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Articles 2491 - 2520 of 4566

Full-Text Articles in Engineering

Freeform Reflector Design With Extended Sources, Florian Fournier Jan 2010

Freeform Reflector Design With Extended Sources, Florian Fournier

Electronic Theses and Dissertations

Reflector design stemmed from the need to shape the light emitted by candles or lamps. Over 2,000 years ago people realized that a mirror shaped as a parabola can concentrate light, and thus significantly boosts its intensity, to the point where objects can be set afire. Nowadays many applications require an accurate control of light, such as automotive headlights, streetlights, projection displays, and medical illuminators. In all cases light emitted from a light source can be shaped into a desired target distribution with a reflective surface. Design methods for systems with rotational and translational symmetry were devised in the 1930s. …

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Quantum Dot Based Mode-Locked Semiconductor Lasers And Applications, Jimyung Kim Jan 2010

Quantum Dot Based Mode-Locked Semiconductor Lasers And Applications, Jimyung Kim

Electronic Theses and Dissertations

In this dissertation, self-assembled InAs/InGaAs quantum dot Fabry-Perot lasers and mode-locked lasers are investigated. The mode-locked lasers investigated include monolithic and curved two-section devices, and colliding pulse mode-locked diode lasers. Ridge waveguide semiconductor lasers have been designed and fabricated by wet etching processes. Electroluminescence of the quantum dot lasers is studied. Cavity length dependent lasing via ground state and/or excited state transitions is observed from quantum dot lasers and the optical gain from both transitions is measured. Stable optical pulse trains via ground and excited state transitions are generated using a grating coupled external cavity with a curved two-section device. …

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Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel Jan 2010

Electro-Optical And All-Optical Switching In Multimode Interference Waveguides Incorporating Semiconductor Nanostructures, Nathan Bickel

Electronic Theses and Dissertations

The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of …

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Accelerating Optical Airy Beams, Georgios Siviloglou Jan 2010

Accelerating Optical Airy Beams, Georgios Siviloglou

Electronic Theses and Dissertations

Over the years, non-spreading or non-diffracting wave configurations have been systematically investigated in optics. Perhaps the best known example of a diffraction-free optical wave is the so-called Bessel beam, first suggested and observed by Durnin et al. This work sparked considerable theoretical and experimental activity and paved the way toward the discovery of other interesting non-diffracting solutions. In 1979 Berry and Balazs made an important observation within the context of quantum mechanics: they theoretically demonstrated that the Schrodinger equation describing a free particle can exhibit a non-spreading Airy wavepacket solution. This work remained largely unnoticed in the literature-partly because such …

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Misalignment Induced Nodal Aberration Fields And Their Use In The Alignment Of Astronomical Telescopes, Tobias Schmid Jan 2010

Misalignment Induced Nodal Aberration Fields And Their Use In The Alignment Of Astronomical Telescopes, Tobias Schmid

Electronic Theses and Dissertations

Following the foundation of aberration theory for rotationally symmetric optical systems established by Seidel, Schwarzschild, Burch, Conrady, Buchdahl, and in its most useful form H.H. Hopkins, Shack, Buchroeder, Thompson, and Rogers developed a vectorial form of the wave aberration theory that enables addressing optical systems without symmetry. In this research, a vectorial theory is utilized and extended for the alignment of two- and three-mirror astronomical telescopes, including the effects of pointing changes and astigmatic figure errors. Importantly, it is demonstrated that the vectorial form of aberration theory, also referred to as nodal aberration theory, not only provides valuable insights but …

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Near-Field Optical Interactions And Applications, David Haefner Jan 2010

Near-Field Optical Interactions And Applications, David Haefner

Electronic Theses and Dissertations

The propagation symmetry of electromagnetic fields is affected by encounters with material systems. The effects of such interactions, for example, modifications of intensity, phase, polarization, angular spectrum, frequency, etc. can be used to obtain information about the material system. However, the propagation of electromagnetic waves imposes a fundamental limit to the length scales over which the material properties can be observed. In the realm of near-field optics, this limitation is overcome only through a secondary interaction that couples the high-spatial-frequency (but non-propagating) field components to propagating waves that can be detected. The available information depends intrinsically on this secondary interaction, …

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Epitaxial Growth, Characterization And Application Of Novel Wide Bandgap Oxide Semiconductors, Jeremy Mares Jan 2010

Epitaxial Growth, Characterization And Application Of Novel Wide Bandgap Oxide Semiconductors, Jeremy Mares

