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Supplement to the ``determination analysis`` (ORNL-6847) and analysis of the NEMA efficiency standard for distribution transformers

Description: This report contains additional information for use by the US Department of Energy in making a determination on proposing energy conservation standards for distribution transformers as required by the Energy Policy Act of 1992. An earlier determination study by the Oak Ridge National Laboratory determined that cost-effective, technically feasible energy savings could be achieved by distribution transformer standards and that these savings are significant relative to other product conservation standards. This study was documented in a final report, ``Determination Analysis of Energy Conservation Standards for Distribution Transformers`` (ORNL-6847, July 1996). The energy conservation options analyzed in this study were estimated to save 5.2 to 13.7 quads from 2000--2030. The energy savings for the determination study cases have been revised downward for a number of reasons. The transformer market, both present and future, was overestimated in the previous study, particularly for dry-type transformers, which have the greatest energy-saving potential. Moreover, a revision downwards of the effective annual loads for utility owned transformers also results in lower energy savings. The present study assesses four of the five conservation cases from the earlier determination study as well as the National Electrical Manufacturers Association energy efficiency standard NEMA TP 1-1996 using the updated data and a more accurate disaggregated analysis model. According to these new estimates, the savings ranged from 2.5 to 10.7 quads of primary energy for the 30-year period 2004 to 2034. For the TP-1 case, data were available to calculate the payback period required to recover the extra cost from the value of the energy saved. The average payback period based on the average national cost of electricity is 2.76 years. 15 figs., 23 tabs.
Date: September 1, 1997
Creator: Barnes, P.R.; Das, S.; McConnell, B.W. & Van Dyke, J.W.
Partner: UNT Libraries Government Documents Department

Energy efficiency in the US economy technical report four: Analysis of energy-efficiency investment decisions by small and medium-sized manufacturers

Description: This report highlights the results of a comprehensive analysis of investment decisions regarding energy-efficiency measures at small and medium-sized manufacturing plants. The analysis is based primarily on the experiences of companies participating in the US Department of Energy`s Industrial Assessment Center (IAC) program.
Date: March 1, 1996
Partner: UNT Libraries Government Documents Department

Making Energy-Efficiency and Productivity Investments in Commercial Buildings: Choice of Investment Models

Description: This study examines the decision to invest in buildings and the types of investment decision rules that may be employed to inform the ''go--no go'' decision. There is a range of decision making tools available to help in investment choices, which range from simple rules of thumb such as payback periods, to life-cycle analysis, to decision theoretic approaches. Payback period analysis tends to point toward lower first costs, whereas life-cycle analysis tends to minimize uncertainties over future events that can affect profitability. We conclude that investment models that integrate uncertainty offer better explanations for the behavior that is observed, i.e., people tend to delay investments in technologies that life-cycle analysis finds cost-effective, and these models also lead to an alternative set of policies targeted at reducing of managing uncertainty.
Date: May 16, 2002
Creator: Jones, D.W.
Partner: UNT Libraries Government Documents Department

Guidelines for technical reviews of software products

Description: A guideline is given for technical review of products developed during a software life cycle. Purposes and benefits of reviews are given. Varieties of reviews, when they should take place, roles of the reviewers and products of the review are described.
Date: March 1, 1982
Creator: Wilburn, N.P.
Partner: UNT Libraries Government Documents Department

Energy Returned On Investment of Engineered Geothermal Systems Annual Report FY2010

Description: Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. EROI analyses of geothermal energy are either out of date or presented online with little supporting documentation. Often comparisons of energy systems inappropriately use 'efficiency' when EROI would be more appropriate. For geothermal electric power generation, EROI is determined by the electric energy delivered to the consumer compared to the energy consumed to build, operate, and decommission the facility.
Date: December 31, 2010
Creator: Mansure, A. J.
Partner: UNT Libraries Government Documents Department

Energy Returned On Investment of Engineered Geothermal Systems Annual Report FY2011

