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Heat Pump Water Heaters and American Homes: A Good Fit?

Description: Heat pump water heaters (HPWHs) are over twice as energy-efficient as conventional electric resistance water heaters, with the potential to save substantial amounts of electricity. Drawing on analysis conducted for the U.S. Department of Energy's recently-concluded rulemaking on amended standards for water heaters, this paper evaluates key issues that will determine how well, and to what extent, this technology will fit in American homes. The key issues include: 1) equipment cost of HPWHs; 2) cooling of the indoor environment by HPWHs; 3) size and air flow requirements of HPWHs; 4) performance of HPWH under different climate conditions and varying hot water use patterns; and 5) operating cost savings under different electricity prices and hot water use. The paper presents the results of a life-cycle cost analysis of the adoption of HPWHs in a representative sample of American homes, as well as national impact analysis for different market share scenarios. Assuming equipment costs that would result from high production volume, the results show that HPWHs can be cost effective in all regions for most single family homes, especially when the water heater is not installed in a conditioned space. HPWHs are not cost effective for most manufactured home and multi-family installations, due to lower average hot water use and the water heater in the majority of cases being installed in conditioned space, where cooling of the indoor environment and size and air flow requirements of HPWHs increase installation costs.
Date: May 14, 2010
Creator: Franco, Victor; Lekov, Alex; Meyers, Steve & Letschert, Virginie
Partner: UNT Libraries Government Documents Department

Exploration of Resource and Transmission Expansion Decisions in the Western Renewable Energy Zone Initiative

Description: The Western Renewable Energy Zone (WREZ) initiative brings together a diverse set of voices to develop data, tools, and a unique forum for coordinating transmission expansion in the Western Interconnection. In this paper we use a new tool developed in the WREZ initiative to evaluate possible renewable resource selection and transmission expansion decisions. We evaluate these decisions under a number of alternative future scenarios centered on meeting 33percent of the annual load in the Western Interconnection with new renewable resources located within WREZ-identified resource hubs. Our analysis finds that wind energy is the largest source of renewable energy procured to meet the 33percent RE target across nearly all scenarios analyzed (38-65percent). Solar energy is almost always the second largest source (14-41percent). We find several load zones where wind energy is the least cost resource under a wide range of sensitivity scenarios. Load zones in the Southwest, on the other hand, are found to switch between wind and solar, and therefore to vary transmission expansion decisions, depending on uncertainties and policies that affect the relative economics of each renewable option. Further, we find that even with total transmission expenditures of $17-34 billion these costs still represent just 10-19percent of the total delivered cost of renewable energy.
Date: June 10, 2010
Creator: Mills, Andrew D.; Phadke, Amol A. & Wiser, Ryan H.
Partner: UNT Libraries Government Documents Department

Field Derived Emission Factors For Formaldehyde and other Volatile Organic Compounds in FEMA Temporary Housing Units

Description: Sixteen previously occupied temporary housing units (THUs) were studied to assess emissions of volatile organic compounds. The whole trailer emission factors wereevaluated for 36 VOCs including formaldehyde. Indoor sampling was carried out in the THUs located in Purvis staging yard in Mississippi, USA. Indoor temperature andrelative humidity (RH) were also measured in all the trailers during sampling. Indoor temperatures were varied (increased or decreased) in a selection of THUs using theheating, ventilation and air conditioning (HVAC) systems. Indoor temperatures during sampling ranged from 14o C to 33o C, and relative humidity (RH) varied between 35percentand 74percent. Ventilation rates were increased in some trailers using bathroom fans and vents during some of the sampling events. Ventilation rates measured during some aselection of sampling events varied from 0.14 to 4.3 h-1. Steady state indoor formaldehyde concentrations ranged from 10 mu g-m-3 to 1000 mu g-m-3. The formaldehyde concentrations in the trailers were of toxicological significance. The effects of temperature, humidity and ventilation rates were also studied. A linearregression model was built using log of percentage relative humidity, inverse of temperature (in K-1), and inverse log ACH as continuous independent variables, trailermanufacturer as a categorical independent variable, and log of the chemical emission factors as the dependent variable. The coefficients of inverse temperature, log relativehumidity, log inverse ACH with log emission factor were found to be statistically significant for all the samples at the 95percent confidence level. The regression model wasfound to explain about 84percent of the variation in the dependent variable. Most VOC concentrations measured indoors in the Purvis THUs were mostly found to be belowvalues reported in earlier studies by Maddalena et al.,1,2 Hodgson et al.,3 and Hippelein4. Emissions of TMPB-DIB (a plasticizer found in vinyl products) were found to be higher than values reported in comparable housing by Hodgson et ...
Date: October 1, 2010
Creator: Parthasarathy, Srinandini; Maddalena, Randy L.; Russell, Marion L. & Apte, Michael G.
Partner: UNT Libraries Government Documents Department

