Climate-based Daylight Modelling Research Articles

Daylight and Electric Lighting in Primary and Secondary School Classrooms in the UK-An Observational Study.

Only a few recent studies report direct assessment or monitoring of light levels in the indoor learning environment, and no consensus exists on minimum exposures for children's health. For instance, myopia is a common progressive condition, with genetic and environmental risk factors. Reduced daylight exposure, electric lighting changes, increased near-work for school children, greater academic focus, and use of display screens and white boards may have important detrimental influences. Published assessment methods had varied limitations, such as incomplete compliance from participants wearing light loggers for extended periods. Climate-Based Daylight Modelling is encouraged in UK school design, but design approaches are impractical for post-occupancy assessments of pre-existing classrooms or ad hoc modifications. In this study, we investigated the potential for direct assessment and monitoring of classroom daylight and lighting measurements. Combined with objective assessments of outdoor exposures and class time use, the classroom data could inform design and light exposure interventions to reduce the various health impacts of inadequate daylight exposure. The relevant environmental measure for myopia depends on the hypothesized mechanism, so the illuminance, spectral distribution, and temporal light modulation from the electric lighting was also assessed.

Formulation of climate-based daylighting design prediction model for high performance tropical school classrooms

Daylighting is beneficial in buildings, including school classrooms, in which daylight can significantly affect the occupants’ performance. Also, daylight varies across different climates, including within the tropical region. Climate-based daylight modelling is recommended to accurately predict annual daylight performance in building spaces; however, it is often too complicated in practice. It is intended to have certain climate variables that can act as predictors for annual daylight performance in tropical school classrooms, where openings are typically installed on opposing façades. This study thus aims to propose a climate-based daylighting design prediction model for tropical school classrooms with symmetrical and asymmetrical opening typologies. The model considers horizontal shading depth and its height, and window-to-wall ratio, in relation with the climate variables. To achieve the objective, two classrooms with asymmetrical and symmetrical bilateral openings are modelled and optimized for 117 site locations in Indonesia. The spatial average UDI250-750lx is proposed as the reference metric that can ensure satisfaction of all daylight criteria. The annual global horizontal radiation (aGHR) is proposed as the predictor in the model, with prediction errors below 5 %. Simple equations have been derived to predict spatial average UDI250-750lx in tropical classrooms as a function of aGHR.

Daylighting Assessment of a Heritage Place of Instruction and Office Building in Alice, South Africa

Mitigation of post-occupancy building energy consumption has resulted in the change of building design to utilise ambient weather factors for indoor thermal conditioning and lighting. This has increased the construction of new buildings with large glazing façades and reduced adaptive use of heritage buildings as they are considered not designed to meet modern energy use requirements. This paper evaluates the daylighting performance of a heritage place of instruction and office building. A quantitative research approach based on building information simulation tools was adopted. Autodesk Revit 2021 and Integrated Environmental Solutions Virtual Environment (IESVE) 2021 were used in modelling and simulating the building daylighting performances. The building’s annual daylight performance analysed with climate-based daylight modelling shows that points in the analysed spaces were within the UDI300-2000 for more than 50% of the occupied period (07h00 to 17h00) in a year. The sDA300,50% was found to be 100% in most spaces, which is considered a favourable daylit space according to the Illuminance Engineering Society of North America (IESNA). Further, discomfort glare analysis revealed that the building daylight glare is imperceptible, with an average daylight glare probability of 21.2%. The 1:14 window–wall ratio contributes to the building daylighting relative to orientation without constituting visual discomfort. Overall, climate-based daylight modelling revealed that the building’s annual daylight level meets the IESNA requirements with an imperceptible daylight glare.