Description: Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. For geothermal electric power generation, EROI is determined by the electricity delivered to the consumer compared to the energy consumed to construct, operate, and decommission the facility. Critical factors in determining the EROI of Engineered Geothermal Systems (EGS) are examined in this work. These include the input energy embodied into the system. The embodied energy includes the energy contained in the materials, as well as, that consumed in each stage of manufacturing from mining the raw materials to assembling the finished plant. Also critical are the system boundaries and value of the energy - heat is not as valuable as electrical energy.
Date: December 31, 2011
Creator: Mansure, A. J.
Partner: UNT Libraries Government Documents Department

Engineered Geothermal Systems Energy Return On Energy Investment

Description: Energy Return On Investment (EROI) is an important figure of merit for assessing the viability of energy alternatives. Too often comparisons of energy systems use “efficiency” when EROI would be more appropriate. For geothermal electric power generation, EROI is determined by the electricity delivered to the consumer compared to the energy consumed to construct, operate, and decommission the facility. Critical factors in determining the EROI of Engineered Geothermal Systems (EGS) are examined in this work. These include the input energy embodied into the system. Embodied energy includes the energy contained in the materials, as well as, that consumed in each stage of manufacturing from mining the raw materials to assembling the finished system. Also critical are the system boundaries and value of the energy – heat is not as valuable as electrical energy. The EROI of an EGS depends upon a number of factors that are currently unknown, for example what will be typical EGS well productivity, as well as, reservoir depth, temperature, and temperature decline rate. Thus the approach developed is to consider these factors as parameters determining EROI as a function of number of wells needed. Since the energy needed to construct a geothermal well is a function of depth, results are provided as a function of well depth. Parametric determination of EGS EROI is calculated using existing information on EGS and US Department of Energy (DOE) targets and is compared to the “minimum” EROI an energy production system should have to be an asset rather than a liability.
Date: December 10, 2012
Creator: Mansure, A J
Partner: UNT Libraries Government Documents Department

Optimal building-integrated photovoltaic applications

Description: Photovoltaic (solar electric) modules are clean, safe and efficient devices that have long been considered a logical material for use in buildings. Recent technological advances have made PVs suitable for direct integration into building construction. PV module size, cost, appearance and reliability have advanced to the point where they can function within the architectural parameters of conventional building materials. A building essentially provides free land and structural support for a PV module, and the module in turn displaces standard building components. This report identifies the highest-value applications for PVs in buildings. These systems should be the first markets for BIPV products in the commercial buildings, and should remain an important high-end market for the foreseeable future.
Date: November 1, 1995
Creator: Kiss, G. & Kinkead, J.
Partner: UNT Libraries Government Documents Department

Cab Heating and Cooling

Description: Schneider National, Inc., SNI, has concluded the Cab Heating and Cooling evaluation of onboard, engine off idling solutions. During the evaluation period three technologies were tested, a Webasto Airtronic diesel fired heater for cold weather operation, and two different approaches to cab cooling in warm weather, a Webasto Parking Cooler, phase change storage system and a Bergstrom Nite System, a 12 volt electrical air conditioning approach to cooling. Diesel fired cab heaters were concluded to provide adequate heat in winter environments down to 10 F. With a targeted idle reduction of 17%, the payback period is under 2 years. The Webasto Parking Cooler demonstrated the viability of this type of technology, but required significant driver involvement to achieve maximum performance. Drivers rated the technology as ''acceptable'', however, in individual discussions it became apparent they were not satisfied with the system limitations in hot weather, (over 85 F). The Bergstrom Nite system was recognized as an improvement by drivers and required less direct driver input to operate. While slightly improved over the Parking Cooler, the hot temperature limitations were only slightly better. Neither the Parking Cooler or the Nite System showed any payback potential at the targeted 17% idle reduction. Fleets who are starting at a higher idle baseline may have a more favorable payback.
Date: October 31, 2005
Creator: Damman, Dennis
Partner: UNT Libraries Government Documents Department