A Formaldehyde Exposure Assessment Tool for Occupants of FEMA Temporary Housing Units

Description: The report outlines the methodology used to develop a web-based tool to assess the formaldehyde exposure of the occupants of Federal Emergency Management Administration (FEMA) temporary housing units (THUs) after Hurricanes Katrina and Rita in 2005. Linear regression models were built using available data to retrospectively estimate the indoor temperature and relative humidity, formaldehyde emission factors and concentration, and hence the formaldehyde exposures. The interactive web-tool allows the user to define the inputs to the model to evaluate formaldehyde exposures for different scenarios.
Date: October 1, 2010
Creator: Parthasarathy, Srinandini; Spears, Michael; Maddalena, Randy L.; Russell, Marion L & Apte, Michael G.
Partner: UNT Libraries Government Documents Department

How People Actually Use Thermostats

Description: Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.
Date: August 15, 2010
Creator: Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel et al.
Partner: UNT Libraries Government Documents Department

HUD PowerSaver Pilot Loan Program

Description: The U.S. Department of Housing and Urban Development (HUD) recently announced the creation of a pilot loan program for home energy improvements. The PowerSaver loan program is a new, energy-focused variant of the Title I Property Improvement Loan Insurance Program (Title I Program) and is planned for introduction in early 2011. The PowerSaver pilot will provide lender insurance for secured and unsecured loans up to $25,000 to single family homeowners. These loans will specifically target residential energy efficiency and renewable energy improvements. HUD estimates the two-year pilot will fund approximately 24,000 loans worth up to $300 million; the program is not capped. The Federal Housing Administration (FHA), HUD's mortgage insurance unit, will provide up to $25 million in grants as incentives to participating lenders. FHA is seeking lenders in communities with existing programs for promoting residential energy upgrades.
Date: December 10, 2010
Creator: Zimring, Mark & Hoffman, Ian
Partner: UNT Libraries Government Documents Department

Frequency Control Performance Measurement and Requirements

Description: Frequency control is an essential requirement of reliable electric power system operations. Determination of frequency control depends on frequency measurement and the practices based on these measurements that dictate acceptable frequency management. This report chronicles the evolution of these measurements and practices. As technology progresses from analog to digital for calculation, communication, and control, the technical basis for frequency control measurement and practices to determine acceptable performance continues to improve. Before the introduction of digital computing, practices were determined largely by prior experience. In anticipation of mandatory reliability rules, practices evolved from a focus primarily on commercial and equity issues to an increased focus on reliability. This evolution is expected to continue and place increased requirements for more precise measurements and a stronger scientific basis for future frequency management practices in support of reliability.
Date: December 20, 2010
Creator: Illian, Howard F.
Partner: UNT Libraries Government Documents Department

Market Trial: Selling Off-Grid Lighting Products in Rural Kenya

Description: In this study, we performed a market trial of off-grid LED lighting products in Maai Mahiu, arural Kenyan town. Our goals were to assess consumer demand and consumer preferences with respect to off-grid lighting systems and to gain feedback from off-grid lighting users at the point of purchase and after they have used to products for some time.
Date: June 21, 2010
Creator: Tracy, Jennifer; Alstone, Peter; Jacobson, Arne & Mills, Evan
Partner: UNT Libraries Government Documents Department

Money for Research, Not for Energy Bills: Finding Energy and Cost Savings in High Performance Computer Facility Designs

