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.
Daylighting design has become prevalent in modern buildings in the effort to create a more sustainable living environment. Past and recent bodies of research emerged are mainly focused on the ...different methods of predicting and measuring daylight level and various range of daylighting technologies available. Despite a wide range of developed and commercially available daylighting systems have been reported, their applications have been limited by a lack of studies on their utilisations and high initial costs. Computer simulations have been frequently used in the past to investigate daylighting performance due to reliable and accurate predictions. However, additional simulation time and variable level of skills and knowledge required are major drawback of computer simulations. This paper includes and pools information on all major daylighting design topic in the built environment. The study critically reviews and compares daylighting design principles, strengths and weaknesses of different range of daylighting systems and calculation methods, such as, scale model with artificial sky, full scale model for field measurement, numerical modelling and manual calculation procedures with the aid of diagrams or tables. Such information could be of useful for engineers, researchers and designers to assess the suitability of applying these systems and technologies in different building types and examine the potential of energy and cost savings.
The usual method for computing natural illuminance for a given location in a building is the daylight factor (DF) approach, which is based on the traditional overcast sky without sunlight, as defined ...by the International Commission on Illumination (CIE). In 2003, the CIE adopted a range of 15 skies as international standard models that represent the actual skies of many places and cover the whole probable spectrum of skies found in nature. Previously, we developed a number of calculation tools to predict daylight illuminance for rooms facing different orientations under various CIE Standard skies. This paper presents the work on the calculation of the point DF (PDF), average DF (ADF) and vertical DF (VDF) under various overcast and non-overcast skies. The strong correlations between these three DF types can help to estimate the required DF values for architectural and daylighting designs and evaluations.
Daylighting is recognized as an important element in architecture and a useful strategy in energy-efficient building designs. Daylight gives a sense of cheeriness and brightness that can have a ...significant positive impact on the people. There is a scope for integrating daylight with electric light to reduce building energy use. The amount of daylight entering a building is mainly through window openings, which create in the indoor environment a more attractive and pleasing atmosphere, in addition to maximise visual access to the pleasant views of the outside world. Determinations of the exterior and interior daylight and lighting energy savings are key issues to demonstrate the benefits based on daylighting designs. This paper provides a review of daylight illuminance determinations and the lighting energy reductions due to daylighting schemes. The study includes daylight measurements, prediction of daylight illuminance under various sky conditions and potential electric lighting energy savings from daylight-linked lighting controls. The article aims at providing building professionals, practitioners and researchers more information and a better understanding of daylight for promoting effective daylighting designs and evaluations.
•Two procedures are proposed to define the daylight factors in courtyards.•Calculation of the sky component is obtained for three points inside a courtyard.•The reflected component is obtained ...following the results of the procedures.•The method is contrasted with the procedures proposed and its accuracy confirmed.•The energy saving is quantified according to the method proposed.
The proper design of courtyards and atriums is key in providing sufficient daylight inside buildings as well as major energy savings in electric lighting. Although a suitable design requires calculations using lighting simulation software or complex algorithms, architects lack a quick and precise procedure to determine proper design. The aim of this research is therefore to offer a fast accurate method for determining the daylight factor for different points on a rectangular courtyard or the central space of an atrium, based on the variable geometry and reflectance of the inner surfaces. Firstly, daylight factors are defined using measurements in scale models in an artificial sky and values obtained in real courtyards under real overcast skies. The sky component is subsequently defined based on earlier studies and Tregenza algorithms in order to quantify the reflected component. Following the curve fitting process, a predictive method of daylight factors is defined and compared with the previous measures. The comparison demonstrates that the predictive method offers an average accuracy of over 90% based on a quick and easy calculation. Finally, the energy saving in electric lighting is quantified following the predictive method established.
•Incidence of windows design on energy and visual comfort is studied under climate change.•The case study is an office building located in representative European climates.•Triple low-emissive ...windows, in oceanic and continental climates achieves energy saving of −35 %.•Double selective windows assures savings from −27 % to −57 % in the warm and oceanic climate.•The primary energy will increase until 27 % in for warn climates considering the 2080 scenario.
