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Financial Innovation Among the Community Wind Sector in the United States

Description: In the relatively brief history of utility-scale wind generation, the 'community wind' sector - defined here as consisting of relatively small utility-scale wind power projects that are at least partly owned by one or more members of the local community - has played a vitally important role as a 'test bed' or 'proving ground' for wind turbine manufacturers. In the 1980s and 1990s, for example, Vestas and other now-established European wind turbine manufacturers relied heavily on community wind projects in Scandinavia and Germany to install - and essentially field-test - new turbine designs. The fact that orders from community wind projects seldom exceeded more than a few turbines at a time enabled the manufacturers to correct any design flaws or manufacturing defects fairly rapidly, and without the risk of extensive (and expensive) serial defects that can accompany larger orders. Community wind has been slower to take root in the United States - the first such projects were installed in the state of Minnesota around the year 2000. Just as in Europe, however, the community wind sector in the U.S. has similarly served as a proving ground - but in this case for up-and-coming wind turbine manufacturers that are trying to break into the broader U.S. wind power market. For example, community wind projects have deployed the first U.S. installations of wind turbines from Suzlon (in 2003), DeWind (2008), Americas Wind Energy (2008) and later Emergya Wind Technologies (2010),1 Goldwind (2009), AAER/Pioneer (2009), Nordic Windpower (2010), Unison (2010), and Alstom (2011). Just as it has provided a proving ground for new turbines, so too has the community wind sector in the United States served as a laboratory for experimentation with innovative new financing structures. For example, a variation of one of the most common financing arrangements in the U.S. wind market ...
Date: January 19, 2011
Creator: Bolinger, Mark
Partner: UNT Libraries Government Documents Department

Max Tech and Beyond: Fluorescent Lamps

Description: Fluorescent lamps are the most widely used artificial light source today, responsible for approximately 70% of the lumens delivered to our living spaces globally. The technology was originally commercialized in the 1930's, and manufacturers have been steadily improving the efficacy of these lamps over the years through modifications to the phosphors, cathodes, fill-gas, operating frequency, tube diameter and other design attributes. The most efficient commercially available fluorescent lamp is the 25 Watt T5 lamp. This lamp operates at 114-116 lumens per watt while also providing good color rendering and more than 20,000 hours of operating life. Industry experts interviewed indicated that while this lamp is the most efficient in the market today, there is still a further 10 to 14% of potential improvements that may be introduced to the market over the next 2 to 5 years. These improvements include further developments in phosphors, fill-gas, cathode coatings and ultraviolet (UV) reflective glass coatings. The commercialization of these technology improvements will combine to bring about efficacy improvements that will push the technology up to a maximum 125 to 130 lumens per watt. One critical issue raised by researchers that may present a barrier to the realization of these improvements is the fact that technology investment in fluorescent lamps is being reduced in order to prioritize research into light emitting diodes (LEDs) and ceramic metal halide high intensity discharge (HID) lamps. Thus, it is uncertain whether these potential efficacy improvements will be developed, patented and commercialized. The emphasis for premium efficacy will continue to focus on T5 lamps, which are expected to continue to be marketed along with the T8 lamp. Industry experts highlighted the fact that an advantage of the T5 lamp is the fact that it is 40% smaller and yet provides an equivalent lumen output to that of a ...
Date: April 1, 2012
Creator: Scholand, Michael
Partner: UNT Libraries Government Documents Department