Technical Support Document: 50% Energy Savings for Small Office Buildings

Description: The Technical Support Document (TSD) for 50% energy savings in small office buildings documents the analysis and results for a recommended package of energy efficiency measures (EEMs) referred to as the advanced EEMs. These are changes to a building design that will reduce energy usage. The package of advanced EEMs achieves a minimum of 50% energy savings and a construction area weighted average energy savings of 56.6% over the ANSI/ASHRAE/IESNA Standard 90.1-2004 for 16 cities which represent the full range of climate zones in the United States. The 50% goal is for site energy usage reduction. The weighted average is based on data on the building area of construction in the various climate locations. Cost-effectiveness of the EEMs is determined showing an average simple payback of 6.7 years for all 16 climate locations. An alternative set of results is provided which includes a variable air volume HVAC system that achieves at least 50% energy savings in 7 of the 16 climate zones with a construction area weighted average savings of 48.5%. Other packages of EEMs may also achieve 50% energy savings; this report does not consider all alternatives but rather presents at least one way to reach the goal. Design teams using this TSD should follow an integrated design approach and utilize additional analysis to evaluate the specific conditions of a project.
Date: April 30, 2010
Creator: Thornton, Brian A.; Wang, Weimin; Huang, Yunzhi; Lane, Michael D. & Liu, Bing
Partner: UNT Libraries Government Documents Department

Energy efficiency opportunities in the brewery industry

Description: Breweries in the United States spend annually over $200 Million on energy. Energy consumption is equal to 3-8% of the production costs of beer, making energy efficiency improvement an important way to reduce costs, especially in times of high energy price volatility. After a summary of the beer making process and energy use, we examine energy efficiency opportunities available for breweries. We provide specific primary energy savings for each energy efficiency measure based on case studies that have implemented the measures, as well as references to technical literature. If available, we have also listed typical payback periods. Our findings suggest that there may still be opportunities to reduce energy consumption cost-effectively for breweries. Major brewing companies have and will continue to spend capital on cost effective measures that do not impact the quality of the beer. Further research on the economics of the measures, as well as their applicability to different brewing practices, is needed to assess implementation of selected technologies at individual breweries.
Date: June 28, 2002
Creator: Worrell, Ernst; Galitsky, Christina & Martin, Nathan
Partner: UNT Libraries Government Documents Department

Economic Analysis of Ilumex, A Project to Promote Energy-Efficient Residential Lighting in Mexico

Description: A higher penetration of compact fluorescent lamps (CFLs) for household lighting can reduce growth in peak electricity demand, reduce sales of subsidized electricity, and lessen environmental impacts. This paper describes an economic analysis of a project designed to promote high penetration rates of CFLs in two cities in Mexico. Our analysis indicates that the project will bring substantial net economic benefits to Mexico, the utility, and the average customer. In the absence of any subsidy to CFLs, most customers will see a payback period longer than two years. By sharing some of the anticipated net benefit, CFE, the utility company, can reduce the payback period to a maximum of two years for all customers. CFE's role is thus crucial to the successful implementation of the project. Expanding the Ilumex project to a Mexico-wide program would make a significant contribution towards meeting the planned addition of generation capacity by the year 2000.
Date: November 1, 1993
Creator: Sathaye, Jayant A.; Friedmann, R.; Meyers, S.; de Buen, O.; Gadgil, A.J.; Vargas, E. et al.
Partner: UNT Libraries Government Documents Department

Federal Energy Management Program technical assistance case study: The Forrestal Building relighting project saves $400K annually

