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Business, Engineering, Architectural Engineering, Computer Science, Acoustics, and 15 moreAesthetics, Glass, Control Systems, Control system, Environmental Concern, Daylight, Energy Saving, Design Tool, Building Design, Daylighting, Facade, Building Envelope, Boolean Satisfiability, Energy Cost, and glazing
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Daylight can reduce electric lighting in buildings. This is facilitated by sensors that relay real-time illuminance data to a light controller. When daylight provides greater than required or desired levels of illuminance, control actions... more
Daylight can reduce electric lighting in buildings. This is facilitated by sensors that relay real-time illuminance data to a light controller. When daylight provides greater than required or desired levels of illuminance, control actions enable electric lights to reduce their output and save energy. Occupant behaviours can block desk sensors and this reduces the amount of energy saved. However, no method exists that can be used to continuously monitor sensors to ensure they operate as intended (e.g. remain unblocked). We carried out a study in an open-plan office building in Singapore, consisting of 39 workstations each fitted with desk illuminance sensors independently controlling a dedicated ceiling light. Power over Ethernet was used to collect individual data signals for both illuminance and power from each workstation. Data were collected across a one month period, sampling signals at every 2-minute interval. A linear support vector machine model accurately classified 99% of the data points using our sensor blocking algorithm. From 447,455 data points analysed, 12% of dataset showed that sensors were blocked and this had an estimated energy penalty of 24%. We do not recommend installing illuminance sensors at the desk. Our study highlights the usefulness of Power over Ethernet for closed-loop daylight harvesting. The data collected can be used to monitor the health of the sensors' performance to help minimise energy use.
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Engineering, Architecture, Energy, Architectural Lighting, Energy Efficiency Buildings, and 14 moreBuilt Environment, Energy and Environment, Green architecture, Environmental Sustainability, LED Lighting, Installation, Lighting Design, Daylight, Architectural Lighting Design, Ethernet, Daylighting, Closed Loop, Illuminance, and Desk
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Author(s): Ko, Won Hee; Brager, Gail; Schiavon, Stefano; Selkowitz, Stephen | Abstract: The goal of this project was to assess the visual effect of selected aspects of the building envelope on human performance and perception, first... more
Author(s): Ko, Won Hee; Brager, Gail; Schiavon, Stefano; Selkowitz, Stephen | Abstract: The goal of this project was to assess the visual effect of selected aspects of the building envelope on human performance and perception, first broadly, and then focused on view clarity. The initial literature review examined human factors that could be explicitly considered in building envelope design, operation and current daylight metrics. We found that debate remains on the practical applicability of these metrics, and gaps exist between daylight and other building envelope-related aspects such as view. Following the literature review, we narrowed down our research question to experimentally investigate the visual performance of fabric shading systems and electrochromic windows under both diffuse and direct sunlight conditions, and develop a view clarity rating method. We introduce and show results from an experimental study done at Lawrence Berkeley National Laboratory’s Windows Testbeds. W...
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Building facades are key to the building systems integration necessary to realise critical health, carbon,resilience, and sustainability goals in buildings and urban habitats. In addition, facade system designand delivery may be the most... more
Building facades are key to the building systems integration necessary to realise critical health, carbon,resilience, and sustainability goals in buildings and urban habitats. In addition, facade system designand delivery may be the most rapidly developing building technology, with novel materials, assembliesand techniques introduced in the marketplace frequently. However, these developments are occurringin the long-running absence of an appropriate framework for facade system performance evaluation.There has been no general convergence on the assessment criteria nor, for the most part, on the metricsto accompany those criteria. The convergence of myriad and often competing variables that characterisethe building facade mark the development of a comprehensive integrative assessment framework asa wicked problem, The lack of such a framework inhibits meaningful development and adoption ofinnovative facade technology, leaving aesthetic considerations to drive application and compromisi...