Max Tech and Beyond: High-Intensity Discharge Lamps

Description: High-intensity discharge (HID) lamps are most often found in industrial and commercial applications, and are the light source of choice in street and area lighting, and sports stadium illumination. HID lamps are produced in three types - mercury vapor (MV), high pressure sodium (HPS) and metal halide (MH). Of these, MV and MH are considered white-light sources (although the MV exhibits poor color rendering) and HPS produces a yellow-orange color light. A fourth lamp, low-pressure sodium (LPS), is not a HID lamp by definition, but it is used in similar applications and thus is often grouped with HID lamps. With the notable exception of MV which is comparatively inefficient and in decline in the US from both a sales and installed stock point of view; HPS, LPS and MH all have efficacies over 100 lumens per watt. The figure below presents the efficacy trends over time for commercially available HID lamps and LPS, starting with MV and LPS in 1930's followed by the development of HPS and MH in the 1960's. In HID lamps, light is generated by creating an electric arc between two electrodes in an arc tube. The particles in the arc are partially ionized, making them electrically conductive, and a light-emitting 'plasma' is created. This arc occurs within the arc tube, which for most HID lamps is enclosed within an evacuated outer bulb that thermally isolates and protects the hot arc tube from the surroundings. Unlike a fluorescent lamp that produces visible light through down-converting UV light with phosphors, the arc itself is the light source in an HID lamp, emitting visible radiation that is characteristic of the elements present in the plasma. Thus, the mixture of elements included in the arc tube is one critical factor determining the quality of the light emitted from the lamp, ...
Date: April 1, 2012
Creator: Scholand, Michael
Partner: UNT Libraries Government Documents Department

Measuring Advances in HVAC Distribution System Design

Description: Substantial commercial building energy savings have been achieved by improving the performance of the HV AC distribution system. The energy savings result from distribution system design improvements, advanced control capabilities, and use of variable-speed motors. Yet, much of the commercial building stock remains equipped with inefficient systems. Contributing to this is the absence of a definition for distribution system efficiency as well as the analysis methods for quantifying performance. This research investigates the application of performance indices to assess design advancements in commercial building thermal distribution systems. The index definitions are based on a first and second law of thermodynamics analysis of the system. The second law or availability analysis enables the determination of the true efficiency of the system. Availability analysis is a convenient way to make system efficiency comparisons since performance is evaluated relative to an ideal process. A TRNSYS simulation model is developed to analyze the performance of two distribution system types, a constant air volume system and a variable air volume system, that serve one floor of a large office building. Performance indices are calculated using the simulation results to compare the performance of the two systems types in several locations. Changes in index values are compared to changes in plant energy, costs, and carbon emissions to explore the ability of the indices to estimate these quantities.
Date: May 1, 1998
Creator: Franconi, E.
Partner: UNT Libraries Government Documents Department

Commissioning: A Highly Cost-Effective Building Energy Management Strategy

Description: Quality assurance and optimization are essential elements of any serious technological endeavor, including efforts to improve energy efficiency. Commissioning is an important tool in this respect. The aim of commissioning new buildings is to ensure that they deliver-if not exceed-the performance and energy savings promised by their design. When applied to existing buildings, one-time or repeated commissioning (often called retrocommissioning) identifies the almost inevitable drift in energy performance and puts the building back on course, often surpassing the original design intent. In both contexts, commissioning is a systematic, forensic approach to improving performance, rather than a discrete technology.
Date: January 6, 2011
Creator: Mills, Evan
Partner: UNT Libraries Government Documents Department

ENERGY EFFICIENT BUILDINGS PROGRAM. CHAPTER FROM THE ENERGY AND ENVIRONMENT DIVISION ANNUAL REPORT 1979

Description: The research reported in this volume was undertaken during FY 1979 within the Energy & Environment Division of the Lawrence Berkeley Laboratory. This volume will comprise a section of the Energy & Environment Division 1979 Annual Report, to be published in the summer of 1980. Work reported relate to: thermal performance of building envelopes; building ventilation and indoor air quality; a computer program for predicting energy use in buildings; study focused specifically on inherently energy intensive hospital buildings; energy efficient windows and lighting; potential for energy conservation and savings in the buildings sector; and evaluation of energy performance standards for residential buildings.
Date: December 1, 1979
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

