Exterior Shading Devices Research Articles

Combined Effects of Exterior Shading and A/C Heat Rejection on Building Energy Consumption and Indoor Air Pollution Exposure

Exterior shading devices and outdoor units can be closely coupled since these two building components are commonly installed next to each other. This study uses a coupled EnergyPlus-Fluent modeling approach to examine how a combination of exterior shading and heat rejection from outdoor units can affect the ambient outdoor environment of a building, and how changes in the ambient outdoor environment can influence cooling loads and indoor PM2.5 exposure. Three exterior shading devices were simulated, including horizontal overhangs, vertical overhangs, and vertical fins. Data from wind-tunnel experiments and field measurements were used to ensure the accuracy of the airflow model, energy model, and pollution model developed in this study. Results indicate that horizontal overhangs could almost offset the increase in cooling loads due to increased ambient outdoor temperatures caused by heat rejection. The use of vertical overhangs did not always mean lower demand for space cooling when heat rejection was considered. Heat rejection, horizontal overhangs, and vertical overhangs could help reduce indoor PM2.5 exposure, while indoor air pollution was worse after the implementation of vertical fins. This study shows how exterior shading devices and outdoor units can be coupled to achieve better building energy efficiency and improved occupant health.

Energy-efficient retrofitting with exterior shading device in hot and humid climate – case studies from fully glazed multi-storied office buildings in Chennai, India

ABSTRACT Many existing buildings are not sustainable, such as poorly insulated office buildings with large glass window panels that significantly increase the cooling energy use in a hot and humid climate. Energy-efficient retrofitting can substantially reduce energy use through a passive façade design. This paper suggests simulation as a method for selecting a façade retrofit solution at the early design stage. A façade retrofit solution that requires the integration of all three sustainability dimensions: energy efficiency, visual comfort, and economics. Two case studies of fully glazed multi-storied office buildings of different sizes demonstrate the methodology. This research adopted two simulation methods: one for façade retrofit solutions with fixed exterior shading device (ESD) types and the other for a dynamic ESD. The results show that fixed ESD with perforated fabric for 100% of the glazing area was 22.7% energy-saving retrofitting solution than the base case for the small sample and 17% energy-saving for the large sample with a low payback period of 7 years for both the case sample. Building practitioners, stakeholders, and end-users can use this simulation methodology for a successful façade retrofit decision-making at the early design stage.

Windows: a study of residents’ perceptions and uses in Sweden

What are inhabitants’ perceptions and uses of windows in multi-dwelling buildings? This paper reports on a field study that explores daylight, the visual connection to the outside and the role of windows in the home during the day and night. Qualitative interviews were held with 20 participants living in multi-dwelling buildings. The thematic analysis identified two main components as characteristic of residents’ experiences with their windows. The first, ‘perceived dwelling comfort’, consists of different types of comfort qualities, for example, keeping the body sufficiently warm or cool, blocking exterior noise, enabling visual tasks, perceiving the room to be adequately daylit, visually pleasant and spacious, obtaining visual privacy, and having an outside view to provide information and engagement. The second, ‘preferred exposure to external elements’ (<em>e.g.</em> air, sound, light, people outside) expresses a desire for personal control and reflects variability over time (momentary, daily, seasonal, ageing) and between individuals or groups. Windows represent an enjoyment of the home and fulfil much more than physical needs. They must allow sufficient personal control over fresh and cool air, sound, sunlight, streetlighting and privacy. <em><strong>Practice relevance</strong></em> An enabling home environment affords residents opportunities to regulate the visual openness to the outside in order to satisfy individual needs for privacy or social connection. Preferences vary within and between household members, so window treatments must be easy for inhabitants to adjust. Housing designers and developers are advised to include exterior shading devices in the design and optional indoor window treatment to facilitate durable shading and privacy solutions. Further adjustments could be offered by landlords to tenants when they move in. Fenestration and shading devices offer the possibility to make full use of the available daylight, reduce electricity demand for indoor lighting and provide inhabitants with increased control of their comfort.

