Solar Control Devices Research Articles

Impact of active façade control parameters and sensor network complexity on comfort and efficiency: A residential Italian case-study

Extensive literature exists on the use of dynamic shading devices for the control of visual and thermal comfort in non-residential buildings, however research in the residential sector is far less widespread. Several control strategies and thresholds are utilised in literature, yet it is unclear how these should be chosen. The aim of this work is to evaluate the impact of several control strategies and parameters on three Key Performance Indicators (KPIs) (adaptive overheating, useful daylight illuminance and heating demand) in a case-study apartment near Bologna, Italy, modelled in TRNSYS 18 and Radiance. Multiple levels of complexity were tested to evaluate the extent of the benefits of each sensor (temperature, irradiance and occupancy). Three commercially available solar control devices were simulated: external and integrated Venetian blinds and electrochromic (EC) glazing. The study has shown that occupancy-based controls can greatly reduce overheating, while irradiance sensors are only beneficial for certain orientations. The cut-off angle’s limited effectiveness was revealed, as fully closing blinds led to significant additional overheating reductions. Complex controls did not always outperform simpler controls. Heating demand was found to be easy to minimise, while the trade-off tends to be between overheating risk and daylighting availability. Each control parameter’s impact on the KPIs has been evaluated. Optimal solutions are identified which yield near-best performance for all three KPIs, however such ‘optimal’ solutions may not represent the wishes of all users, therefore more studies are required to calibrate the control to the user experience.

Can urban heat be mitigated in a single urban street? Monitoring, strategies, and performance results from a real scale redevelopment project

Urban overheating affects the health and wellbeing of communities, the environmental quality, and the economic performance of cities. This study demonstrates that outdoor thermal comfort can be improved in a single street by decreasing ambient (Ta) and surface (Ts) temperatures by implementing innovative and traditional heat mitigation strategies. Ten scenarios were modelled in ENVI-met and evaluated based on detailed in-situ and airborne-based meteorological data collected along Phillip Street (Parramatta) in Sydney, Australia. The best-performing scenario combining reflective materials, increased greenery, spray systems, and traditional shading provides a very significant reduction of Ta and Ts of up to 3.3 °C and 30.9 °C, respectively. On its own, radiative cooling materials applied on shading devices offer a comparable incanyon cooling capacity with maximum Ta and Ts decrease of up to 1.6 °C and 24.2 °C. Similar results are obtained by applying traditional solar control devices, which reduce peak Ta by 1.3 °C and Ts by 21.8 °C. When reflective pavements are accompanied by an increment in greenery, peak Ta and Ts are additionally reduced by 0.2 °C and 3.6 °C, respectively. When applied individually, an increase in evaporative cooling and greenery shows a strong local effect with a maximum in-canyon Ta decrease of 2.7 °C and 0.5 °C, respectively. Results show increased wind speeds have a positive impact on greenery, shading, radiative and reflective technologies and an unfavourable effect on spray systems. Future research should concentrate on examining the cooling potential of radiative coolers in different proportions and arrangements and quantifying the contributions and interactions between different strategies when applied simultaneously.

Geometric Optimization of Atriums with Natural Lighting Potential for Detached High-Rise Buildings

Detached high-rise office buildings with more than 15 floors in high density areas have floor plans with large surfaces that prevent natural lighting from entering their central areas. Therefore, artificial lighting is used to substitute the lighting comfort needs of their occupants for a large proportion of operational hours, resulting in high energy expenses for the building. The goal of this study is to evaluate the lighting potential of a central atrium with added clerestories and/or side lighting every four levels in a parametric 15-floor theoretical model and two floor surface areas of 900 m2 and 2500 m2, compared to a 40% glazed surface on façades without solar control devices. A total of 108 geometric variations of the atrium and adjoining spaces were analyzed using a climate-based daylight dynamic simulation method (CBDM), using DIVA-for-Rhino as the integrated evaluation tool in Rhino’s Grasshopper software, where the parametric model was built. The geometric optimization results show the design variables that allowed a significant illuminance of between 60 and 70%, using the Useful Daylighting Illuminance (UDI) indicator in a range of 100 to 2000 lux, demonstrating that the incorporation of atrium spaces as a controlled natural lighting strategy in these buildings is an environmental and sustainable perspective for architectonic design.

