Daylight In Buildings Research Articles

Comparing the performance of four shading strategies based on a multi-objective genetic algorithm: A case study in a university library

Through the control of excessive daylight in buildings, shading devices can reduce glare and improve occupants' visual comfort. However, shading devices may overly reduce illuminance levels. Many shading strategies are available, but they do not perform equally well, and traditionally, it has been difficult to select the most suitable shading strategy. This study proposed a parameterization method for the selection and design of a shading strategy that would reduce glare while maintaining a satisfactory daylighting level, through the construction of Pareto sets based on a multi-objective genetic algorithm. The objective function was created by combining a dynamic glare evaluation indicator, the spatial glare autonomy (sGA), and a self-constructed daylight index, the spatial daylight vote autonomy (sDVA), developed from a field survey. As a case study, the proposed method was used to compare the performance of four shading strategies, including vertical slats (Vs), a perforated aluminum sheet (PAS), serrated windows with southern orientation (Sw_S), and serrated windows with northern orientation (Sw_N) in a university library in Shanghai, China. It was found that the Sw_S and PAS had a relatively bad performance; the Vs performed better than the Sw_N in providing a more satisfactory illuminance level; and the Sw_N was more effective in reducing the glare. The multi-objective optimization process can be used to obtain near-optimal design parameters that create a visual environment with reduced glare while maintaining an acceptable illuminance level, for all four shading strategies. The developed method can be a helpful tool in the design of an appropriate daylighting environment.

Advocating for view and daylight in buildings: Next steps

With the exponential growth in population and commensurate increased density in urban cities, access to daylight and views to nature is being severely curtailed in buildings. In parallel, increasingly urgent demands to sharply reduce building energy use and associated greenhouse gas emissions are being made to mitigate climate change. There are many challenges and performance tradeoffs associated with the building facade (i.e., daylight and view versus solar and glare control); increased prioritization of health and well-being as a fundamental human requirement could adversely affect building energy-efficiency. Given the current state of knowledge on the effects of daylight and view on health and well-being in buildings, we identify critical needs in research, tools and technologies that if satisfied may enable more effective use of daylight and view in buildings within the constraints of climate change. Lack of knowledge regarding the complex causal mechanisms of window views on human factors is a severely limiting factor in forward progress. Current models and methods to derive bidirectional scattering distribution functions (BSDFs) will need to be modified. Developers of energy-efficient window technologies will need more guidance to shape product development. Advanced window technologies and integrated design can enable attainment of both health and well-being and net zero energy goals, but considerable work will be needed to make such options turnkey and broadly available.

Simple correlations between point daylight factor, average daylight factor and vertical daylight factor under all sky conditions and building design implications

The customary method for calculating daylight illuminance in a building is the daylight factor approach, which is assumed under the conventional overcast sky. However, such an approach is not flexible enough to predict diffuse illuminance in the presence of non-overcast skies. The daylight factor is invariant to building orientation and cannot take realistic and time-varying climatic conditions into account. Daylight in buildings is estimated using computer simulation techniques. However, full-scale computer simulations can be costly and time-consuming. Practitioners welcome simple calculation aids established via comprehensive analysis. Such easy tools would give building professionals and students basic and concise insight into the independency of different daylight parameters. Recently, daylight factor calculations have been extended to non-overcast skies. It means that the daylight factor approach can be a dynamic metric. This paper presents the calculation of the point daylight factor, the average daylight factor and the vertical daylight factor under all sky conditions, as well as building façade design implications. The performance of the three types of daylight factor for a typical room at various scattering angles is elaborated and evaluated; simple correlations between them are developed.

TROPICAL DAYLIGHT AVAILABILITY AND SKY TYPOLOGIES FOR DAYLIGHTING EVALUATION AND DESIGN

Daylighting in buildings is a critical functional requirement in the tropical climate. It has numerous benefits, whereas poor implementation is bound to create high energy consumption and user's discomfort, unlike in the temperate region. Daylight data for design is fundamental toward achieving optimal daylighting due to variations for different locations. Like most regions in the tropics, Nigeria has limited data in this regard. Therefore, this study investigated the availability of daylight and skies using daylight modelling methods. The global illuminance and irradiance data were input to model the outdoor daylight and sky types. The modelled, measured, and RadianceIES outdoor illuminance data were comparatively analysed relative to the design time and date. The results show that the sky is predominantly intermediate. More so, the monthly mean outdoor illumination varies from 47 to 67 klux at noon and as low as 9 klux during the morning and late afternoon. The study concluded that the mean outdoor illuminance for design is 30.7klux, 60.0klux, and 46.0klux at 0900, 1200, and1500 hours, respectively. In architecture, the use and applications of these data are to improve thermal, visual comfort, low-energy and task illuminance design in buildings, thus resulting in enhanced performance, cost savings, and user satisfaction.