Handshaking towards zero-concept analysis and technical measures of LEED zero-energy building in connection with technical standard of nearly zero-energy building in China

To achieve zero-energy building target, both China and the US have planned pathway by formulating guidelines and standards. China has published National China technical standard for nearly zero energy building (CTS-NZEB), which defines detailed principles of zero-energy building. The US LEED zero energy evaluation system has been released based on LEED rating system. Defined target and scope have been introduced in this evaluation system; however, there are no technical and detailed approaches in the rating system. To support future projects achieving the LEED Zero Energy certification in China, accessible applications have been analyzed in perspectives of technology and economy in this article. The comparison and analysis results show that the strategies and technical index of CTS-NZEB can be adopted comprehensively in LEED Zero Energy rating system for Chinese buildings except for renewable energy resources because air source or ground source heat pump system, which are extensively used in China but not acceptable in LEED Zero Energy rating system. High-performance strategies, including low U-value envelope, exterior shading devices, high air tightness envelope, high-efficiency heating, ventilation, and air-conditioning system, and low thermal bridge impact, can be applied to pursue LEED Zero Energy rating system. The incremental costs of NZEBs in China are also supported by government through market and financial policies. This would make significant impacts on Chinese buildings to achieve the LEED Zero Energy target.

Impact of different control strategies of perforated curved louvers on the visual comfort and energy consumption of office buildings in different climates

Highly glazed façades in office buildings are often affected by excessive solar heat gains and daylighting. The use of exterior shading devices is one of the most effective strategies for controlling daylighting and solar heat gains through glazed façades and for maintaining the thermal and visual comfort. Exterior shading systems can either be fixed or movable (tilting and/or retracting). The latter are frequently used with control systems. The objective of this study was to evaluate the impact of four control strategies applied to a shading device made of movable curved and perforated louvers on the visual comfort and total energy consumption (for heating, cooling and artificial lighting) of an office space using integrated thermal and lighting simulations. The investigated control strategies were: an incident irradiance control, a vertical eye illuminance based control, a cut-off angle control and a blocking control. The obtained results were compared to those of three systems with fixed (unmovable) louvers. Simulations were performed for four cities with different climatic conditions: Montreal (Canada), Santiago (Chile), Boulder (USA) and Miami (USA). The assessment of the visual comfort was based on the spatial daylight autonomy (sDA) and simplified daylight glare probability (DGPs). The results indicate that, for the cities of Montreal, Santiago and Boulder, the optimal strategy is the ‘vertical eye illuminance control’, together with the ‘incident irradiance control’ in the case of Santiago. These strategies minimize the total energy consumption of the office space while ensuring visual comfort. In Miami, the best strategy corresponds to the ‘blocking control’ for the south façade orientation while blinds with fixed louvers (tilt angle of 60°) perform better than the active control strategies studied for the west façade orientation. The real world implementation complexity of each control strategy is also discussed.

Avaliação do desempenho da luz natural em ambientes residenciais

A utilização da luz natural contribui com a redução do uso de iluminação artificial em ambientes internos. Esta pesquisa tem como objetivo avaliar o desempenho da luz natural em ambientes de cozinha e de área de serviço de residências multifamiliares com diferentes configurações espaciais na cidade de Porto Alegre – RS, por meio dos critérios da NBR 15575-2013 e da métrica de avaliação Useful Daylight Illuminance (UDI). Os objetos de estudo foram divididos em dois grupos: modelos com iluminação natural direta para ambos os ambientes e modelos com iluminação natural indireta para a cozinha. As análises foram realizadas por meio de simulação computacional com o software DIALux e o plug-in DIVA para Rhinoceros. Com base nas análises realizadas pela NBR 15575-2013, classificou-se como desempenho lumínico intermediário apenas a cozinha com brise de proteção solar, à medida que todos os outros ambientes foram classificados como desempenho superior, indicando que o uso de iluminação artificial não se faz necessário ao longo do dia. O valor de iluminância obtido no ponto do centro geométrico não coincidiu com a bancada da pia da cozinha, assim, não se teve a garantia do mesmo nível de desempenho lumínico nessa superfície. Os resultados obtidos pela métrica UDI indicaram a prevalência do intervalo autônomo nos modelos com iluminação direta e o intervalo suplementar nos modelos com iluminação indireta. Diferentemente das análises por meio da norma, a métrica UDI considera a média da iluminância do recinto, abrangendo os ambientes como um todo.

Numerical study on the energy performance of building zones with transparent water storage envelopes

