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Improving the Performance of Lithium Manganese Phosphate Through Divalent Cation Substitution

Description: Highly crystalline samples of LiMnPO{sub 4} and its analogs with partial substitution of Mn by divalent Mg, Cu, Zn, and Ni were prepared by hydrothermal synthesis and characterized by x-ray diffraction and infrared spectroscopy. Chemical oxidation produced two-phase mixtures of the initial phases LiMn{sub (1-y)}M{sub y}PO{sub 4} and the delithiated forms, Li{sub y}Mn{sub (1-y)}M{sub y}PO{sub 4}, all with the olivine structure. The extent of oxidation depended upon the quantity of oxidizing agent used and on the identity of the substituent ions. Mg, Ni and Cu were found to increase the level of delithation relative to that in pure LiMnPO{sub 4}. Mg was also shown to reduce the tendency of the oxidized phase to absorb water.
Date: March 3, 2008
Creator: Chen, Guoying & Richardson, Thomas J.
Partner: UNT Libraries Government Documents Department

Supporting Solar Power in Renewables Portfolio Standards: Experience from the United States

Description: Among the available options for encouraging the increased deployment of renewable electricity, renewables portfolio standards (RPS) have become increasingly popular. The RPS is a relatively new policy mechanism, however, and experience with its use is only beginning to emerge. One key concern that has been voiced is whether RPS policies will offer adequate support to a wide range of renewable energy technologies and applications or whether, alternatively, RPS programs will favor a small number of the currently least-cost forms of renewable energy. This report documents the design of and early experience with state-level RPS programs in the United States that have been specifically tailored to encourage a wider diversity of renewable energy technologies, and solar energy in particular. As shown here, state-level RPS programs specifically designed to support solar have already proven to be an important, albeit somewhat modest, driver for solar energy deployment, and those impacts are projected to continue to build in the coming years. State experience in supporting solar energy with RPS programs is mixed, however, and full compliance with existing requirements has not been achieved. The comparative experiences described herein highlight the opportunities and challenges of applying an RPS to specifically support solar energy, as well as the importance of policy design details to ensuring that program goals are achieved.
Date: October 1, 2010
Creator: Wiser, Ryan; Barbose, Galen & Holt, Edward
Partner: UNT Libraries Government Documents Department

Thermal Instability of Olivine-Type LiMnP04 Cathodes

Description: The remarkable thermal stability of LiFePO{sub 4} and its charged counterpart, FePO{sub 4}, have been instrumental in its commercialization as a lithium ion battery cathode material. Despite the similarity in composition and structure, and despite the high thermal stability of the parent compound, LiMnPO{sub 4}, we find that the delithiated phase Li{sub y}MnPO{sub 4}, (which contains a small amount of residual lithium), is relatively unstable and reactive toward a lithium ion electrolyte. The onset temperature for heat evolution in the presence of 1M LiPF{sub 6} in 1:1 ethylene carbonate/propylene carbonate is around 150 C, and the total evolved heat is 884 J/g, comparable to that produced under similar conditions by charged LiCoO{sub 2} electrodes.
Date: July 7, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Partner: UNT Libraries Government Documents Department

Contam airflow models of three large buildings: Model descriptions and validation

Description: Airflow and pollutant transport models are useful for several reasons, including protection from or response to biological terrorism. In recent years they have been used for deciding how many biological agent samplers are needed in a given building to detect the release of an agent; to figure out where those samplers should be located; to predict the number of people at risk in the event of a release of a given size and location; to devise response strategies in the event of a release; to determine optimal trade-offs between sampler characteristics (such as detection limit and response time); and so on. For some of these purposes it is necessary to model a specific building of interest: if you are trying to determine optimal sampling locations, you must have a model of your building and not some different building. But for many purposes generic or 'prototypical' building models would suffice. For example, for determining trade-offs between sampler characteristics, results from one building will carry over other, similar buildings. Prototypical building models are also useful for comparing or testing different algorithms or computational pproaches: different researchers can use the same models, thus allowing direct comparison of results in a way that is not otherwise possible. This document discusses prototypical building models developed by the Airflow and Pollutant Transport Group at Lawrence Berkeley National Laboratory. The models are implemented in the Contam v2.4c modeling program, available from the National Institutes for Standards and Technology. We present Contam airflow models of three virtual buildings: a convention center, an airport terminal, and a multi-story office building. All of the models are based to some extent on specific real buildings. Our goal is to produce models that are realistic, in terms of approximate magnitudes, directions, and speeds of airflow and pollutant transport. The three models vary ...
Date: September 30, 2009
Creator: Black, Douglas R. & Price, Phillip N.
Partner: UNT Libraries Government Documents Department