ENERGY USE AND CONSERVATION IN INDUSTRIALIZED COUNTRIES

Description: One of the important aspects of America's painful adjustment to energy realities since 1973 has been an overwhelming effort to look carefully at how we use energy. Much to our surprise there was tremendous slack in energy use at home even before the Oil Embargo, slack that could have been eliminated profitably. One suggestion that there was waste in our economy came from careful inspection of energy use elsewhere. But early discussion of energy use in other lands has been marred by many distortions and misunderstandings, not only on the part of those who tend to doubt the potential for energy conservation but even among conservation's strongest supporters. This misunderstanding arises from comparisons of energy use and gross national product, two quantities that have charmed correlators and energy statisticians for decades. Though serious work cannot be based upon relationships between two such aggregated quantities, it is useful to review some of the popular myths surrounding energy comparisons among countries.
Date: November 1, 1978
Creator: Schipper, L.
Partner: UNT Libraries Government Documents Department

Effect of Environmental Factors on Sulfur Gas Emissions from Drywall

Description: Problem drywall installed in U.S. homes is suspected of being a source of odorous and potentially corrosive indoor pollutants. The U.S. Consumer Product Safety Commission's (CPSC) investigation of problem drywall incorporates three parallel tracks: (1) evaluating the relationship between the drywall and reported health symptoms; (2) evaluating the relationship between the drywall and electrical and fire safety issues in affected homes; and (3) tracing the origin and the distribution of the drywall. To assess the potential impact on human health and to support testing for electrical and fire safety, the CPSC has initiated a series of laboratory tests that provide elemental characterization of drywall, characterization of chemical emissions, and in-home air sampling. The chemical emission testing was conducted at Lawrence Berkeley National Laboratory (LBNL). The LBNL study consisted of two phases. In Phase 1 of this study, LBNL tested thirty drywall samples provided by CPSC and reported standard emission factors for volatile organic compounds (VOCs), aldehydes, reactive sulfur gases (RSGs) and volatile sulfur compounds (VSCs). The standard emission factors were determined using small (10.75 liter) dynamic test chambers housed in a constant temperature environmental chamber. The tests were all run at 25 C, 50% relative humidity (RH) and with an area-specific ventilation rate of {approx}1.5 cubic meters per square meter of emitting surface per hour [m{sup 3}/m{sup 2}/h]. The thirty samples that were tested in Phase 1 included seventeen that were manufactured in China in 2005, 2006 and 2009, and thirteen that were manufactured in North America in 2009. The measured emission factors for VOCs and aldehydes were generally low and did not differ significantly between the Chinese and North American drywall. Eight of the samples tested had elevated emissions of volatile sulfur-containing compounds with total RSG emission factors between 32 and 258 micrograms per square meter per hour [{micro}g/m{sup ...
Date: August 20, 2011
Creator: Maddalena, Randy
Partner: UNT Libraries Government Documents Department

Analysis of Casualty Risk per Police-Reported Crash for Model Year 2000 to 2004 Vehicles, using Crash Data from Five States

Description: In this report we compare two measures of driver risks: fatality risk per vehicle registration-year, and casualty (fatality plus serious injury) risk per police-reported crash. Our analysis is based on three sets of data from five states (Florida, Illinois, Maryland, Missouri, and Pennsylvania): data on all police-reported crashes involving model year 2000 to 2004 vehicles; 2005 county-level vehicle registration data by vehicle model year and make/model; and odometer readings from vehicle emission inspection and maintenance (I/M) programs conducted in urban areas of four of the five states (Florida does not have an I/M program). The two measures of risk could differ for three reasons: casualty risks are different from fatality risk; risks per vehicle registration-year are different from risks per crash; and risks estimated from national data are different from risks from the five states analyzed here. We also examined the effect of driver behavior, crash location, and general vehicle design on risk, as well as sources of potential bias in using the crash data from five states.
Date: March 20, 2011
Creator: Wenzel, Tom
Partner: UNT Libraries Government Documents Department

Austin's Home Performance with Energy Star Program: Making a Compelling Offer to a Financial Institution Partner

