Life Cycle Cost Savings Research Articles

Experience of duplex stainless steels as structural materials for bridges

The use of duplex stainless steel (DSS) in bridge construction has increased significantly in the last twenty years because of the material’s high strength and good corrosion resistance. The high corrosion resistance of DSS results in a low maintenance requirement and hence low life cycle costs. There is now a range of DSS grades available and it is possible during the design phase to undertake a material selection exercise for DSS to align the required material performance with the bridge environment. Lean alloyed and less costly DSS grades can be specified in less harsh environments. This paper presents the results from inspection of various existing road, rail and pedestrian bridges. In each case a DSS was used for the main structure and each bridge illustrates the performance of the material in a representative European environment. The environments were retrospectively classified in accordance with the recently introduced EN 1993-1-4 Annex A and a comparison of actual performance made with the guidance given in this annex. Previous high-level cost studies have indicated that durable, low-maintenance bridge designs using DSS are achievable without incurring excessive initial construction costs, and that significant life cycle cost savings can be made over the life of the structure. The present work has confirmed that, when appropriately selected and used, DSS can be anticipated to give long service lives in bridge structures, greatly reducing corrosion problems that may necessitate re-painting and remediation of carbon steel structures.

A multiple lifecycle-based approach to sustainable product configuration design

Research on end-of-life (EoL) product recovery has focused on adopting reuse, remanufacturing, and/or recycling after product use. These product EoL strategies need to be considered early during product design in order to reduce the total lifecycle cost, minimize environmental impact, and enhance overall product sustainability. Considering the implementation of such EoL strategies across multiple lifecycles of a product will enable maximum recovery of the materials and embedded energy from previous lifecycle products for use in subsequent lifecycle products. Such practices can help companies increase global manufacturing competitiveness and promote corporate social responsibility for more sustainable economic growth. However, a multi-lifecycle based approach to product configuration design optimization, simultaneously considering conflicting objectives, has not been well addressed in previous studies. In this study, a multi-lifecycle based methodology is proposed to solve multi-objective product configuration design problems considering conflicting economic and environmental objectives. The methodology addresses issues across all the lifecycle stages, from extracting raw materials to product EoL recovery (i.e., pre-manufacturing, manufacturing, use, and post-use), and the entire demand cycle. The multi-objective optimization problem can be solved by introducing a non-dominated sorting genetic algorithm II using which various product design solutions can be generated by considering the tradeoff between several objectives. The proposed methodology is implemented on an industrial case study for the configuration design of toner cartridges. The Pareto optimal solutions yield better economic and environmental performances compared to the performance of the base toner cartridge. The results show that following the multi-lifecycle based approach to implement EoL strategies (i.e., reuse, remanufacturing, and recycling) could provide over 20% savings in total lifecycle cost, total global warming potential, and total water use in comparison to the same product configuration made up with entirely new components.

Thermo-economic analysis of a waste-to-energy integrated multi-generation power plant

ABSTRACTThis paper presents the thermo-economic analysis of a waste-to-energy integrated multi-generation power plant using the municipal solid waste generated in Onitsha, Nigeria at latitude 6°9′N and longitude 6°49′E. The chemical energy in the municipal solid waste was converted to that of a synthetic gas, and subsequently converted into electrical energy in an integrated multi-generation power plant composed of gas turbine, steam turbine, micro turbine and absorption refrigeration cycles. The analysis was implemented in the HYSYS, EES, MATLAB and Microsoft environments. Results showed that the municipal solid waste had a power plant capacity of 168 MW, exergetic efficiency of 51%, life cycle cost of $143 million, breakeven point of 9 years, and a unit cost of electricity of $0.01/kWh. Compared to the combined power plant of similar capacity, the life cycle cost savings and reduction in the flue gas exit stack temperature were $49.07 million and 73°C, respectively.