Evaluation of household waste materials for façade components in primary educational workshops. Mechanical and fire properties

An important amount of human household waste can be reused, as it is presently done all over the world in numerous social initiatives such as “Do It Yourself” proposals. Some waste containers have sufficiently good mechanical properties that make these containers promising candidates as some architectural elements. For example, this waste can become non-load bearing façade components, which have to withstand much smaller stresses than structural elements such as columns and beams. This article is part of a broader research project that is developing low-cost new solar control devices for school façades reusing household waste. These façade components will be assembled during workshops by elementary school communities. This present research paper studies this cladding use of the household waste and analyzes these waste-based components mechanical and fire properties by carrying out laboratory tests. These test results will be the base of future simulations and friendly-use tables for children during the aforementioned workshops. Conclusions for this research article are: a) that plastic waste materials have similar properties to new plastic materials for construction although they have been built for packaging purposes and their implementation in façades requires further studies and caution; b) tetra pack has particularly interesting properties which had been largely unexplored.

Comportamiento Térmico de fachada ventilada opaca en clima cálido seco extremo

Energy consumption attributed to buildings amounts to approximately 30% globally. This consumption is even greater in buildings that lack climate adaptation strategies. In warm climates, solar control devices protect from thermal gains by direct solar radiation as a strategy to avoid overheating in buildings. Ventilated facades increase the energy efficiency of said devices when harnessing the convective cooling produced by the temperature and pressure differential inside the ventilated facade. The present research shows the thermal behaviour of an opaque ventilated facade through numerical modelling in ANSYS Fluent® computational fluid dynamics software in an extreme hot dry climate. The objective of the study was to analyze the effect of a ventilated facade on the thermal performance of the wall immediately adjacent to the living space as a passive convective cooling system. The variables analyzed were thickness of the air cavity, ambient temperature and wind speed of the external environment, as well as its effect on the surface temperature of the wall adjacent to the living space. The results show a decrease in the surface temperature of the wall, which reduces the total cooling load of the building.

Influence of thin-film device with curvature on natural frequency of rectangle membrane under uniaxial tension

A solar power sail demonstrator “IKAROS” demonstrated solar sailing technology in 2010. The membrane of the spinning solar sail IKAROS is estimated to be deformed toward the Sun. The deformation was kept even under low spin-rate. Previous studies suggest that curvature of thin-film solar cells on the membrane increases the out-of-plane stiffness by finite element analysis. Shape, out-of-plane stiffness, and natural frequency of membranes have to be predicted for solar sails with thin-film devices, such as thin-film solar cells, dust counters, and reflectivity control devices in order to reduce the margins of sail size and propellant mass against disturbance solar pressure torque acting on the membrane. In this paper, the effect of a curved thin-film device on the natural frequency of a rectangle membrane under uniaxial tension was investigated. Three types of membranes were evaluated: a membrane with a curved thin-film device, a membrane with a flat thin-film device, and a plane membrane. Geometric nonlinear finite element analysis and eigenvalue analysis were conducted to investigate the natural frequencies under varying tension. The simulations were verified by vibration experiments. It was found that under low tension, the natural frequency of the membrane with the curved thin-film device is significantly higher than that of the others and that under high tension, the natural frequency of the membrane with the thin-film device is slightly lower than that of the plane membrane. In addition, parametric analysis on the curvature of the thin-film device shows that natural frequency at low tension is sensitive to the curvature. The eigenvalue analysis of a whole solar sail with the curved thin-film devices also suggests that the curvature remarkably affects the vibration modes. In conclusion, curved thin-film devices have a significant impact on the out-of-plane stiffness of a membrane under low tension.