Description: Launched in 2006, over 8,700 residential energy upgrades have been completed through Austin Energy's Home Performance with Energy Star (HPwES) program. The program's lending partner, Velocity Credit Union (VCU) has originated almost 1,800 loans, totaling approximately $12.5 million. Residential energy efficiency loans are typically small, and expensive to originate and service relative to larger financing products. National lenders have been hesitant to deliver attractive loan products to this small, but growing, residential market. In response, energy efficiency programs have found ways to partner with local and regional banks, credit unions, community development finance institutions (CDFIs) and co-ops to deliver energy efficiency financing to homeowners. VCU's experience with the Austin Energy HPwES program highlights the potential benefits of energy efficiency programs to a lending partner.
Date: March 18, 2011
Creator: Zimring, Mark
Partner: UNT Libraries Government Documents Department

Co-Simulation of Building Energy and Control Systems with the Building Controls Virtual Test Bed

Description: This article describes the implementation of the Building Controls Virtual Test Bed (BCVTB). The BCVTB is a software environment that allows connecting different simulation programs to exchange data during the time integration, and that allows conducting hardware in the loop simulation. The software architecture is a modular design based on Ptolemy II, a software environment for design and analysis of heterogeneous systems. Ptolemy II provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run-time. The BCVTB provides additions to Ptolemy II that allow the run-time coupling of different simulation programs for data exchange, including EnergyPlus, MATLAB, Simulink and the Modelica modelling and simulation environment Dymola. The additions also allow executing system commands, such as a script that executes a Radiance simulation. In this article, the software architecture is presented and the mathematical model used to implement the co-simulation is discussed. The simulation program interface that the BCVTB provides is explained. The article concludes by presenting applications in which different state of the art simulation programs are linked for run-time data exchange. This link allows the use of the simulation program that is best suited for the particular problem to model building heat transfer, HVAC system dynamics and control algorithms, and to compute a solution to the coupled problem using co-simulation.
Date: August 22, 2010
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department

Using Qualified Energy Conservation Bonds (QECBs) to Fund a Residential Energy Efficiency Loan Program: Case Study on Saint Louis County, MO

Description: Qualified Energy Conservation Bonds (QECBs) are federally-subsidized debt instruments that enable state, tribal, and local government issuers to borrow money to fund a range of qualified energy conservation projects. QECBs offer issuers very attractive borrowing rates and long terms, and can fund low-interest energy efficiency loans for home and commercial property owners. Saint Louis County, MO recently issued over $10 million of QECBs to finance the Saint Louis County SAVES residential energy efficiency loan program. The county's experience negotiating QECB regulations and restrictions can inform future issuers.
Date: June 23, 2011
Creator: Zimring, Mark
Partner: UNT Libraries Government Documents Department

The Value of Energy Performance and Green Attributes in Buildings: A Review of Existing Literature and Recommendations for Future Research

Description: Labels, certifications, and rating systems for energy efficiency performance and “green” attributes of buildings have been available in the U.S. for over 10 years, and used extensively in the European Union and Australia for longer. Such certifications and ratings can make energy efficiency more visible, and could help spur demand for energy efficiency if these designations are shown to have a positive impact on sales or rental prices. This policy brief discusses the findings and methodologies from recent studies on this topic, and suggests recommendations for future research. Although there have been just a handful of studies within the last 10 years that have investigated these effects, a few key findings emerge: To maximize sales price impact, label or rating information must be disclosed early and visibly in the sales process; The approach to evaluating energy efficiency labels (e.g., ENERGY STAR) and general “green” certifications (e.g., LEED or GreenPoint Rated) may need to be different, depending on the type, vintage and market penetration of the label; Collaborative efforts to promote label adoption and build a large dataset of labeled buildings will be required to produce reliable study results.
Date: September 7, 2011
Creator: Stuart, Elizabeth
Partner: UNT Libraries Government Documents Department

