Shading Elements Research Articles

Hotspot development and shading response of shingled PV modules

The shingled architecture has gained attention in recent years for its improved packing density and reduced ohmic losses that have led to greater module efficiencies. In the photovoltaics industry where land and auxiliary costs scale with area utilization, shingling is a promising emergent technology. However, because current designs use smaller cell areas and upwards of 34 cell strips in series per string, shingled modules are vulnerable to hotspots, particularly due to smaller shading elements. In this work, we experimentally characterize the hotspot and power response of shingled modules. Two operating scenarios are considered, simulating both utility scale systems and standardized testing conditions. We report maximum hotspot temperatures of 145 °C at partial shading and show how non-uniformities in the cell properties lead to variations in module shading response and hotspot temperature. Furthermore, we observe that shingled modules develop higher hotspot temperatures than conventional half-cell modules. Finally, we demonstrate how unshaded parallel strings in a shingled module can concurrently develop minor hotspots at the onset of bypass diode activation.

Microclimate and crop performance in a tunnel greenhouse shaded by organic photovoltaic modules – Comparison with conventional shaded and unshaded tunnels

The use of flexible and semi-transparent organic photovoltaic (OPV) modules as shading elements in a greenhouse tunnel with a tomato crop is presented. Experiments were performed in two similar greenhouse tunnels, covered by diffuse polyethylene sheet, during two summer growing seasons. In 2018, one tunnel was shaded using OPV modules (covering 37% of the roof area and resulting in 23% shading) and the second tunnel served as a control. In 2019, a 25% black shading screen was added to the control tunnel. The microclimate, yield, and physiological parameters were examined in the two tunnels. Results show that at noon (11:00 to 13:00), there was no significant difference in the mean seasonal (June–September 2018, May–August 2019) air temperature and humidity between the tunnels. In 2018, the tunnels differed in terms of the spatial radiation transmittance and leaf temperature. The average radiation level along the OPV tunnel centreline was much lower, and the radiation distribution was less homogeneous than in the control. In 2019, with similar shading percentages in the tunnels, similar average radiation levels were observed. The leaf temperature in the OPV was lower than in the control in 2018 and varied from higher to lower in 2019. The leaf area index (LAI), cumulative yield, and average fruit mass were higher in the OPV than in the control in 2018, and similar in 2019. The average value of the maximum power output of three OPV modules increased roughly linearly with irradiance.

Influence of Roof Windows Area Changes on the Classroom Indoor Climate in the Attic Space: A Case Study

Windows are a complex part of building design and provide a considerable benefit, including to school buildings. For the evaluation of the daylighting conditions prevailing in classrooms, the daylight factor (DF) was considered as the most appropriate parameter for indicating the quantity of admitted daylight. The DF values and CIE overcast sky were calculated using Velux Daylight Visualizer 3 software. The task of the paper is to compare various roof window openings in relation to the level of daylight in the attic, looking to optimize the use of the attic for teaching. The indoor air temperature has a general influence on comfort in the interior, in addition to daylight. In winter, the situation is not critical. The thermal insulation properties of packaging structures are sufficient. The situation is worse in summer, due to the fact that the heat-storage properties are undersized and there is excessive overheating of the indoor air. Four variants of roof windows and their influence on the overall microclimate in the attic are compared. The variant without roof windows is a suitable solution with regard to minimum overheating, but the worst situation for daylight. In order to receive even more light from the window (by moving windows to the top of the roof), we can use variant 2. Based on a combination of daylight calculations and summer temperature, a graphical dependence on window size prediction in terms of top and combined lighting is derived. This was hypothesized without shading the windows. Of course, the shading elements of these windows or cooling are expected in the summer. Finally, the energy required for cooling is compared depending on the size of the windows and achievement of the permissible temperature.