Optimization of Daylighting Outdoor Availability in Urban Kampung

Liveability interprets as making residents comfortable in their built environment. As daylighting becomes a necessity for human beings, daylight availability can improve the liveability of dwelling habitats, especially in high-density urban areas. Relayouting the building block without reducing the usable floor area can improve daylight availability. Kampung Braga is an example of how a heavy slum area has a low liveability quality and classifies into impoverished slum settlements at the stake of being resettled. The spatial arrangement becomes necessary to enhance the community’s quality of life. This article aims to examine how the intervention through urban layout can affect daylight availability to improve the liveability for kampung Braga. This research uses simulation methods with climate-based daylight modelling (CBDM) software to simulate daylighting with a dynamic approach. Rhinoceros for modelling, Honeybee for vertical sky component (VSC) simulation, and DIVA for daylight availability simulation. Based on the simulation on three alternative urban layouts in line with spatial plan context, it is shown that intervention through urban layout and typology of kampung Braga has shown better VSC and daylight availability values than the existing conditions. It is necessary to pay attention to the context of the building around the site when designing a specific building typology. Modifying configuration, floor height, model, and orientation show a better VSC reception and vertical facade illumination. City stakeholders need to be aware of the low liveability of the urban kampung. Planning the right urban plan design can improve daylighting availability and increase the liveability of the urban kampung.

Assessing daylight performance in use: A comparison between long-term daylight measurements and simulations

Climate-Based Daylight Modelling (CBDM) methods have been validated against long-term measurements in laboratory settings and found to exhibit errors small enough to make such assessments useful for daylight performance prediction. However, real occupied spaces are affected by a higher number of uncertainties than laboratory or controlled conditions. This study aims at validating CBDM methods against measurements collected in an occupied classroom space, where a monitoring system based on High Dynamic Range Imaging was installed. Four vertical regions were identified on two of the room’s walls, and mean illuminance was calculated for these regions at every time step, both from HDR images and from simulated results. Two simulation methods were evaluated: the 2-phase and the 4-component methods. Sun and sky conditions for the simulations were derived from simultaneous monitored irradiation measurements. Both simulation methods led to moderate over-prediction of HDR-derived results, when considering instantaneous illuminance means and when looking at long-term metrics (cumulative irradiation and Useful Daylight Illuminance). Wall regions exposed to more direct sky- and sunlight were characterised by smaller systematic errors (rMBE = 4%) but similar variance (r2 = 0.83) than regions situated at the back of the room (rMBE = 17–34% and rMAE = 27–37%). Further studies are needed to identify and separate the sources of such errors.

The implementation of natural lighting for human health from a planning perspective

This paper makes the case that a significant factor in the failure to ensure adequate daylighting performance for interior spaces is often due to the inadequacy of methods used at the early stages of planning. All of the methods currently used for daylight/sunlight planning share common failings: they cannot make meaningful estimations of performance at the outset, nor can the methods used be extended/refined to overcome these failings. Thus, it is argued, a new approach is required. The paper gives an overview of the history and development of methods to predict performance; from the conception of the daylight factor to climate-based daylight modelling. The impact of prescriptive planning regulations is described using New York City as the example. The paper concludes with an outline of a new modelling schema which can provide the much needed link between the real-world practicalities of building planning and the need to determine realistic indicators of building performance at the earliest stages of obtaining planning consent.

Daylight Annual Illuminance Investigation in Elementary School Classrooms for the Tropic of Lhokseumawe, Indonesia

ABSTRACT This study investigated twenty-two (22) state elementary schools, regarding daylight annual illuminance in the classrooms, using climate-based daylight modelling (CBDM) metrics. This is due to the missing information on the annual daylight performance inside the classroom in Indonesia. Over 250 classrooms were assessed using Rhinoceros and Grasshopper computational platforms. Furthermore, Daysim simulation engine was employed through the advantage of Ladybug tools to connect and automate the simulation workflow parametrically. Since there were no prior studies using CBDM metrics for daylight assessment of classrooms in the Indonesian context, the illuminance range from 250 to 750 lux was taken as the target for the annual useful daylight illuminance (UDI), as suggested in the Indonesian daylighting standard. Result shows 35 classrooms under the good daylight performance, 171 classrooms in sufficient category and 50 others under unsatisfactory of annual illuminance. The most sensitive contributors are both corridor and back shading depth with Spearman correlation of -0.70 and -0.76 respectively. The strong sensitive variables both has p-values lower than 0.05 which indicates statistically significant for the model.

