Choi, Kunhee; Lee, Hyun Woo; Bae, Junseo; Bilbo, David. (2016). Time-Cost Performance Effect of Change Orders from Accelerated Contract Provisions. Journal Of Construction Engineering And Management, 142(3).
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Abstract
Accelerated contract provisions (ACPs) such as cost-plus-time (A+B) and incentives/disincentives (I/D) are increasingly common, yet very little is known about their pure time-cost performance effects on change orders. To fill this large knowledge gap, a two-stage research methodology drawing on 1,372 highway improvement projects completed in California was adopted for this study. The Stage I study investigated the marginal change-order impacts of two ACPs, pure A+B and I/D combined with A+B. How ACP change orders affect projects' time-cost performance was numerically modeled and successfully validated over the Stage II study. The results clearly showed that both ACPs led to more schedule-change and cost-change orders than conventionally contracted projects, whereas I/D combined with A+B performed significantly better than pure A+B in terms of the magnitude of schedule-change orders. This conveys an important recommendation to state transportation agencies (STAs) that A+B be used with an I/D provision. The results and numerical models of this study would help STAs better assess and justify the impact of change orders on the duration and cost of projects, enabling them to more effectively use contingency amounts. Use of the models can also benefit contractors requesting a change order because the models can provide them with advanced knowledge of the probable time-cost growth rates specifically for the pursued ACP. (C) 2015 American Society of Civil Engineers.
Keywords
Construction Industry; Contracts; Costing; Incentive Schemes; Numerical Analysis; Order Processing; Performance Evaluation; Roads; Scheduling; Time Management; Transportation; Projects Time-cost Performance Effect; Cost-change Order; Accelerated Contract Provision; Knowledge Gap; California; Acp; Schedule-change Order; State Transportation Agency; Numerical Model; Sta; Incentive; Highway Improvement Project; Labor Productivity; Construction; Impact; Model; Projects; Change Order; Highway Rehabilitation; Decision Modeling; Regression; Validation; Contracting
Rodriguez, Barbara X.; Huang, Monica; Lee, Hyun Woo; Simonen, Kathrina; Ditto, Jim. (2020). Mechanical, Electrical, Plumbing and Tenant Improvements over the Building Lifetime: Estimating Material Quantities and Embodied Carbon for Climate Change Mitigation. Energy And Buildings, 226.
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Abstract
The building industry is expanding its ability to mitigate the environmental impacts of buildings through the application of life cycle assessment (LCA). Most building LCA studies focus on core and shell (C&S) and rarely assess mechanical, electrical, and plumbing (MEP) and tenant improvements (TI). However, C&S typologies in the commercial sector pose particular challenges to achieving net zero carbon due to the numerous renovations these building undergo through during their service life. MEP and TI are installed multiple times over the lifetime of commercial buildings leading to cumulative environmental impact caused by increasing material quantities and embodied carbon (EC). This study aimed to establish a preliminary range of material quantities and embodied carbon impacts for MEP and TI components, focusing on commercial office buildings in the Pacific Northwest. The first research stage involved quantifying material quantities while a second stage aimed to calculate Embodied Carbon Coefficients (ECC) and LCA impacts using different data sources. The embodied carbon estimates ranged from 40 to 75 kg CO(2)e/m(2) for MEP and 45-135 kg CO(2)e/m(2) for TI. However, with recurring instalments during a life span of 60 years the impacts become comparable to known impacts of core and shell systems. (C) 2020 Elsevier B.V. All rights reserved.
Keywords
Embodied Carbon; Life Cycle Assessment; Tenant Improvement; Mechanical; Electrical And Plumbing
Choi, Kunhee; Lee, Hyun Woo; Mao, Zhuting; Lavy, Sarel; Ryoo, Boong Yeol. (2016). Environmental, Economic, and Social Implications of Highway Concrete Rehabilitation Alternatives. Journal Of Construction Engineering And Management, 142(2).
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Abstract
Currently, there is no comprehensive benchmark of life-cycle assessment for the rigid pavement alternatives for highway rehabilitation. To fill this gap, the major objective of this study is to investigate the environmental, economic, and social impacts of the three most widely adopted rigid pavement choices through a life-cycle assessment approach with custom-built economic input-output life-cycle assessment (EIO-LCA) models. Quantity takeoffs were performed for each alternative assuming a 1-lane-km highway rehabilitation. Subsequently, the construction costs of each alternative were computed in order to determine the present values for a life span of 50years, while at the same time accounting for a different life expectancy for each pavement rehabilitation strategy. The present values were then incorporated into a corresponding EIO-LCA model. The results clearly indicate that continuously reinforced concrete pavement (CRCP) is the most sustainable choice and much preferable to the other alternatives for minimizing negative environmental, economic and social impacts from the life-cycle perspective. This finding champions a wider adoption of CRCP for future sustainable transportation infrastructure development projects, as CRCP's relatively high initial construction cost can be recouped by long-term sustained benefits. The results and findings of this study can serve as a solid foundation for industry practitioners and decision-makers to make better-informed project decisions when choosing the most sustainable pavement alternatives from a life-cycle perspective. (C) 2015 American Society of Civil Engineers.