The Impact of Rate Design and Net Metering on the Bill Savings from Distributed PV for Residential Customers in California

Description: Net metering has become a widespread policy in the U.S. for supporting distributed photovoltaics (PV) adoption. Though specific design details vary, net metering allows customers with PV to reduce their electric bills by offsetting their consumption with PV generation, independent of the timing of the generation relative to consumption - in effect, compensating the PV generation at retail electricity rates (Rose et al. 2009). While net metering has played an important role in jump-starting the residential PV market in the U.S., challenges to net metering policies have emerged in a number of states and contexts, and alternative compensation methods are under consideration. Moreover, one inherent feature of net metering is that the value of the utility bill savings it provides to customers with PV depends heavily on the structure of the underlying retail electricity rate, as well as on the characteristics of the customer and PV system. Consequently, the value of net metering - and the impact of moving to alternative compensation mechanisms - can vary substantially from one customer to the next. For these reasons, it is important for policymakers and others that seek to support the development of distributed PV to understand both how the bill savings varies under net metering, and how the bill savings under net metering compares to other possible compensation mechanisms. To advance this understanding, we analyze the bill savings from PV for residential customers of California's two largest electric utilities, Pacific Gas and Electric (PG&E) and Southern California Edison (SCE). The analysis is based on hourly load data from a sample of 215 residential customers located in the service territories of the two utilities, matched with simulated hourly PV production for the same time period based on data from the nearest of 73 weather stations in the state.
Date: March 30, 2010
Creator: Darghouth, Naim; Barbose, Galen & Wiser, Ryan
Partner: UNT Libraries Government Documents Department

Achieving Energy Savings with Highly-Controlled Lighting in an Open-Plan Office

Description: An installation in a Federal building tested the effectiveness of a highly-controlled, workstation-specific lighting retrofit. The study took place in an open-office area with 86 cubicles and low levels of daylight. Each cubicle was illuminated by a direct/indirectpendant luminaire with three 32 watt lamps, two dimmable DALI ballasts, and an occupancy sensor. A centralized control system programmed all three lamps to turn on and off according to occupancy on a workstation-by-workstation basis. Field measurements taken over the course of several monthsdemonstrated 40% lighting energy savings compared to a baseline without advanced controls that conforms to GSA's current retrofit standard. A photometric analysis found that the installation provided higher desktop light levels than the baseline, while an occupant survey found that occupants in general preferred the lighting system to thebaseline.Simple payback is fairly high; projects that can achieve lower installation costs and/or higher energy savings and those in which greenhouse gas reduction and occupant satisfaction are significant priorities provide the ideal setting for workstation-specific lighting retrofits.
Date: April 19, 2010
Creator: Rubinstein, Francis & Enscoe, Abby
Partner: UNT Libraries Government Documents Department

Preliminary Evaluation of the Impact of the Section 1603 Treasury Grant Program on Renewable Energy Deployment in 2009