Researches on water wall passive solar technologies, especially the numerical study on the energy performance of building zones with Transparent Water Storage Envelopes (TWSEs), are reported in this paper. TWSE is a climatic adaptive building envelope consisting of visually transparent modular water containers, exterior shading devices, water supply and return pipes. It is an upgraded water wall that can serve both as an energy efficient facade and an auxiliary water cistern in a building. Currently the energy simulation involving transparent water walls cannot be explicitly done in all energy simulation programs because transparent envelopes are always predefined as the surfaces without thermal mass due to the embedded algorithms complied with ISO15099 standard. A numerical approach based on the integrated energy and computational fluid dynamics (IE&CFD) simulation was developed for solving the energy simulation problem related with TWSEs. A simplified optical model of TWSE was proposed and validated through light transmission testing. Meanwhile, cooling and heating loads of a zone with TWSEs and conventional glazing in summer and winter months were studied. The thermal performance of a TWSE relative to the conventional glazing was also investigated via the comparative thermal box testing. Based on the simulation and testing results, it reveals that TWSEs can exceed most high performance coated glazing with regard to solar radiation control, and they are also exceptional energy efficient transparent envelopes that can outperform the ASHRAE standard window and conventional glazing in terms of cooling and heating load reduction as long as being configured and operated properly according to their physical characteristics and outdoor climatic condition. Furthermore, the innovative technical paradigm of TWSEs, along with the numerical approach developed for their energy simulation, demonstrates a wide range of versatility to be implemented in research and practice for ultra low energy buildings.

Performance evaluation of a photovoltaic thermal-compound thermoelectric ventilator system

External fixed shading devices are generally used to adjust solar influx radiation and save energy in summer. However, they could block the beneficial solar radiation in winter. In this paper, a photovoltaic thermal-compound thermoelectric ventilator (PVT–TEV) system is proposed and investigated. The PVT–TEV system not only could prevent direct solar radiation from going into buildings in summer, but also could heat fresh air by the air-type PVT coupled with a thermoelectric ventilator system in winter. A PVT–TEV system was built in a room for testing the system. Results demonstrate that the performance of the PVT–TEV system is mainly affected by solar radiation when the system works in the sunny days of winter. The stronger the solar radiation is, the more the heat of PVT–TEV system gains and the higher the fresh air temperature is. The average electrical efficiency of PVT is 10%, the average thermal efficiency of PVT–TEV is 26.7% and the average COPh of PVT–TEV is 6.4. In the rainy day, the outdoor fresh air is heated when it flows through heat pipe exchangers of the thermoelectric ventilator. The higher the working voltage is, the more the heat TEV system gains and the lower the COPh of the TEV system is. The average COPh of PVT–TEV system is 1.73 when the operating voltage is 24 V. The PVT–TEV system provides an active and green method for building exterior shading device and supplying fresh air.

Influence of orientation and the impact of external window shading on building thermal performance in tropical climate

Energy saving in buildings is a high-priority in developed countries as buildings are responsible for a substantial part of the energy consumption. Typically heating, cooling and artificial ventilation systems of a building are major consumer of energy. A validated Fortran 77 compiler program has been used to elaborate the influence of building orientation on building energy consumption. The amount of heat influx through windows on different oriented vertical walls for various direction has been compared and it has been found that heat gain through south oriented windows is maximum followed by East, West and North bound windows in a tropical climate of northern hemisphere. An experimentally designed, Programmable Logic Controller based movable exterior window shading device linked with sun path has been introduced through a validated TRNSYS building model to show the reduction in cooling load of a hospital building in tropical climate. The simulation study shows that maximum energy savings can be achieved in the month of June i.e. 14.9% and average energy savings is 9.8% annually by movable exterior window shading for a building in tropical climate. Through an economic analysis it has been established that the proposed exterior shading device is financially viable and the payback comes within 6 months. This study is useful for professionals who are responsible for decision-making during the design phase of energy-efficient buildings and can show a path for sustainable building design.

Horizontal or vertical? Windows’ layout selection for shading devices optimization

Purpose The purpose of this paper is to constitute an efficient way to improve energy efficiency and occupants comfort in buildings through reduction of direct solar heat gains by exterior shading devices. The shadings orientation and layout depends on the building location and façade orientation, and influence consequently the windows layout. It is still debated which type of window layout is preferable for a specific building location and façade orientation. Design/methodology/approach The paper presents a method to determine the most efficient windows’ layout, horizontal or vertical, for shading devices optimization by mean of integrating energy simulations and computational design. A parametric model has been built by visual programming language to simulate, iterate and compare the results. Findings The research shows the most efficient layouts of windows to be shaded for three latitudes and locations, and the 16 cardinal directions, to be used by architects and designers. The results show a significant prevalence of the horizontal window type on the south façades but also on the east and west orientations for all the three locations, while the rules of thumb would suggest the vertical layout for the sunrise and sunset façades. Originality/value The task of designing exterior shading devices presents two main issues: the shading period selection and the method of calculating its size and shape. The present research uses the innovative method Shaderade that existing literature demonstrates superior comparing other more dated like the section method and the solar vectors one.