A structured approach to the evaluation of indoor environments’ecological valency

Buildings typically are expected to provide their inhabitants with the opportunity to influence the indoor environment using various control devices. These include, for example, windows, luminaires, radiators, and shading elements. The quality and adequacy of the indoor environment is thus dependent on the availability and effectiveness of such devices. There is arguably a lack of generally agreed-upon evaluation procedures for this aspect of buildings’ indoor environment, namely its controllability by building users, or – in the terminology of Human Ecology – its “ecological valency”. In this context, the present contribution explores the possibility to specify buildings’ ecological valency in a systematic and reproducible manner. Toward this end, first appropriate theoretical foundations for this purpose are explored and previous related efforts are briefly reviewed. Subsequently, a specific approach toward an ecological valency evaluation method is presented. As part of this approach, five main categories of control devices are documented in various rooms of a building, including windows, shading, lights, heating and cooling systems. Whereas, the first part of this method deals with the basic availability of these control devices and elements, the second part looks at their spatial distribution, effectiveness (both objective and subjective), interface quality (to support user interaction), and ecological quality. The presented evaluation method is tested for six different rooms of an office area in an educational building in Vienna, Austria. Thirty participants independently evaluated this area based on the proposed method and associated protocol. The results point to high degree of congruence between the evaluation results of different participants while judging the principle availability and typology of the control devices. Higher variation was observed in the evaluation of the quality of devices and their interfaces. As a whole, the results suggest that methods similar to the one presented in this contribution may indeed provide an opportunity to extend building performance evaluation procedures beyond energy and cost criteria so as to cover aspects pertaining to user control and satisfaction.

KAJIAN KONSEP EKOLOGIS PADA GEDUNG PERPUSTAKAAN PUSAT UGM


 
 
 Title: The Study of Ecological Concept in the Central Library of Gadjah Mada University
 Ecological architecture becomes one of the concept as well as solutions in the building design which minimizes environmental damages and maintains the quality of human life. The central library of Gadjah Mada University in Yogyakarta is used as the research object to rate its ecological level. This study uses a quantitative method to rate its ecological level based on the ecological design principles of Sim Van der Ryn such as ecological accounting, design with nature, and making nature visible. The assessment parameters are based on some references such as the greenship of GBCI, the principles of tropical architecture, and the principle of building accessibility. The results showed that generally, the library has applied ecological concept well through some strategies such as extensive greening, energy efficiency, adequate natural lighting, slim building masses, shading elements, and some facilities for the difable. Some measurements are done to find out the ecological performance of the building such as energy efficiency by 39.17%; daylighting 300 lux at 60.67% of indoor area, visualization of solar radiation reception, and OTTV value by 19,85 watt/m2. However, there are some necessary evaluations such as leakage on the ceiling or the application of greenroof that can be further optimized.
 
 

Hyperspectral image clustering with Albedo recovery Fuzzy C-Means

ABSTRACT Hyperspectral image clustering is usually used for unsupervised learning in different applications. However, the traditional clustering methods have not been considered the complex relationships among neighbouring pixels. The Albedo and Shading elements can define pixel values in the HyperSpectral Images (HSIs). In HSIs, features are different from each other because of their natural physical characteristics and the physical nature of different image features can be described by the Albedo element. Therefore, in this paper, we generate the natural Albedo feature of the HSIs by applying Albedo recovery step to exploit main information from HSIs. Then, we utilized the Fuzzy C-means clustering method to cluster the natural Albedo dataset. In this paper, we propose a novel accurate Albedo Recovery based Fuzzy C-Means (ARFCM) method to cluster HSIs. In the dataset, each feature vector is processed by the Albedo recovery step to create a new feature vector. This new feature vector can describe the dataset better than the original one. Comparing clustering methods as one of the powerful clustering algorithms are widely used in the remote sensing fields of studying. The experiments conducted on several benchmark datasets demonstrated that the proposed clustering method achieves higher performance than other methods and present the efficiency and effectiveness of the proposed method. The results of experiments over different HSI datasets indicated that the proposed method could produce reliable and suitable results compared to the other methods. This shows the robustness of the proposed ARFCM algorithm over the various HSI datasets. Other methods may provide a good response in a given dataset and do not perform well in the other data. Consequently, the ARFCM method, regardless of the study area characteristics and the sensor features, always renders remarkable clustering accuracy.