Description: Federal support for renewable energy deployment in the United States has traditionally been delivered primarily through tax benefits, including the production tax credit ('PTC') in Section 45 of the U.S. tax code, investment tax credits ('ITC') in Sections 25D and 48, and accelerated tax depreciation in Section 168. Many renewable power project developers are unable to use the majority of these tax benefits directly or immediately, however, and have therefore often relied on third-party 'tax equity' investors for the necessary investment capital in order to monetize the available tax benefits. As has been well-publicized, most of these tax equity investors were hit hard by the global financial crisis that unfolded in the last months of 2008 and, as a result, most either withdrew from the renewable power market at that time or reduced their available investment capital. This left a significant financing gap beginning in late 2008, and placed at some risk the continued near-term growth of renewable energy supply in the U.S. In recognition of these developments, the U.S. Congress passed two stimulus bills - The Energy Improvement and Extension Act ('the Extension Act') in October 2008 and The American Recovery and Reinvestment Act ('the Recovery Act') in February 2009 - parts of which were intended to address the growing shortage of finance for renewable power projects. Most notably, Section 1603 of the Recovery Act enables qualifying commercial renewable energy projects to choose between the Section 45 PTC, the Section 48 ITC, or a cash grant of equal value to the Section 48 ITC (i.e., 30% of the project's eligible basis in most cases). By giving developers the option to receive a 30% cash grant (administered by the U.S. Department of the Treasury) in lieu of either the ITC or the PTC, Congress hoped to 'temporarily fill the gap ...
Date: March 31, 2010
Creator: Bolinger, Mark; Wiser, Ryan & Darghouth, Naim
Partner: UNT Libraries Government Documents Department

Energy-Efficiency Improvement Opportunities for the Textile Industry

Description: The textile industry is one of the most complicated manufacturing industries because it is a fragmented and heterogeneous sector dominated by small and medium enterprises (SMEs). Energy is one of the main cost factors in the textile industry. Especially in times of high energy price volatility, improving energy efficiency should be a primary concern for textile plants. There are various energy-efficiency opportunities that exist in every textile plant, many of which are cost-effective. However, even cost-effective options often are not implemented in textile plants mostly because of limited information on how to implement energy-efficiency measures, especially given the fact that a majority of textile plants are categorized as SMEs and hence they have limited resources to acquire this information. Know-how on energy-efficiency technologies and practices should, therefore, be prepared and disseminated to textile plants. This guidebook provides information on energy-efficiency technologies and measures applicable to the textile industry. The guidebook includes case studies from textile plants around the world and includes energy savings and cost information when available. First, the guidebook gives a brief overview of the textile industry around the world, with an explanation of major textile processes. An analysis of the type and the share of energy used in different textile processes is also included in the guidebook. Subsequently, energy-efficiency improvement opportunities available within some of the major textile sub-sectors are given with a brief explanation of each measure. The conclusion includes a short section dedicated to highlighting a few emerging technologies in the textile industry as well as the potential for the use of renewable energy in the textile industry.
Date: September 29, 2010
Creator: Group, China Energy & Hasanbeigi, Ali
Partner: UNT Libraries Government Documents Department

Assessment of Energy Savings Potential from the Use of Demand Control Ventilation Systems in General Office Spaces in California

Description: Demand controlled ventilation (DCV) was evaluated for general office spaces in California. A medium size office building meeting the prescriptive requirements of the 2008 California building energy efficiency standards (CEC 2008) was assumed in the building energy simulations performed with the EnergyPlus program to calculate the DCV energy savings potential in five typical California climates. Three design occupancy densities and two minimum ventilation rates were used as model inputs to cover a broader range of design variations. The assumed values of minimum ventilation rates in offices without DCV, based on two different measurement methods, were 81 and 28 cfm per occupant. These rates are based on the co-author's unpublished analyses of data from EPA's survey of 100 U.S. office buildings. These minimum ventilation rates exceed the 15 to 20 cfm per person required in most ventilation standards for offices. The cost effectiveness of applying DCV in general office spaces was estimated via a life cycle cost analyses that considered system costs and energy cost reductions. The results of the energy modeling indicate that the energy savings potential of DCV is largest in the desert area of California (climate zone 14), followed by Mountains (climate zone 16), Central Valley (climate zone 12), North Coast (climate zone 3), and South Coast (climate zone 6). The results of the life cycle cost analysis show DCV is cost effective for office spaces if the typical minimum ventilation rates without DCV is 81 cfm per person, except at the low design occupancy of 10 people per 1000 ft{sup 2} in climate zones 3 and 6. At the low design occupancy of 10 people per 1000 ft{sup 2}, the greatest DCV life cycle cost savings is a net present value (NPV) of $0.52/ft{sup 2} in climate zone 14, followed by $0.32/ft{sup 2} in climate zone 16 ...
Date: July 8, 2009
Creator: Hong, Tianzhen & Fisk, William J.
Partner: UNT Libraries Government Documents Department