Description: High-performance computing facilities in the United States consume an enormous amount of electricity, cutting into research budgets and challenging public- and private-sector efforts to reduce energy consumption and meet environmental goals. However, these facilities can greatly reduce their energy demand through energy-efficient design of the facility itself. Using a case study of a facility under design, this article discusses strategies and technologies that can be used to help achieve energy reductions.
Date: July 1, 2010
Creator: Drewmark Communications
Partner: UNT Libraries Government Documents Department

Introduction to the Buildings Sector Module of SEDS

Description: SEDS is a stochastic engineering-economics model that forecasts economy-wide energy consumption in the U.S. to 2050. It is the product of multi-laboratory collaboration among the National Renewable Energy Laboratory (NREL), Pacific Northwest National Laboratory (PNNL), Argonne National Laboratory (ANL), Lawrence Berkeley National Laboratory (LBNL), and Lumina Decision Systems. Among national energy models, SEDS is unique, as it is the only model written to explicitly incorporate uncertainty in its inputs and outputs. The primary purpose of SEDS is to estimate the impact of various US Department of Energy (DOE)R&D and policy programs on the performance and subsequent adoption rates of technologies relating to every energy consuming sector of the economy (shown below). It has previously been used to assist DOE in complying with the Government Performance and Results Act of 1993 (GPRA). The focus of LBNL research has been exclusively on develop the buildings model (SBEAM), which is capable of running as a stand-alone forecasting model, or as a part of SEDS as a whole. The full version of SEDS, containing all sectors and interaction is also called the 'integrated' version and is managed by NREL. Forecasts from SEDS are often compared to those coming from National Energy Modeling System (NEMS). The intention of this document is to present new users and developers with a general description of the purpose, functionality and structure of the buildings module within the Stochastic Energy Deployment System (SEDS). The Buildings module, which is capable of running as a standalone model, is also called the Stochastic Buildings Energy and Adoption Model (SBEAM). This document will focus exclusively on SBEAM and its interaction with other major sector modules present within SEDS. The methodologies and major assumptions employed in SBEAM will also be discussed. The organization of this report will parallel the organization of the model itself, being ...
Date: December 31, 2010
Creator: DeForest, Nicholas; Bonnet, Florence; Stadler, Michael & Marnay, Chris
Partner: UNT Libraries Government Documents Department

Commercial and Industrial Base Intermittent Resource Management Pilot

Description: This scoping study summarizes the challenges with integrating wind and solar generation into the California's electricity grid. These challenges include: Smoothing intra-hour variability; - Absorbing excess renewable energy during over-generation periods; - Addressing morning and evening ramping periods. In addition, there are technical challenges to integrating retail demand response (DR) triggered by the wholesale conditions into the CAISO markets. The study describes the DR programs available to the consumers through the utilities in California and CAISO's ancillary services market because an integration of the wholesale and retail DR requires an understanding of these different offerings and the costs associated with acquiring them. Demand-side active and passive storage systems are proposed as technologies that may be used to mitigate the effects of intermittence due to renewable generation. Commercial building technologies as well as industrial facilities with storage capability are identified as targets for the field tests. Two systems used for ancillary services communications are identified as providing the triggers for DR enablement. Through the field tests, issues related to communication, automation and flexibility of demand-side resources will be explored and the performance of technologies that participate in the field tests will be evaluated. The major outcome of this research is identifying and defining flexibility of DR resources and optimized use of these resources to respond to grid conditions.
Date: November 30, 2010
Creator: Kiliccote, Sila; Sporborg, Pamela; Sheik, Imran; Huffaker, Erich & Piette, Mary Ann
Partner: UNT Libraries Government Documents Department

Compliance and Verification of Standards and Labeling Programs in China: Lessons Learned