Experimental Investigation of Photovoltaic Partial Shading Losses under Different Operation Conditions

The partial shading conditions have a significant effect on the performance of Photovoltaic system and the ability of delivering energy. In this study, the impact of different partial shading on the mono crystalline (88W) PV module performance was investigated in this study. Horizontal string, vertical string, and single cell shading at different percentage of shading area have been studied. It is found that the horizontal string shading is more severe on the efficiency of the PV panel. In contrast, the efficiency of PV panel with cellular and vertical cell shading was less during the tests. The experimental results showed that the power losses were 99.8%, 66% and 56.8 % for horizontal, cellular and vertical shading respectively via applied non transparent material as shading element by 100% of shading area at 500 W/m2. Moreover, transparent material used to shade whole module horizontally, different shading area and different radiation level applied to find electrical characteristics of the module under these conditions. The results show that at 800W/m2 of irradiation levels and no shading condition the power was 68.6W, by increase shading area by 20% in each step, the power reducing by 44.94, 47.58, 49.42, 50.57 and 52.4% in compared with their initial value at no shading condition.

Thermal Comfort Improvement for Atrium Building with Double-Skin Skylight in the Mediterranean Climate

Atria are added to buildings for their aesthetical, environmental, and economic benefits; the appropriate atrium design can enhance an atrium’s thermal performance and the adjacent spaces’ temperatures. However, inappropriate design decisions cause thermal discomfort and consequently, higher energy consumption. Since the Mediterranean climate has diverse climatic conditions around the year, a central atrium with a top-lit skylight is recommended, but during the summer period it can cause overheating, and the insertion of shading elements shrinks the lighting performance: thus, the atrium skylight design is supposed to improve thermal comfort without affecting the lighting level. This study investigated the improvement of thermal performance in the atrium building by the implementation of a double-skin skylight (DSS) to enhance the atrium thermal performance without shading. The research conducted computer simulations with Environmental Design Solutions (EDSL) Tas software sequentially. The study prepared various design strategies, and different proposals were tested and compared in terms of indoor temperatures, with reference to American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE-55). The implementation of DSS achieved an average of 77% comfort in working hours around the year with different opening percentages according to the outdoor conditions. Moreover, results show that changing the DSS glazing materials did not affect the thermal performance of the atrium.

A comparison between the daylighting and energy performance of courtyard and atrium buildings considering the hot climate of Saudi Arabia

Daylighting is a healthy and energy-efficient building design strategy that has increasingly attracted the attention of researchers. This study investigates daylighting and the energy performance of courtyard and atrium office buildings, considering different window-to-wall ratios (WWR) applicable to the hot climate of Saudi Arabia. In such a climate, it is recommended to reduce window area and use shading devices in addition to the shaded daylighting elements such as courtyards and atria. This study analysed several cases in this regard and found that the examined courtyard and atrium building configurations presented equivalent cooling and artificial lighting energy performance in general. As for daylighting performance, the most balanced option of those examined was the use of a moderate WWR value of 30%, given that shading devices were used. This moderate value provided a better balance between daylight availability and glare reduction. Increasing WWR to 40% or 50% would only increase cooling energy demand and visual discomfort through glare.

Rational design of sun and wind shaded evaporative cooling vests for enhanced personal cooling in hot and dry climates

As heatwaves become more frequent and intense, personal cooling becomes increasingly important for maintaining outdoor activities and for individuals without access to air conditioning. For about one-third of the current global population living in drylands, evaporating water from clothing is the simplest method of augmenting natural thermoregulation. To cool off, one can simply wear a water-soaked cotton shirt or a highly water-absorbing commercial cooling garment. However, of the stored water, the vast majority is wasted if such apparel is exposed to solar radiation or even slow air flow. Here I show that this issue can be mostly mitigated by incorporating sun and wind shading elements over surface of the cooling garment. First, to enable rational design of these multifunctional shading elements, I develop and benchmark a comprehensive multiphysics finite element model. This model couples conductive, convective, evaporative, and radiative heat transfer with mass transport in natural or forced laminar flow. In the case of natural convection, the model accounts for air buoyancy induced by both temperature and water vapor concentration, which in conditions of interest have a competing effect that can induce flow reversal. Second, I use the model to quantify the impact of geometry and radiative properties of louver and slitted shades on the performance of an evaporative cooling vest in hot and arid conditions. Under natural convection conditions, wearer cooling and water usage efficiency are optimized by introducing about 1.5 cm ventilation gap between the vest surface and the shading structures. In forced convection conditions, however, such a gap results in excessive evaporation rates that are highly wind-speed dependent. Based on these results, I propose a slitted shade design with a collapsible ventilation gap that can provide nearly sun and wind independent moderate cooling rate. If required due to high wearer exertion rate, the intelligently shaded evaporative vest could also provide a higher cooling rate by maintaining the gap. This shaded evaporative vest design concept can minimize the weight of the water stored in the garment and/or significantly increase its cooling period.