Comparison of Test Procedures and Energy Efficiency Criteria in Selected International Standards and Labeling Programs for Clothes Washers, Water Dispensers, Vending Machines and CFLs

Description: Since the late 1970s, energy labeling programs and mandatory energy performance standards have been used in many different countries to improve the efficiency levels of major residential and commercial equipment. As more countries and regions launch programs covering a greater range of products that are traded worldwide, greater attention has been given to harmonizing the specific efficiency criteria in these programs and the test methods for measurements. For example, an international compact fluorescent light (CFL) harmonization initiative was launched in 2006 to focus on collaboration between Australia, China, Europe and North America. Given the long history of standards and labeling programs, most major energy-consuming residential appliances and commercial equipment are already covered under minimum energy performance standards (MEPS) and/or energy labels. For these products, such as clothes washers and CFLs, harmonization may still be possible when national MEPS or labeling thresholds are revised. Greater opportunity for harmonization exists in newer energy-consuming products that are not commonly regulated but are under consideration for new standards and labeling programs. This may include commercial products such as water dispensers and vending machines, which are only covered by MEPS or energy labels in a few countries or regions. As China continues to expand its appliance standards and labeling programs and revise existing standards and labels, it is important to learn from recent international experiences with efficiency criteria and test procedures for the same products. Specifically, various types of standards and labeling programs already exist in North America, Europe and throughout Asia for products in China's 2010 standards and labeling programs, namely clothes washers, water dispensers, vending machines and CFLs. This report thus examines similarities and critical differences in energy efficiency values, test procedure specifications and other technical performance requirements in existing international programs in order to shed light on where Chinese programs currently stands ...
Date: June 1, 2010
Creator: Fridley, David; Zheng, Nina & Zhou, Nan
Partner: UNT Libraries Government Documents Department

Assessment of Building Energy-Saving Policies and Programs in China During the 11th Five Year Plan

Description: China's 11th Five-Year Plan (FYP) sets an ambitious target to reduce the energy intensity per unit of gross domestic product (GDP) by 20% from 2005 to 2010 (NDRC, 2006). In the building sector, the primary energy-saving target allocated during the 11 FYP period is 100 Mtce. Savings are expected to be achieved through the strengthening of enforcement of building energy efficiency codes, existing building retrofits and heat supply system reform, followed by energy management of government office buildings and large scale public buildings, adoption of renewable energy sources. To date, China has reported that it achieved the half of the 20% intensity reduction target by the end of 2008, however, little has been made clear on the status and the impact of the building programs. There has also been lack of description on methodology for calculating the savings and baseline definition, and no total savings that have been officially reported to date. This paper intend to provide both quantitative and qualitative assessment of the key policies and programs in building sector that China has instituted in its quest to fulfill the national goal. Overall, this paper concludes that the largest improvement for building energy efficiency were achieved in new buildings; the program to improve the energy management in government and large scale public buildings are in line with the target; however the progress in the area of existing building retrofit particularly heat supply system reform lags the stated goal by a large amount.
Date: June 7, 2010
Creator: Zhou, Nan; McNeil, Michael & Levine, Mark
Partner: UNT Libraries Government Documents Department

Eliminating Electricity Deficit through Energy Efficiency in India: An Evaluation of Aggregate Economic and Carbon Benefits