Environmental and economic impact of using new-generation wide-base tires

New-generation wide-base tire (NG-WBT) is known for improving fuel economy and at the same time for potentially causing a greater damage to pavement. No study has been conducted to evaluate the net environmental saving of the combined system of pavements and NG-WBT. This study adopted a holistic approach (life cycle assessment [LCA] and life cycle costing [LCC]) to quantitatively evaluate the environmental and economic impact of using NG-WBT. The net effect of different levels of market penetration of NG-WBT on energy consumption, global warming potential (GWP), and cost based on the fatigue cracking and rutting performance of two different asphalt concrete (AC) pavement structures was evaluated. The performance of pavements was determined based on pavement design lives; pavement surface characteristics, and pavement critical strain responses obtained from the artificial neural network (ANN) based on finite element (FE) simulations were used to calculate design lives of pavements. Based on the calculated design lives, life cycle inventory (LCI) and cost databases, and rolling resistance (RR) models previously developed by the University of Illinois at Urbana-Champaign (UIUC) were used to calculate the environmental and economic impact of the combined system. The fuel economy improvement using NG-WBT is 1.5% per axle. Scenario-based case studies were conducted. Considering 0% NG-WBT market penetration (or 100% standard dual tire assembly [DTA]) as a baseline, scenario 1 assumed the same fatigue and rutting potential between NG-WBT and DTA; therefore, the only difference came from fuel economy improvement of using NG-WBT. In scenario 2, pavement fatigue cracking potential determined the pavement design life; both thick and thin AC overlay sections experienced positive net environmental savings, but mixed net economic savings. In scenario 3, pavement rutting potential determined the pavement design life; the thick AC overlay section experienced positive net environmental savings, but mixed net economic savings. The thin section experienced negative net environmental and economic savings. The outcomes of scenario-based case studies indicated that NG-WBT can result in significant savings in life cycle energy consumption and cost, and GWP; however, these benefits were sensitive to the method used to determine the pavement performance; especially, a small change in pavement strain can result in significant change in pavement life. In addition, the effect of fuel price/economy improvement, discount rate, and International Roughness Index (IRI) threshold values was studied in the sensitivity analyses.

Optimal FM Strategy for Commercial Office Buildings Using Fuzzy Synthetic Evaluation

AbstractFor owners of aged buildings, considerable attention needs to be devoted to efficient facility management (FM) to extend building life and achieve life-cycle cost savings. The fundamental s...

Holistic impact assessment and cost savings of rainwater harvesting at the watershed scale.

We evaluated the impacts of domestic and agricultural rainwater harvesting (RWH) systems in three watersheds within the Albemarle-Pamlico river basin (southeastern U.S.) using life cycle assessment (LCA) and life cycle cost assessment. Life cycle impact assessment (LCIA) categories included energy demand, fossil fuel, metals, ozone depletion, global warming, acidification, smog, blue and green water use, ecotoxicity, eutrophication, and human health effects. Building upon previous LCAs of near-optimal domestic and agricultural RWH systems in the region, we scaled functional unit LCIA scores for adoption rates of 25%, 50%, 75%, and 100% and compared these to conventional municipal water and well water systems. In addition to investigating watershed-scale impacts of RWH adoption, which few studies have addressed, potential life cycle cost savings due to reduced cumulative energy demand were scaled in each watershed for a more comprehensive analysis. The importance of managing the holistic water balance, including blue water (surface/ground water), green water (rainwater) use, and annual precipitation and their relationship to RWH are also addressed. RWH contributes to water resource sustainability by offsetting surface and ground water consumption and by reducing environmental and human health impacts compared to conventional sources. A watershed-wide RWH adoption rate of 25% has a number of ecological and human health benefits including blue water use reduction ranging from 2–39 Mm3, cumulative energy savings of 12–210 TJ, and reduced global warming potential of 600–10,100 Mg CO2 eq. Potential maximum lifetime energy cost savings were estimated at $5M and $24M corresponding to domestic RWH in Greens Mill and agricultural RWH in Back Creek watersheds.