Climate-based annual daylight modelling for greenhouses with supplemental electric lighting

Climate-based annual daylight modelling for greenhouses with supplemental electric lighting

Improving the daylighting performance of residential light wells by reflecting and redirecting approaches

The light well is a well-known architectural resource used in dense cities to provide daylight to the core of residential buildings. Due to its elongated shape, the propagation of light through it highly depends on the properties of its surfaces. This study focuses on the improvements in daylighting performance achieved through minor interventions in a conventional light well, namely, changing the surface optical properties and installing mirrors to redirect the sunrays. The performance is evaluated using Climate-Based Daylight Modelling (CBDM). The illuminance threshold is set to 100 lx for residential areas, where a small amount of daylight represents a significant benefit for the inhabitants. The proposed radiosity algorithm allows a precise and fast calculation of the interreflections, which play a crucial role. This study shows that small changes in diffuse reflectance have significant effects on lighting conditions, and that the use of specular surfaces is also improving the results. Solar redirecting devices are particularly efficient for periods and latitudes with low solar paths. They are providing satisfying lighting conditions during the whole year.

THE EFFECTS OF INTERNAL PARTITION ON INDOOR DAYLIGHTING PERFORMANCE OF STUDENT RESIDENTIAL BUILDING IN IPOH, PERAK

The installation of an internal partition has resulted in lowering the illumination level inside a building. Therefore, this study is intended to evaluate the effects of several internal partition layout on indoor daylighting performance in student residential rooms. Several options of internal partition were simulated using Climate Based Daylight Modelling (CBDM) to suggest the effective partition layout to overcome low daylighting level inside the room at the annual level. The findings indicate that the internal partition perpendicular to the window layout has been proven to have the highest annual daylight sufficiency in a student residential room in the tropics.

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.

Evaluation of climate-based daylighting techniques for complex fenestration and shading systems

The latest advancements in glazing technology are driving facade design towards complex and adaptive fenestration systems. Accurate simulation of their optical properties and operational controls for building daylight performance evaluation requires advanced modelling techniques, such as climate-based daylight modelling (CBDM). At the same time, computational efficiency is key to quickly simulate this complex performance over a full year. Over the years, several CBDM techniques were developed to answer these two main challenges, but they were never systematically benchmarked against each other. This paper compares state-of-the-art Radiance-based simulation techniques in terms of annual daylight performance metrics required by national guidelines and international green building rating schemes. The comparison is performed on three different shading systems: diffuse Venetian blinds, specular Venetian blinds, and perforated solar screens. Findings show that simulation methods are characterised by significant differences in their implementation and visual rendering, but most annual daylight metrics result in consistent values (within ± 20%). A notable exception is Annual Sunlight Exposure, which is highly sensitive to the chosen simulation method, with differences of up to 47 percentage points. Additional outcomes from the present work are used to compile a list of generalised recommendations for designers and policy makers.

A circadian design assist tool to evaluate daylight access in buildings for human biological lighting needs

This paper reports on the development of a simulation-based Design Assist Tool capable of assessing the circadian performance of architectural daylighting strategies during the design process. The tool integrates GIS site data, parametric modeling of multi-level building forms and multi-spectral lighting simulation of biological lighting effects into a Climate Based Daylight Modelling (CBDM) workflow capable of automatically performing hourly (or sub-hourly) time-series evaluations over selected days throughout the year. Outputs of the tool can be used to visually and quantitatively assess the extent to which a prospective daylighting design complies with emerging circadian lighting requirements over an annual period using daylight. An example application of the Design Assist Tool is presented to differentiate performance of varying building forms located on an urban site in Downtown Los Angeles.

Photon mapping in image-based visual comfort assessments with BSDF models of high resolution

Data-driven models replicate the irregular Bidirectional Scattering Distribution Functions (BSDFs) of optically Complex Fenestration Systems in daylight simulation. RADIANCE employs the tensor tree to store the BSDF at high directional resolution. Its application in backward ray-tracing is however challenging, since the density of stochastic samples must match the model resolution. BSDF proxy and peak extraction address this problem, but are limited to cases when either the fenestration geometry, or the shape and direction of the transmission peak are known. Photon Mapping is proposed to efficiently sample arbitrary BSDFs from the known sun direction. The existing implementation in RADIANCE is extended to account for light sources and their reflections in the field of view, that are of particular importance for visual comfort assessments. The method achieves a high degree of accordance with ray-tracing, and reduces simulation times by ≈95% with data-driven models of high resolution.Abbreviations: BRT: Backward Ray-Tracing; BSDF: Bidirectional Scattering Distribution Function; CBDM: Climate-Based Daylight Modelling; CFS: Complex Fenestration System; DGI: Daylight Glare Index; DGP: Daylight Glare Probability; FPM: Five Phase Method; GPGPU: General Purpose Graphics Processing Unit; LCP: Laser Cut Panel; OoC: Out-of-Core; PM: Photon Mapping; RMSE: Root Mean Squared Error