Description: The US Department of Energy (DOE) believes energy efficiency begins at home -- in this case the James A. Forrestal Building in Washington, D.C. Since 1969, the 1.7 million-square-foot Forrestal Building has served as DOE Headquarters. In 1989, a team of in-house energy specialists began searching for opportunities to make the Forrestal Building more energy efficient. The team, on which personnel from the Federal Energy Management Program (FEMP) served, identified lighting as an area in which energy use could be reduced substantially. A monitoring program showed that the building`s more than 34,000 1-foot by 4-foot fluorescent lighting fixtures were responsible for 33% of the building`s total annual electric energy use, which represents more than 9 million kilowatt-hours (kWh) per year. In initiating the relighting program, DOE hoped to achieve these broad goals: Reduce energy use and utility bills, and improve lighting quality by distributing the light more uniformly. Funding was also an important consideration. DOE sought financing alternatives through which the lighting retrofit is paid for without using government-appropriated capital funds. DOE cut lighting costs more than 50% and paid for the project with the money saved on energy bills.
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department

Effectiveness of duct sealing and duct insulation in multi-family buildings. Final report

Description: This research investigated the cost-effectiveness of sealing and insulating the accessible portions of duct systems exposed to unconditioned areas in multifamily housing. Airflow and temperature measurements were performed in 25 apartments served by 10 systems a 9 multi-family properties. The measurements were performed before and after each retrofit, and included apartment airflow (supply and return), duct system temperatures, system fan flow and duct leakage area. The costs for each retrofit were recorded. The data were analyzed and used to develop a prototypical multifamily house. This prototype was used in energy simulations (DOE-2.1E) and air infiltration simulations (COMIS 2.1). The simulations were performed for two climates: New York City and Albany. In each climate, one simulation was performed assuming the basement was tight, and another assuming the basement was leaky. Simulation results and average retrofit costs were used to calculate cost-effectiveness. The results of the analysis indicate that sealing leaks of the accessible ductwork is cost-effective under all conditions simulated (simple payback was between 3 and 4 years). Insulating the accessible ductwork, however, is only cost-effective for buildings with leaky basement, in both climates (simple paybacks were less than 5 years). The simple payback period for insulating the ducts in buildings with tight basements was greater than 10 years, the threshold of cost-effectiveness for this research. 13 refs., 5 figs., 27 tabs.
Date: July 1, 1997
Creator: Karins, N.H.; Tuluca, A. & Modera, M.
Partner: UNT Libraries Government Documents Department

Lighting energy efficiency opportunities at Cheyenne Mountain Air Station

Description: CMAS is an intensive user of electricity for lighting because of its size, lack of daylight, and 24-hour operating schedule. Argonne National Laboratory recently conducted a lighting energy conservation evaluation at CMAS. The evaluation included inspection and characterization of existing lighting systems, analysis of energy-efficient retrofit options, and investigation of the environmental effects that these lighting system retrofits could have when they are ready to be disposed of as waste. Argonne devised three retrofit options for the existing lighting systems at various buildings: (1) minimal retrofit--limited fixture replacement; (2) moderate retrofit--more extensive fixture replacement and limited application of motion detectors; and (3) advanced retrofit--fixture replacement, reduction in the number of lamps, expansion of task lighting, and more extensive application of motion detectors. Argonne used data on electricity consumption to analyze the economic and energy effects of these three retrofit options. It performed a cost analysis for each retrofit option in terms of payback. The analysis showed that lighting retrofits result in savings because they reduce electricity consumption, cooling load, and maintenance costs. The payback period for all retrofit options was found to be less than 2 years, with the payback period decreasing for more aggressive retrofits. These short payback periods derived largely from the intensive (24-hours-per-day) use of electric lighting at the facility. Maintenance savings accounted for more than half of the annual energy-related savings under the minimal and moderate retrofit options and slightly less than half of these savings under the advanced retrofit option. Even if maintenance savings were excluded, the payback periods would still be impressive: about 4.4 years for the minimal retrofit option and 2 years for the advanced option. The local and regional environmental impacts of the three retrofit options were minimal.
Date: June 1, 1996
Creator: Molburg, J.C.; Rozo, A.J.; Sarles, J.K.; Haffenden, R.A.; Thimmapuram, P.R. & Cavallo, J.D.
Partner: UNT Libraries Government Documents Department

