Daylight Simulation Research Articles

Building energy optimization in the early design stages: A simplified method

This paper presents the application of multi-objective genetic algorithms for holistic building design that considers multiple criteria; building energy use, capital cost, daylight distribution and thermal indoor environment. The optimization focus is related to building envelope parameters. To obtain relevant feedback from multi-objective optimizations in early design stages, evaluation speed is a key concern. The paper presents a fast evaluation method fit for the early design stages. It uses a combination of two different quasi-steady-state methods for energy and indoor environment evaluations, a Radiance implementation for daylight simulations and a scripted algorithm for capital cost evaluations. The application of the method is developed around an integrated dynamic model which allows visual design feedback from all evaluations to be an integrated part of the design tool experience. It is concluded, that quasi-steady-state methods implemented as part of integrated dynamic models are fast and flexible enough to support building energy-, indoor environment- and cost-optimization the early design stages.

Evaluation of Daylight Availability for Energy Savings

Dynamic daylight simulations are very useful instruments in daylighting design process. They allow an in depth analysis of indoor daylight availability levels and define if they are adequate to perform a particular visual task. Their results can be used to design shading devices or lighting control systems and compare different technical solutions. The use of these simulations is likely to spread in the common design practice since some regulations and green building rating systems suggest their use. This paper presents dynamic daylight simulation results related to an open-plan office, performed with Autodesk 3ds Max Design ® , which is a calculation software validated by recent researches. It is not used in academic context but it is very widespread between technicians for photorenderings production purposes. The goal of this research is to demonstrate the functionality of this software also in dynamic daylight simulations field and propose an analysis' methodology to use it.

Dynamic daylight simulations: Impact of weather file’s choice

This paper is the second step of a research project aimed at investigating the impact of the use of different weather data files on daylight simulations’ results. Simulations were carried out for a simple standalone office using three weather files (IWEC, Meteonorm and Satel-Light) for two European locations (Copenhagen and Rome); moreover the office’s exposure was changed according to the four main orientations (North, East, South and West).Results were analyzed both in terms of Annual and Monthly Light Exposures, dynamic daylight performance metrics (DA, DAcon, UDI) and sunlight’s incidence.It was demonstrated that differences between the results obtained with the different weather files are more significant considering Annual and Monthly Light Exposures (highest value 20%), whereas they decrease when analyzing illuminances with a statistical approach (DA, DAcon, UDI). The analysis of sunlight’s incidence also determined similar results using the three weather data files and the maximum difference is 5% independently from the orientation.

Parametric regression model for lighting calibration

This article aims to assess some of the main lighting software programs currently available for architecture. It compares the daylight simulation results from programs, Flamingo nXt rendering, DIVA and Lightscape with the physical measurements carried out on a flat plate surface and in a model box. Identical parameters of geometry and lighting conditions were set. Two strategies were used to investigate the difference and correlation between the measurements and simulations. One test simulated several angles which were identical to the real-time sun position during daytime by rotating the box for both the simulation and field test, and the other test conducted every hour during daytime simulated three typical days (spring equinox, summer solstice and winter solstice). The output from simulation programs was conducted on a set grid of identical surface locations. The simulation programs and physical measurements were used to generate a parametric model. The results suggested that the accuracy of all these inspected simulation programs was acceptable for design exploration and that the parametric model could be used to calibrate the programs to give more accurate, real-time illuminance and luminance.

Analysis of Prediction Accuracy for Annual Daylight Simulation Methods

Analysis of Prediction Accuracy for Annual Daylight Simulation Methods

Sustainable Design of Buildings using Semantic BIM and Semantic Web Services

In response to the growing concerns about climate change and the environment, sustainable design of buildings is increasingly demanded by building owners and users. However, fast evaluation of various design options and identification of the optimized design requires application of design analysis tools such as energy modeling, daylight simulations, and natural ventilation analysis software. Energy analysis requires access to distributed sources of information such as building element material properties provided by designers, mechanical equipment information provided by equipment manufacturers, weather data provided by weather reporting agencies, and energy cost data from energy providers. Gathering energy related information from different sources and inputting the information to an energy analysis application is a time consuming process. This causes delays and increases the time for comparing different design alternatives. This paper discusses how Semantic Web technology can facilitate information collection from several sources for energy analysis. Semantic Web enables sharing, accessing, and combining information over the Internet in a machine process-able format. This would free building designers to concentrate on building design optimization rather than spending time on data preparation and manual entry into energy analysis applications.