Climate-Based Daylight Modelling for compliance verification: Benchmarking multiple state-of-the-art methods

Climate-Based Daylight Modelling (CBDM) gives designers the possibility to evaluate complex, long-term luminous environment dynamics. This complexity can be challenging to simulate, and even more challenging to communicate effectively through the use of performance metrics. A multiplicity of CBDM techniques and metrics has been developed over the last two decades, but these were rarely assessed against each other. This paper reviews four state-of-the-art techniques based on the Radiance raytracing engine and systematically compares them against a benchmark CBDM method. Four classroom spaces are used to carry out an inter-model comparison between performance metrics commonly used for compliance verification obtained from all analysed techniques. Additional sensitivity analyses assessed how changes in input variables influence such metrics.Results from the inter-model comparison showed that the representation of direct sunlight is markedly different between the various CBDM techniques, and that metrics based on horizontal direct sunlight are very sensitive to the choice of simulation method. This led to differences in predicted Annual Sunlight Exposure up to 39 percentage points. Metrics that consider both direct and inter-reflected light were found to be more robust, with variations from benchmark results within ±15%. The analysis of the input variables showed that sensor grid spacing and time-step interpolation do not significantly affect any of these metrics. Changes in orientation and sky discretisation scheme had different effects depending on the metric and technique considered. The need for authoritative benchmarking systems when introducing new performance metrics for compliance verification or new simulation methods is also discussed.

Dynamic evaluation of daylight availability in a highly-dense Chinese residential area with a cold climate

Daylight utilization in urban areas is receiving increasing attention from urban planners and developers, architects and engineers. This study investigated the daylighting availability within buildings of a highly dense residential urban area under a cold climate in north-east China. Based on innovative simulations using climate-based daylight modelling (CBDM), three typical urban layouts have been assessed according to vertical daylight illuminance at the building facade. A comprehensive analysis of daylighting potential has been completed through various approaches including typical time (9 a.m., 12 p.m. and 3 p.m.), yearly average daylight illuminance and a proposed external daylight metric based on the frequency. Several interesting relationships are found between daylighting potential, urban forms, and climate conditions. A number of design strategies and guidelines are produced to support early stage urban planning and design.

Daylighting Metrics: an Approach to Dynamic Cubic Illuminance

Advances in research work in the field of numerical analysis of daylight performance have generated in-depth knowledge on photometric measurements of daylight quality. Most dynamic metrics are based on illuminance, which is a two-dimensional concept insofar as it is concerned with the density of luminous flux incident at a point on a surface. In order to extend dynamic metrics into the third dimension and consider the distribution of illumination at a point in space, it is important to generate new advances in simulation environments and consider spatial illumination metrics. In this context, the main objective of the present work was to advance in the development of cubic dynamic daylight metrics, as a complement to the two dimensional analysis currently employed, promoting the use of Climate Based Daylight Modelling (CBDM). For this purpose, cylindrical to horizontal illuminance ratio is applied to dynamic simulation paradigm developing the concept of useful modeling indexs (UMIs). The research methodology applied in this work is divided into two main parts: (i) two dimensional concept: spatial daylight autonomy (sDA(300lx,50%) -horizontal-, sDA(175lx,50%) -vertical-) and uniformity, and (ii) three dimensional concept: useful cylindrical to horizontal illuminance ratio (uEcl/Eh(0.3-0.6)). In order to assess this method, two spaces (RR1 and RR2) of the Lavalle Public Library, located in Mendoza-Argentina, were taken as a case study. Results show important differences in horizontal illuminance between RR1 and RR2 (∆sDA(300lx, 50%) > 80%). Similar values of uEcl/Ewp(0.3-0.6) -useful cylindrical to horizontal illuminance ratio- are detected in both rooms (RR1= 69.32 % and RR2= 72.24 %) in nodes near north opening. Yet there are significant differences (< 36%) of uEcl/Ewp(0.3-0.6) between nodes located near the south wall, this is due to the obstruction of a south opening in RR2. Furthermore, it is important to mention that 2D metrics display a more uniform behavior than 3D metrics. This shows itself clearly if we take into account that difference in sDA are much lower than difference in uEcl/Eh(0.3-0.6), if we compare nodes closest to the north windows to does that are far from it, in both rooms (RR1 and RR2). This results from the fact that cubic metrics are more sensitive to the direction of light. This is of crucial importance for daylight studies in clear sky condition, due to the defined direction of direct solar radiation. Finally, a new approach to daylighting performance analysis based on the addition of cubic metrics to dynamic daylight paradigm is proposed: useful modelling indexs (UMIs). UMIs make it possible to quantify annual occurrence of proper light modelling conditions. As an initial approach, cylindrical to horizontal illuminance ratio (Ecl/Ewp(0.3-0.6)) has been considered, due to its current use in international standards.