Stereoscopic Images and Virtual Reality techniques in daylighting research: A method-comparison study

Visualization and presentation techniques are experiencing a rapid development and application in the architectural profession and beyond. As such, Stereoscopic Images (SI) and Virtual Reality (VR), both advanced visualization techniques, have found their way in daylighting research. This paper explores the correspondence between these two techniques using both quantitative and qualitative methods. The study focused on two small rooms with the same dimensions, with alternately white and black surfaces, and three different windows sizes. Seven architectural qualities were studied: Pleasantness, Calmness, Interest, Excitement, Complexity, Spaciousness, and Amount of View. The attributes were evaluated by 20 participants using a Likert-type scale. The collected data was analyzed using Wilcoxon signed-rank tests and the Bland-Altman method. The results revealed that the attributes Pleasantness, Calmness, Interest, and Complexity in rooms with both white and black surfaces, and Excitement and Spaciousness in a room with white surfaces are evaluated similarly in both VR and SI. The attributes Excitement and Spaciousness in a room with black surfaces and the Amount of View in rooms with both white and black surfaces were not evaluated similarly with both methods. In addition, qualitative results indicated that the visualization technique affects how a space is perceived. Indeed, the Virtual Reality's nature as an immersive environment provides the feeling of ‘presence’ which does not apply to SI. The results of this paper can help researchers working with daylighting in buildings in selecting the appropriate visualization technique to reduce experimental and logistical constraints caused by varying daylight conditions.

Delightful Daylighting: A Framework for Describing the Experience of Daylighting in Nordic Homes and Coupling It with Quantitative Assessments

In this conceptual article we propose a framework for describing the experience of delightful daylighting in Nordic homes and a method to correlate it with an existing quantitative daylighting assessment. In contrast to earlier research on daylighting, the present work gives priority to developing the methodology for researching the experience of the inhabitant in a real situation and relying the quantitative assessment on an existing method. In this way, we shift the focus of daylight studies from quantitative evaluations towards qualitative descriptions of the human experience of daylight. The framework enables future research that can broaden the way the experience of daylighting is described and to see if the quantitative assessment according to the standard EN 17037:2018 Daylighting in buildings correlates with these descriptions. Firstly, the current state of research on subjective daylight preferences and daylight assessment is reviewed. Secondly, a novel method, the long-term spatial interview, is introduced. The aim of the method is to describe a long-term experience of a spatial phenomenon, in this case, delightful daylighting of Nordic homes, through a phenomenological perspective and enable localisation of the qualitative research results. Finally, the use of the existing EN-standard as a tool to quantitatively describe the daylight situation of spaces is explained and a correlation analysis of the quantitative and qualitative results is explicated. Future research based on the framework can provide useful information for designers aiming at creating delightful daylighting experiences in Nordic homes.

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.

Design Optimization of Hyperboloid Wooden House Concerning Structural, Cost, and Daylight Performance

The use of parametric and multi-objective optimization (MOO) as a new way of approaching architectural design has been growing in line with current breakthroughs in computational architecture. Wood, on the other hand, is a living and unique building material that provides durability, manufacturing flexibility, and local availability. One of the structure types that provides high structural stability is the hyperboloid. However, the exploration of hyperboloid structures in building design, together with the building daylight objective, is still limitedly reported. This paper presents the application of the parametric approach and multi-objective optimization in optimizing the structure and daylight objectives of a hyperboloid two-story wooden house in Japan, made of 105 mm × 105 mm × 4000 mm Japanese timber. The method involves iterating dynamic parameters such as radius bottom, offset distance, timber members, twisting level, building height, radius-top, and roof slope to optimize the structural objective of minimizing normal force average, displacement, and cost while simultaneously maximizing building volume. Regarding daylight objectives, unit movement and glazing ratio that control the glazing strategies were explored to optimize useful daylight illumination (UDI) in summer and winter. The optimization and exploration yielded 10,098 solutions in structural analysis and 406 solutions in daylight exploration. Based on the data analysis, the proposed methodology has successfully produced the best design solution, discovering the balance between the objective trade-offs. In addition, the most influential parameter that shapes the value of design objectives has been identified. The findings of this research were expected to contribute to and enhance the performance-based design optimization, and support design decision-making process in the early design stage of a wooden house with a hyperboloid structure.