The design of the glazed elements of the building envelope is a critical issue for both new and refurbished building when the effect of climate changes and expected overheating conditions are considered. Indeed, the windows affect the building energy balance and also the natural lighting that impacts both on visual comfort and illuminance consumptions. This paper develops a methodological approach for performing a parametric analysis aimed at quantifying the effects of different window’s designs on the total primary energy and visual comfort of an office in the most representative European climatic zones. The considered parameters are: windows’ orientation, window to wall ratio, glass and frame type and the installation of shading system. A new approach for evaluating the resilience of the optimal solution selected for the current climates is introduced by taking into account medium and long-term emissions scenarios. This analysis suggests that in the warm-summer humid continental climate, a double selective window may be resilient. Indeed, in the worst emission scenario, the achievable annual energy saving will be around −26 % if compared with a clear double window. Meanwhile it will be lower than −10 % if compared with the same optimal solution but simulated in the short-term emission scenario. For the humid subtropical climates and hot-summer Mediterranean climates, the scientific community should be focused the development of new solutions because also a dynamic system as the electrochromic one, is not able to guaranteed energy saving in the future scenario. Indeed, also the optimal configuration selected under the current conditions would be characterized by higher primary energy request (between 16 % and 27 %) under the future emissions scenarios.
•We introduce BIM into building design methods.•We combine BIM and PSO together to get optimal design by their interaction.•Efficiency and effectiveness of the design method are largely ...improved.•Searching space of designs is enlarged by this proposed model.
Environmental problems, especially climate change, have become a serious global issue waiting for people to solve. In the construction industry, the concept of sustainable building is developing to reduce greenhouse gas emissions. In this study, a building information modeling (BIM) based building design optimization method is proposed to facilitate designers to optimize their designs and improve buildings’ sustainability. A revised particle swarm optimization (PSO) algorithm is applied to search for the trade-off between life cycle costs (LCC) and life cycle carbon emissions (LCCE) of building designs. In order to validate the effectiveness and efficiency of this method, a case study of an office building is conducted in Hong Kong. The result of the case study shows that this method can enlarge the searching space for optimal design solutions and shorten the processing time for optimal design results, which is really helpful for designers to deliver an economic and environmental-friendly design scheme.
Nowadays building performance optimization is extended to urban planning Multi-Objective Optimization (MOO). Most research focuses on the optimization of energy use and daylight performance of ...building design. Buildings optimized for performance metrics rarely consider different performances together. Without integrating different building performance areas, the solution found from optimization will not be a balanced or trade-off one. This paper proposes a method to extend the use of optimization to cover multi-discipline areas that optimize visual comfort and outdoor thermal performances on the layout of high-rise residential buildings.
Daylight, sunlight hours, the sky view, and outdoor thermal comfort were the performance objectives. A parametric building model was built to control the buildings’ layout and simulation tools were used to find the performance of objectives. To accelerate the simulation process, an Artificial Neural Network (ANN) was applied to the building simulation models to calculate the performance results rapidly.
ANN model had an average accuracy of 89.9% across all outcomes. The MOO method was conducted to find integrated solutions to the building layouts on site. By ranking the optimized solutions based on five combined performance targets, the top 10 out of 150 building layout options were identified, indicating an almost 21% better performance than the baseline case.
Moreover, the top 30 out of 150 optimum cases performed better than the baseline. The study demonstrates that the proposed MOO method that combines visual comfort and outdoor thermal measurements can improve and contribute to a sustainable building layout design.
•Evaluate indoor and outdoor built environment performances on the layout of high-rise residential buildings.•Artificial Neural Network (ANN) was applied into the building simulation models for reducing running multi simulation.•Parametric building model was established to show how the design layout can be altered to improve performance.•Multi-Objective Optimization (MOO) was conducted to find solutions of layout of high-rise residential buildings.•The optimized solutions shows that the top 10 building layouts were almost 21% better performance than the baseline case.
The Semitransparent Photovoltaic (STPV) module could replace the glazing materials of the skylight in residential buildings, which minimizes the energy consumption in artificial lighting, heating, ...and cooling load of the building. In this study, the electrical, thermal and daylight performance of STPV skylights are investigated for actual outdoor environmental condition by installing it on the rooftop window of the experimental room at Kovilpatti (9°10′0″N, 77°52′0″E), Tamilnadu, India. The STPV modules are specially designed and fabricated for the skylight with specific PV cell coverage ratio (PVCCR) values are 0.62, 0.72, and 0.85. The various parameters are analysed such as power generation, electrical efficiency, module surface temperatures, solar heat gain, and reduction in cooling load, illuminance, daylight factor and CO2 mitigation by the STPV skylights. It is revealed that the maximum daylight factor of 4% and indoor illuminance of 850 lux is obtained in 0.62 PVCCR and reduction in cooling load due to the installation of PV skylight is calculated as 248 kWh/year during summer. On observation, it is found that the overall maximum energy saving potential is 450 kWh/year for 0.72 PVCCR, and its unit cost of the power generation is estimated as 0.0354 $/kWh.
•STPV skylights with specific PV cell coverage ratio (0.62, 0.72 and 0.85) is investigated.•The effect of STPV skylight in building is compared with clear glass window.•The optimum PVCCR ratio of daylight and reduction in cooling load is 0.72.•The energy metrics and economic analysis of the STPV skylights are investigated.
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