A View on Future Building System Modeling and Simulation

Description: This chapter presents what a future environment for building system modeling and simulation may look like. As buildings continue to require increased performance and better comfort, their energy and control systems are becoming more integrated and complex. We therefore focus in this chapter on the modeling, simulation and analysis of building energy and control systems. Such systems can be classified as heterogeneous systems because they involve multiple domains, such as thermodynamics, fluid dynamics, heat and mass transfer, electrical systems, control systems and communication systems. Also, they typically involve multiple temporal and spatial scales, and their evolution can be described by coupled differential equations, discrete equations and events. Modeling and simulating such systems requires a higher level of abstraction and modularisation to manage the increased complexity compared to what is used in today's building simulation programs. Therefore, the trend towards more integrated building systems is likely to be a driving force for changing the status quo of today's building simulation programs. Thischapter discusses evolving modeling requirements and outlines a path toward a future environment for modeling and simulation of heterogeneous building systems.A range of topics that would require many additional pages of discussion has been omitted. Examples include computational fluid dynamics for air and particle flow in and around buildings, people movement, daylight simulation, uncertainty propagation and optimisation methods for building design and controls. For different discussions and perspectives on the future of building modeling and simulation, we refer to Sahlin (2000), Augenbroe (2001) and Malkawi and Augenbroe (2004).
Date: April 1, 2011
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department

SOLAR ENERGY PROGRAM: CHAPTER FROM THE ENERGY AND ENVIRONMENT ANNUAL REPORT 1979

Description: Solar energy has become a major alternative for supplying a substantial fraction of the nation's future energy needs. The Department of Energy (DOE) supports activities ranging from the demonstration of existing technology to research on future possibilities; and at LBL projects are in progress which span that range of activities. To assess various solar applications it is important to quantify the solar resource. In one project, LBL is cooperating with the Pacific Gas and Electric Company in the implementation and operation of a solar radiation data collection network in northern California. Special instruments have been developed and are now in use to measure the solar and circumsolar (around the sun) radiation. These measurements serve to predict the performance of solar designs which use focusing collectors (mirrors or lenses) to concentrate the sunlight. Efforts are being made to assist DOE in demonstrating existing solar technology. DOE's San Francisco Operations Office (SAN) has been given technical support for its management of commercial-building solar demonstration projects. The installation of a solar hot water and space heating system on an LBL building established model techniques and procedures as part of the DOE Facilities Solar Demonstration Program. Technical support is also provided for SAN in a DOE small scale technology pilot program in which grants are awarded to individuals and organizations to develop and demonstrate solar technologies appropriate to small scale use. In the near future it is expected that research will exert a substantial impact in the areas of solar heating and cooling. An absorption air conditioner is being developed that is air cooled yet suitable for use with temperatures available from flat plate collectors. With inexpensive but sophisticated micro-electronics to control their operation, the performance of many-component solar heating and cooling systems may be improved, and work is under way to develop such ...
Date: October 1, 1980
Creator: Authors, Various
Partner: UNT Libraries Government Documents Department

ROUTINE SPECTRAL MEASUREMENTS OF INFRARED RADIATION FROM THE ATMOSPHERE

Description: Infrared radiative cooling is a natural process continually underway in our environment. Thus, this process contributes in an important manner to the heat balance of buildings. An increase in radiative losses during the summer or a reduction of radiative losses during the winter will reduce energy consumption. A quantitative knowledge of the infrared radiative transfer between the atmosphere and a building's surface requires detailed information regarding the angular and spectral distribution of the radiation from the atmosphere. Routine information of this type has apparently never been gathered; most observations are limited to several days in time. The filter spectrometer system described here is intended to provide data records at 30 minute intervals for weeks and months of continuous operation. The spectrometer design incorporates a Barnes Corporation model 12-880 radiometer equipped with an eight-position filter wheel, germanium lens, and pyroelectric detector. Of the eight filter positions, one is an open hole and one is a closed hole used to determine the instrument's zero offset. The remaining 6 filter positions contain infrared interference filters with 'halfpower' cut-on and cut-off points given in microns by (8.1, 13.7), (8.3, 9.1), (9.4, 9.9), (10.0, 11.4), (14.0, 15.8), and (16.6, 21.6). In addition to a stepping mechanism which allows the filter wheel to be positioned automatically, the instrument contains a rotating mirror assembly which allows the instrument's 2{sup o} field of view to be directed into the vertical direction or into a 70 C black body cavity. The entire instrument is under microprocessor control and is accessible to Lawrence Berkeley Laboratory through a MODEM telephone link. The accumulating data is transmitted over this link at intervals of one to three days. Three radiometers are located in the field at the time of this writing. Systems were installed at Tucson, Arizona in August, 1978; at San Antonio, ...
Date: March 1, 1979
Creator: Berdahl, P.
Partner: UNT Libraries Government Documents Department