Comparative Investigation of Daylight Glare Probability (DGP) Comfort Classes in Clear Sky Condition

Glare is considered one of the most important variables to reach visual comfort and visual quality. It represents one of the fundamental barriers for an effective use of daylighting in buildings. One of the best performing and robust glare prediction models, relative to other available metrics, is a Daylight Glare Probability (DGP). Based on a validated and precise methodology (RADIANCE) the aim of this work is to compare the DGP model (original cut-off values) with new cut-off values that differ according to the time of day (morning, noon and afternoon). Both cut-off values were compared at more than 300 simulated conditions of daylighting in an interior space. This work offers the originality of studying recently proposed cut-off values in climate luminous with predominant clear sky conditions. Currently, the application of these new cutoff values is reduced to the field of science or simulation professionals. The results showed important differences (64.86%) between the categories proposed by both cut-off values. Nevertheless, these differences do not have a significant impact in glare prediction (< 2.7%), in terms of glare absence (DGP <0.38) and presence (DGP >0.38). This analysis made it possible: (i) to regionally apply the main current corpus criteria regarding glare issues as well as emergent proposals and (ii) to present new experimental data aimed at helping the field and, together with other works, improving the tools used by professionals on a daily basis.

Utilization of programmable cameras for web-based sensing and control of daylight in buildings

The concept of integrating programmable low-cost cameras into the office infrastructure and BMS for real-time, web-based sensing and control of the luminous environment in buildings is presented in this study. Experiments were conducted to evaluate the potential of predicting the luminance field perceived by an office occupant using a programmable calibrated HDR camera installed at the rear side of a computer monitor or on the wall behind the occupant, for a variety of sky conditions and shading options. The generated luminance maps using Python scripts with OpenCV packages were further processed to extract daylighting and glare metrics using Evalgare. The results showed that: (i) among the different camera resolutions that were compared, the 330x330 resolution was selected as the best option to balance between accurate capturing of visual environment and comfort and computational efficiency; (ii) a camera sensor embedded on the rear side of a computer screen could capture interior visual conditions consistently similarly to those viewed by the occupant, except for sunny conditions without proper shading protection. This prototype study paves the way for luminance monitoring and daylight control using programmable low-cost camera sensors embedded into the office infrastructure.

Experiences using EN 17037 in evaluation of daylighting of dwellings in Slovakia

The daylighting of indoor spaces depends particularly on the urban and architectural parameters of the building environment. The new standard EN 17037, Daylight in Buildings, has brought several changes and uncertainties in design process of daylighting for buildings. The submitted paper is focused on analysis of the philosophy of the new standard criteria in relation to the daylighting of dwellings along with the criteria that have been used in Central European countries for decades. EN 17037 does not distinguish between differences in the functional use of indoor spaces in terms of daylight provision. The new European standard requires at the half of subjectively determined reference plane to achieve the same value of illumination for half of daylight hours per year for any occupied room. The EN standard does not sufficiently respect the specifics of daylighting of dwellings.

Daylight in Buildings and Visual Comfort Evaluation: the Advantages and Limitations

Exposure to daylight significantly affects the psychological well-being of occupants by diminishing headaches, eye tensions, or stress. Daylight penetration is a matter of collaboration between building façade and perimeter zones that can be controlled through façade design features. This study reviews available daylighting systems to block or redirect natural light inside the space and their overall performance. Adaptation found to be the main key feature of daylighting systems to improve their effectiveness in indoor environments. As the main implication of such systems on the visual comfort performance of occupants, a list of quantitative indices is studied based on their mathematical equation to outline their advantages and limitations. Findings revealed a lack of agreement on acceptable indoor illuminance thresholds for most of the indices and the absence of a reliable glare index in presence of sun within the view field of the occupant. Similarly, many green building certifications propose a specific criterion to assess view out but remained a challenge for future studies.

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.