Development and Innovation of Exterior Shading Devices for Climate Responsive Architecture

The current energy crisis and global warming drive many issues of architectural practice and research fields including sustainable architecture and design guidelines for environmentally friendly. The effective strategy of reducing the solar radiation passing into the building, is to design building skins responsive to the climate and radiation from the sun. However, today few of intelligent systems imparted to the responsive building skins, have been already invented and selling, unfortunately, these equipments cannot be offered to all consumers, but only for the high-end projects due to their high technology process and expensive cost as mostly the same as other eco-friendly products in the market, especially in Thailand. The question arises as to whether it is possible to develop the climate responsive building skins by low-cost technology. This article aims to review the developments of climate responsive building skins in term of solar shading device, and to propose the innovation of automatically adjustable sun louvers with real-time solar tracking systems. Enhancing the efficiency of solar radiation protection into the building, the operable sun louvers can be gained the indirect natural daylight in the same time. With emphasis in the low-cost technology, this product is composed of light weight steel blades installed with inexpensive adjustable prefab hinges, solar tracker system with sensor of LDR (Light Dependent Resistors), and local microcontroller board. This climate responsive sun louvers with simple, uncomplicated, and economical systems can be integrated into both existing buildings and new design buildings, and be an ideal part of the “green” architectural solution affordable for every single households.

외부 가변차양 장치의 내풍성능 시험 방법 도출

Exterior shading devices can easily be affected from the surrounding environment such as snow, rain, wind, and outside temperature. Therefore, it has to be tested and reviewed whether the exterior shading devices are safe from the surrounding environment. Especially, wind resistance performance of the exterior shading devices is important because the deterioration or falling parts of the devices can be dangerous for the person. There are several test methods for wind resistance performance of the exterior shading devices, however they are limited to the lab test. The purpose of this study is to develop the field test method for wind resistance performance of the exterior movable shading devices such as a exterior venetian blind, roll blind, shutter, and awning. As a first step, various purposes of international standards for the shading devices were reviewed in order to derive compulsory test items which should be conducted in the field related to the construction quality including safety. And, it was found that wind resistance, operation in frosty condition, and snow resistance are crucial items for the field test items. In order to develop field test method for wind resistance performance, the major field issues such as setting apparatus and finding proper test wind speed were discussed with the current lab test methods. Finally, field test set about the wind speed measuring point and the location of the apparatus were proposed, and also three of test wind speed for safety, operation, and control were proposed.

Design and Energy Performance of a Buoyancy Driven Exterior Shading Device for Building Application in Taiwan

Traditional dynamic shading systems are usually driven by electricity for continuously controlling the angle of blind slats to minimize the indoor solar heat gain over times. This paper proposed a novel design of buoyancy driven dynamic shading system, using only minimum amount of electricity. The energy performance and the improved thermal comfort induced by the system were simulated by EnergyPlus for a typical office space under the context of Taiwanese climate. The design processes are composed of three parts: an alterable angle of blind slats that raises the energy performance to be suitable for every orientation, the buoyancy driven transmission mechanism, and a humanized controller that ensures its convenience. The environmental friendly design aspects and control mechanisms to fulfill demands for manufacturing, assembling, maintenance and recycling, etc., were also presented as readily for building application. Besides, the effectiveness of cooling energy saving and thermal comfort enhancing were compared against the cases without exterior blinds and with traditional fixed blinds installed. The results show that the cooling energy is drastically reduced over times and the blind system is effectively enhancing the indoor thermal comfort.

Viability of exterior shading devices for high-rise residential buildings: Case study for cooling energy saving and economic feasibility analysis

Proper use of building shading devices can only improve the thermal comfort in indoor environment, but also reduce cooling energy consumption effectively. Researches on this topic have been mostly conducted for office buildings, but were limited for exterior shading devices of high-rise buildings, where cooling is a major energy consumer. This paper presents an integrated approach for exterior shading design analysis about energy performance and economic feasibility in a high-rise residential building (Seoul, Korea) by both numerical simulations and field mock-up test for possibility of installing. The sun-shading/daylighting performance analysis of the 48 exterior shading devices was measured with 4.0m×3.2m window module size during the period of May–September. Furthermore, quantitative analysis of the cooling energy saving potential of solar radiation controls was conducted with DOE-2.1E simulation program. The cooling energy saving potential was about 20%, while the reducing of solar heat gain by the two exterior shading devices (the horizontal overhang and the vertical panel) would lead to a decrease of the cooling energy demand 19.7% and 17.3%, respectively. Cost benefit and economic feasibility was also analyzed, in consideration of the OPEX and CAPEX, depending on the shading type. The significance of this study lies in providing basic information for rational exterior shading planning, when designing high-rise residential buildings.

