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Abstract Together with the evolution of the daylight introduction into building facade systems, energy consumption assessment becomes more and more crucial to evaluate the synthetic performance. Traditional method for evaluating the shading effect was not sufficient to consider the dynamic lighting and energy performance of window configurations due to the varying sun position. In this paper, the field measurements combined with lighting and energy simulations were carried out to explore the optimization of window configurations and characteristics. The shading factors for complex configurations were inspected by field measurements conducted within a lighting sphere, as well as a scaled physical model. It resulted that the complex configurations provided higher energy performance and enough light transmission. Furthermore a new method which integrated the shading factor and solar heat gain coefficient was proposed to investigate the dynamic shading effect of different window configurations. The following energy analysis on a full size building was conducted in e-Quest for energy consumption evaluation. It predicted the considerable potential energy conservation for windows with dynamic solar heat gain coefficient, which encourages the architects to introduce the novel independent design proposal for windows.

Abstract In building integrated photovoltaic (BIPV) systems, PV elements are integrated along with the building which often serves as the exterior weathering skin. PV researchers from various countries have been working for several years to optimize these systems. Sustainable BIPV system has many benefits such as the building itself becomes the PV support structure, and the BIPV components displace the conventional building materials and labor cost, thereby reducing the net installed cost of the PV system and building construction. It also provides on-site generation of electricity and architectural elegance, which increases the market acceptance of the buildings. The BIPV systems can be interfaced with the available utility grid or used as off-grid systems. This paper identifies sustainable building concept in South Asian countries and role of BIPV applications in sustainable building. This article gives review of BIPV applications in South Asian countries. Finally, Barrier and challenges of BIPV system have been discussed and future direction is highlighted.

Abstract Buildings often have fixed function spaces that are complimentary or incompatible with thermal comfort (18–28 °C). Synergetic relationships ameliorates energy shortage and affords comfort. Galvanized iron roof two-storey houses of North-East India were studied to develop a theory-and-strategy to optimize design process and energy conservation. Methods include affordance theory criticism, surveys, simulations, synergy analysis. Parametric strategy on passive design affordances examines human comfort and temperature on diurnal time scales: Daytime (08–17 h), Evening (17–22 h), Night (22–08 h) in various seasons. Under flexible ventilation, living-dining space (S1) shows optimum temperature ranges: 20–28 °C in autumn (M1), 17–22 °C in winter (M2), and 20–31 °C in summer (M3) due to the complementary combination of passive design elements and can function as bedroom, living-room, kitchen, and social space in most seasons. In the attic-space flexible ventilation shows peak temperatures of 42 °C (autumn) and 48 °C (summer) due to low thermal mass but high thermal conductivity envelopes, and low air-changes rate (0.5 ACR) above 28 °C. Normal ventilations with 30 ACR in autumn, and a combination of 30 ACR (night) and 0.5 ACR (day) in summer reduced maximum temperature to ≤35 °C in autumn, and ≤41 °C in summer. Attic-space (S2) shows ≤29 °C in winter daytime and ≥20 °C in summer nights due to the envelope’s high heat emissivity (0.8) and function as day space in winter and summer bedroom. Shaded veranda (S3) shows low temperature (18–28 °C) in summer evening and afternoon and can function as shaded space for light work and enjoying fresh air. Passive design connotes responsiveness of spaces to the climate, and affordance theory’s complementarity lifestyle adds novelty, and it is critical to energy and space efficiency. Climate analysis affords perceptions of space and climate relationship. Parametric strategy straddles differences between space, climate, and functions to ameliorate energy needs and optimize design process.

Abstract This study analyzes the PV potential on rooftops and vertical facades in the research area of West Central District of Tainan City, a rich insolation area in Taiwan. By using the energy calculating software EnergyPlus and the grid-based computational fluid dynamics (CFD) software Windperfect, the electrical energy generated by PV modules on vertical walls from eight directions in both shading-covered areas and non-shading-covered areas was simulated and calculated. Three databases – the database of the electrical energy generated by building facades, of spatial information, and of shadow coverage – are established to estimate the potential electrical energy. The covered-shading condition was simulated by sunshine trajectory method, and the insolation potential of building surface was evaluated by analyzing the accumulating insolation hours and the spatial location data. It was observed that shading affects vertical facades more significantly. The average electricity generation of per unit area on rooftops demonstrates that the electrical energy in summer is twice as much as that in winter. Although the electrical energy generated by that of per unit area on vertical facades is higher in winter, it is only 1.1 times greater than that in summer. If the amount of electrical energy generated is taken into consideration, the installation area for the southwest walls should be 1.5 times larger than that of the rooftops so that the same amount of electrical energy can be generated. When considering the installation of PV panels in the research area of this study and other geographically similar locations, the priority should be the rooftops, followed by southeast-, southwest-, and south-facing vertical facades.