Description: After implementing several energy efficiency standards and labels (30 products covered by MEPS, 50 products covered by voluntary labels and 19 products by mandatory labels), the China National Institute of Standardization (CNIS) is now implementing verification and compliance mechanism to ensure that the energy information of labeled products comply with the requirements of their labels. CNIS is doing so by organizing check testing on a random basis for room air-conditioners, refrigerators, motors, heaters, computer displays, ovens, and self -ballasted lamps. The purpose of the check testing is to understand the implementation of the Chinese labeling scheme and help local authorities establishing effective compliance mechanisms. In addition, to ensure robustness and consistency of testing results, CNIS has coordinated a round robin testing for room air conditioners. Eight laboratories (Chinese (6), Australian (1) and Japanese (1)) have been involved in the round robin testing and tests were performed on four sets of samples selected from manufacturer's production line. This paper describes the methodology used in undertaking both check and round robin testing, provides analysis of testing results and reports on the findings. The analysis of both check and round robin testing demonstrated the benefits of a regularized verification and monitoring system for both laboratories and products such as (i) identifying the possible deviations between laboratories to correct them, (ii) improving the quality of testing facilities, (iii) ensuring the accuracy and reliability of energy label information in order to strength the social credibility of the labeling program and the enforcement mechanism in place.
Date: August 1, 2010
Creator: Saheb, Yamina; Zhou, Nan; Fridley, David & Pierrot, Andre
Partner: UNT Libraries Government Documents Department

Energy Audit Practices in China: National and Local Experiences and Issues

Description: China has set an ambitious goal of reducing its energy use per unit of GDP by 20% between 2006 and 2010. Since the industrial sector consumes about two-thirds of China's primary energy, many of the country's efforts are focused on improving the energy efficiency of this sector. Industrial energy audits have become an important part of China's efforts to improve its energy intensity. In China, industrial energy audits have been employed to help enterprises indentify energy-efficiency improvement opportunities for achieving the energy-saving targets. These audits also serve as a mean to collect critical energy-consuming information necessary for governments at different levels to supervise enterprises energy use and evaluate their energy performance. To better understand how energy audits are carried out in China as well as their impacts on achieving China's energy-saving target, researchers at the Lawrence Berkeley National Laboratory (LBNL) conducted an in-depth study that combines a review of China's national policies and guidelines on energy auditing and a series of discussions with a variety of Chinese institutions involved in energy audits. This report consists of four parts. First, it provides a historical overview of energy auditing in China over the past decades, describing how and why energy audits have been conducted during various periods. Next, the report reviews current energy auditing practices at both the national and regional levels. It then discusses some of the key issues related to energy audits conducted in China, which underscore the need for improvement. The report concludes with policy recommendations for China that draw upon international best practices and aim to remove barriers to maximizing the potential of energy audits.
Date: December 21, 2010
Creator: Shen, Bo; Price, Lynn & Lu, Hongyou
Partner: UNT Libraries Government Documents Department

Energy Efficiency Design Options for Residential Water Heaters: Economic Impacts on Consumers

Description: The U.S. Department of Energy (DOE) recently completed a rulemaking process in which it amended the existing energy efficiency standards for residential water heaters. A key factor in DOE?s consideration of new standards is the economic impacts on consumers. Determining such impacts requires a comparison of the additional first cost of energy efficiency design options with the savings in operating costs. This paper describes the method used to conduct the life-cycle cost (LCC) and payback period analysis for gas and electric storage water heaters. It presents the estimated change in LCC associated with more energy-efficient equipment, including heat pump electric water heaters and condensing gas water heaters, for a representative sample of U.S. homes. The study included a detailed accounting of installation costs for the considered design options, with a focus on approaches for accommodating the larger dimensions of more efficient water heaters. For heat pump water heaters, the study also considered airflow requirements, venting issues, and the impact of these products on the indoor environment. The results indicate that efficiency improvement relative to the baseline design reduces the LCC in the majority of homes for both gas and electric storage water heaters, and heat pump electric water heaters and condensing gas water heaters provide a lower LCC for homes with large rated volume water heaters.
Date: November 24, 2010
Creator: Lekov, Alex; Franco, Victor; Meyers, Steve; Thompson, Lisa & Letschert, Virginie
Partner: UNT Libraries Government Documents Department

Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry An ENERGY STAR(R) Guide for Energy and Plant Managers

