic office building located in Oslo, Norway. In the first scenario a constant air volume (CAV) ventilation system with a local radiator in each zone was used, while an all-air system equipped with a demand control ventilation (DCV) was applied in the second scenario. Findings showed that, compared to the reference design, significant reduction of total building energy use, around 77% and 79% in the first and second scenarios, was achieved respectively, and thermal and visual comfort conditions were also improved considerably. However, the overall thermal and visual comfort satisfactions were higher when all-air system was applied.

Non-visual effects of office light environment: Field evaluation, model comparison, and spectral analysis

Light environment is an important part of the office environment. Aside from visual effects, light also has non-visual effects, for example, on mood, alertness, and performance. Although essential for healthy light design, current office lighting rarely considers non-visual effects. The evaluation of non-visual light environment is predominantly based on two physiological models: the equivalent melanopic lux (EML) and circadian stimulus (CS) models. EML is similar to visual illuminance but the spectral sensitivity function is non-visually converted. CS indicates the percentage of melatonin suppression and is more complex as it considers the interaction between different photoreceptors. Model comparison and spectral analysis of field measurements are required to verify the applicability of these models. Therefore, this study conducted field evaluations of non-visual effects in several typical office environments with different window orientations, then compared the calculation differences between EML and CS models. Errors in the spectral approximation calculations were also analyzed. According to the analysis of 571 measured data sets, no workstation with existing layout met the non-visual standards under overcast conditions. EML and CS models are similar in office indoor environment compliance evaluation, but CS model gets more reasonable results at high eye-level illuminance. Moreover, daylight irradiances were effectively approximated by the CIE standard illuminants D50 and D55. The conclusions of this study can be used as guidelines for interior design, field evaluations, and daylight simulations of the non-visual effects of light in office environments.

Greenhouse Daylight Illuminance for Users’ Satisfaction in Hot and Humid Climate

The greenhouse is vital to protect indoor crops from the harsh hot-humid climate. This study firstly identifies design attributes of greenhouses such as dimension, shapes, orientation, and shading. Secondly, it assesses the impacts of design attributes on the greenhouse daylight performance using VeluxVisualizer. The results showed an increase in the number of skylights caused higher average daylight illuminance in the greenhouse. All the models passed the requirement for plants with small sunlight claim between 7 and 9 hours per day. This study paves the way for energy-efficient buildings with the aid of building simulation to benefit the users. Keywords: Greenhouse Design Features, Daylight Simulation, Hot and Humid Climate eISSN: 2398-4287© 2021. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians/Africans/Arabians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. DOI: https://doi.org/10.21834/ebpj.v6i16.2711

Optimising Daylighting Performance in Tropical Courtyard and Atrium Buildings for Occupants’ Wellbeing

Daylighting has attracted increasing attention from researchers as an energy-efficient and sustainable building design technique. This research investigates the daylighting of atrium and courtyard building by comparing the performance of various Window to Wall Ratios (WWR) appropriate to Malaysia's tropical climate. The most acceptable option for daylight performance was to specify a moderate WWR value of 30% with shading devices. The results of The Radiance Daylighting Simulations confirmed the daylight performance by a comparison of calculated data and modelling. The findings show the combinations of daylighting parameters that work for courtyard and atrium buildings for the occupants' wellbeing. Keywords: Daylighting Performance, Courtyard, Atrium, Tropical, Radiance Simulations eISSN: 2398-4287© 2021. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians/Africans/Arabians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. DOI: https://doi.org/10.21834/ebpj.v6i16.2710

Improving Daylight Availability in Heritage Buildings: A Case Study of Below-grade Classrooms in Tehran

Refurbished heritage buildings usually lack in meeting the required standards defined for the new function especially when reused as educational buildings. Therefore, they are usually equipped with different post-occupancy retrofit strategies to achieve an acceptable level of environmental quality and energy demand. Daylight quality and the distribution of natural light is a critical issue in educational spaces, given that the low level of illuminance in classrooms can decrease students' performance and disrupt visual tasks. In this study, daylight performance of below-grade south-facing classrooms in a heritage building in Tehran, Iran is investigated by implementing 57 different daylighting retrofit strategies using climate-based daylight simulations, in relation to the metric Useful Daylight Illuminance 300-3000lux (UDI-Autonomous). The research proposes the use of reflectors on the interior ceiling and exterior side of the windows (on the ground) to achieve the highest result possible. Although, applying these two systems individually, can boost the spatial distribution of daylight to 75 % and 71%, respectively, the combination of them provide users with UDI-Autonomous in 99% of the classroom space for more than half of the occupancy time.

Daylighting Analysis and Simulation Tools in Architectural Design:Review of Tools and Compatibility with Architectural CAD Platforms

Purpose: This research is a review of current and past daylighting simulation tools from the perspective of the Architect, one of the key stakeholder in the integration of the science of daylighting into architectural practice. The review is evaluated based on criteria identified through existing literature. First, a review of integration and interoperability with mainstream architectural CAD platform is initiated and second an evaluation of select tools were performed based on a simple simulation task involving a typical classroom. Method: Over fifty daylighting simulation tools are categorized based on its integration and plotted on an “integration matrix” to illustrate compatibility with mainstream architectural software. The matrix is used as a basis to identify daylighting simulation tools for further evaluation. Evaluation of the tools are based on functionality, ease of use, and visualization. Result: Findings include recent increase in available daylighting simulation tools in the form of plug-ins to existing architectural CAD platforms. In addition, the integration matrix provides valuable information to architects and designers in the selection of Daylighting Simulation Tool, one of the key hurdles that designers face in the implementation of daylighting in architectural design practice. Furthermore, the evaluation of the tools provides information in the aid and development of future Daylighting Simulation Tools.