An empirical study of performance characteristics of BIPV (Building Integrated Photovoltaic) system for the realization of zero energy building

In this study, we analyze the performance characteristics of BIPV (Building Integrated Photovoltaic) system of Climate Change Research Building of National Environment Research Institution which was designed with the aim of zero carbon building. This building totaling 2449 m2 is consist of five laboratories, PR (Performance Ratio) department, conference room and others, and the area of conditioned space is 1668 m2. In addition, the remaining residual load was predicted to 99,200 kWh when load reducing system was applied such as insulation, exterior shading device and lighting control.BIPV system, which is consist of three modules; G to G (Glass to Glass), G to T (Glass to Tedlar/Crystal) and Amorphous, has 116.2 kWp of total capacity, and is applied to wall, window, atrium and pagora on roof.After the completion of building, the total amount of energy consumption and the gross generation of BIPV system were 104602.4 kWh and 105266.6 kWh through a year from April 2011 to March 2012, respectively. It was evaluated to achieve zero carbon building because the energy surplus was 664.2 kWh.

Conventional fixed shading devices in comparison to an electrochromic glazing system in hot, dry climate

Electrochromic glazing or exterior shading devices offer shading of the intense direct sun, reduce glare, and improve the daylight luminance within buildings. Additionally, they are important factors affecting energy performance of buildings as they impact the heating and cooling consumption. This analysis investigated the performance and the effectiveness of electrochromic glazing to prevent unwanted solar heat gains from entering a conditioned space. Then, these performances are compared to those offered by conventional fixed exterior shading devices in identical conditions. The aim of this analysis is to provide architects and designers with general guidance and appropriate design strategies for different window treatments and shading techniques during early design stages in hot, dry climate. A typical office building is modeled using DesignBuilder software. Building envelope characteristics, internal loads, and operating schedules including schedules for equipment, occupancy, interior lighting, heating, ventilating, air conditioning, and weather data are all unchanged throughout the simulation process. The windows shading condition and the glazing type are the only varying parameters. The output data show that electrochromic glazing provides the best performance in reducing solar heat gains compared to other tested shading conditions.

Using phase change materials in window shutter to reduce the solar heat gain

A significant amount of the solar heat gain in buildings comes through the windows, and the most effective way to reduce it is to install exterior shading devices, such as window shutters. The window shutters are typically made of foam filled aluminum rolling shutter slat. In this research, a technique of solar heat gain reduction in building through windows using phase change material (PCM) in the shutter instead of foam is investigated using finite element method. The objective of using PCM in the shutters is to utilize its high latent heat of fusion to reduce the heat gain by absorbing the heat gain before it reaches the indoor space. The thermal effectiveness of the proposed PCM shutter system is evaluated by comparing the gain at the indoor space to the heat gain of foam shutter during typical working hours. A parametric study is conducted to assess the effect of different design parameters, such as PCM's type and quantity in the shutter. The result indicates that PCM with the highest examined melting temperature shows the best thermal performance, and the heat gain through windows can be reduced as high as 23.29%.

Comparative advantage of an exterior shading device in thermal performance for residential buildings

Optimal shading systems should increase daylight levels while controlling the amount of excessive sunlight and reducing discomfort and glare for the occupants. To eliminate the effect of absorbing solar heat, shading systems should be located in the external part of the window. An external shading device requires many design consideration such as solar geometry, physical dimension of the elements, materials, finishes, control strategies, and aesthetics. This study proposes an experimental configuration of an external shading device can be applied to apartment houses in South Korea. To verify the advantage of the external device, conventional daylighting devices have been examined and compared in terms of energy savings for heating and cooling. A series of simulations by an energy analysis program, IES_VE, has revealed that the experimental shading device promises the most efficient performance with various adjustments of the slat angle. A secondary advantage is that it also provides better views for occupants.

A comparative analysis of the radiant effect of external sunshades on glass surface temperatures

The paper is part of a larger study, in which the author investigates the effects of radiant heat transfer from exterior shading devices on the surface temperatures of glass using an experimental setup at the Solar Laboratory at Arizona State University, Arizona, USA. Shading devices play an important role in controlling the amount of direct solar radiation entering the interior of a building. Designers provide various material alternatives while designing these exterior-shading devices. The main idea is to improve the aesthetic appearance of the building facade while at the same time providing an efficient shading system to the fenestration. One important effect that is overlooked by most of the currently available whole building simulation tools is the long-wave radiant (re-radiation) effect these shading devices have on the glass temperatures. The paper investigates the radiant effect using sunshades made of three different materials and compares the effectiveness of RADTHERM (a simulation tool used to simulate the experiment).