Financing Non-Residential Photovoltaic Projects: Options and Implications

Description: Installations of grid-connected photovoltaic (PV) systems in the United States have increased dramatically in recent years, growing from less than 20 MW in 2000 to nearly 500 MW at the end of 2007, a compound average annual growth rate of 59%. Of particular note is the increasing contribution of 'non-residential' grid-connected PV systems--defined here as those systems installed on the customer (rather than utility) side of the meter at commercial, institutional, non-profit, or governmental properties--to the overall growth trend. Although there is some uncertainty in the numbers, non-residential PV capacity grew from less than half of aggregate annual capacity installations in 2000-2002 to nearly two-thirds in 2007. This relative growth trend is expected to have continued through 2008. The non-residential sector's commanding lead in terms of installed capacity in recent years primarily reflects two important differences between the non-residential and residential markets: (1) the greater federal 'Tax Benefits'--including the 30% investment tax credit (ITC) and accelerated tax depreciation--provided to commercial (relative to residential) PV systems, at least historically (this relative tax advantage has largely disappeared starting in 2009) and (2) larger non-residential project size. These two attributes have attracted to the market a number of institutional investors (referred to in this report as 'Tax Investors') seeking to invest in PV projects primarily to capture their Tax Benefits. The presence of these Tax Investors, in turn, has fostered a variety of innovative approaches to financing non-residential PV systems. This financial innovation--which is the topic of this report--has helped to overcome some of the largest barriers to the adoption of non-residential PV, and is therefore partly responsible (along with the policy changes that have driven this innovation) for the rapid growth in the market seen in recent years.ii Specifically, due to financial innovation, non-residential entities interested in PV no longer face prohibitively ...
Date: January 9, 2009
Creator: Bolinger, Mark
Partner: UNT Libraries Government Documents Department

Generic Optimization Program User Manual Version 3.0.0

Description: GenOpt is an optimization program for the minimization of a cost function that is evaluated by an external simulation program. It has been developed for optimization problems where the cost function is computationally expensive and its derivatives are not available or may not even exist. GenOpt can be coupled to any simulation program that reads its input from text files and writes its output to text files. The independent variables can be continuous variables (possibly with lower and upper bounds), discrete variables, or both, continuous and discrete variables. Constraints on dependent variables can be implemented using penalty or barrier functions. GenOpt uses parallel computing to evaluate the simulations. GenOpt has a library with local and global multi-dimensional and one-dimensional optimization algorithms, and algorithms for doing parametric runs. An algorithm interface allows adding new minimization algorithms without knowing the details of the program structure. GenOpt is written in Java so that it is platform independent. The platform independence and the general interface make GenOpt applicable to a wide range of optimization problems. GenOpt has not been designed for linear programming problems, quadratic programming problems, and problems where the gradient of the cost function is available. For such problems, as well as for other problems, special tailored software exists that is more efficient.
Date: May 11, 2009
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department