Selection Methods and Procedure for Evaluation of LED Roadway Luminaires

ABSTRACTThis study evaluated the existing light emitting diode (LED) roadway luminaires available in the U.S. market for field implementation to displace the high intensity discharge (HID) luminaires. Four methods were proposed for selection of qualified LED luminaires, including, in order, specification evaluation, computer simulation, implementation cost-effectiveness analysis, and field mock-up tests. A total of 148 LED roadway luminaires were collected and evaluated over 28 factors. Those luminaires were tested in computer simulations for optimized roadway layout and preferred lighting performance in compliance with the codes and standards. An approved products list (APL) of 88 luminaires was selected for potential field implementation. A lighting economics calculator was developed for cost-effectiveness analysis on their implementation. Guidance on the field mock-up tests was also proposed. The present study then evaluated the selection methods in an assumed replacement project of 1000 luminaires in Kansas. In this project, the APL was shortened to a short list of 13 standard pole and three high-mast LED luminaires based on their efficacy, year released, availability of manufacturer sales representatives, and simple payback time period for roadway implementation. The short-list products were compared to their equivalent existing HID luminaire counterparts for cost–benefit analysis that revealed significant 12-year life cycle cost savings with an average payback time period less than 3 years. The present study then evaluated the four selection methods in their effective procedure for future uses in the selection of qualified replacement LED luminaires with expected adjustments and timely update.

The effects of under-sleeper pads on sleeper-ballast interaction

Under-sleeper pads (USPs), typically made from polyurethane, are used by railways in certain parts of the world to reduce ballast settlement and consequently lengthen the ballast tamping cycle. The rationale behind this relatively new addition to the conventional ballasted track structure is that the pad increases the contact area between the angular ballast particles and the underside of the concrete sleeper, with the effect that ballast breakdown and total track settlement are reduced. This paper describes two experiments on the effects of USPs on four aspects of sleeper-ballast interaction, namely contact area, contact pressure, ballast settlement and ballast breakdown. Static and dynamic tests up to 1 million loading cycles were performed under controlled laboratory conditions on concrete sleepers with and without USPs. Sophisticated pressure sensors revealed an increase in contact area from 12% to 35% for static loading tests, and from 8% to 20% for dynamic tests, with a resulting 70% reduction in contact pressure. In addition, a 44% reduction in ballast settlement and a 23% reduction in ballast breakdown were achieved by the introduction of USPs. In conclusion it is argued that the introduction of USPs specifically on heavy-haul lines would offer significant advantages with respect to ballast settlement and breakdown. These advantages are most likely to lengthen general ballast tamping and screening cycles, resulting in significant life cycle cost savings.

Coupled oil analysis trending and life-cycle cost analysis for vessel oil-change interval decisions

ABSTRACTExtending lube oil-drain intervals is a practical way to save money on engine operating costs. At the same time, there may be increased risk of engine damage with increased drain intervals. The risks and benefits can be difficult to weigh and, as a result, starting an oil-drain interval extension programme can be an intimidating endeavour. This paper combines oil-analysis programme data interpretation and life-cycle cost analysis (LCCA) into a methodology for weighing oil-drain interval options. LCCA has shown decreasing incremental cost savings as oil-drain intervals are further extended, indicating that highly extended drain intervals may not be necessary to reap the majority of available cost benefits. Using oil-analysis property trending with life-cycle cost savings can allow an engine operator to set an hours-based extended drain interval based on projected risks and benefits. This interval is set as the baseline under the protocol, but continual oil analysis is used as a precaution to protect against unpredictable events. This methodology helps to reduce the risk of engine damage and ensure that the most easily attainable cost savings are still captured, making the decision about how to extend oil-drain intervals more approachable.