Description: Energy is an important cost factor in the U.S iron and steel industry. Energy efficiency improvement is an important way to reduce these costs and to increase predictable earnings, especially in times of high energy price volatility. There are a variety of opportunities available at individual plants in the U.S. iron and steel industry to reduce energy consumption in a cost-effective manner. This Energy Guide discusses energy efficiency practices and energy-efficient technologies that can be implemented at the component, process, facility, and organizational levels. A discussion of the structure, production trends, energy consumption, and greenhouse gas emissions of the iron and steel industry is provided along with a description of the major process technologies used within the industry. Next, a wide variety of energy efficiency measures are described. Many measure descriptions include expected savings in energy and energy-related costs, based on case study data from real-world applications in the steel and related industries worldwide. Typical measure payback periods and references to further information in the technical literature are also provided, when available. The information in this Energy Guide is intended to help energy and plant managers in the U.S. iron and steel industry reduce energy consumption and greenhouse gas emissions in a cost-effective manner while maintaining the quality of products manufactured. Further research on the economics of all measures?and on their applicability to different production practices?is needed to assess their cost effectiveness at individual plants.
Date: October 21, 2010
Creator: Worrell, Ernst; Blinde, Paul; Neelis, Maarten; Blomen, Eliane & Masanet, Eric
Partner: UNT Libraries Government Documents Department

Evaluating Energy Efficiency Policies with Energy-Economy Models

Description: The growing complexities of energy systems, environmental problems and technology markets are driving and testing most energy-economy models to their limits. To further advance bottom-up models from a multidisciplinary energy efficiency policy evaluation perspective, we review and critically analyse bottom-up energy-economy models and corresponding evaluation studies on energy efficiency policies to induce technological change. We use the household sector as a case study. Our analysis focuses on decision frameworks for technology choice, type of evaluation being carried out, treatment of market and behavioural failures, evaluated policy instruments, and key determinants used to mimic policy instruments. Although the review confirms criticism related to energy-economy models (e.g. unrealistic representation of decision-making by consumers when choosing technologies), they provide valuable guidance for policy evaluation related to energy efficiency. Different areas to further advance models remain open, particularly related to modelling issues, techno-economic and environmental aspects, behavioural determinants, and policy considerations.
Date: August 1, 2010
Creator: Mundaca, Luis; Neij, Lena; Worrell, Ernst & McNeil, Michael A.
Partner: UNT Libraries Government Documents Department

Dynamic Simulation Studies of the Frequency Response of the Three U.S. Interconnections with Increased Wind Generation

Description: Utility Systems Efficiencies, Inc. was tasked by Lawrence Berkeley National Laboratory (LBNL) to conduct dynamic simulation studies of the three U.S. interconnections (Eastern, Western, and Texas). The simulations were prepared in support of LBNL's project for the Federal Energy Regulatory Commission to study frequency-response-related issues that must be addressed to operate the power system reliably with large amounts of variable renewable generation. The objective of the simulation studies of each interconnection was to assess the effects of different amounts of wind generation on frequency behavior of each interconnection following a sudden loss of generation. The scenarios created to study these effects considered an operating circumstance in which system load is at or close to its minimum. The event studied was the sudden loss of the largest amount of generation recorded within each interconnection. The simulations calculated the impact of this event on interconnection frequency for three levels of wind generation. In addition to varying the amount of wind generation, the simulations varied the amount of operating reserves between a high level representative of current operating practices and a low level representative of the minimum required by present operating rules.
Date: December 20, 2010
Creator: Mackin, Peter; Daschmans, R.; Williams, B.; Haney, B.; Hung, R. & Ellis, J.
Partner: UNT Libraries Government Documents Department

Economics of Condensing Gas Furnaces and Water Heaters Potential in Residential Single Family Homes