The design, construction, and monitoring of photovoltaic power system and solar thermal system on the Georgia Institute of Technology Aquatic Center. Volume 1

Description: This is a report on the feasibility study, design, and construction of a PV and solar thermal system for the Georgia Tech Aquatic Center. The topics of the report include a discussion of site selection and system selection, funding, design alternatives, PV module selection, final design, and project costs. Included are appendices describing the solar thermal system, the SAC entrance canopy PV mockup, and the PV feasibility study.
Date: December 31, 1996
Creator: Long, R.C.
Partner: UNT Libraries Government Documents Department

Measured impacts of high efficiency domestic clothes washers in a community

Description: The US market for domestic clothes washers is currently dominated by conventional vertical-axis washers that typically require approximately 40 gallons of water for each wash load. Although the current market for high efficiency clothes washers that use much less water and energy is quite small, it is growing slowly as manufacturers make machines based on tumble action, horizontal-axis designs available and as information about the performance and benefits of such machines is developed and made available to consumers. To help build awareness of these benefits and to accelerate markets for high efficiency washers, the Department of Energy (DOE), under its ENERGY STAR{reg_sign} Program and in cooperation with a major manufacturers of high efficiency washers, conducted a field evaluation of high efficiency washers using Bern, Kansas as a test bed. Baseline washing machine performance data as well as consumer washing behavior were obtained from data collected on the existing machines of more than 100 participants in this instrumented study. Following a 2-month initial study period, all conventional machines were replaced by high efficiency, tumble-action washers, and the study continued for 3 months. Based on measured data from over 20,000 loads of laundry, the impact of the washer replacement on (1) individual customers` energy and water consumption, (2) customers` laundry habits and perceptions, and (3) the community`s water supply and waste water systems were determined. The study, its findings, and how information from the experiment was used to improve national awareness of high efficiency clothes washer benefits are described in this paper.
Date: July 1, 1998
Creator: Tomlinson, J. & Rizy, T.
Partner: UNT Libraries Government Documents Department

Energy efficiency and carbon dioxide emissions reduction opportunities in the U.S. cement industry

Description: This paper reports on an in-depth analysis of the U.S. cement industry, identifying cost-effective energy efficiency measures and potentials. The authors assess this industry at the aggregate level (Standard Industrial Classification 324), which includes establishments engaged in manufacturing hydraulic cements, including Portland, natural, masonry, and pozzolana when reviewing industry trends and when making international comparisons. Coal and coke are currently the primary fuels for the sector, supplanting the dominance of natural gas in the 1970s. Between 1970 and 1997, primary physical energy intensity for cement production (SIC 324) dropped 30%,from 7.9 GJ/t to 5.6 GJ/t, while carbon dioxide intensity due to fuel consumption (carbon dioxide emissions expressed in tons of carbon per ton cement) dropped 25%, from 0.16 tC/ton to 0.12 tC/ton. Carbon dioxide intensity due to fuel consumption and clinker calcination dropped 17%, from 0.29 tC/ton to 0.24 tC/ton. They examined 30 energy efficient technologies and measures and estimated energy savings, carbon dioxide savings, investment costs, and operation and maintenance costs for each of the measures. They constructed an energy conservation supply curve for U.S. cement industry which found a total cost-effective reduction of 0.6 GJ/ton of cement consisting of measures having a simple payback period of 3 years or less. This is equivalent to potential energy savings of 11% of 1994 energy use for cement making and a savings of 5% of total 1994 carbon dioxide emissions by the U.S. cement industry. Assuming the increased production of blended cement in the U.S., as is common in many parts of the world, the technical potential for energy efficiency improvement would not change considerably. However, the cost-effective potential, would increase to 1.1 GJ/ton cement or 18% of total energy use, and carbon dioxide emissions would be reduced by 16%.
Date: August 1, 1999
Creator: Martin, Nathan; Worrell, Ernst & Price, Lynn
Partner: UNT Libraries Government Documents Department