APPRAISAL OF APPLICATION OF VALUE ENGINEERING METHODOLOGY IN MECHANICAL AND ELECTRICAL SERVICES INSTALLATIONS

Value engineering (VE) is a structured team-oriented problem solving approach that can be applied throughout the lifecycle of a building project. However, the methodology is rarely applied in mechanical and electrical services (M&E) installations in buildings because clients are not aware of the potential benefits of adopting VE and different members of design team lack the requisite knowledge about VE methodology. As a result, a great deal of unnecessary cost is created due to the increasingly complex nature of M&E services in buildings leading to cost overruns and unhappy clients. The purpose of this study is to investigate the level of adoption of VE methodology in the design and installations of M&E services in buildings in Malaysian construction industry. The research method adopted is questionnaire survey to industry practitioners and inferential statistics was adopted for data analysis. Findings from the study show that, VE is not well appreciated in the industry and there is no structured approach adopted for its adoption for the procurement of mechanical and electrical services. Practitioners are of the opinion that implementation of VE could lead to: significant capital and life cycle cost savings in buildings generally; alignment of stakeholders and construction process improvement; improved client satisfaction, and shared understanding among key participants. An implementation framework was developed which emphasised on the need for early involvement of consultants and collaboration between the downstream supply chain for effective implementation of VE methodology on mechanical and electrical services.

OPTIMIZING BUILDING UPGRADES TO MINIMIZE ENERGY AND WATER CONSUMPTION

Building sector in the United States is responsible for 41% of energy consumption, 73% of electricity consumption, and 14% of water consumption. Energy and water consumption of buildings can be significantly reduced by identifying and implementing green building upgrade measures based on available budgets especially in aging buildings which represent 70% of existing buildings in the United States. This paper presents the development of an optimization model that is capable of identifying the optimal selection of building upgrade measures to minimize energy and water consumption of existing buildings while complying with limited upgrade budgets and building operational performance requirements. This optimization model is designed to estimate building energy consumption using energy simulation software packages, is integrated with databases of building products, and performs analysis of replacing existing building fixtures/equipment and installing renewable energy systems during optimization computations to identify the replacement of building products that minimizes energy and water consumption. The model is designed to provide detailed results for building owners, which include specifications for the recommended upgrade measures and their location in the building; required upgrade cost; expected energy and water, operational, and life-cycle cost savings; and expected payback period.

Energy performance and economic viability of advanced window technologies for a new Finnish townhouse concept

Among the elements of a typical building envelope, windows are responsible for the greatest energy loss due to their high U-value. Conventional windows tend to have poor glazing properties, which causes significant heat loss during the winter season and undesirable heat gain during the summer season. Advanced window technologies are therefore required to mitigate the energy consumption of buildings. The key hypothesis in this study is that advanced windows become economically viable for end-users if the difference in life-cycle cost between advanced window types and the state-of-the-art (reference) window is equal to zero. To verify this hypothesis, we calculate the allowable additional investment costs (dIC) for three types of advanced windows over a given life span. Different advanced windows; electrochromic, PV and vacuum windows together with a self-cleaning feature were compared with a state-of-the-art window with excellent properties (reference window) in terms of energy performance and life-cycle cost for a conceptual residential house (i.e. townhouse) in Finland. By performing a whole-building simulation using IDA ICE, the impact of these windows on the total delivered energy needs of the townhouse were estimated. Among the alternatives, the vacuum window (lowest U-value) offers the highest dIC value, due to its maximum energy savings. With a generic efficiency of 6%, the PV window holds the intermediate position between the vacuum and reference window in terms of dIC value. Hypothetically, with a U-value of 0.6W/m2K, the PV window would become the most energy efficient window alternative. The self-cleaning feature proved to be a dominant factor toward the increase of dIC value by avoiding maintenance costs. Electrochromic glazing is not economically feasible due to its negative dIC value as it doesn’t offer life cycle cost savings.