Description: Residential space and water heating accounts for over 90percent of total residential primary gas consumption in the United States. Condensing space and water heating equipment are 10-30percent more energy-efficient than conventional space and water heating. Currently, condensing gas furnaces represent 40 percent of shipments and are common in the Northern U.S. market. Meanwhile, manufacturers are planning to develop condensing gas storage water heaters to qualify for Energy Star? certification. Consumers, installers, and builders who make decisions about installing space and water heating equipment generally do not perform an analysis to assess the economic impacts of different combinations and efficiencies of space and water heating equipment. Thus, equipment is often installed without taking into consideration the potential life-cycle economic and energy savings of installing space and water heating equipment combinations. Drawing on previous and current analysis conducted for the United States Department of Energy rulemaking on amended standards for furnaces and water heaters, this paper evaluates the extent to which condensing equipment can provide life-cycle cost-effectiveness in a representative sample of single family American homes. The economic analyses indicate that significant energy savings and consumer benefits may result from large-scale introduction of condensing water heaters combined with condensing furnaces in U.S. residential single-family housing, particularly in the Northern region. The analyses also shows that important benefits may be overlooked when policy analysts evaluate the impact of space and water heating equipment separately.
Date: May 14, 2010
Creator: Lekov, Alex; Franco, Victor & Meyers, Steve
Partner: UNT Libraries Government Documents Department

Experimental Evaluation of Installed Cooking Exhaust Fan Performance

Description: The installed performance of cooking exhaust fans was evaluated through residential field experiments conducted on a sample of 15 devices varying in design and other characteristics. The sample included two rear downdraft systems, two under-cabinet microwave over range (MOR) units, three different installations of an under-cabinet model with grease screens across the bottom and no capture hood, two devices with grease screens covering the bottom of a large capture hood (one under-cabinet, one wall-mount chimney), four under-cabinet open hoods, and two open hoods with chimney mounts over islands. Performance assessment included measurement of airflow and sound levels across fan settings and experiments to quantify the contemporaneous capture efficiency for the exhaust generated by natural gas cooking burners.Capture efficiency is defined as the fraction of generated pollutants that are removed through the exhaust and thus not available for inhalation of household occupants. Capture efficiency (CE) was assessed for various configurations of burner use (e.g., single front, single back, combination of one front and one back, oven) and fan speed setting. Measured airflow rates were substantially lower than the levels noted in product literature for many of the units. This shortfall was observed for several units costing in excess of $1000. Capture efficiency varied widely (from<5percent to roughly 100percent) across devices and across conditions for some devices. As expected, higher capture efficiencies were achieved with higher fan settings and the associated higher air flow rates. In most cases, capture efficiencies were substantially higher for rear burners than for front burners. The best and most consistent performance was observed for open hoods that covered all cooktop burners and operated at higher airflow rates. The lowest capture efficiencies were measured when a front burner was used with a rear backdraft system or with lowest fan setting for above the range systems that do not ...
Date: November 1, 2010
Creator: Singer, Brett C.; Delp, William W. & Apte, Michael G.
Partner: UNT Libraries Government Documents Department

Do Heat Pump Clothes Dryers Make Sense for the U.S. Market

Description: Heat pump clothes dryers (HPCDs) can be as much as 50percent more energy-efficient than conventional electric resistance clothes dryers, and therefore have the potential to save substantial amounts of electricity. While not currently available in the U.S., there are manufacturers in Europe and Japan that produce units for those markets. Drawing on analysis conducted for the U.S. Department of Energy's (DOE) current rulemaking on amended standards for clothes dryers, this paper evaluates the cost-effectiveness of HPCDs in American homes, as well as the national impact analysis for different market share scenarios. In order to get an accurate measurement of real energy savings potential, the paper offers a new energy use calculation methodology that takes into account the most current data on clothes washer cycles, clothes dryer usage frequency, remaining moisture content, and load weight per cycle, which is very different from current test procedure values. Using the above methodology along with product cost estimates developed by DOE, the paper presents the results of a life-cycle cost analysis of the adoption of HPCDs in a representative sample of American homes. The results show that HPCDs have positive economic benefits only for households with high clothes dryer usage or for households with high electricity prices and moderately high utilization.
Date: May 14, 2010
Creator: Meyers, Steve; Franco, Victor; Lekov, Alex; Thompson, Lisa & Sturges, Andy
Partner: UNT Libraries Government Documents Department

Does Mixing Make Residential Ventilation More Effective?