Design and experimental study of a low-cost prefab Trombe wall to improve indoor temperatures in social housing in the Biobío region in Chile

A renewed interest in bioclimatic strategies for building retrofitting is noticed because more than 40% of the total annual world energy consumption is used in buildings. In Chile, the social housing stock is more than 5.5 million units built with government subsidies. Thermal regulations improvement started in 2000, nevertheless, solar passive strategies are still not present on the immediate retrofitting agenda.The Bioclimatic Prosthesis Project aims to design-develop prefabricated small scale passive solar systems for the refurbishment of social housing reducing their energy use. These systems should be affordable and easy to build and install.This paper focuses on an adaptable and low-cost prefabricated Trombe wall with a vertical storage system. Mobile insulation during winter nights and external shading during summer were also tested. The system was built and installed in a test cell similar to the most used area of a social housing. The thermal efficiency of it, was monitored and compared to a similar test cell without the passive component. Two different microclimate scenarios were tested: in the coast and in the interior valley.Results show the addable Trombe wall can reduce energy demands and winter firewood consumption by nearly 33%, increasing the indoor temperature in 5 °C in the better cases measured during the cold season. In winter, the indoor thermal comfort hours are increased by 69.35% for the city in the central valley (Chillán).For the coastal city (Coronel), the results were 56.29%. In summer, the comfort hours were also increased by 10% on the coast, and in almost 19.5% in the interior valley, adding an external shading element to solve the overheating risk.

Evaluating the Influence of Varied External Shading Elements on Internal Daylight Illuminances

This paper presents an assessment and comparison of the effects of static and kinetic external shading elements on the dynamic measurement of daylighting. For this purpose, we used a method and parametric tool developed previously for the design and analysis of external shading elements in buildings. The proposed approach was used to compare static and dynamic movement scenarios for achieving optimal internal adjusted useful daylight illuminances (AUDI). The current paper presents the results of a methodical analysis, which compared various types of louvers in static and dynamic operation scenarios for a typical office in a Mediterranean climate. The results show that dynamically adjusted louvers perform notably better than fixed or seasonally adjusted modes of operation. The results show that dynamic operation scenarios can increase the AUDI by up to 51%. The results also show that in some conditions the existing rules of thumb fail to predict the correct design approach to louver geometry and that the use of rules of thumb in architectural daylight design needs to be revaluated.

Thermal analysis of a portable DSSC mini greenhouse for botanical drugs cultivation

Photovoltaic farms in Malaysia are being developed tremendously as a form of supporting fossil fuel setbacks in Malaysia power generation. An important parameter of the PV installation is the power (Watts) accumulated over sunlight retrieval. Considerable losses may arise from the conversion, where the efficiency is typically 15% to 23%, with the remainder becoming losses in the form of accumulated heat under the PV array or panel installations. PV heat dissipation is dependent on solar radiation, air convection and PV cell conduction. Dye Sensitized Solar Cell (DSSC) has been applied as a greenhouse shading element, having the ability of enabling specified spectrum of light color penetration during electric accumulation. Furthermore, only light of wavelength between 400 and 700 nm (PAR) is absorbed by the greenhouse plants which is essential for their growth and photosynthesis. A Portable DSSC Mini Greenhouse (PDMG) can provide simple, effective and suitable light source for botanical drugs. Light which is associated with increasing temperature and heat is critical to be measured. A measurement of average heat gain flowing into a building through building envelope (OTTV- Overall Thermal Transfer Value) is a well-known method adopted in green building design. In this paper, the OTTV approach is applied to calculate heat transfer properties, from outdoor surroundings to the PDMG structure, giving justification of the PDMG thermal conditions.