Opportunities for Saving Energy and Improving Air Quality in Urban Heat Islands

Description: World energy use is the main contributor to atmospheric CO2. In 2002, about 7.0 giga metric tons of carbon (GtC) were emitted internationally by combustion of gas, liquid, and solid fuels (CDIAC, 2006), 2 to 5 times the amount contributed by deforestation (Brown et al., 1988). The share of atmospheric carbon emissions for the United States from fossil fuel combustion was 1.6 GtC. Increasing use of fossil fuel and deforestation together have raised atmospheric CO{sub 2} concentration some 25% over the last 150 years. According to global climate models and preliminary measurements, these changes in the composition of the atmosphere have already begun raising the Earth's average temperature. If current energy trends continue, these changes could drastically alter the Earth's temperature, with unknown but potentially catastrophic physical and political consequences. During the last three decades, increased energy awareness has led to conservation efforts and leveling of energy consumption in the industrialized countries. An important byproduct of this reduced energy use is the lowering of CO{sub 2} emissions. Of all electricity generated in the United States, about one-sixth is used to air-condition buildings. The air-conditioning use is about 400 tera-watt-hours (TWh), equivalent to about 80 million metric tons of carbon (MtC) emissions, and translating to about $40 billion (B) per year. Of this $40 B/year, about half is used in cities that have pronounced 'heat islands'. The contribution of the urban heat island to the air-conditioning demand has increased over the last 40 years and it is currently at about 10%. Metropolitan areas in the United States (e.g., Los Angeles, Phoenix, Houston, Atlanta, and New York City) have typically pronounced heat islands that warrant special attention by anyone concerned with broad-scale energy efficiency (HIG, 2006). The ambient air is primarily heated through three processes: direct absorption of solar radiation, convection of ...
Date: July 1, 2007
Creator: Akbari, Hashem
Partner: UNT Libraries Government Documents Department

Performance Evaluation for a Modular, Scalable Passive Cooling System in Data Centers

Description: Scientific and enterprise data centers, IT equipment product development, and research data center laboratories typically require continuous cooling to control inlet air temperatures within recommended operating levels for the IT equipment. The consolidation and higher density aggregation of slim computing, storage and networking hardware has resulted in higher power density than what the raised-floor system design, coupled with commonly used computer rack air conditioning (CRAC) units, was originally conceived to handle. Many existing data centers and newly constructed data centers adopt CRAC units, which inherently handle heat transfer within data centers via air as the heat transfer media. This results in energy performance of the ventilation and cooling systems being less than optimal. Understanding the current trends toward higher power density in IT computing, more and more IT equipment manufacturers are designing their equipment to operate in 'conventional' data center environments, while considering provisions of alternative cooling solutions to either their equipment or supplemental cooling in rack or row systems. In the meanwhile, the trend toward higher power density resulting from current and future generations of servers has created significant opportunities for precision cooling to engineer and manufacture packaged modular and scalable systems. The modular and scalable cooling systems aim at significantly improving efficiency while addressing the thermal challenges, improving reliability, and allowing for future needs and growth. Such pre-engineered and manufactured systems may be a significant improvement over current design; however, without an energy efficiency focus, their applications could also lead to even lower energy efficiencies in the overall data center infrastructure. The overall goal of the project supported by California Energy Commission was to characterize four commercially available, modular cooling systems installed in a data center. Such modular cooling systems are all scalable localized units, and will be evaluated in terms of their operating energy efficiency in a ...
Date: May 1, 2009
Creator: Xu, TengFang
Partner: UNT Libraries Government Documents Department

Performance Evaluation for Modular, Scalable Liquid-Rack Cooling Systems in Data Centers

Description: Scientific and enterprise data centers, IT equipment product development, and research data center laboratories typically require continuous cooling to control inlet air temperatures within recommended operating levels for the IT equipment. The consolidation and higher density aggregation of slim computing, storage and networking hardware has resulted in higher power density than what the raised-floor system design, coupled with commonly used computer rack air conditioning (CRAC) units, was originally conceived to handle. Many existing data centers and newly constructed data centers adopt CRAC units, which inherently handle heat transfer within data centers via air as the heat transfer media. This results in energy performance of the ventilation and cooling systems being less than optimal. Understanding the current trends toward higher power density in IT computing, more and more IT equipment manufacturers are designing their equipment to operate in 'conventional' data center environments, while considering provisions of alternative cooling solutions to either their equipment or supplemental cooling in rack or row systems. In the meanwhile, the trend toward higher power density resulting from current and future generations of servers has created significant opportunities for precision cooling suppliers to engineer and manufacture packaged modular and scalable systems. The modular and scalable cooling systems aim at significantly improving efficiency while addressing the thermal challenges, improving reliability, and allowing for future needs and growth. Such pre-engineered and manufactured systems may be a significant improvement over current design; however, without an energy efficiency focus, their applications could also lead to even lower energy efficiencies in the overall data center infrastructure. The overall goal of the project supported by California Energy Commission was to characterize four commercially available, modular cooling systems installed in a data center. Such modular cooling systems are all scalable localized units, and will be evaluated in terms of their operating energy efficiency in ...
Date: May 1, 2009
Creator: Xu, TengFang
Partner: UNT Libraries Government Documents Department

