Papers by Keyword: Daylighting

Abstract: Daylight in buildings can be evaluated using dynamic and static daylight metrics. The daylight factor is a static daylight metric which evaluates daylight conditions under the overcast sky model according to the International Commission on Illumination. However, the dynamic daylight metrics (e.g. daylight autonomy, spatial daylight autonomy, useful daylight illuminance) can be more complex evaluation criteria because they are based on annual daylight illuminance data for a building site. While the daylight factor value depends only on a room geometry, optical properties of surfaces and positioning of daylight obstructions, the dynamic daylight metrics also include an effect of a building location, window orientation or building occupancy pattern. The article deals with a comparison of a daylight evaluation using dynamic and static daylight metrics in the case of buildings whose daylight is obstructed by external barriers.

Abstract: Daylight in nature is characterized by daily permanent changes of sunlight and skylight. Real measurements of daylight availability are showing that different daylight exterior illuminance for building interiors can be expected each minute. This brings some complications in the window design and the choice of criteria for daylight evaluations. There are several ways how to find basic conditions and typical relations combining sunlight beam with diffuse skylight from the whole sky vault. The older assumption considered that interiors have to be sufficiently illuminated under the worst overcast conditions. The newer approach is based on the utilization of daylight in specific localities and the determination of changes in sunlight and skylight occurrence probability. Therefore, both daylight sources are researched in detail specifying sky luminance distributions and sun influences to find conditions for their simulation in laboratory facilities. The most sophisticated equipment to study daylighting in exterior and interior architectural spaces are artificial skies with the artificial sun. These have to be precisely calibrated with a verified zenith luminance and horizontal illuminance levels by theoretical calculations and checked by experimental measurements. Reference daylight conditions defined in the ISO/CIE 15469:2004 standard have to be respected with trials to determine natural sun and sky as sources of daylight in the real environment and modelling these in the artificial sky in a certain intensity scale. This paper presents the method and results of modelling daylight applying electrical light sources in artificial sky which is installed in the Institute of Construction and Architecture, Slovak Academy of Sciences (ICA SAS) and discusses possibilities of their simulation in laboratory conditions.

Abstract: The subject of this article takes benefit from advanced shading technology thought the integration of anidolic collector at clerestory window of building for achieving increment of daylight flux entering into the rear area of the room. This technology is likely to investigate the influence of clerestory aperture on the performance of daylighting collector in term of the interior daylight illuminance distribution by using the lighting tool AGi32. The empirical correlations from the use of anidolic configurations for tropical sky are proposed with high confidence interval (>85%).

Abstract: Daylighting simulation programs use different methods and algorithms for illuminance calculations in buildings. It is widely known that results of different lighting simulation programs does not have to be the same for two or more identical rooms. Hence CIE issued Technical Report 171: 2006 which presents test cases to assess the accuracy of lighting computer programs. However, these test cases are simple and the accuracy of daylighting computer programs can be different for more complex cases. The purpose of this paper is a comparison of differences in the results computed by various daylighting simulation programs for selected test cases according to CIE 171: 2006 and for more complex cases.

Abstract: Lighting conditions in buildings are verified by experts on a daily basis. Such verifications may be done at several phases in various ways. In the field of daylighting, it is common to make an assessment within the pre-design and in-design phases of a construction work throughout calculations, only rarely by measurements. This approach is the opposite of artificial lighting design, which is done within the in-design phase by calculations and is verified by measurements in post-realization phase. The verification of artificial lighting design is required by the building and public health authority otherwise buildings cannot be approved to use. In the field of daylighting, measurements could be performed as well, nevertheless those are often problematic because regulations usually require fulfilments of the daylight factor which can be determined only under CIE overcast sky. Howbeit, both artificial lighting and daylighting measurements are influenced by many errors, e.g. errors of light measurement instruments, measurement conditions, measurement methods and human factor. The paper is focused on this aspect of lighting design, more specifically on the daylighting measurement errors.

Abstract: To compute energy demand based on the reference years hourly averages of external variables are often generated in the smooth form. On the other hand, daylight should be evaluated in a shorter interval because human eyes perceive light in the moment of its occurrence. This study shows alternative to the description of annual daylight conditions based on statistic characteristics mean and median to create Daylight Standard Reference Year for Bratislava. Both methods are presented as contribution to the development of daylighting engineering. Authors are interested in lighting engineering to ensure satisfactory luminous environment at workplaces and in buildings for housing and recreation. Good daylighting in interiors is also related to the reduction of electricity consumption for lighting. This paper presents method for generation of daylight standard reference year DSRY based on one minute data measured at CIE IDMP stations. This reference year can be applied for evaluation of daylighting in the specific locality.

Abstract: Daylighting strategies and control of it, plays a significant role in energy efficiency and provision of visual comforts in buildings. This study conducted a review of literature and observation in a hot and dry region of Iran in order to investigate daylighting strategies and control of it by shading devices in the vernacular residential buildings. The results show thatdaylight in vernacular rooms was provided through door, window, Rozan, Moshabak, and Goljam. These components were equipped with thevertical and horizontalshading devices such as Orsi, Sarsayeh, Tabeshband and Kharakpoushto control the sunlight. The vernacular lighting strategy was in response to the energy efficiency and provided visual comfort.The vernacular concepts and schemes still can be adopted and reused by architects and developers. The study recommends appropriate daylight schemes and shading devices in design phase to achieve energy efficiency in new residential buildings.

Abstract: Skylight roofing construction isa practical complement to electric lighting even in various climatic conditions. However, a purely energy efficient building that ignores what the environment can contribute, particularly in tropical regions, will consume more energy. This problem can be found in landed houses specifically in Malaysia due to high impact of solar radiation and the length of the daylight period all year round. The lack of understanding the potential of skylight design is one of the main challenges. This paper aims to examine several passive glazing materials in the form of glass and plastic as well as dimensions and orientations under the Malaysian environmental conditions to determine the efficiency of this skylight construction design. The study was carried out by computer simulation to specify the thermal and daylighting loads in a specific room size. The resultsshow the significance of polycarbonate glazing as an efficient skylight material in the tropical houses. This materialdelivers well distributed natural light with less heat impact. This study provides useful quantitative and qualitative information for building professionals and architects in the tropics.

Abstract: Energy savings led to design requirements for buildings with thermally insulated envelopes. Window glazing with better thermal insulation properties have in many cases reduced transmittance of solar radiation. They decrease solar thermal gains and daylight level in buildings. A study of influence of selected windows on solar gains and daylighting in a reference room is presented in the paper.

Abstract: The study capability of pupils depends on many factors. One of the factors is the level and the quality of daylighting in classrooms. The daylighting quality is particularly important for very young pupils in primary schools and nurseries. This article deals with natural light in classrooms with different school equipment and furniture and various parameters of window constructions.