Description: Electricity demand has consistently exceeded available supply in India. While the electricity deficit varies across states, nationally it was estimated to be of the order of 12percent on peak and 11percent for electricity during 2008-09. This paper explores a demand-side focused potential for energy efficiency improvement to eliminate the electricity deficit compared to a business as usual (BAU) supply-side focused scenario. The limited availability of finance and other legal and administrative barriers have constrained the construction of new power plant capacity in India. As a result, under the BAU scenario, India continues to face an electricity deficit beyond the end of the Twelfth Five Year Plan. The demand-side cost-effective potential achieved through replacement of new electricity-using products, however, is large enough to eliminate the deficit as early as 2013 and subsequently reduce the future construction of power plants and thus reduce air pollutant emissions. Moreover, energy efficiency improvements cost a fraction of the cost for new supply and can lead to a substantial increase in India's economic output or gross domestic product (GDP). Eliminating the deficit permits businesses that have experienced electricity cutbacks to restore production. We estimate the size of the cumulative production increase in terms of the contribution to GDP at a $505 billion between 2009 and 2017, the end of India's Twelfth Five Year Plan, which may be compared with India's 2007-08 GDP of $911 billion. The economic output is influenced by the size of the electricity savings and rate of penetration of energy efficient technologies, and that of self-generation equipment and inverters used by businesses faced with electricity cuts. Generation and inverters are estimated to service 23percent of these customers in 2009, which increase to 48percent by 2020. The reduction in the construction and operation of new power plants reduces the cumulative CO2 emissions by 65 ...
Date: April 30, 2010
Creator: Sathaye, Jayant & Gupta, Arjun
Partner: UNT Libraries Government Documents Department

Continuity and Performance in Composite Electrodes

Description: It is shown that the rate performance of a lithium battery composite electrode may be compromised by poor internal connectivity due to defects and inhomogeneities introduced during electrode fabrication or subsequent handling. Application of a thin conductive coating to the top surface of the electrode or to the separator surface in contact with the electrode improves the performance by providing alternative current paths to partially isolated particles of electroactive material. Mechanistic implications are discussed and strategies for improvement in electrode design and fabrication are presented.
Date: December 23, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Partner: UNT Libraries Government Documents Department

Quantitative Analysis of the Principal-Agent Problem in Commercial Buildings in the U.S.: Focus on Central Space Heating and Cooling

Description: We investigate the existence of the principal-agent (PA) problem in non-government, non-mall commercial buildings in the U.S. in 2003. The analysis concentrates on space heating and cooling energy consumed by centrally installed equipment in order to verify whether a market failure caused by the PA problem might have prevented the installation of energy-efficient devices in non-owner-occupied buildings (efficiency problem) and/or the efficient operation of space-conditioning equipment in these buildings (usage problem). Commercial Buildings Energy Consumption Survey (CBECS) 2003 data for single-owner, single-tenant and multi-tenant occupied buildings were used for conducting this evaluation. These are the building subsets with the appropriate conditions for assessing both the efficiency and the usage problems. Together, these three building types represent 51.9percent of the total floor space of all buildings with space heating and 59.4percent of the total end-use energy consumption of such buildings; similarly, for space cooling, they represent 52.7percent of floor space and 51.6percent of energy consumption. Our statistical analysis shows that there is a usage PA problem. In space heating it applies only to buildings with a small floor area (<_50,000 sq. ft.). We estimate that in 2003 it accounts for additional site energy consumption of 12.3 (+ 10.5 ) TBtu (primary energy consumption of 14.6 [+- 12.4] TBtu), corresponding to 24.0percent (+- 20.5percent) of space heating and 10.2percent (+- 8.7percent) of total site energy consumed in those buildings. In space cooling, however, the analysis shows that the PA market failure affects the complete set of studied buildings. We estimate that it accounts for a higher site energy consumption of 8.3 (+-4.0) TBtu (primary energy consumption of 25.5 [+- 12.2]TBtu), which corresponds to 26.5percent (+- 12.7percent) of space cooling and 2.7percent (+- 1.3percent) of total site energy consumed in those buildings.
Date: May 14, 2010
Creator: Blum, Helcio & Sathaye, Jayant
Partner: UNT Libraries Government Documents Department

Quality and Performance of LED Flashlights in Kenya: Common End User Preferences and Complaints