Electronic Theses and Dissertations

In this work, a body of knowledge is presented which pertains to the growth, characterization and exploitation of high quality, novel II-IV oxide epitaxial films and structures grown by plasma-assisted molecular beam epitaxy. The two compounds of primary interest within this research are the ternary films NixMg1-xO and ZnxMg1-xO and the investigation focuses predominantly on the realization, assessment and implementation of these two oxides as optoelectronic materials. The functioning hypothesis for this largely experimental effort has been that these cubic ternary oxides can be exploited - and possibly even juxtaposed - to realize novel wide band gap optoelectronic technologies. The …

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Micro-Electro-Mechanical Systems (Mems) And Agile Lensing-Based Modules For Communications, Sensing And Signal Processing., Syed Reza Jan 2010

Micro-Electro-Mechanical Systems (Mems) And Agile Lensing-Based Modules For Communications, Sensing And Signal Processing., Syed Reza

Electronic Theses and Dissertations

This dissertation proposes the use of the emerging Micro-Electro-Mechanical Systems (MEMS) and agile lensing optical device technologies to design novel and powerful signal conditioning and sensing modules for advanced applications in optical communications, physical parameter sensing and RF/optical signal processing. For example, these new module designs have experimentally demonstrated exceptional features such as stable loss broadband operations and high > 60 dB optical dynamic range signal filtering capabilities. The first part of the dissertation describes the design and demonstration of digital MEMS-based signal processing modules for communication systems and sensor networks using the TI DLP (Digital Light Processing) technology. Examples of …

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Fast Response Dual Frequency Liquid Crystal Materials, Qiong Song Jan 2010

Fast Response Dual Frequency Liquid Crystal Materials, Qiong Song

Electronic Theses and Dissertations

Dual frequency liquid crystal (DFLC) exhibits a positive dielectric anisotropy at low frequencies and negative dielectric anisotropy at high frequencies. The frequency where dielectric anisotropy is zero is called crossover frequency. DFLC can achieve fast rise time and fast decay time with the assistance of applied voltage. However, one drawback of DFLC is that it has dielectric heating effect when driven at a high frequency. Thus, the first part of this dissertation is to develop low crossover frequency DFLC materials. The dielectric relaxation and physical properties of some single- and double-ester compounds were investigated. Experimental results indicate that the double-ester …

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Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu Jan 2010

Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu

Electronic Theses and Dissertations

The general goal of this dissertation is to provide a comprehensive description of the limitations of established theories on bound electronic nonlinearities in direct-gap semiconductors by performing various experiments on wide and narrow bandgap semiconductors along with developing theoretical models. Nondegenerate two-photon absorption (2PA) is studied in several semiconductors showing orders of magnitude enhancement over the degenerate counterpart. In addition, three-photon absorption (3PA) is studied in ZnSe and other semiconductors and a new theory using a Kane 4-band model is developed which fits new data well. Finally, the narrow gap semiconductor InSb is studied with regard to multiphoton absorption, free-carrier …

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Silicon-Sensitized Erbium Excitation In Silicon-Rich Silica For Integrated Photonics, Oleksandr Savchyn Jan 2010

Silicon-Sensitized Erbium Excitation In Silicon-Rich Silica For Integrated Photonics, Oleksandr Savchyn

Electronic Theses and Dissertations

It is widely accepted that the continued increase of processor performance requires at least partial replacement of electronic interconnects with their photonic counterparts. The implementation of optical interconnects requires the realization of a silicon-based light source, which is challenging task due to the low emission efficiency of silicon. One of the main approaches to address this challenge is the use of doping of silicon based matrices with optical centers, including erbium ions. Erbium ions incorporated in various hosts assume the trivalent state (Er3+) and demonstrate a transition at 1.54 μm, coinciding with optical transmission windows in both silicon and silica. …

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A Fpga-Based Architecture For Led Backlight Driving, Zhaoshi Zheng Jan 2010

A Fpga-Based Architecture For Led Backlight Driving, Zhaoshi Zheng

Electronic Theses and Dissertations

In recent years, Light-emitting Diodes (LEDs) have become a promising candidate for backlighting Liquid Crystal Displays [1] (LCDs). Compared with traditional Cold Cathode Fluorescent Lamps (CCFLs) technology, LEDs offer not only better visual quality, but also improved power efficiency. However, to fully utilized LEDs' capability requires dynamic independent control of individual LEDs, which remains as a challenging topic. A FPGA-based hardware system for LED backlight control is proposed in this work. We successfully achieve dynamic adjustment of any individual LED's intensity in each of the three color channels (Red, Green and Blue), in response to a real time incoming video …