Reuse Waste Material and Carbon Dioxide Emissions to Save Energy and Approach Sustainable Lightweight Portable Shelters

Abstract Despite their great significance, lightweight structures have poor thermal inertia. In order to enhance the thermal comfort inside such buildings, architects need lightweight thermal storage. In this paper a model was used to experimentally investigate Heating Load profiles in lightweight shelters. The profiles were created for the climate in Jordan, then simulated for other climate zones. The proposed design concept was used to create a replacement for a thermal mass in lightweight structures such as shelters; by combining passive solar gain with energy storage embodied within the shelter floor (thermal-floor) to absorb solar radiation. This shelter design decreased the Heating Load during the winter season by acting as heat storage that releases energy at night time after being exposed to solar radiation during the day. The passive design depends on shading elements and overhangs shades to control solar gain during different seasons to prevent overheating during the summer. An experimental investigation of this model was performed to validate the simulation results. Validated simulation results showed that the designed thermal-floor is 25 % of the total shelter’s floor area, which was crucial for obtaining favourable results. With CO2 as a thermal mass, heat load was reduced up to 68 % compared to a 20 cm concrete slab floor. The use of this thermal storage material yielded a reduction in annual heating demand by 85 kWh/m2.

Project Spotlight: UHPC helps Manateq headquarters make a strong statement

Using ultra-high-performance concrete enabled an open and light design for the precast concrete panels that form the facade of the new Manateq headquarters building complex in Doha, Qatar. The contractor for the shading elements was Doha Cladding Systems (DCS).

Analysis of the Effect of Using External Venetian Blinds on the Thermal Comfort of Users of Highly Glazed Office Rooms in a Transition Season of Temperate Climate—Case Study

Improving the energy efficiency of buildings is among the most urgent social development tasks due to the scale of energy consumption in this industry. At the same time, it is essential to meet high requirements for indoor environmental quality and thermal comfort. The issue of overheating is most often analysed in summer but it also occurs in transition seasons, when the cooling systems do not operate. The paper attempts to evaluate the effectiveness of external mobile shading elements on the microclimate of rooms with large glazed areas in the transition season. Passive solutions, such as shading elements, which limit the increase of indoor temperature, do not always allow the acquisition and maintenance of comfortable solutions for the duration of the season, as demonstrated by the authors. Temporary cooling of the rooms may be necessary to maintain comfortable conditions for the users, or other solutions should be devised to improve comfort (e.g., reduction of clothing insulation characteristics). The novelty of the study consists in the analysis of comfort in a “nearly zero energy consumption” building (NZEB) during a period not analyzed by other scientists. This is a transition period during which heating/cooling systems do not operate. The research task set by the authors involved the assessment of the possibility to reduce office space overheating in the transition season (spring) by using external shading equipment in rooms with large glazed areas. An additional research task aimed at checking the extent to which user behaviour, such as reduction in clothing insulation characteristics, can improve comfort in overheated rooms. The results of the tests reveal that the difference in the ambient air temperature between a room with external venetian blinds and an identical room with no venetian blinds in the transition season, i.e., from 27 March to 6 April 2017, ranged from 12.3 to 2.1 °C. The use of a shading system (external venetian blinds positioned at an angle of 45°) reduced the number of discomfort hours by 92% (during working hours) compared to the room without external venetian blinds. A reduction in the thermal insulation of the clothes worn by people working in the room with no venetian blinds helped to reduce the number of discomfort hours by 31%.