Description: Flashlights that use LED technology have quickly emerged as the dominant source of portable lighting in Kenya. While flashlights do not normally provide a substitute for kerosene and other highly inefficient fuels, they are an important early manifestation of LED lighting in the developing world that can serve as a platform - or deterrent - to the diffusion of the technology into the broader off-grid lighting market. The lead acid batteries embedded in flashlights also represent an important source of hazardous waste, and flashlight durability is thus an important determinant of the rate of waste disposal. Low-cost LED flashlights with prices from $1 to $4 are now widely available in shops and markets throughout Kenya. The increased penetration of LED technology in the flashlight market is significant, as over half of all Kenyan households report owning a flashlight (Kamfor, 2002). While this shift from conventional incandescent technology to modern LEDs may appear to be a promising development, end users that our research team interviewed expressed a number of complaints about the quality and performance of these new flashlights. This raises concerns about the interests of low-income flashlight users, and it may also indicate the onset of a broader market spoiling effect for off-grid lighting products based on LED technology (Mills and Jacobson, 2008; Lighting Africa, 2007). The quality of low-cost LED flashlights can contribute to market spoiling because these products appear to represent the first contact that most Kenyans have with LED technology. In this report, our team uses interviews with 46 end users of flashlights to collect information about their experiences, perceptions, and preferences. We focus especially on highlighting common complaints from respondents about the flashlights that they have used, as well as on noting the features that they indicated were important when evaluating the quality of a flashlight. ...
Date: September 14, 2009
Creator: Tracy, Jenny; Jacobson, Arne & Mills, Evan
Partner: UNT Libraries Government Documents Department

Modeling diffusion of electrical appliances in the residential sector

Description: This paper presents a methodology for modeling residential appliance uptake as a function of root macroeconomic drivers. The analysis concentrates on four major energy end uses in the residential sector: refrigerators, washing machines, televisions and air conditioners. The model employs linear regression analysis to parameterize appliance ownership in terms of household income, urbanization and electrification rates according to a standard binary choice (logistic) function. The underlying household appliance ownership data are gathered from a variety of sources including energy consumption and more general standard of living surveys. These data span a wide range of countries, including many developing countries for which appliance ownership is currently low, but likely to grow significantly over the next decades as a result of economic development. The result is a 'global' parameterization of appliance ownership rates as a function of widely available macroeconomic variables for the four appliances studied, which provides a reliable basis for interpolation where data are not available, and forecasting of ownership rates on a global scale. The main value of this method is to form the foundation of bottom-up energy demand forecasts, project energy-related greenhouse gas emissions, and allow for the construction of detailed emissions mitigation scenarios.
Date: November 22, 2009
Creator: McNeil, Michael A. & Letschert, Virginie E.
Partner: UNT Libraries Government Documents Department

Managing Your Energy: An ENERGY STAR(R) Guide for Identifying Energy Savings in Manufacturing Plants

Description: In the United States, industry spends over $100 billion annually to power its manufacturing plants. Companies also spend on maintenance, capital outlay, and energy services. Improving energy efficiency is vital to reduce these costs and increase earnings. Many cost-effective opportunities to reduce energy consumption are available, and this Energy Guide discusses energy-efficiency practices and energy-efficient technologies that can be applied over a broad spectrum of companies. Strategies in the guide address hot water and steam, compressed air, pumps, motors, fans, lighting, refrigeration, and heating, ventilation, and air conditioning. This guide includes descriptions of expected energy and cost savings, based on real-world applications, typical payback periods, and references to more detailed information. The information in this Energy Guide is intended to help energy and plant managers achieve cost-effective energy reductions while maintaining product quality. Further research on the economics of all measures--as well as on their applicability to different production practices?is needed to assess their cost effectiveness at individual plants.
Date: July 27, 2010
Creator: Worrell, Ernst; Angelini, Tana & Masanet, Eric
Partner: UNT Libraries Government Documents Department