Networks in Buildings: Which Path Forward?

Description: To date, digital networks have principally been installed for connecting information technology devices, with more modest use in consumer electronics, security, and large building control systems. The next 20 years will see much greater deployment of networks in buildings of all types, and across all end uses. Most of these are likely to be introduced primarily for reasons other than energy efficiency, and add energy use for network interfaces and network products. Widespread networking could easily lead to increased energy use, and experience with IT and CE networks suggests this may be likely. Active engagement by energy efficiency professionals in the architecture and design of future networks could lead to their being a large and highly cost-effective tool for efficiency. However, network standards are complex and take many years to develop and negotiate so that lack of action on this in the near term may foreclose important opportunities for years or decades to come. Digital networks need to be common globally, providing another challenge to building systems and elements that are more commonly designed only for national or regional markets. Key future networks are lighting, climate control, and security/presence. This paper reviews some examples of past network designs and use and the lessons they hold for future building networks. It also highlights key needed areas for research, policy, and standards development.
Date: August 17, 2008
Creator: Nordman, Bruce
Partner: UNT Libraries Government Documents Department

A Modelica-based Model Library for Building Energy and Control Systems

Description: This paper describes an open-source library with component models for building energy and control systems that is based on Modelica, an equation-based objectoriented language that is well positioned to become the standard for modeling of dynamic systems in various industrial sectors. The library is currently developed to support computational science and engineering for innovative building energy and control systems. Early applications will include controls design and analysis, rapid prototyping to support innovation of new building systems and the use of models during operation for controls, fault detection and diagnostics. This paper discusses the motivation for selecting an equation-based object-oriented language. It presents the architecture of the library and explains how base models can be used to rapidly implement new models. To demonstrate the capability of analyzing novel energy and control systems, the paper closes with an example where we compare the dynamic performance of a conventional hydronic heating system with thermostatic radiator valves to an innovative heating system. In the new system, instead of a centralized circulation pump, each of the 18 radiators has a pump whose speed is controlled using a room temperature feedback loop, and the temperature of the boiler is controlled based on the speed of the radiator pump. All flows are computed by solving for the pressure distribution in the piping network, and the controls include continuous and discrete time controls.
Date: April 7, 2009
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department

Modelica-based Modeling and Simulation to Support Research and Development in Building Energy and Control Systems

Description: Traditional building simulation programs possess attributes that make them difficult to use for the design and analysis of building energy and control systems and for the support of model-based research and development of systems that may not already be implemented in these programs. This article presents characteristic features of such applications, and it shows how equation-based object-oriented modelling can meet requirements that arise in such applications. Next, the implementation of an open-source component model library for building energy systems is presented. The library has been developed using the equation-based object-oriented Modelica modelling language. Technical challenges of modelling and simulating such systems are discussed. Research needs are presented to make this technology accessible to user groups that have more stringent requirements with respect to the numerical robustness of simulation than a research community may have. Two examples are presented in which models from the here described library were used. The first example describes the design of a controller for a nonlinear model of a heating coil using model reduction and frequency domain analysis. The second example describes the tuning of control parameters for a static pressure reset controller of a variable air volume flow system. The tuning has been done by solving a non-convex optimization problem that minimizes fan energy subject to state constraints.
Date: February 12, 2009
Creator: Wetter, Michael
Partner: UNT Libraries Government Documents Department