Simulation-supported shading design optimisation for a multi-storey building with passive cooling

This contribution reports on an ongoing research effort to reduce the heating demand and overheating risk in the cold and warm seasons respectively. A simulation-supported optimisation strategy for life cycle oriented buildings was pursued, resulting also in improved ratings in terms of the concurrently calculated mandatory Austrian energy certificate. Thereby, a range of different building types was considered, including a multi-storey building that uses locally available ecological construction materials and renewable energy. Apart from the heating demand of the building, the indoor environment for selected living units was specifically examined to avoid overheating risk and to increase the thermal comfort for the occupants. To reduce the indoor temperatures for different thermal zones, the dimensions of external shading elements were investigated. Likewise, natural ventilation scenarios were explored to improve summer-time thermal comfort conditions. The results suggest that by using properly dimensioned external fixed shading devices, especially in combination with natural ventilation, the indoor temperatures and also the thermal comfort can be improved significantly, while maintaining the passive house standard according to the Austrian energy certificate.

CFD simulation of external CHTC on a high-rise building with and without façade appurtenances

Many high-rise buildings have intricate façade appurtenances such as balconies, mullions, or egg-crates shading elements. These façade systems interact with the external microclimate in a complex manner that affects the convective heat transfer coefficient (CHTC) significantly. In this study, CFD and heat transfer simulations are carried out for buildings with balconies, vertical shading element, egg-crates, and a smooth façade. Comparisons of local-CHTC distribution between buildings with and without the façade appurtenances for rooms on different floor heights and located at a corner or a center region of the building are performed. Two equation SST κ-ω turbulence modeling is used for momentum closure. The result of this study shows that the local and surface-averaged CHTC values at the surfaces of each building are dependent on building aerodynamics and forms of the façade appurtenances. For instance, for a 100 m tall building case study with rectangular floor plan, having an egg-crate shading with a depth of 1 m decreased the local-CHTC of a room around the corner-zone by 35%, 37%, and 38% on the 1st, 15th, and 30th floors, respectively compared to a room in building a smooth façade. Thus, necessitating detail local-CHTC variations and wind directionality effect assessments especially on glazed buildings characterized by weak thermal performances.

Application of conjoint analysis to the optimum design for fabric printing patterns

PurposeThe purpose of this paper is to construct the best combination of fabric printing pattern’s attributes to obtain the optimum design to meet the markets need.Design/methodology/approachThis study reviewed the morphological analysis of fashion design expert groups regarding the fashionable fabric printing patterns, as well as the attribute preferences for different groups of fabric printing patterns through focus group discussions. In addition, the conjoint analysis was used to calculate the part-worth of these patterns’ design attributes and design levels to obtain the optimum design for fabric printing patterns.FindingsThe results of this study showed that the most importance of fabric attributes is the secondary pattern (32.59 percent), while the weights of shading element (24.80 percent) and primary pattern (24.46 percent) are almost the same. This study found that a wide range of intertwining image primary pattern can be applied to create interesting and popular fabric printing pattern designs. In practical applications of this result, when the primary pattern is supported by the buyer, fabric designers may use New Classic composite plants, with simple shading and different cycling configuration, to reproduce the optimum designs of the fabric printing patterns.Originality/valueThis proposed a novel solution to figure out the combination basis for optimizing fabric printing pattern designs. In addition, this result helps fabric printing pattern designers to establish an optimal design method for a specific brand to create a unique printing pattern design.

Embedded BIPV module-level DC/DC converters: Classification of optimal ratings

Building-integrated photovoltaics (BIPV) is seen as a key technology to reduce the environmental impact and net power consumption of buildings. The integration of PV into building components, such as façade, window, roof or shading elements, leads to a distributed generation over the building envelope with a profound impact on the electrical installation. Designing the electrical system with string inverters and a possible wide variety of module sizes and technologies is a challenging task. To overcome this issue, Module-Level Converters (MLCs) can be used. A supplementary benefit is that the consequences of partial shading can strongly be reduced. This paper investigates whether the current generation of MLCs is suited for embedment in facade BIPV modules. The PV output is categorized and compared to the input parameters of the converters. Besides the discrepancy between the physical dimensions of the converters and the desired installation location, thermal and electrical measurements on a prototype BIPV curtain wall element reveal that daily energy losses can be as high as 50% due to thermal overload when used in a moderate climate such as Belgium. The paper concludes by discussing further standardization of BIPV module-level converters.