A comparison of scale-model photometry and computer simulation in day-lit spaces using a normalized daylight performance index

A process to compare results of building daylighting computer simulations to the results obtained using scale-model photometry under real skies is outlined. The process uses the illuminance values in a subject space under study and normalizes the values with those obtained in a space considered to be the base case. The normalized factor is termed Normalized Daylight Performance Index (NDI). An example on how this can be done is applied to an open plan office space with two different furniture layouts. Sources of experimental errors are outlined. NDI was found to be a viable metric for comparing daylighting simulations with scale-model photometry.

Comparative Analysis of Prediction Accuracy from Daylighting Simulation Tools

ABSTRACTIn this article, a validation analysis of predictions from selected daylighting simulation capabilities is presented. The daylighting simulation tools considered in the study include EnergyPlus Detailed, EnergyPlus DELight, DAYSIM, and SPOT (Sensor Placement and Orientation Tool). The National Research Council of Canada provided detailed site and sensor data for an experiment recording daylight exposure throughout a side-lit private office space using various daylighting strategies. The site information provided included geometry of the space and daylighting test cases through detailed SketchUp models. Reflectivity and transmittance properties of experiment surfaces and windows were well documented to enable accurate replication in daylighting models. On-site weather data were also collected to allow the test environment to be repeated. Illuminance measurements at 5-min intervals at 12 sensor locations within the space allowed computer simulations to be thoroughly tested. The three daylighting test cases chosen for the validation study, no daylighting device, interior light shelf, and exterior horizontal blinds, were selected to test each software’s ability to model direct sunlight, interior obstructions, and exterior reflections. Through graphical observation and statistical measures DAYSIM was determined to be the most accurate overall. However, it is important for users to consider the intended application of the daylighting software selected. Depending on the daylighting conditions, facade construction, and sensor location, other software performed equally well. Each of the studied software also has other features such as photosensor modeling, integration with thermal simulations, and occupancy predictive models that must be weighted when selecting the appropriate daylighting software for your application.

The role of weather data files in Climate-based Daylight Modeling

This paper illustrates the results of daylight simulations of a simple standalone office carried out using different weather data files (IWEC, Meteonorm, Satel-Light and TRY), for five European locations (Copenhagen, London, Milan, Nancy, Rome).The aim was to analyze the impact of choosing one weather file or another on the prediction of daylight availability in an indoor environment. Results were analyzed both in terms of Annual and Monthly Light Exposures and dynamic daylight performance metrics.It was demonstrated that IWEC, Meteonorm and Satel-Light weather files determine similar outcomes, instead TRY weather data always produces considerably lower values. Moreover the differences between the results obtained with the different weather files appear more significant considering Annual and Monthly Light Exposures, whereas they decrease when analyzing illuminances with a statistical approach (DA, DAcon, UDI).

An HDRi-based data acquisition system for the exterior luminous environment in the daylight simulation model

This paper proposes an HDRi-based data acquisition system to improve the quality of the Sky Component (SC) and the Exterior Reflected Component (ERC) in the daylight simulation model. The proposed system consists of an HDRi device equipped with shadow ring for high-frequency sky luminance capture and the HDRi-based gray card referencing procedure to measure the reflectances of surrounding structures. This system can provide timely updates of the exterior luminous environment for model-based real-time daylight control. Physical experiments with a test chamber were conducted to evaluate the performance of the prototypical system. In the experiments, HDRi techniques were applied to capture luminance distributions of the sky, window view and interior surfaces. Simulations of the indoor luminance distributions of the test chamber were conducted under two sets of daylight descriptions. The first simulation, derived from the concept of highly accurate image-based rendering, uses the HDRi daylight scene of the window view. The second simulation, the proposed method, uses a combination of the Tregenza sky derived from HDRi sky view and the model of the surrounding structures. Comparisons were made between both sets of simulations and the measured interior luminance levels. The RMSE and MBE were calculated using cells from the sub-divisions of the interior surface. The statistical analysis demonstrates that the proposed system in continuous operation can achieve a level of accuracy comparable to that of the image-based daylighting description from the window view.

The development of visible sky area as an alternative daylight assessment method for high-rise buildings in high-density urban environments

This research aims to develop a new daylight assessment method for high-rise residential buildings located in high-density urban environments. The new visible sky area (VSA) method was developed based on data gathered from an extensive survey of high-rise residential building plans and layouts in Hong Kong and followed by a large number of daylight simulation experiments. The results of simulations showed a very small daylight quantity arriving at windowpane of lower floor level of high-rise residential buildings due to high-obstruction from nearby buildings and also self-obstruction. The new method would guarantee the availability of sky area seen from windowpane in order to provide a good vertical daylight factor (VDF), which has been adopted as a performance-based daylight indicator in Hong Kong. A minimum VSA of 12% and 6% for habitable rooms and kitchens, respectively, is proposed for this situation.