Designing a facade by biomimicry science to effectively control natural light in buildings (Glare analysis)

The increasingly popular design trend of glazed facades using daylight in buildings has made it essential for innovations to eliminate the unnecessary intrusion of sunlight in spaces. This study aims to create a kinetic façade pattern by referring DNA structure and photosynthetic behaviour to mimic biomimicry science characteristics in Wallacei evolutionary software for generating possible patterns. Daylight glare thresholds were determined as an essential factor for user productive work. Comparison of three-building envelope potential was made for preparing spaces (zones A, B) in Bangkok condition; without a façade, with a static facade, and with a kinetic façade. DIVA software was used to analyse glare in terms of daylight glare probability (DGP). First, DGP (without façade) for zones A and B were 100% and 55%, or intolerable glare. Second, DGP (static façade) for zones A and B were 59%, 30%; zone A was intolerable, and B imperceptible. Third, DGP (kinetic façade) for zones A and B were 28% (imperceptible glare). Therefore, a kinetic façade has a high potential for protecting against unsuitable glare. These findings may serve as preliminary evidence for understanding kinetic façade potential for self-adjustment by light intensity to improve quality of life for occupant use of spaces.

Effects of neighbourhood morphological characteristics on outdoor daylight and insights for sustainable urban design

ABSTRACT Urban daylight significantly affects the physical and mental health of urban residents. Many previous studies focused on how outdoor daylight conditions affect indoor daylighting of buildings, whereas the design of outdoor daylighting conditions, which also exerted an equally significant part, was relatively overlooked. There are also few studies empirically explored the outdoor daylight in various forms of mature urban neighbourhoods. Through investigating the outdoor pedestrian daylight performances of 11 representative open urban neighbourhood units in inner-city Shenzhen, this study aims to identify the influence of urban design factors. Through field investigation, mapping and on-site measurement, this study explored and analysed the horizontal illuminance level and site illuminance uniformity of 84 outdoor spaces. As the results revealed, urban morphological characteristics significantly affected the daytime pedestrian illumination. Specifically, the high-density mid-rise urban villages and the urban park demonstrated the best daytime outdoor visual comfort conditions. The multivariate regression test demonstrated that sky view factor exerted the greatest influence on the daytime outdoor illumination, followed by the mean building height, ground surface albedo and vertical uniformity. Hence, urban morphological patterns have great potential in optimizing urban design for outdoor daylighting behaviours and energy use, which is of great reference value in setting specific standards to achieve the goals of the initiatives of “Healthy Cities.”

No-Greenery Line and Greenery-View Factor, New Architectural Design Tools

The paper proposes a new tool for evaluation of the degree of visual contact with the outdoor greenery, the Greenery-View factor (GV), intended to be easy to grasp and simple to use. It starts with the construction of a No-greenery line (similar to the No-sky line) on the vertical section of the building with the neighbouring greenery included. No-greenery line divides the space into a part with the view to the greenery and the rest of the room from which the greenery is not visible. To find out the part of the floor area of the room from which the greenery can be seen, the section-point between the no-greenery line and the line representing the eye-level is projected down at the floor plan. The GV factor stands for the part of the floor area with the view to the greenery expressed as a percentage of the whole floor area of the room. The No-sky line and the No-greenery line can be used together by architects and urban planners as extremely simple and powerful couple of graphical tools. The paper discusses also how the GV factor could be implemented in the new European daylight standard EN-17037 Daylight in buildings (2018).

An immersive performative architectural design tool with daylighting simulations: a building information modeling-based approach