Parameterization and solar radiation simulation for optimization of a modular canopy

Este estudo compreende o processo de desenvolvimento de modelagem paramétrica em Grasshopper® para superfícies complexas na construção, utilizando, como critérios de desempenho, a radiação difusa e direta. O objetivo principal deste artigo é criar, simular e otimizar uma cobertura modular, semipermeável, baseada no estudo e interpretação de folhas de árvores como estruturas de engenharia. O método aplicado envolveu a definição de parâmetros e critérios para a otimização do processo de simulação e foi dividido em três estágios: estudo da forma, parametrização da forma e simulação e otimização. O plugin Ladybug® para Grasshopper® foi usado para realizar as simulações e o Octopus® foi adotado como motor de otimização. O objeto de estudo escolhido foi o processo de criação de uma cobertura, pois em climas quentes e úmidos, como no Brasil, as áreas de cobertura são uma parte crítica do envelope construtivo, altamente susceptíveis à radiação solar e outras mudanças ambientais, influenciando nas condições de conforto interno dos ocupantes. Devido à parametrização, o produto final, embora criado para uma zona climática específica, pode ser aplicado para quaisquer outras zonas bioclimáticas com poucas alterações nos parâmetros. Como principais resultados, o dispositivo de controle solar contribuiu para a redução de 86% da média anual de radiação solar horária para radiação direta, mantendo os níveis de radiação difusa.

Effectiveness of different strategies in the retrofit of Italian school buildings: Influence of thermal inertia and solar control

Most of the Italian school buildings were built before the 1973 energy crisis, so they need a retrofit to reduce their primary energy demand and improve indoor environment quality. These buildings are equipped with large windows, therefore it is necessary a solar control strategy to ensure thermal and visual comfort and contain energy demand. Furthermore the older buildings have heavy masonry, in these cases the problem is where it is more convenient to place an additional layer of insulation: inside or outside the buildings opaque envelope elements. This work is aimed to explore, by means of computer simulations, the effects of various retrofit strategies on primary energy demand and general comfort conditions. The examined strategies are characterized by different positions of the additional insulation and various solar control devices. At present, the case studies consist in two school buildings in the city of Bologna in the North of Italy. In order to assess the influence of internal gains and time profile of use, other possible intended uses for the same buildings, such as offices or dwellings, were simulated.

РАСЧЕТ ПАРАМЕТРОВ СОЛНЦЕЗАЩИТНЫХ УСТРОЙСТВ

Questions of overheating of premises at the expense of solar radiation in various regions of the country are considered. The assessment of the existing normative documents on design of solar control and shading devices is carried out. Are shown absence in them effective methods of calculation of optimum carrying out of the shading elements of solar control and shading devices. Methods of calculation of parameters of the main types of solar control and shading devices (SCSD) in the form of awnings, vertical and horizontal lamellae established before fenestrationareoffered. Methods consider orientation of windows, a trajectory of apparent motion of the sun on the heavenly sphere, the latitude of the area, a power component of solar radiation. Are brought numerical an example of calculation of parameters of solar control and shading devices and the recommendation about effective use of solar control and shading devices in the form of awnings, vertical and horizontal lamellae. Calculations and the analysis of protective characteristics of SCSD are carried out that allows to create preliminary recommendations about efficiency of the SCSD various types. Solar control and shading devices in the form of stationary awnings both continuous, and trellised will be effective only at high values of heights of standing of the sun. With average heights of the sun and furthermore with low heights stationary awnings become not expedient because of disproportionately big carrying out. SCSD in the form of blinds with horizontal and vertical arrangement of the lamellae located are more effective as it is perpendicular to a wall surface, and under some corner to it. Recommendations about effective use of different types of blinds depending on orientation of fenestrationare provided in article.