Self-benchmarking Guide for Cleanrooms: Metrics, Benchmarks, Actions

Description: This guide describes energy efficiency metrics and benchmarks that can be used to track the performance of and identify potential opportunities to reduce energy use in laboratory buildings. This guide is primarily intended for personnel who have responsibility for managing energy use in existing laboratory facilities - including facilities managers, energy managers, and their engineering consultants. Additionally, laboratory planners and designers may also use the metrics and benchmarks described in this guide for goal-setting in new construction or major renovation. This guide provides the following information: (1) A step-by-step outline of the benchmarking process. (2) A set of performance metrics for the whole building as well as individual systems. For each metric, the guide provides a definition, performance benchmarks, and potential actions that can be inferred from evaluating this metric. (3) A list and descriptions of the data required for computing the metrics. This guide is complemented by spreadsheet templates for data collection and for computing the benchmarking metrics. This guide builds on prior research supported by the national Laboratories for the 21st Century (Labs21) program, supported by the U.S. Department of Energy and the U.S. Environmental Protection Agency. Much of the benchmarking data are drawn from the Labs21 benchmarking database and technical guides. Additional benchmark data were obtained from engineering experts including laboratory designers and energy managers.
Date: July 13, 2009
Creator: Mathew, Paul; Sartor, Dale & Tschudi, William
Partner: UNT Libraries Government Documents Department

Solar access of residential rooftops in four California cities

Description: Shadows cast by trees and buildings can limit the solar access of rooftop solar-energy systems, including photovoltaic panels and thermal collectors. This study characterizes residential rooftop shading in Sacramento, San Jose, Los Angeles and San Diego, CA. Our analysis can be used to better estimate power production and/or thermal collection by rooftop solar-energy equipment. It can also be considered when designing programs to plant shade trees. High-resolution orthophotos and LiDAR (Light Detection And Ranging) measurements of surface height were used to create a digital elevation model of all trees and buildings in a well-treed 2.5-4 km{sup 2} residential neighborhood. On-hour shading of roofing planes (the flat elements of roofs) was computed geometrically from the digital elevation model. Values in future years were determined by repeating these calculations after simulating tree growth. Parcel boundaries were used to determine the extent to which roofing planes were shaded by trees and buildings in neighboring parcels. For the subset of S+SW+W-facing planes on which solar equipment is commonly installed for maximum solar access, absolute light loss in spring, summer and fall peaked about two to four hours after sunrise and about two to four hours before sunset. The fraction of annual insolation lost to shading increased from 0.07-0.08 in the year of surface-height measurement to 0.11-0.14 after 30 years of tree growth. Only about 10% of this loss results from shading by trees and buildings in neighboring parcels.
Date: May 14, 2010
Creator: Levinson, Ronnen; Akbari, Hashem & Pomerantz, Melvin
Partner: UNT Libraries Government Documents Department

Solid Solution Phases in the Olivine-Type LiMnPO4/MnPO4 System

Description: Nonstoichiometry is reported in the LiMnPO{sub 4}/MnPO{sub 4} system for the first time. As lithium is removed from crystalline LiMnPO{sub 4} by chemical or electrochemical methods, the resulting two phase mixture consists of stoichiometric LiMnPO{sub 4} and a delithiated phase, Li{sub y}MnPO{sub 4}, whose lattice parameters depend upon the global extent of delithiation and on the crystalline domain size of the delithiated phase. This behavior is reproduced during electrochemical insertion of lithium. Again, no evidence for nonstoichiometry was found in the vicinity of LiMnPO{sub 4}. Attempts to create single phase solid solutions by heating mixtures of the two phases failed due to the thermal instability of Li{sub y}MnPO{sub 4}.
Date: April 7, 2009
Creator: Chen, Guoying & Richardson, Thomas J.
Partner: UNT Libraries Government Documents Department