Essential Power Systems Workshop - OEM Perspective

Description: In California, idling is largely done for climate control. This suggests that climate control devices alone could be used to reduce idling. Line-haul truck drivers surveyed require an average of 4-6 kW of power for a stereo, CB radio, light, refrigerator, and climate control found in the average truck. More power may likely be necessary for peak power demands. The amount of time line-haul trucks reported to have stopped is between 25 and 30 hours per week. It was not possible to accurately determine from the pilot survey the location, purpose, and duration of idling. Consulting driver logs or electronically monitoring trucks could yield more accurate data, including seasonal and geographic differences. Truck drivers were receptive to idling alternatives. Two-thirds of truck drivers surveyed support a program to reduce idling. Two-thirds of drivers reported they would purchase idling reduction technologies if the technology yielded a payback period of two years or less. Willingness to purchase auxiliary power units appears to be higher for owner-operators than for company drivers. With a 2-year payback period, 82% of owner- operators would be willing to buy an idle- reducing device, while 63% of company drivers thought their company would do the same. Contact with companies is necessary to discern whether this difference between owner- operators and companies is true or simply due to the perception of the company drivers. Truck stops appear to be a much more attractive option for electrification than rest areas by a 48% to 21% margin. Much of this discrepancy may be due to perceived safety problems with rest areas. This survey did not properly differentiate between using these areas for breaks or overnight. The next, full survey will quantify where the truck drivers are staying overnight, where they go for breaks, and the duration of time they spend at ...
Date: December 12, 2001
Creator: Gouse, Bill
Partner: UNT Libraries Government Documents Department

Desiccant-Based Preconditioning Market Analysis

Description: A number of important conclusions can be drawn as a result of this broad, first-phase market evaluation. The more important conclusions include the following: (1) A very significant market opportunity will exist for specialized outdoor air-handling units (SOAHUs) as more construction and renovation projects are designed to incorporate the recommendations made by the ASHRAE 62-1989 standard. Based on this investigation, the total potential market is currently $725,000,000 annually (see Table 6, Sect. 3). Based on the market evaluations completed, it is estimated that approximately $398,000,000 (55%) of this total market could be served by DBC systems if they were made cost-effective through mass production. Approximately $306,000,000 (42%) of the total can be served by a non-regenerated, desiccant-based total recovery approach, based on the information provided by this investigation. Approximately $92,000,000 (13%) can be served by a regenerated desiccant-based cooling approach (see Table 7, Sect. 3). (2) A projection of the market selling price of various desiccant-based SOAHU systems was prepared using prices provided by Trane for central-station, air-handling modules currently manufactured. The wheel-component pricing was added to these components by SEMCO. This resulted in projected pricing for these systems that is significantly less than that currently offered by custom suppliers (see Table 4, Sect. 2). Estimated payback periods for all SOAHU approaches were quite short when compared with conventional over-cooling and reheat systems. Actual paybacks may vary significantly depending on site-specific considerations. (3) In comparing cost vs benefit of each SOAHU approach, it is critical that the total system design be evaluated. For example, the cost premium of a DBC system is very significant when compared to a conventional air handling system, yet the reduced chiller, boiler, cooling tower, and other expense often equals or exceeds this premium, resulting in a rapid payback period while providing significant energy savings.
Date: January 11, 2001
Creator: Fischer, J.
Partner: UNT Libraries Government Documents Department

Scenario analysis of hybrid class 3-7 heavy vehicles.