Sustainability Assessment of Household Waste Based Solar Control Devices for Workshops in Primary Schools

Part of the large amounts of waste generated by human activities could have a second use while solving social problems. In this sense, the authors are carrying out a research project involving the participative development of innovative solar control devices integrated into school architecture using household waste. In general, the objectives of this research project are to: (a) optimize pupils’ learning process by improving lighting and thermal comfort levels and (b) reduce the generation of Spanish household waste by reusing part of it and increase the teaching community’s awareness about this waste. This research article reports on the steps taken to achieve these objectives by characterizing the most sustainable types of the waste-based solar control device. In this sense, this research paper defines and applies a new methodology which combines General Morphology Analysis (GMA), a new tool based on The Integrated Value Model for Sustainable Assessment and Focus groups. First, up to 96 different types of solar control devices composed of household waste have been defined using GMA and, second, these 96 types and conventional roller shutters have been assessed using this new tool. Based on these article results, one of the best alternatives has been prototyped during an initial workshop.

Domus method for predicting sunlit areas on interior surfaces

Abstract This pilot study aims to analyze the solar radiation transmission, daylight performance and glare reduction probability of complex shape solar control devices, developed with parametric modeling and digital fabrication. As methodology, initially the Rhinoceros3D+Grasshopper digital tools suite was used for the parametric modeling of solar control devices. Performance evaluations were performed by computational simulation and measurements in prototypes. For the simulations, the Diva-for-Rhino and Ladybug plug-ins were used. For the measurements, through digital fabrication, a prototype used for glare evaluations through HDR photographs was made. As main results, the solar control devices contributed to the control of solar radiation admission, better daylight distribution and glare reduction in the indoor analysis environment, confirming the reliability of the methodological procedures employed. It is important to highlight the effects of depth and inclination of the devices analyzed, respectively on the daylight distribution and selectivity in the admission of solar radiation between winter and summer. Finally, the shading masks show that despite all the development of modeling and simulation tools, the simple understanding of the solar geometry is still essential for the adequate performance of the solar control devices.

State of the art of advanced solar control devices for buildings

This paper deals with the state of the art of advanced solar control devices for buildings, with the comparative evaluation of solar-control systems and with guidelines for the development of new solar control systems. It includes multifunctional systems with building integrated photovoltaic (BIPV) and/or building integrated solar thermal (BIST) energy conversion. In order to facilitate and to structure the understanding of solar control systems two multidimensional spaces are introduced: the design space and the evaluation space. The design space contains the design parameters which are to be selected by the designer when solar control devices are to be chosen for specific buildings or when new systems are to be developed, such us the color of the slat of a venetian blind or the fraction of holes (direct transmittance) of a fabric for a roller blind. The evaluation space contains the performance parameters or evaluation criteria, which indicate the design‘s ability to satisfy the functional and aesthetic requirements, such us passive solar gain control or visual comfort. All the design parameters and evaluation criteria are explained in detail in the paper. A chapter with examples of advanced solar control systems completes the overview of the state of the art of solar control systems.

Elementos de controle solar desenvolvidos com modelagem paramétrica e algoritmos evolutivos

Considerando a importância do controle da radiação solar e admissão da luz natural no desempenho das edificações, os elementos de controle solar, quando corretamente aplicados, podem contribuir significativamente com o conforto e a eficiência energética no ambiente construído. Paralelamente, destaca-se na produção arquitetônica contemporânea o crescente emprego de ferramentas computacionais no suporte às decisões de projeto. Nesse contexto, o objetivo desta pesquisa é analisar a admissão de radiação solar e o desempenho lumínico de elementos de controle solar desenvolvidos com modelagem paramétrica e algoritmos evolutivos. A metodologia foi organizada em quatro etapas: (1) modelagem paramétrica dos elementos de controle solar; (2) simulações computacionais referentes à admissão de radiação solar e ao desempenho lumínico; (3) otimização através de algoritmos evolutivos; e (4) análises de mascaramentos gerados por simulação computacional. Os aplicativos utilizados foram a suíte de modelagem paramétrica Rhinoceros3D+Grasshopper; o plug-in de desempenho ambiental Diva-for-Rhino; a ferramenta de algoritmos evolutivos Galapagos Evolutionary Solver; e as ferramentas de geometria da insolação do plug-in Ladybug. Os resultados demonstram que os elementos desenvolvidos foram capazes de controlar seletivamente a admissão de radiação solar, além de melhorar a distribuição da luz natural nos ambientes de análise, destacando-se respectivamente a importância dos componentes direcionais e horizontais. Por fim, os mascaramentos demonstram, complementarmente aos resultados das simulações, que a compreensão da geometria da insolação apresenta-se imprescindível para o desempenho dos elementos de controle solar.