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A Self-Organizing Hybrid Sensor System With Distributed Data Fusion For Intruder Tracking And Surveillance, Ravishankar Palaniappan Jan 2010

A Self-Organizing Hybrid Sensor System With Distributed Data Fusion For Intruder Tracking And Surveillance, Ravishankar Palaniappan

Electronic Theses and Dissertations

A wireless sensor network is a network of distributed nodes each equipped with its own sensors, computational resources and transceivers. These sensors are designed to be able to sense specific phenomenon over a large geographic area and communicate this information to the user. Most sensor networks are designed to be stand-alone systems that can operate without user intervention for long periods of time. While the use of wireless sensor networks have been demonstrated in various military and commercial applications, their full potential has not been realized primarily due to the lack of efficient methods to self organize and cover the …

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Investigating Solutions To Wind Washing Issues In 2-Story Florida Homes; Phase 1, Florida Solar Energy Center, Charles Withers, Jr. Dec 2009

Investigating Solutions To Wind Washing Issues In 2-Story Florida Homes; Phase 1, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Wind washing has been identified as a potentially significant issue regarding energy, demand, comfort, and humidity in some two-story Florida homes. In its most common configuration, wind washing occurs when attic spaces over first-floor portions of the home abut the second story, and the floor cavity of the second story is open to that attic space. Wind blowing into attic vents can push hot attic air into the inter-story floor cavity, bypassing the typical thermal boundaries of the building and introducing considerable heat into the house. Wind washing can also occur when there is little or no attic involved, where …

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Nightcool: Nocturnal Radiation Cooling Concept, Long Term Performance Evaluation, Florida Solar Energy Center, John Sherwin Dec 2009

Nightcool: Nocturnal Radiation Cooling Concept, Long Term Performance Evaluation, Florida Solar Energy Center, John Sherwin

FSEC Energy Research Center®

An experimental evaluation has been conducted on a building-integrated night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling - largely during nighttime hours. Available house mass is used to store sensible cooling. The system's capability for solar dehumidification with minimal electricity input is demonstrated with long-term performance data taken over 2007 - 2009. A year-long study period …

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Final Report: Space Coast Clean Cities Coalition Programmatic Support, Florida Solar Energy Center, William Young Nov 2009

Final Report: Space Coast Clean Cities Coalition Programmatic Support, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

This Final Report summarizes the work performed by the Florida Solar Energy Center for U.S. Department of Energy for the National Clean Cities Program to reduce emissions and energy consumption of transportation vehicles. This report describes the activities and events of Florida Space Coast Clean Cities Coalition encompassing a nine county area in east central Florida. FSEC administers the Coalition and support the Coalition Board of Directors with meetings, workshop, reports, mailing list, membership, activities, questionnaires, fuel pricing, alternative vehicle and infrastructure deployment.

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Developing G-Rim And Participants Tests For Specific Commercial Programs For The Florida Natural Gas Association, Florida Solar Energy Center, Richard Raustad Nov 2009

Developing G-Rim And Participants Tests For Specific Commercial Programs For The Florida Natural Gas Association, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The Florida Solar Energy Center performed an economic assessment for 7 common commercial appliances. This assessment calculates the gas rate impact measure and participants test score for selecting natural gas equipment over comparable electric equipment over a 20-year period. This type of analysis provides an indication whether or not the specific appliance program favors the end use customer and/or the utility company as economic beneficiaries. Given the project assumptions, all natural gas equipment types, with the exception of the pool heat pump water heater, show measures greater than 1 indicating that the natural gas appliance will have lower life-cycle costs …

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Developing Natural Gas Cost Escalation Rates For The Associated Gas Distributors Of Florida, Florida Solar Energy Center, Richard Raustad Nov 2009

Developing Natural Gas Cost Escalation Rates For The Associated Gas Distributors Of Florida, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The Florida Solar Energy Center (FSEC) created a spreadsheet tool used to calculate the fuel escalation rates for electricity and natural gas for the previous 5-year and 10-year periods. These escalation rates are calculated at the local, State, and national level for both residential and commercial customers. The previous 5-year and 10-year general inflation rate as determined by the U.S. Department of Labor's Bureau of Labor Statistics consumer price index are also included. These calculations are made in accordance with rules established by the Florida Building Commission pursuant to rule 9B-13.0071, Cost Effectiveness of Amendments to Energy Code.