Daylight Performance of Classrooms in a Mediterranean School Heritage Building

In school buildings, natural light has considerable physiological benefits, and increases energy efficiency while reducing the operational energy consumption of buildings. It is thus crucial to maximize the amount of daylight, as well as to improve its quality, in educational premises. In Italy and other European countries, many historic buildings are reused as school buildings, changing their original function. This process of adaptive reusing is one method for conserving heritage buildings, however sometimes this process sacrifices the quality of daylight and well being of pupils. It has therefore become apparent that it is difficult to reconcile the cultural value of historic buildings with comfort standards. This study aimed to investigate the natural lighting performance of a school located in an historic building, and proposes different technological solutions to improve the visual comfort in classrooms whilst also respecting the cultural value of built heritage. Daylight performance was carried out in a representative classroom in the ‘Caserma Gaetano Abela’, an historical building located in Siracusa (Italy). A daylight model built in Radiance was first validated against an illuminance measurement campaign, and was then used to run detailed dynamic simulations. Climate Based Daylight Modelling (CBDM) metrics were used to show the achievable improvements in visual comfort conditions by means of proposed retrofit interventions. These interventions may also be used in other areas of southern Europe with similar climatic and constructive/distributive characteristics of architectural heritage.

Application of Climate Based Daylight Modelling to the Refurbishment of a School Building in Sicily

This paper aims at promoting the use of Climate Based Daylight Modelling (CBDM) and related state-of-the-art metrics by discussing a range of design options to improve daylight fruition in rooms with different orientation, shape, function, and furniture of an elementary school that is located in the Mediterranean climate of Agira (Italy). The local climatic conditions, with clear skies for most of the year, require the integration of different shading and re-directing systems with the existing envelope and rooms’ layout. Results show that the dynamic modelling is a powerful and ‘creative’ tool in the designer’s hands, which helps to inform about the choice of the most appropriate technological solutions and on their architectural integration. Comparison with mostly used static daylight metrics, such as the average Daylight Factor (aDF) and the Uniformity Ratio (UR), reveals a contrast with what would be suggested if considering these metrics alone, as prescribed by the Italian legislation. These outcomes rebate the need of performing more accurate and dynamic daylight simulations using recorded (i.e., varying) rather than fixed sky conditions to correctly inform the design process.

Some simple methods for reducing daylight simulation time

ABSTRACTA significant barrier to routine use of Climate-Based Daylight Modelling in early design is the long time that it takes to run full annual simulations. Quick checks of design ideas are thus inconvenient, which discourages examining large numbers of design options or doing routine sensitivity analysis. Two ways of reducing required simulation time are to not simulate all the daytime hours of the year, or to simulate far fewer grid ‘measurement’ points. This paper demonstrates the effectiveness of taking smaller samples of random days throughout the year to reduce simulation time. By using a selection process to select “representative” samples of hours, simulations using only 5 days/month provide results with <6% error in performance estimates – well within accepted tolerances. The paper also shows the insignificant difference in design information provided by oft-recommended dense sensor grids compared to a 5 × 3 or 10 × 5 grid across a room plan.