Evaluation of Illuminance of Rooms Oriented to Different Cardinal Points

Daylighting levels in interiors are changed every day since sunrise to sunset in dependence on luminous exterior conditions. Indoors are illuminated by diffuse skylight prevailing time of the year in Central European counties while a lot of sunny situations occur mainly during transitional and summer periods. The later can produce overheating as well as glare or disturbing luminance due to excessive sunlight in the space close to windows. If interiors are designed with screened work places the influence of direct sunlight during working time has to be evaluated.The article will present results of computer daylight simulations in a side-lit office room oriented to cardinal points. The study is focused on daylighting evaluation of the room orientation influence on levels under clear sky conditions and compared with results achieved for the CIE overcast sky model. The calculations were run in software Daylight Visualizer 2.6.7. The daylight simulation show that applying the clear sky model for illumination of oriented rooms, the substantial different illuminances can be resulted compared to outputs from the common overcast sky daylight metrics.

일조환경을 고려한 가구형(街區型) 집합주택의 형태 구성 방법론 연구

Perimeter block housing has been implemented in various new town development in Korea since 2000 as an alternative urban housing type as verse to high-rise development mostly common in urban residential areas. Perimeter blocks are relatively new built forms in Korea and considered more inferior in natural daylighting to free-standing buildings. Natural light is one of the most important amenities to insure inhabitable residential spaces, and perimeter block housing has to be carefully designed in consideration of natural daylighting. The objective of this research is to develop a design methodology of Perimeter block housing with the optimization of natural daylighting satisfying Rights to light. The case of Eunpyung Newtown is analyzed extensively in order to define the principles of solar shading and daylighting in Seoul. The result shows that the minimum distances between perimeter block housing, south-north=1.8h, east-west=0.7h, need to be satisfied in order to meet minium two hours of daylighting for the livingroom windows facing south or east. In addition, The minium distance between the buildings at each <TEX>$15^{\circ}$</TEX> azimuth angle is calculated based on the daylighting simulation. Azimuth angle <TEX>$45^{\circ}$</TEX>, <TEX>$60^{\circ}$</TEX>, <TEX>$-30^{\circ}$</TEX>, and <TEX>$-45^{\circ}$</TEX> are turned out to be the optimum azimuth angle. The design explorations are implemented to the preliminary massing of perimeter block housing using the principles of south-north=1.8h for closed blocks and the principles of minium distances between the buildings at various azimuth angle for open blocks with tower. The simulations are verified that the design alternatives meet the standard of Rights to light and the high Floor Area Ratio(FAR).

Energy Saving Effects of Sidelighting Strategy

In a daylighted space, windows can introduce considerable heat gain and loss that may offset the benefits of electric light savings and cause an increase in yearly net energy use. The use of shading devices is necessary to prevent overheating and provide a glare-free visual environment. The common shading devices that have been in use in buildings are exterior overhangs, interior blinds and roller shades. This study examines the impacts of an exterior louvered overhang, translucent roller shade, and blinds on the total yearly energy loads for a prototypical classroom space situated in Boulder, Colorado. Coordinated modeling, with an advanced daylight and electric lighting simulation program and a building thermal simulation program based on hourly weather data, was used to compute total yearly building energy use. Annual lighting, cooling and heating loads for a side-lit space using these shading devices were compared with those of a base case with no shading device. It was found that the total energy performance of the roller shade with a total transmittance of 10.4% was similar to blinds tilted 45o with 60% reflectance. The roller shade consumed 12.5% more total building energy than exterior 1.2m overhang.

Predicting the hourly Hong Kong representative sky from Typical Meteorological Year data for dynamic daylighting simulation

This paper proposes a method to predict the hourly Hong Kong representative sky from Typical Meteorological Year data. An evaluation of the sensitivity of the vertical sky component demonstrates that the Hong Kong representative sky can provide better results than the Perez all-weather sky model. Error reductions of 9–23% can be expected in the four cardinal directions. To predict the Hong Kong representative sky from the Typical Meteorological Year data, a clear sky index can be derived from global horizontal irradiance. Three Hong Kong representative skies can be classified by the clear sky index corresponding to skies 1, 8 and 13 of the Hong Kong representative sky, respectively. The predicted hourly Hong Kong representative sky can provide the sky luminance data for the dynamic simulation of buildings.