Self-benchmarking Guide for Laboratory Buildings: Metrics, Benchmarks, Actions

Description: This guide describes energy efficiency metrics and benchmarks that can be used to track the performance of and identify potential opportunities to reduce energy use in laboratory buildings. This guide is primarily intended for personnel who have responsibility for managing energy use in existing laboratory facilities - including facilities managers, energy managers, and their engineering consultants. Additionally, laboratory planners and designers may also use the metrics and benchmarks described in this guide for goal-setting in new construction or major renovation. This guide provides the following information: (1) A step-by-step outline of the benchmarking process. (2) A set of performance metrics for the whole building as well as individual systems. For each metric, the guide provides a definition, performance benchmarks, and potential actions that can be inferred from evaluating this metric. (3) A list and descriptions of the data required for computing the metrics. This guide is complemented by spreadsheet templates for data collection and for computing the benchmarking metrics. This guide builds on prior research supported by the national Laboratories for the 21st Century (Labs21) program, supported by the U.S. Department of Energy and the U.S. Environmental Protection Agency. Much of the benchmarking data are drawn from the Labs21 benchmarking database and technical guides. Additional benchmark data were obtained from engineering experts including laboratory designers and energy managers.
Date: July 13, 2009
Creator: Mathew, Paul; Greenberg, Steve & Sartor, Dale
Partner: UNT Libraries Government Documents Department

Investigation of IAQ-Relevant Surface Chemistry and Emissions on HVAC Filter Materials

Description: Chemical reactions involving ozone of outdoor origin and indoor materials are known to be significant sources of formaldehyde and other irritant gas-phase oxidation products in the indoor environment. HVAC filters are exposed to particularly high ozone concentrations--close to outdoor levels. In this study, we investigated chemical processes taking place on the surface of filters that included fiberglass, polyester, cotton/polyester blend and synthetic (e.g., polyolefin) filter media. Ozone reactions were studied on unused filter media, and on filters that were deployed for 3 months in two different locations: at the Lawrence Berkeley National Laboratory and at the Port of Oakland. Specimens from each filter were exposed to ozone under controlled conditions in a laboratory flow tube at a constant flow of dry or humidified air (50percent relative humidity). Ozone was generated with a UV source upstream of the flow tube, and monitored using a photometric detector. Ozone breakthrough curves were recorded for each sample exposed to ~;;150 ppbv O3 for periods of ~;;1000 min, from which we estimated their uptake rate. Most experiments were performed at 1.3 L/min (corresponding to a face velocity of 0.013 m/s), except for a few tests performed at a higher airflow rate, to obtain a face velocity of 0.093 m/s, slightly closer to HVAC operation conditions. Formaldehyde and acetaldehyde, two oxidation byproducts, were collected downstream of the filter and quantified. Emissions of these volatile aldehydes were consistently higher under humidified air than under dry conditions, at which levels were near the limit of detection. Our results confirm that there are significant reactions of ozone as air containing ozone flows through HVAC filters, particularly when the filters are loaded with particles and the air is humidified. The amount of ozone reacted was not clearly related to the types of filter media, e.g., fiberglass versus synthetic. Specific fiberglass ...
Date: February 1, 2010
Creator: Destaillats, Hugo & Fisk, William J.
Partner: UNT Libraries Government Documents Department

Life Cycle Assessment of Pavements: A Critical Review of Existing Literature and Research

Description: This report provides a critical review of existing literature and modeling tools related to life-cycle assessment (LCA) applied to pavements. The review finds that pavement LCA is an expanding but still limited research topic in the literature, and that the existing body of work exhibits methodological deficiencies and incompatibilities that serve as barriers to the widespread utilization of LCA by pavement engineers and policy makers. This review identifies five key issues in the current body of work: inconsistent functional units, improper system boundaries, imbalanced data for asphalt and cement, use of limited inventory and impact assessment categories, and poor overall utility. This review also identifies common data and modeling gaps in pavement LCAs that should be addressed in future work. These gaps include: the use phase (rolling resistance, albedo, carbonation, lighting, leachate, and tire wear and emissions), asphalt fumes, feedstock energy of bitumen, traffic delay, the maintenance phase, and the end-of-life phase. This review concludes with a comprehensive list of recommendations for future research, which shed light on where improvements in knowledge can be made that will benefit the accuracy and comprehensiveness of pavement LCAs moving forward.
Date: April 20, 2010
Creator: Santero, Nicholas; Masanet, Eric & Horvath, Arpad
Partner: UNT Libraries Government Documents Department