Influence of selected solar positions for shading device calculations in building energy performance simulations

Control strategies of building shading devices can achieve important savings in the air conditioning and lighting energy consumption of a building. Calculation procedures of the different solar control devices (overhangs, side fins, etc.) are of special interest in annual energy performance simulation programs, which have to obtain solar gains in hourly time-steps and, more recently, in five minute time-steps. A common approach used to overcome this problem in the past was to select a representative day of a certain period of time and maintain the same results of shading calculations for the rest of the period. Nowadays, the new generation computers have drastically reduced computational costs, but some programs still use the former approach. The present paper assesses the error made by the use of it. Different overhang and side fin typologies and orientations, location latitudes and simulation time-steps have been analysed. 25% of the studied cases have shown annual average relative errors of 5% or greater in the incident solar radiation over the glazing surface. Common configurations, such as south oriented overhangs, show daily deviations of incident solar energy up to 0.48kWh/m2, with a relative error of 17%, having hourly errors as high as 26%.

Evaluation of three solar and daylighting control systems based on Calumen II, Ecotect and radiance simulation programmes to obtain an energy efficient and healthy interior in the experimental building Prototype SD10

The SD10 Prototype is an experimental building used as the Headquarters of the organization during the Solar Decathlon Europe Competitions 2010 and 2012. The project aim is to develop a new industrialized, light, sustainable and energy efficient construction system. The active modular glazing panel is a 2D glazing module on the south façade.In high solar radiation climates, the effect of the large amount of light and the usual lack of daylighting control devices cause exterior sunscreen abuse, paradoxically generating artificially illuminated interior spaces. The consequences of living in areas with not enough daylight go beyond the impact on electricity consumption. Natural lighting can have both positive and negative effects on health, productivity and user satisfaction of a space.The objective of this study is to evaluate the modular active glazing panel and to determine the influence of different types of solar and light control devices in relation to the quantity and quality of natural light, in order to determine which are suitable for the use of solar radiation in high radiation climates.

Improving the Microclimate in a Dense Urban Area Using Experimental and Theoretical Techniques - The Case of Marousi, Athens

An urban heat island results in higher urban temperatures than the surrounding area and is considered as the most documented phenomenon of climate change. This increase in urban temperature has a serious impact on the energy consumption for cooling and also contributes to higher urban pollution levels. Athens suffers from high summer temperatures that affect the quality of life of citizens. In response to the problem, a major rehabilitation plan was designed and applied, based on the use of advanced mitigation techniques. The present paper reports the results of a major urban climatic rehabilitation in the Marousi area, in Athens. This project is currently under construction. Detailed monitoring techniques have been applied and the main climatic problems have been identified. Using accurate simulation techniques the specific climatic environment under peak summer conditions was computed. Based on the results of experimental and theoretical analysis a detailed rehabilitation plan was designed using advanced mitigation and passive cooling techniques. The design involves the use of cool materials for pavements and streets, earth to air heat exchangers, solar control devices, photovoltaic panels and extensive use of green spaces and water. The climatic impact of the proposed design was evaluated and estimated to reduce ambient urban temperatures by up to 3.4 K under peak summer climatic conditions. At the same time, an important decrease of the surface temperature was calculated, resulting in a very significant improvement of thermal comfort conditions. The results of the present analysis are valid inside the climatic boundaries of the whole study.