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Architectural Engineering, Computer Science, Curtain Wall, Curtainwall and Structural Glazing, Façades, and 9 moreFacade, Curtain Walling, External Curtain Wall Glazing, Sustainability, Curtain Wall and Cladding Systems, High performance facades, passive house facades, facades and sustainability, and facades and resilience
August 3, 2010 Berkeley Lab talk: In the fourth of five Carbon Smackdown matches, Berkeley Lab researchers Delia Milliron of the Materials Sciences Division and Stephen Selkowitz of the Environmental Energy Technologies Division talk... more
August 3, 2010 Berkeley Lab talk: In the fourth of five Carbon Smackdown matches, Berkeley Lab researchers Delia Milliron of the Materials Sciences Division and Stephen Selkowitz of the Environmental Energy Technologies Division talk about their work on energy-saving smart windows.
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Author(s): Selkowitz, S; Hart, R; Curcija, C | Abstract: Windows account for about 4 Quads of US energy consumption or 12% of building energy use. After 20 years of public/private investment (from 1980 to 2000) in technology RaD, coupled... more
Author(s): Selkowitz, S; Hart, R; Curcija, C | Abstract: Windows account for about 4 Quads of US energy consumption or 12% of building energy use. After 20 years of public/private investment (from 1980 to 2000) in technology RaD, coupled with new rating and labeling organizations (NFRC) and with subsequent voluntary ENERGY STAR programs and tighter codes and standards, windows using low-E/argon gas fill (~R3) gained a dominant market share and now account for g86% of all annual sales. However, this remarkable transformation of prior markets has stagnated, with triple glazing (~R5-R7) comprising less than 2% of all window sales in 2016. U.S. Department of Energy (DOE) estimates the national technical potential savings using R5-R7 windows at ~ 2Q annually, but manufacturers claim they would have to redesign their entire sash/frame inventory to accommodate the thicker and heavier insulating glass units (IGUs) in conventional triple glazed window designs. This paper outlines the initial...
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This paper presents the annual overall energy performance and energy-saving potential of a ventilated photovoltaic double-skin facade (PV-DSF) in a cool-summer Mediterranean climate zone. A numerical simulation model based on EnergyPlus... more
This paper presents the annual overall energy performance and energy-saving potential of a ventilated photovoltaic double-skin facade (PV-DSF) in a cool-summer Mediterranean climate zone. A numerical simulation model based on EnergyPlus was utilized to simulate the PV-DSF overall energy performance, simultaneously taking into account thermal power and daylight. Based on numerical model, sensitivity analyses about air gap width and ventilation modes have been lead in Berkeley (California) with the aim to optimize unit’s structure design and operational strategy of PV-DSF. Via simulation, the overall energy performance including thermal, power and daylighting of the optimized PV-DSF was evaluated using the typical meteorological year (TMY) weather data. It was found that per unit area of the proposed PV-DSF was able to generate about 65kWh electricity yearly. If high efficiency cadmium telluride (CdTe) semi-transparent PV modules are adopted, the annual energy output could be even doubled. The PV-DSF studied, also featured good thermal and daylighting performances. The PV-DSF can effectively block solar radiation while still providing considerable daylighting illuminance. Due simply to excellent overall energy performance, a PV-DSF at Berkeley can reduce net electricity use by about 50% compared with other commonly used glazing systems. Efficiency improvements of semi-transparent PV modules would further increase the energy saving potential of a PV-DSF and thus making this technology more promising.
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Windows in the U.S. consume 30 percent of building heating and cooling energy, representing an annual impact of 4.1 quadrillion BTU (quads) of primary energy. Windows have an even larger impact on peak energy demand and on occupant... more
Windows in the U.S. consume 30 percent of building heating and cooling energy, representing an annual impact of 4.1 quadrillion BTU (quads) of primary energy. Windows have an even larger impact on peak energy demand and on occupant comfort. An additional 1 quad of lighting energy could be saved if buildings employed effective daylighting strategies. The ENERGY STAR{reg_sign} program has
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Edison through the Califor-
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Electrochromic windows can reduce buildings’ energy demand and improve occupants’ comfort, yet they struggle to fully meet market needs. Now, researchers demonstrate that polymer additives improve light and solar heat modulation of... more
Electrochromic windows can reduce buildings’ energy demand and improve occupants’ comfort, yet they struggle to fully meet market needs. Now, researchers demonstrate that polymer additives improve light and solar heat modulation of reflective electrochromic windows, with potential for durable, large-scale and low-cost manufacturing.