Model-Based Conceptual Design Optimization Methods: Disaggregated Weather System Follow-On

The future of space-based defense weather systems is uncertain due to the cancellation of the National Polar-Orbiting Operational Environmental Satellite System and Defense Weather Satellite System programs. The U.S. Department of Defense Weather Satellite Follow-On program has been identified as the follow-on program and a potential pathfinder for the concept of disaggregation. The concept of disaggregation has the potential to reduce costs and increase system resiliency. However, current research literature does not address a systematic method for performing conceptual trades between large multifunction and small functionally cohesive spacecraft. A multifunction/multiorbit disaggregated space-system optimization methodology is proposed and applied to the weather system follow-on conceptual architecture problem. Real-coded mixed-integer optimization techniques are implemented to identify, assess, and compare alternative space-based weather system conceptual architectures. The resulting cost and performance figures of merit are analyzed to assess disaggregated space-based weather constellation cost effectiveness. The potential estimated life-cycle cost savings of approximately 3 billion U.S. dollars are modeled for a disaggregated weather system follow-on program versus a Defense Weather Satellite System analogous architecture. The resulting analysis is intended to demonstrate the applicability of the disaggregated integral system concept optimization methodology to assess multifunction, multiorbit disaggregation problems.

Minimizing Energy Consumption and Carbon Emissions of Aging Buildings

The building sector in the United States is responsible for 41% of energy consumption and 39% of carbon footprint while the majority of energy consumption and carbon footprint are caused by aging buildings which represent 70% of existing buildings in the United States. The energy consumption of aging buildings can be significantly reduced by identifying and implementing green building upgrade measures based on available budgets. Aging buildings are often in urgent need for upgrading to improve their operational, economic, and environmental performance. This paper presents the development of an optimization model that is capable of identifying the optimal selection of building upgrade measures to minimize energy consumption of aging buildings while complying with limited upgrade budgets and building operational performance. This optimization model is designed to estimate building energy consumption using energy simulation software packages such as eQuest and it is integrated with databases of building products. This optimization model performs analysis of replacing existing building fixtures and equipment during the optimization computations to identify the optimal replacement of building products that minimizes building energy consumption and carbon emissions. The model is designed to provide detailed results for building owners and operators, which include specifications for the recommended upgrade measures and their location in the building; upgrade cost; expected energy, operational, and life-cycle cost savings; and expected payback period. This paper illustrates the new and unique capabilities of the developed optimization model.

Optimal design of residential building envelope systems in the Kingdom of Saudi Arabia

In this paper, a comprehensive analysis study is presented in order to improve the energy performance of residential buildings in the Kingdom of Saudi Arabia (KSA) through optimizing the building envelope elements. The building envelope energy conservation measures included in the study are wall insulation, roof insulation, window area, window glazing, window shading, and thermal mass. The optimization process was based on life cycle cost and energy savings. Optimum packages of energy efficiency measures for a residential building located in five climate zones in KSA have been determined for subsidized and non-subsidized energy costs. The results showed optimal energy savings of 39.5%, 33.7%, 35%, 32.7% and 22.7% for Riyadh, Jeddah, Dhahran, Tabuk and Abha, respectively, can be obtained for the subsidized energy cost case. For the non-subsidized energy cost case, the optimal energy savings were 47.3%, 41.5%, 43.19%, 41.1% and 26% for Riyadh, Jeddah, Dhahran, Tabuk and Abha, respectively. Moreover, a sensitivity cost analysis indicated that the cost of energy has more influence on optimal energy savings and life cycle costs than the initial costs of the energy efficiency measures. Finally, this study concluded that substantial savings in annual energy costs subsidies can be achieved by the KSA government if it aggressively promotes, through investments and incentives, energy efficiency programs for both existing and new buildings.

Optimization Analysis and Design of Solar Water Heating System by Lifecycle Cost Savings Method

The objective of this work is to do theoretically investigation about the solar fraction changing laws affected by some factors, so that we can do optimization for solar system designing, specially for household solar water heating system. The calculation of solar fraction was established on a more effective day-to-day simulation model rather than traditional method. It is found that the collector area and the water storage tank volume are the main influence factors. Economic analysis by means of lifecycle cost savings evaluation was carried out based on the calculated model.