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Evaluation Of Alternatives For Florida's 2010 Energy Code Update For Residential Buildings, Florida Solar Energy Center, Philip W. Fairey Oct 2009

Evaluation Of Alternatives For Florida's 2010 Energy Code Update For Residential Buildings, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

This report provides results of analysis of the Florida Energy Code (FEC) with respect to requirements of Florida House Bill 7135. The analysis uses Florida's performance-based code compliance software, EnergyGauge® USA, to conduct detailed analysis of H.B 7135 requirements to significantly increase the efficiency of new homes over time. First, results of an analysis of the long-term, year 2019 requirement for a 50% increase in new home energy efficiency are presented. Next, the 2009 edition of the International Energy Conservation Code (IECC) is analyzed with respect to the H.B. 7135 dual requirements that the 2009 IECC become the foundation code …

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Clean Cities Annual Operating Plan 2009: Florida Space Coast Clean Cities Coalition, Florida Solar Energy Center, William Young Oct 2009

Clean Cities Annual Operating Plan 2009: Florida Space Coast Clean Cities Coalition, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

In March, 1997, the Florida Solar Energy Center (FSEC) joined the U.S. Department of Energy (DOE) Clean Cities program to form the Florida Space Coast Clean Cities Coalition in East Central Florida. Space Coast Coalition now consists of 10 counties, as the State is divided into eight Clean Cities regions. Florida Solar Energy Center is located in Cocoa in the approximate center of the coalition area. On October 1, 1999, the expanded Florida Space Coast Clean Cities Coalition was designated and authorized as the 75th Clean Cities Coalition. The Florida Space Coast Clean Cities Coalition is a 501-3c non-profit corporation …

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Stormwater Irrigation Volume Iii: Transport Of The Cyanotoxin Microcystin In Groundwater Beneath Stormwater Ponds: Results Of Soil Column Experiments, Martin Wanielista Sep 2009

Stormwater Irrigation Volume Iii: Transport Of The Cyanotoxin Microcystin In Groundwater Beneath Stormwater Ponds: Results Of Soil Column Experiments, Martin Wanielista

BMP Trains Research and Publications

As the demand for fresh water increases in central Florida to meet both public supply and irrigation needs, stormwater is increasingly being managed as a resource to help offset possible future declines in aquifer water levels. Water quality is an important consideration when using stormwater for recharge or harvesting. A constituent of recent concern is cyanobacteria (popularly known as blue-green algae) because some of these can produce toxins (cyanotoxins) that are detrimental to animal and human health. Microcystins are the most commonly found type of cyanotoxin in Florida and have been detected in a variety of rivers, natural lakes, and …

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Comparison Of The Energygauge Usa And Beopt Building Energy Simulation Programs, Florida Solar Energy Center, Danny Parker Aug 2009

Comparison Of The Energygauge Usa And Beopt Building Energy Simulation Programs, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Two hourly energy simulation software, BEopt and Energy Gauge USA, were compared to ensure accuracy and evaluate agreement on the impact of various energy efficiency improvements. Within the Building America program, these software aid design teams working toward the U.S. Department of Energy's goal to make Zero Energy Homes economically viable by 2025. Builders use the software to achieve the extensive energy savings (70%-80%) from various measures before adding solar electric power generation. The study found that in general, BEopt and EnergyGauge USA agree fairly well on the impact of energy efficiency improvements, while identifying several discrepancies that need further …

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Geographic Variation In Potential Of Residential Solar Hot Water System Performance In The United States, Florida Solar Energy Center, Camilo Gil Aug 2009

Geographic Variation In Potential Of Residential Solar Hot Water System Performance In The United States, Florida Solar Energy Center, Camilo Gil

FSEC Energy Research Center®

This paper describes an assessment of residential solar water heater performance around the continental United States. We performed annual simulations using an hourly simulation model (EGUSA) for 212 TMY3 weather locations around the nation. The annual simulations show how standard hot water energy use for electric and gas systems vary geographically (kWh and therms) as well as the potential energy savings from solar water heaters. A key finding is that the energy necessary for water heating varies by 2:1 around the U.S. with implications for solar water heating system design and sizing. Our results provide information on expected water heater …

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Preliminary Report On Integration Of Florida's Code Energy Efficiencies Using The 2009 Iecc As The Foundation Code, Florida Solar Energy Center, Philip W. Fairey Jul 2009

Preliminary Report On Integration Of Florida's Code Energy Efficiencies Using The 2009 Iecc As The Foundation Code, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

The Florida Building Commission is in the initial phase of it triennial revision of the Florida Building Code. The Florida Building Code has included specific energy provisions since its inception in 2001. Those provisions are the Florida Energy Code (FEC), which was initiated in 1979. In 2008, the Florida legislature enacted HB 7135, requiring the 2010 FEC to provide 20% energy savings compared with the 2007 FEC. HB 7135 also requires that the energy provisions of the Florida Building Code use the 2009 IECC as the foundation and that the IECC shall be modified to maintain the efficiencies of the …