Abstract In the severe cold zones of China, solar radiation is one of the most important issues in architectural design. The design seeks to make buildings receive more direct sunlight within the limits of the user’s comfort and simultaneously save energy and space. So far in China, the design of solar radiation has usually been qualitative, not quantitative, and it is often implemented by architects with experience or those following convention. This rough and rigid design approach is not accurate or efficient, particularly in the design of free-form buildings, which comprise a class of irregular-form buildings popular in current architectural design. Moreover, solar radiation is not the only thing that needs to be considered; shape coefficient and space efficiency should also be considered in free-form building design. This study proposes a method for a free-form building that receives more solar radiation though shape optimization and takes into account the other two objectives mentioned above. This paper provides a method with a “Modeling–Simulation–Optimization” framework. In the process of applying this method, parametric modeling with Rhinoceros and Grasshopper is used to build up the free-form building model, and the shape optimization of the building is processed by using the multi-objective genetic algorithm to make sure the three objectives—i.e., to maximize solar radiation gain, to maximize space efficiency, and to minimize the shape coefficient—are all achieved. Finally, a Pareto frontier is generated to show the optimal solutions and to assist designers in making final decisions. The case study shows that compared with the cube-shaped reference building, the total solar radiation gain of the optimized free-form shape building is 30–53% higher, and the shape coefficient value is reduced by 15–20%, with a decrease of less than 5% of the space-efficiency values. The proposed method, according to the basic process of architecture design, uses a performance-driven approach to find solutions that satisfy the requirements. It can be used in real architectural design to solve practical optimization problems.

Abstract Solar heating, as an alternative technology to coal-fired heating, could significantly alleviate the air pollution in China. The value of design radiation should be carefully determined when designing a solar system, as it would commonly affect the solar collector area, and then the economics and performance of the system. However, in the existing publications, most studies ignore the influence of the daily and seasonal variation of radiation, and commonly choose the fixed value of design radiation in some typical days, leading to a non-optimal performance of the system with unreasonable setting parameters. To solve this problem in the design stage, a method is proposed to determine the design radiation of a parabolic trough collector (PTC) heating system. In this method, the concept of non-guaranteed days is introduced to quickly and conveniently determine the system rated capacity. Additionally, the cost of unit heating supply is employed in this method as an optimized object of the heating system. Based on the proposed method, a case study for four typical solar radiation districts in China is conducted. Firstly, the design radiation values of each district are decided through the proposed method. Then, the relationship between non-guaranteed days and the initial investment of the system under the optimal design radiation is obtained. Finally, the economic analysis of the PTC system in Mentougou (suburbs of Beijing) is performed. This work could be a practical guide to select the design radiation for a PTC heating system without the auxiliary boiler. Moreover, the method could also be applied to more types of solar systems and regions.

Abstract The development and promotion of nearly zero-energy buildings (NZEBs) is an inevitable trend of building energy conservation, and external venetian blind shading (EVBS) is one of the most effective technologies for NZEBs. Therefore, this study aims to analyze and optimize the energy-saving performance of EVBS for NZEBs in different climate regions of China. Based on EnergyPlus, the optimal shading arrangements of NZEBs are obtained by evaluating the shading performance of different shading slat angles, orientations, window-to-wall ratios (WWRs) and locations. The results show that the energy saving potential of EVBS for NZEBs is significant, especially in southwest of China. And the energy-saving trends of EVBS with different shading arrangements are similar regardless of the climates, and the maximum energy saving potential per unit window area of EVBS is obtained in slat angle of 0°, west orientation and low WWR. The total energy saving potential (P) gradually decreases first and then increases rapidly as the slat angle increases for all slat angle (0°~180°) shading conditions. And the multi-orientation shading effect is the sum of each single-orientation shading effect. In addition, the cooling efficiency index (CEI) is proposed to evaluate the importance of shading to reduce the cooling demand of buildings, and to guide the improvement of the self-performance of shading. This research will be helpful in guiding the application of EVBS for residential NZEBs in different climate regions of China.

Abstract In a solar chimney power plant, only a fraction of the available total pressure difference can be used to run the turbine to generate electrical power. The optimal ratio of the turbine pressure drop to the available total pressure difference in a solar chimney system is investigated using theoretical analysis and 3D numerical simulations. The values found in the literature for the optimal ratio vary between 2/3 and 0.97. In this study, however, the optimal ratio was found to vary with the intensity of solar radiation, and to be around 0.9 for the Spanish prototype. In addition, the optimal ratios obtained from the analytical approach are close to those from the numerical simulation and their differences are mainly caused by the neglect of aerodynamic losses associated with skin friction, flow separation, and secondary flow in the theoretical analysis. This study may be useful for the preliminary estimation of power plant performance and the power-regulating strategy option for solar chimney turbines.

Abstract This work develops air-conditioning-type building materials suitable for different climate regions. Results show that using traditional building materials alone is unsuitable for any climate region, and that building materials of various thermal properties are needed to satisfy the requirements specific to each location. Low solar absorptance and high emittance materials are appropriate for hot climates, whereas high solar absorptance and low emittance materials are suitable for cold climates. Materials with variable solar absorptance and emittance properties are applicable to regions characterized by cold winters and hot summers. In addition, cement that is reversibly thermochromic at normal temperature and materials with variable transmittance properties can warm buildings in winter and prevent overheating in summer, thereby satisfying the need to create a thermally comfortable building environment.