PurposeIn performative architectural design, daylighting is a crucial design consideration; however, the evaluation of daylighting in the design process can be challenging. Immersive environments (IEs) can create a dynamic, multi-sensory, first-person view in computer-generated environments, and can improve designers' visual perception and awareness during performative design processes. This research addresses the need for interactive and integrated design tools for IEs toward better-performing architectural solutions in terms of daylighting illumination. In this context, building information modeling and performance simulations are identified as critical technologies to be integrated into performative architectural design.Design/methodology/approachThis research adopts a design science research (DSR) methodology involving an iterative process of development, validation and improvement of a novel and immersive tool, HoloArch, that supports design development during daylighting-informed design processes. HoloArch was implemented in a game engine during a spiral software development process. HoloArch allows users to interact with, visualize, modify and explore architectural models. The evaluation is performed in two workshops and a user study. A hybrid approach that combines qualitative and quantitative data collection was adopted for evaluation. Qualitative data analyses involve interviews, while quantitative data analyses involve both daylighting simulations and questionnaires (e.g. technology acceptance model (TAM), presence and system usability scale (SUS)).FindingsAccording to the questionnaire results, HoloArch had 92/100 for SUS, a mean value of 120.4 for presence questionnaire (PQ) and 9.4/10 for TAM. According to the simulation results, all participants improved the given building's daylighting performance using HoloArch. The interviews also indicated that HoloArch is an effective design tool in terms of augmented perception, continuous design processes, performative daylighting design and model interaction. However, challenges still remain regarding the complete integration of tools and simultaneous simulation visualization. The study concludes that IEs hold promising potentials where performative design actions at conceptual, spatial and architectural domains can take place interactively and simultaneously with immediate feedback.Originality/valueThe research integrates building information modeling (BIM), performative daylighting simulations and IEs in an interactive environment for the identification of potentials and limitations in performative architectural design. Different from existing immersive tools for architecture, HoloArch offers a continuous bidirectional workflow between BIM tools and IEs.

Computational and experimental evaluation of view out according to European Standard EN17037

This paper presents an experimental evaluation of view out based on EN17037:2018 Daylight in Buildings within an educational building. The primary motivation to conduct the research was an introduction of a view out appraisal criteria by the mentioned standard. The study gives insights into the following: (i) the use of computational evaluation of an outside view according to the EN17037 criteria (ii) the use of the direct simultaneous questionnaire to assess the view out (iii) a description of the relationships between the normative criteria and users' subjective assessments of view out, and (iv) the link between the quantitative and qualitative parameters of the evaluation of view out. The study was conducted using a three step approach: S1 – a computational evaluation of the outside view according to the standard's recommendations: distance to the nearest obstacle, number of visible layers and angle of the view; S2 – a view out evaluation based on a direct questionnaire in the selected indoor spaces under various daylight conditions; S3 – analysis and comparison of the results. The data was collected in 2019 and 2020 with 169 evaluations from volunteering architecture students. The key findings are: (i) the outcome of the subjective participants' evaluation of the view out differs from the results generated through computational simulations based on the EN17037 ratings (ii) similar results were recorded in reference to the estimation of the layers of the view, and (iii) the responders rated the view out one rank lower than the computational evaluation suggests.

Applicability of a Prismatic Panel to Optimize Window Size and Depth of a South-facing Room for a Better Daylight Performance

This study examines the performance of attached prismatic panels, which have shading capability, in a side-lit deep plan room to find out the least possible WWR value in relation to room depth satisfying the required daylight availability. The methodology is based on simulating a base model in Relux and testing it with alternative models composed of incrementally defined WWR and room depth values. In accordance with minimum IES requirements, the most satisfying sDA value was found to be 48.54 % in a room of 12 m depth with 67 % WWR. An sDA of 51.59 % and 59.26 % was achieved in a room of 9m depth with 43 % WWR and 6m depth with 30 % WWR, respectively. The least ASE values were obtained with the least WWR alternative of 30 % in all room depths. This study presents a new approach with the consideration of innovative daylight redirecting systems to propose revisions for the requirements mentioned in standards about daylight in buildings but based on conventional fenestration systems.

Low-cost radiative cooling blade coating with ultrahigh visible light transmittance and emission within an “atmospheric window”

Radiative cooling is a passive means of cooling that does not require the consumption of additional energy and has broad application potential. While experimental spectral measurements have been conducted, the daylighting of buildings, photovoltaic (PV) cells, and vehicles has seldom been considered. Here, we use spectrum-selective coatings to resolve the competing demands of daylighting (or appearance) and radiative cooling. A simple liquid blade-coating method that was inexpensive, convenient, and scalable was used to achieve radiative cooling with ultrahigh transmittance in visible light and excellent cooling performance. Resonant polar dielectric SiO2 microparticles with optimized volumetric fractions and diameters were randomly mixed into an acrylic resin and manually bladed at room temperature with natural evaporation drying. Spectrometry results showed that a mean visible light transmittance >91.3% was achieved, which was much higher than reported in previous studies; a mean emittance >93.7% within the “atmospheric window” was also reached. Over four days testing of a silver-plated aluminum sheet in a populous area at sea level, we achieved a maximum sub-ambient decrease in temperature of ~8.7 °C and a maximum cooling power of 108.49 W/m2.