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Puerto Rico - Pv Training Program Study - Final Report, Florida Solar Energy Center, William Young Jul 2009

Puerto Rico - Pv Training Program Study - Final Report, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

This Final Report summarizes the work preformed on the program entitled "Puerto Rico PV Training Program Study" for the period April 14, 2008 to June 30, 2009. The program was a contract effort between Mech-Tech College, Caguas, Puerto Rico and the Florida Solar Energy Center/University of Central Florida, Cocoa, Florida. Mech-Tech College was interested in learning about and applying renewable energy technologies and providing college level courses for the future workforce of a renewable energy industry in Puerto Rico. This report documents the activities of Florida Solar Energy Center to assist Mech-Tech College in the design, development and implementation of …

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Analysis Of The Energy Star Reference Home Concept As Proposed For Epa's 2011 National Program Requirements, Florida Solar Energy Center, Philip W. Fairey Jul 2009

Analysis Of The Energy Star Reference Home Concept As Proposed For Epa's 2011 National Program Requirements, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

Using EnergyGauge® USA v.2.8.02, the Florida Solar Energy Center (FSEC) has conducted an analysis of EPA’s proposed ENERGY STAR Reference Design Home specification. A single-story, 2344 ft², slab-on-grade, 3-bedroom, frame home is evaluated in each of the seven contiguous U.S. climate zones. The ENERGY STAR Reference Design Home was evaluated using three metrics: 1) EPS’s threshold qualifying HERS Index (including the Size Adjustment Factor – 0.984 for this home), 2) the 2006 IECC Standard Reference Design and 3) the 2009 IECC Standard Reference Design. Evaluations using the IECC Standard Reference Design were computed using source energy, where the source energy …

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Top 10 Checklist - Energy-Efficient Buildings For The Southern United States, Florida Solar Energy Center, James Cummings Jun 2009

Top 10 Checklist - Energy-Efficient Buildings For The Southern United States, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The following Top Ten Checklist provides recommendations for creating energy efficient commercial buildings in areas with hot and humid summers. Commercial and institutional buildings vary greatly, from one to another, in size, use, and type of construction. For purposes of this Top Ten Checklist we are assuming a medium-sized (20,000 to 50,000 ft2) office building located in areas with hot and humid summers. The issues that are raised here may equally apply to schools, churches, theaters, and some retail buildings.

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Effectiveness Of Florida's Residential Energy Code: 1979-2009 (Revision Of 1979-2007 Report), Florida Solar Energy Center, Philip W. Fairey Jun 2009

Effectiveness Of Florida's Residential Energy Code: 1979-2009 (Revision Of 1979-2007 Report), Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

The 2007 Florida Legislature authorized the Florida Building Commission (FBC) and Department of Community Affairs (DCA) to evaluate cost effectiveness of energy conservation measures including appliance efficiencies that could be implemented through the Florida Energy Code for certain buildings. Additionally, Governor Crist's Executive Order #07-127 requires the Secretary of DCA to convene the Florida Building Commission for the purposes of revising the Florida Energy Code for Building Construction to increase the energy performance of new construction in Florida by at least 15% from the 2007 Energy Code. The Commission should consider incorporating standards for appliances and standard lighting in the …

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Interim Report On Iso Tc163 Working Group 3, Florida Solar Energy Center, Philip W. Fairey Apr 2009

Interim Report On Iso Tc163 Working Group 3, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

This report covers the initial year efforts of the International Standards Organization (ISO) to develop international standards for rating the energy performance of buildings. The author of this report is a participant in this effort. This report summarizes the activities of the ISO Working Group charged with development of these standards and makes recommendations to the sponsors for future U.S. involvement in this ISO effort.

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Energy Efficiency Cost-Effectiveness Tests For Residential Energy Code Update Processes, Florida Solar Energy Center, Philip W. Fairey Feb 2009

Energy Efficiency Cost-Effectiveness Tests For Residential Energy Code Update Processes, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

The 2008 Florida Energy Act directed the Florida Building Commission (FBC) to develop an administrative rule for determining the cost-effectiveness of energy efficiency updates to the Florida Building Code. This report addresses the economics of building energy efficiency, standard economic cost-effectiveness indicators that could be used for code update purposes and makes specific recommendations on economic assessment standards to be included in the cost-effectiveness test administrative rule.

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