Exterior Shading Research Articles

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.

Techno-Economic Optimization for Buildings’ Exterior Shading Programs

For multi-floor public buildings, exterior shading plays a more and more important role in architectural design. In this paper, a program at lowest investment costs on premise of equivalent function value is selected for projects with several alternative shading programs by using value engineering method and by conducting techno-economic comprehensive appraisals on aspects of shading, ventilation, cost, appearance and maintenance and some other factors.

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.

The zero-peak house: Full-scale experiments and demonstration

Houses represent a substantial fraction of the summer peak electrical load, and therefore measures to reduce peak demand at the household level may be valuable in stabilizing the grid and lowering peak costs. We conducted studies in geometrically-identical, side-by-side full-scale detached houses. One house was operated in a conventional manner and provided a typical reference case. In the other house we applied a variety of measures designed to reduce or shift load from peak periods. Our results demonstrated that a combination of practical operational modifications (air-conditioner cycling, doing laundry later in the evening) and commercially-available technology (exterior shading, modest PV array, energy-efficient lighting) was able to dramatically reduce (in some cases to zero) the peak electrical demand from the grid on the hottest days of the year.

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.

Indoor Environment State of Classrooms Situated in the Loft Spaces of Civil Engineering Faculty TU in Kosice – Dynamic Analysis Using Design Builder

A purpose of this submission is a dynamic analysis of indoor environment on the suitably chosen classrooms, which are situated in loft spaces of Civil Engineering Faculty TU of Kosice. The evaluation was doing by using energy simulation tool DesignBuilder. In this submission there are compared different modes of natural ventilation during a day, with or without night ventilation. The next subject of presented analysis is to consider the installation of the exterior shading elements and their influence on a modification of an operative temperature in classrooms. The purpose of the whole submission is to obtain a dynamic view of indoor environment changes that are determined by internal and external factors.

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.

Visual Comfort Analysis of Innovative Interior and Exterior Shading Systems for Commercial Buildings using High Resolution Luminance Images

The objective of this study was to explore how calibrated high dynamic range (HDR) images (luminance maps) acquired in real world daylit environments can be used to characterize, evaluate, and compare visual comfort conditions of innovative facade shading and light-redirecting systems. Detailed (1536 × 1536 pixel) luminance maps were time-lapse acquired from two view positions in an unoccupied full scale testbed facility. These maps were analyzed using existing visual comfort metrics to quantify how innovative interior and exterior shading systems compare to conventional systems under real sun and sky conditions over a solstice-to-solstice test interval. The results provide a case study in the challenges and potential of methods of visualizing, evaluating and summarizing daily and seasonal variation of visual comfort conditions computed from large sets of image data.

Integration of distributed generation systems into generic types of commercial buildings in California

Distributed generation (DG) of combined cooling, heat, and power (CCHP) has been gaining momentum in recent years as an efficient, secure alternative for meeting increasing power demands in the world. One of the most critical and emerging markets for DG-CCHP systems is commercial and institutional buildings. The present study focuses analysis on the main economic, energy-efficiency, and environmental impacts of the integration of three types of advanced DG technologies (high-temperature fuel cells, micro-turbines, and photovoltaic solar panels) into four types of representative generic commercial building templates (small office building, medium office building, hospital, and college/school) in southern California (e.g., mild climate), using eQUEST as energy simulation tool. Detailed load profiles for the four commercial building types during times of peak electric and peak gas consumption were analyzed and complementary strategies to further increase overall building energy efficiencies such as energy efficiency measures (e.g., day lighting, exterior shading, improved HVAC performance) and thermally activated absorption cooling were also investigated. Results show that the high-temperature fuel cell (HTFC) performance is best matched with the hospital energy loads, resulting in a 98% DG capacity factor, 85% DG heat recovery factor, and $860,000 in energy savings (6 years payback). The introduction of thermally driven double-effect absorption cooling (AC) in the college building with HTFC reduces significantly the building electricity-to-thermal load ratio and boosts the heat recovery factor from 37% to 97%.

Energy and visual comfort performance of electrochromic windows with overhangs

DOE-2 building energy simulations were conducted to determine if there were practical architectural and control strategy solutions that would enable electrochromic (EC) windows to significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. The EC performance was compared to a state-of-the-art spectrally selective low-e window with the same divided window wall, window size, and overhang as the EC configuration. The reference window was also combined with an interior shade which was manually deployed to control glare and direct sun. Both systems had the same daylighting control system to dim the electric lighting. Results were given for south-facing private offices in a typical commercial building. In hot and cold climates such as Houston and Chicago, EC windows with overhangs can significantly reduce the average annual daylight glare index (DGI) and deliver significant annual energy use savings if the window area is large. Total primary annual energy use was increased by 2–5% for moderate-area windows in either climate but decreased by 10% in Chicago and 5% in Houston for large-area windows. Peak electric demand can be reduced by 7–8% for moderate-area windows and by 14–16% for large-area windows in either climate. Energy and peak demand reductions can be significantly greater if the reference case does not have exterior shading or state-of-the-art static glass.

Recommendations for Horizontal Shading Depths for Vertical Building Facades in the Tropic Region with particular reference to Penang, Malaysia

In the tropics, direct penetrating sunlight brings in heat and glare as well. Architects have various openings in various orientations and need a simple and fast method to calculate the extent of exterior shading depth required for each opening. A computer program was used to analyze incoming sunlight through openings of various orientations in Penang, in all the twelve months of the year. Simulations done also took into consideration the various nett openings that can occur in any particular floor section. Results were then tabulated in a simple form that can easily be understood and used by consultant architects. It is hoped that guidelines like this can be incorporated in the building by laws as they can help reduce heat gain and glare problems of interiors in the tropical climate.

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).

Energy Performance Assessment of Multiple-Skin Facades

This paper discusses modeling the energy performance of an office equipped with a conventional insulated glazing unit with exterior shading and with three multiple-skin facade typologies (an airflow window, a supply air window, and a naturally ventilated window) under typical Belgian weather conditions. It is found that multiple-skin facades may improve the energy efficiency. However, the analysis shows that variants performing well in winter are not necessarily beneficial in summer. Combining typologies or changing the systems' settings according to the particular situation will be necessary to obtain an overall year-round improvement. The results further indicate that evaluating the energy efficiency of multiple-skin facades cannot be performed by solely analyzing the transmission losses and gains. It is imperative to take into account the enthalpy change of the cavity air and to perform a whole building energy analysis.

A software tool for user-friendly interface with PC Superlite 2.0

SYNOPSIS The PC Superlite 2.0 is a research tool which can handle with sufficient accuracy a complex room under different sky conditions (C.I.E. clear sky with direct sun, clear without direct sun, overcast sky, uniform sky), also modelling exterior shading surfaces and nearby buildings. In particular the input file requires a series of numbers that describe for instance the geometry of the room being studied and the weather data; this involves a “waste time” in deciphering and consulting the accompanying manual. The output file also requires supplemental work to show the results in tabular or graphic form. A great amount of time is invested to learn how to use and then manipulate the program. A new simple software tool was developed to aid architects and designers in daylighting analysis. The software, written in Microsoft Visual Basic programing system version 3.0 for Windows 3.1 or later, permits an easy and fast input file management, with a user friendly interface and comprehensive help on line. The ...