A method to optimize the scope of a software product platform based on end-user features

ContextDue to increased competition and the advent of mass customization, many software firms are utilizing product families – groups of related products derived from a product platform – to provide product variety in a cost-effective manner. The key to designing a successful software product family is the product platform, so it is important to determine the most appropriate product platform scope related to business objectives, for product line development. AimThis paper proposes a novel method to find the optimized scope of a software product platform based on end-user features. MethodThe proposed method, PPSMS (Product Platform Scoping Method for Software Product Lines), mathematically formulates the product platform scope selection as an optimization problem. The problem formulation targets identification of an optimized product platform scope that will maximize life cycle cost savings and the amount of commonality, while meeting the goals and needs of the envisioned customers’ segments. A simulated annealing based algorithm that can solve problems heuristically is then used to help the decision maker in selecting a scope for the product platform, by performing tradeoff analysis of the commonality and cost savings objectives. ResultsIn a case study, PPSMS helped in identifying 5 non-dominated solutions considered to be of highest preference for decision making, taking into account both cost savings and commonality objectives. A quantitative and qualitative analysis indicated that human experts perceived value in adopting the method in practice, and that it was effective in identifying appropriate product platform scope.

The impacts of duct design on life cycle costs of central residential heating and air-conditioning systems

Many central residential HVAC systems in the U.S. operate at high external static pressures due to a combination of system restrictions. Undersized and constricted ductwork are thought to be key culprits that lead to excess external static pressures in many systems, although the magnitude of energy impacts associated with restrictive ductwork and the costs or benefits associated with addressing the problem are not well known. Therefore, this work uses annual energy simulations of two typical new single-family homes in two separate climates in the United States (Austin, TX and Chicago, IL) to predict the impacts of various external static pressure ductwork designs from independent HVAC contractors (using both flexible and rigid sheet metal ductwork materials) on annual space conditioning energy use. Results from the simulations are combined with estimates of the initial installation costs of each duct design made by each contractor to evaluate the total life cycle costs or savings of using lower pressure duct designs in the two homes over a 15-year life cycle. Lower pressure ductwork systems generally yielded life cycle cost savings, particularly in homes with PSC blowers and particularly when making comparisons with constant ductwork materials (i.e., comparing flex only or rigid only).

Proposed Method for Analyzing Infrastructure Investment Decisions Involving Rapidly Evolving Technology: Case Study of LED Streetlights

Infrastructure projects have typically involved long-term investments in mature technologies characterized by stable performance and cost. However, with the ever-increasing rate of technological innovation, an increasing number of potential infrastructure investments involve a decision to replace a mature technology with a rapidly evolving technology. Therefore, the primary objective of this research was to develop a method to strategically determine the optimal year to replace an existing infrastructure item with a more cost-effective but rapidly evolving technology, where both the cost and performance of the technology are improving. The utility of this method is illustrated by evaluating the replacement of existing high-pressure sodium streetlights on 64 U.S. Air Force installations with light-emitting diode (LED) streetlights. A model is thus provided to predict the optimal year for replacement as a function of electricity rate. Potential life-cycle cost savings of the proposed approach ranged from 0.2 to 11.7% per installation, with an average of 5.4 percent.

Framework of Non-Nuclear Methods Evaluation for Soil QC and QA in Highway Pavement Construction

This study introduces a methodology to evaluate different types of non-nuclear technologies to see how they are competitive to the nuclear technology for quality control (QC) and quality assurance (QA) in soil condition measurement for highway pavement construction. The non-nuclear methods including the Electrical Density Gauge (EDG) and the Light Weight Deflectometer (LWD) were tested for their performance against a nuclear gauge, and traditional methods were used as baselines. An innovative way of comparing a deflection gauge to a density gauge was introduced. Results showed that the nuclear gauge generally outperformed the non-nuclear gauge in accuracies of soil density and moisture content measurements. Finally, a framework was developed as a guideline for evaluating various types of non-nuclear soil gauges. From other perspectives rather than accuracy, it was concluded that the non-nuclear gauges would be better alternative to the nuclear gauge when the followings are considered: (1) greater life-cycle cost savings; (2) elimination of intense federal regulations and safety/security concerns; and (3) elimination of licensing and intense training.