Description: Ventilation dilutes or removes indoor contaminants to reduce occupant exposure. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. The total ventilation rate is the most important factor in determining the exposure of occupants to given sources, but the zone- specific distribution of exhaust and supply air, and the mixing of ventilation air can have significant roles. Different types of ventilation systems will provide different amounts of mixing depending on several factors such as air leakage through the building envelope, air distribution systems and the location of sources and occupants. This paper reports recent results of investigations to determine the impact that air mixing has on exposures of residential occupants to prototypical contaminants of concern. Evaluations of existing field measurements and simulations reported in the literature are combined with new analyses to provide an integrated overview of the topic. The results show that for extreme cases additional mixing can be a significant factor but for typical homes looking at average exposures mixing is not helpful and can even make exposures worse.
Date: August 16, 2010
Creator: Sherman, Max & Walker, Iain
Partner: UNT Libraries Government Documents Department


Description: As American drinking water agencies face higher production costs, demand, and energy prices, they seek opportunities to reduce costs without negatively affecting the quality of the water they deliver. This guide describes resources for cost-effectively improving the energy efficiency of U.S. public drinking water facilities. The guide (1) describes areas of opportunity for improving energy efficiency in drinking water facilities; (2) provides detailed descriptions of resources to consult for each area of opportunity; (3) offers supplementary suggestions and information for the area; and (4) presents illustrative case studies, including analysis of cost-effectiveness.
Date: September 30, 2010
Creator: Melody, Moya; Dunham Whitehead, Camilla & Brown, Richard
Partner: UNT Libraries Government Documents Department

Ice Formation in Gas-Diffusion Layers

Description: Under sub-freezing conditions, ice forms in the gas-diffusion layer (GDL) of a proton exchange membrane fuel cell (PEMFC) drastically reducing cell performance. Although a number of strategies exist to prevent ice formation, there is little fundamental understanding of the mechanisms of freezing within PEMFC components. Differential scanning calorimetry (DSC) is used to elucidate the effects of hydrophobicity (Teflon® loading) and water saturation on the rate of ice formation within three commercial GDLs. We find that as the Teflon® loading increases, the crystallization temperature decreases due to a change in internal ice/substrate contact angle, as well as the attainable level of water saturation. Classical nucleation theory predicts the correct trend in freezing temperature with Teflon® loading.
Date: July 10, 2010
Creator: Dursch, Thomas; Radke, Clayton J. & Weber, Adam Z.
Partner: UNT Libraries Government Documents Department

Illuminating the Pecking Order in Off-Grid Lighting: A Demonstration of LED Lighting for Saving Energy in the Poultry Sector

Description: The Lumina Project and Lighting Africa conducted a full-scale field test involving a switch from kerosene to solar-LED lighting for commercial broiler chicken production at an off-grid farm in Kenya. The test achieved lower operating costs, produced substantially more light, improved the working environment, and had no adverse effect on yields. A strategy using conventional solar-fluorescent lighting also achieved comparable yields, but entailed a six-fold higher capital cost and significantly higher recurring battery replacement costs. Thanks to higher energy and optical efficiencies, the LED system provided approximately twice the illumination to the chicken-production area and yet drew less than half the power.At the study farm, 3000 chickens were grown in each of three identical houses under kerosene, fluorescent, and LED lighting configurations. Under baseline conditions, a yearly expenditure of 1,200 USD is required to illuminate the three houses with kerosene. The LED system eliminates this fuel use and expense with a corresponding simple payback time of 1.5 years, while the solar-fluorescent system has a payback time of 9.3 years. The corresponding reduction in fuel expenditure in both cases represents a 15percent increase in after-tax net income (revenues minus expenses) across the entire business operation. The differential cost-effectiveness between the LED and fluorescent systems would be substantially greater if the fluorescent system were upsized to provide the same light as the LED system. Providing light with the fluorescent or LED systems is also far more economical than connecting to the grid in this case. The estimated grid-connection cost at this facility is 1.7 million Kenya Schillings (approximately 21,250 USD), which is nearly six-times the cost of the fluorescent system and 35-times the cost of the LED system.The LED system also confers various non-energy benefits. The relative uniformity of LED lighting, compared to the fluorescent or kerosene lighting, reduced crowding which in ...
Date: November 6, 2010
Creator: Tracy, Jennifer & Mills, Evan
Partner: UNT Libraries Government Documents Department