Comparative energy and economic performance analysis of an electrochromic window and automated external venetian blind

A virtual test cell representing a portion of an office building was modeled in order to evaluate the energy balance and the economic convenience related to the use, as solar control devices, of a switchable electrochromic glazing system (EG) and of an automated external venetian blind system (VB). Furthermore, results were compared with a so-called base case (BC) of the glazed component, with no exterior solar shading. The virtual test cell is supposed located in Milan, Italy. The operation of both shading systems was set in order to minimize undesirable solar heat gains during cooling season and to maximize them during heating season and also in order to optimize the daylighting performance without having glare effect on the work plane. The energy balance of the selected systems was done considering the annual primary energy consumption for heating, cooling, lighting, shading system operation and the glazed systems’ embodied energy annual quota. Finally, a further comparison in terms of economic convenience was done. Simulations were performed using EnergyPlus 7.0 dynamic simulation engine in conjunction with BESTenergy Graphic User Interface.

Fabrication and optical characterization of improved electroless chemically deposited strontium fluoride (SrF2) thin films at 320KFabrication and optical characterization of improved electroless chemically deposited strontium fluoride (SrF2) thin films at 320K

Thin semi conductor films of strontium fluoride (SrF2) were successfully deposited on glass microscope slides using simple and cheap electroless chemical bath deposition methods at 320K and pH values of 9, 10 and 12. Controlled addition of ethylenediamine tetra acetate (EDTA), another complexing agent with pH to oppose that of bath constitutions, was used to vary the deposition pH values. X-ray diffractometry technique was used to confirm the depositions. Absorbance spectra data of the films were obtained by a single bean spectrophotometer (Pharmacia LKB Biochrom 4060) at wavelength range 200 to 900nm. Other optical and solid state properties were calculated from the data and compared with other deposited thin films. Average optical and solid state properties include absorbance ranging from 0.034 to 0.086, transmittance 0.820 to 0.925, reflectance 0.041 to 0.094, refractive index 1.51 to 1.88 absorption coefficient 0.078 to 0.198x 106m) -1 , electrical conductivity 0.40 to 0.49 (ohm cm) -1 , film thickness 0.013 to 0.074μm and bandgap 2.55 to 2.75 eV. The deposited thin films could find applications in antireflection coatings for eyeglass, solar thermal control devices and solar cells JONAMP Vol. 11 2007: pp. 415-422

On the air flow and radiation transfer through partly covered external building openings

Solar control devices placed in front of large building openings disturb air flow and the radiation transfer. Although solar radiation transfer through obstructed openings is a relatively well researched area, very little information is available regarding the air flow perturbations and daylighting alterations created by external solar control devices. The present paper reports a series of experiments aiming at investigating natural ventilation and daylight phenomena associated with the use of specific shading devices. Experiments have been carried out in outdoor test cells, and 28 different configurations have been tested for several window characteristics under various climatic and radiation characteristics. Based on the experimental results, specific modeling activities have been undertaken and theoretical methods of calculating air flow and daylight through openings equipped with specific solar control devices have been developed and are now presented. Theoretical predictions are compared with the corresponding experimental data and a very satisfactory agreement has been found for both air flow and daylight processes.

Optical properties of tungsten oxide films as a function of their stoichiometry as determined by LIMA and XPS

Tungsten oxide can be produced as a thin film with a variety of compositions and doping to give coloured films which can be electrochromic. Electrochromic films are of interest in large areas as solar control devices and as alternatives to liquid crystal display panels. The preparation of such films by reactive planar magnetron sputtering is described. The compositions of the deposited films were obtained by laser induced mass analysis (LIMA) and X-ray photoelectron spectroscopy (XPS). The stoichiometry was then related to both the film properties and to the deposition conditions. The use of these two analytical techniques also allowed the influence of doping by hydrogen to be assessed. This information was used to create a system which would coat tungsten oxide films, with controlled stoichiometry, on to long polyester sheets which had previously been coated with a transparent electrically conducting coating. This coated polyester was then suitable for use as part of an electrochromic device.