Building Information Modeling (BIM)-based daylighting simulation and analysis

Daylighting is an important aspect in designing high performance buildings. Many simulation tools have been developed to study the daylighting performance of buildings. These tools primarily use CAD environments for creating architectural models, which are then converted into daylighting models to run on the daylighting simulation engines. Once the architect defines the architectural model in CAD, a simulation expert creates the simulation input file to perform daylighting analysis. Each tool has its own rules that the architect and the engineer have to follow to prepare the simulation input files, and the complexity depends on the tools. Currently, Building Information Modeling (BIM) is widely used in the AECO industries and BIM models are used as a means of exchanging data among different professionals involved in the design and construction of buildings. The present paper discusses the use of BIM for building performance simulations and mainly focuses on how daylighting analysis can be incorporated into a BIM environment, and what challenges and benefits exist in the process of integrating BIM with daylighting simulation tools. The paper presents the development and validation of a prototype to integrate the BIM tool, Revit with the daylighting simulation tools, Radiance and DAYSIM.

Daylight evaluation for educational facilities established in high-rise housing complexes in Daegu, South Korea

This study conducted a daylight evaluation of schools established in high-rise housing complexes in a Korean city. This was accomplished through a daylight simulation test and a questionnaire survey on students' perception of and satisfaction with daylight in their classrooms. The simulation test showed that the amount of daylight to which a school was exposed could be affected by the surrounding high-rise housing complex, and that the distance between the complex and the school had an influence on the amount of daylight seen in classrooms. When the total daylight hours numbered less than four, or when the number of continuous daylight hours was less than two, students' satisfaction with daylight was low. According to survey results, most students felt that daylight had an influence on their educational environment and learning performance. It is therefore deemed necessary to fully consider the surroundings when designing education facilities.

Experimental and simulating examination of computer tools, Radlink and DOE2, for daylighting and energy simulation with venetian blinds

Venetian blinds are widely used to properly adjust the amount of incoming daylight for energy savings in lighting and cooling and to deal with glare for visual comfort. Two computer tools, Radlink in Adeline and DOE2, have been popularly used for long-term daylighting simulation with venetian blinds because they are computationally efficient and relatively convenient for use. Unlike Radiance, DOE2 and Radlink simplify the simulation by adopting some assumptions for high computational efficiency. However, the two tools and the assumptions adopted by them for the simulation of venetian blinds have not been fully validated until now. Therefore, indoor illuminances with and without venetian blinds were measured in a full-scale classroom under variant sky conditions, and were used to examine them. Experimental and simulated results show that without blinds, both DOE2 and Adeline with Radiance can accurately predict indoor daylight distribution, except that DOE2 gives relatively large errors near and far away from windows. With blinds, the root mean square error (RMSE) between the measured illuminances and those computed by Radlink and DOE2 are 80% and 48% under overcast sky, respectively, and 68% and 75% under clear sky. Analysis of the results shows that it is the assumptions used in Radlink and DOE2 that result in large simulation errors and unrealistic indoor illuminance distribution. It also reveals that any assumption that does not take into account the different features of daylight passing through blinds in their optical transfer process could result in significant computation errors.

Evolution of CODYRUN from Thermal Simulation to Coupled Thermal and Daylight Simulation Software

CODYRUN is a multi-zone software integrating thermal building simulation, airflow, and pollutant transfer. Described in numerous publications, this software was originally used for the passive design of buildings, both for research and teaching purposes. In this context, the data treated were mainly concerned with volumes (zones), surfaces and thicknesses (walls and windows), materials, and systems, with the aim to determine temperatures, heat fluxes, energy consumed, air transfers, and so on.The question thus arose as to the integration of indoor lighting conditions into the simulation. Hence, previous data structures had to be amended to incorporate the spatial positioning of entities (walls, windows, and artificial lighting sources) through vertexes. A set of procedures was also developed for polygons as well as calculating natural and artificial lighting.The results of this new daylighting module were then compared with other results of simulation codes and experimental cases both in artificial and natural environments. Excellent agreements were obtained, such as the values for luminous efficiencies in a tropical and humid climate.A simulation exercise was conducted in a classroom located in Reunion Island (French overseas territory in the Indian Ocean), thus confirming the interest for thermal and daylighting designs in low-energy buildings.

Indoor daylight simulation performed on automatically generated as-built 3D models

Daylighting has an important influence in two of the main consumption sources of a building: whereas solar gain makes a great influence on the consumption of the heating and cooling systems, solar illuminance can reduce the use of artificial light and its electrical equipment. Whatever the final objective, lighting analysis of indoor rooms implies the knowledge not only of its location and orientation toward the North, but also of the location, dimensions and geometry of its main entrances of natural light, commonly windows and glass exterior doors. In this paper, as-built 3D models are proposed for their use as input in lightning analysis given their adequacy for providing information about the geometry and the semantics of the building. Furthermore, a methodology for their generation is presented, taking as a basis the geometric information of the reality of the building, acquired only with a laser scanning device.