Description: The effects of hybridization on heavy-duty vehicles are not well understood. Heavy vehicles represent a broader range of applications than light-duty vehicles, resulting in a wide variety of chassis and engine combinations, as well as diverse driving conditions. Thus, the strategies, incremental costs, and energy/emission benefits associated with hybridizing heavy vehicles could differ significantly from those for passenger cars. Using a modal energy and emissions model, they quantify the potential energy savings of hybridizing commercial Class 3-7 heavy vehicles, analyze hybrid configuration scenarios, and estimate the associated investment cost and payback time. From the analysis, they conclude that (1) hybridization can significantly reduce energy consumption of Class 3-7 heavy vehicles under urban driving conditions; (2) the grid-independent, conventional vehicle (CV)-like hybrid is more cost-effective than the grid-dependent, electric vehicle (EV)-like hybrid, and the parallel configuration is more cost-effective than the series configuration; (3) for CV-like hybridization, the on-board engine can be significantly downsized, with a gasoline or diesel engine used for SUVs perhaps being a good candidate for an on-board engine; (4) over the long term, the incremental cost of a CV-like, parallel-configured Class 3-4 hybrid heavy vehicle is about %5,800 in the year 2005 and $3,000 in 2020, while for a Class 6-7 truck, it is about $7,100 in 2005 and $3,300 in 2020; and (5) investment payback time, which depends on the specific type and application of the vehicle, averages about 6 years under urban driving conditions in 2005 and 2--3 years in 2020.
Date: December 23, 1999
Creator: An, F.; Stodolsky, F.; Vyas, A.; Cuenca, R. & Eberhardt, J. J.
Partner: UNT Libraries Government Documents Department

Field Test Evaluation of Conservation Retrofits of Low-Income, Single-Family Buildings in Wisconsin: Blower-Door-Directed Infiltration Reduction Procedure, Field Test Implementation and Results

Description: A blower-door-directed infiltration retrofit procedure was field tested on 18 homes in south central Wisconsin. The procedure, developed by the Wisconsin Energy Conservation Corporation, includes recommended retrofit techniques as well as criteria for estimating the amount of cost-effective work to be performed on a house. A recommended expenditure level and target air leakage reduction, in air changes per hour at 50 Pascal (ACH50), are determined from the initial leakage rate measured. The procedure produced an average 16% reduction in air leakage rate. For the 7 houses recommended for retrofit, 89% of the targeted reductions were accomplished with 76% of the recommended expenditures. The average cost of retrofits per house was reduced by a factor of four compared with previous programs. The average payback period for recommended retrofits was 4.4 years, based on predicted energy savings computed from achieved air leakage reductions. Although exceptions occurred, the procedure's 8 ACH50 minimum initial leakage rate for advising retrofits to be performed appeared a good choice, based on cost-effective air leakage reduction. Houses with initial rates of 7 ACH50 or below consistently required substantially higher costs to achieve significant air leakage reductions. No statistically significant average annual energy savings was detected as a result of the infiltration retrofits. Average measured savings were -27 therm per year, indicating an increase in energy use, with a 90% confidence interval of 36 therm. Measured savings for individual houses varied widely in both positive and negative directions, indicating that factors not considered affected the results. Large individual confidence intervals indicate a need to increase the accuracy of such measurements as well as understand the factors which may cause such disparity. Recommendations for the procedure include more extensive training of retrofit crews, checks for minimum air exchange rates to insure air quality, and addition of the basic cost of ...
Date: May 21, 2001
Creator: Gettings, M.B.
Partner: UNT Libraries Government Documents Department

Deriving metrics for relating complexity measures to software maintenance costs

Description: Managers of software maintenance functions know that maintenance costs often increase with the age of software, and that maintenance costs are frequently proportional to software complexity. When the service to expense ratio degrades, sometimes a rewrite of the software results in a payoff. This research is a case study, presenting factors which contributed to the expense of one maintenance function. A descriptive model was used. It is suggested how the descriptive model could be a building block toward the derivation of a predictive model. A predictive model could be used in the preparation of a breakeven/payoff analysis, justifying the expense of rewriting existing software to contain minimum complexity by incorporating modern techniques.
Date: January 1, 1982
Creator: Brice, L.; Connell, J. & Taylor, J.
Partner: UNT Libraries Government Documents Department