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In most areas of the United States, windows are by far the poorest insulating material used in buildings. As a result, approximately 3 percent of the nation’s energy use is used to offset heat lost through windows. Under cold conditions,... more
In most areas of the United States, windows are by far the poorest insulating material used in buildings. As a result, approximately 3 percent of the nation’s energy use is used to offset heat lost through windows. Under cold conditions, conventional double glazings create uncomfortable spaces and collect condensation. However, with the recent introduction of low-emissivity (low-E) coatings and low/conductivity gas filling to respectively reduce radiative and conductive/convective heat transfer between glazing layers, some manufacturers are beginning to offer windows with R-values (resistance to heat transfer) of 4 hr-ft2-F/Btu (0.70 m2-C/W). This papers presents designs for and analysis and test results of an insulated glass unit with a center-of-glass R-value of 8-10; approximately twice as good as gas-filled low-E units, and four times that of conventional double glazing. This high-R design starts with a conventional insulated-glass unit and adds two low-emissivity coatings, a th...
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Engineering, Architectural Engineering, Architecture, Resilience, Energy, and 12 moreVision, Building Construction, Building, Neutrality, Technologies, Building Environment, Carbon Fibers, Sustainability, Zero Energy Building, Greenhouse Gas Emission, ENVIRONMENTAL SCIENCE AND MANAGEMENT, and Carbon neutrality
Results of a parametric study of the energy performance of a prototypical single-family ranch-style house are presented. The DOE-2.1B computer program was used to analyze the variation in heating, cooling, and total energy requirements... more
Results of a parametric study of the energy performance of a prototypical single-family ranch-style house are presented. The DOE-2.1B computer program was used to analyze the variation in heating, cooling, and total energy requirements due to changes in the following fenestration characteristics: orientation, size, conductance, and shading coefficient. These parameters allow us to estimate the performance of hypothetical fenestration systems using advanced aperture materials as well as commercially available products. The work represents the initial phase of a study in which the influence of other residential parameters such as internal loads, infiltration levels, natural ventilation, use of night insulation, shade management, and overhangs will also be investigated. Climate sensitivity was established by considering results from Madison, Wisconsin, and Lake Charles, Louisiana. To simplify the analysis, multiple regression techniques were used to generate a simplified algebraic expr...
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The emergence of low energy and Zero Net Energy (ZNE) building performance requirements combined with a growing array of human-factors objectives for light is driving a reversal of the conventional process of design and performance... more
The emergence of low energy and Zero Net Energy (ZNE) building performance requirements combined with a growing array of human-factors objectives for light is driving a reversal of the conventional process of design and performance analysis. Rather than using a predetermined design as a starting point for analysis, practitioners and researchers are exploring how performance requirements can be used to identify promising solutions among multiple early-stage design alternatives. In an ideal case, exploration begins in the earliest stages of conceptual design, enabled using iterative, simulation-based analysis and informed by emerging “form-finding” workflows. In a conventional design process, energy/environmental analysis tools are rarely used to inform design decision-making in early stages of design, if at all. Rather, analysis occurs after design development, often for code-compliance purposes or to obtain green building certification. Consequently, feedback from analysis cannot be...
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A project was undertaken to test the energy efficiency of ballasts. Two ballast types were used and retrofitted into existing fixtures on 3 floors in an office building in San Francisco. A core-coil energy efficient ballast was... more
A project was undertaken to test the energy efficiency of ballasts. Two ballast types were used and retrofitted into existing fixtures on 3 floors in an office building in San Francisco. A core-coil energy efficient ballast was demonstrated also. The demonstration ballasts proved to be more efficient than the standard core-coil ballasts they replaced. Their energy demand reduction has resulted in a lower weekly peak demand. Operating above 20 KHz they have produced less audible noise. They also have lower heat dissipation. RFI radiation, although increased, has caused no apparent difficulties. Light output has been reduced slightly by all three demonstration ballasts. Ballast energy usage has been measured successfully with standard utility metering but there remain doubts as to the effects of the harmonics associated with solid-state circuitry. While no adverse effects have been observed, research must continue on the accuracy of electrical metering and on the effect on utility sys...