Keywords
Construction Industry; Environmental Management; Life Cycle Costing; Product Life Cycle Management; Project Management; Reinforced Concrete; Road Building; Socio-economic Effects; Sustainable Development; Economic Implications; Environmental Implications; Industry Practitioners; Sustainable Transportation Infrastructure Development Projects; Continuously Reinforced Concrete Pavement; Crcp; Eio-lca Model; Life Span; Construction Costs; Custom-built Economic Input-output Life-cycle Assessment Models; Rigid Pavement Alternatives; Highway Concrete Rehabilitation Alternatives; Life-cycle Assessment Approach; Social Implications; Life-cycle Assessment; Pavement; Asphalt; Pavement Rehabilitation; Environmental Assessment; Economic Factors; Land Use
Shang, Luming; Lee, Hyun Woo; Dermisi, Sofia; Choe, Youngjun. (2020). Impact of Energy Benchmarking and Disclosure Policy on Office Buildings. Journal Of Cleaner Production, 250.
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Abstract
Building energy benchmarking policies require owners to publicly disclose their building's energy performance. In the US, the adoption of such policies is contributing to an increased awareness among tenants and buyers and is expected to motivate the owners of less efficient buildings to invest in energy efficiency improvements. However, there is a lack of studies specifically aimed at investigating the impact of such policies on office buildings among major cities through quantitative analyses. In response, this study evaluated the effectiveness of the benchmarking policy on energy efficiency improvements decision-making and on real estate performances, by applying two interrupted time series analyses to office buildings in downtown Chicago. The initial results indicate a lack of statistically strong evidence that the policy affected the annual vacancy trend of the energy efficient buildings (represented by ENERGY STAR labeled buildings). However, the use of interrupted time series in a more in-depth analysis shows that the policy is associated with a 6.7% decrease in vacancy among energy efficient buildings. The study proposed a method to quantitatively evaluate the impact of energy policies on the real estate performance of office buildings, and the result confirms the positive impact of energy-efficient retrofits on the real estate performance. The study findings support the reasoning behind the owners' decision in implementing energy efficiency improvements in their office buildings to remain competitive in the market. (C) 2019 Elsevier Ltd. All rights reserved.
Keywords
Office Buildings; Building Failures; Time Series Analysis; Real Property; Energy Consumption; Metropolis; Building Performance; Chicago (ill.); Building Energy Benchmarking And Disclosure Policies; Building Energy Efficiency; Time Series Modeling; Energy Star (program); Building Management Systems; Buildings (structures); Decision Making; Energy Conservation; Maintenance Engineering; Time Series; Disclosure Policy; Energy Benchmarking Policies; Building; Benchmarking Policy; Energy Efficiency Improvements Decision-making; Estate Performance; Energy Efficient Buildings; Energy Star; Energy Policies; Energy-efficient Retrofits; Interrupted Time-series; Regression; Behavior; Designs; Building Energy Benchmarking And; Disclosure Policies; Buildings; Cities; Energy Efficiency; Energy Policy; Markets; Quantitative Analysis; United States
Kim, Tae-hyung; Lee, Hyun Woo; Hong, Seok-woo. (2016). Value Engineering for Roadway Expansion Project over Deep Thick Soft Soils. Journal Of Construction Engineering And Management, 142(2).
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Abstract
A roadway expansion that takes place on soft ground is susceptible to differential settlement because of the high consolidation of soft soils. Therefore, steps must be taken to lessen the risk of such settlement; yet, this often only results in costly drainage solutions. In that, applying a systematic value engineering (VE) process can be beneficial to develop cost-effective design alternatives. However, VE studies specifically targeting for this problem are absent from the field. Thus, the goal of this study is to supplement this knowledge gap by applying a systematic VE process to an expansion project on soft ground to demonstrate the benefits of performing VE. A case study was performed on an expansion project over a soft soil layer approximately 50m thick. Through the VE process, the original design was reviewed, problems were discussed, and three alternatives were proposed. Then value analysis techniques were applied to evaluate these alternatives in terms of cost saving, function improvement, and value improvement with respect to the original design. The VE process and design alternatives as applied in this study are expected to serve as a guideline for engineers and decision-makers in roadway expansion projects on soft ground. (C) 2015 American Society of Civil Engineers.
Keywords
Construction Industry; Costing; Project Management; Road Building; Soil; Value Engineering; Engineers; Decision-makers; Value Improvement; Function Improvement; Knowledge Gap; Cost-effective Design; Deep Thick Soft Soils; Soft Ground; Roadway Expansion Project; Systematic Value Engineering Process; Value Engineering (ve); Job Plan; Roadway Expansion; Deep Soft Ground; Differential Settlement; Cost Saving; Project Planning And Design
Choi, Kunhee; Bae, Junseo; Yin, Yangtian; Lee, Hyun Woo. (2021). Act(2): Time Cost Tradeoffs from Alternative Contracting Methods. Journal Of Management In Engineering, 37(1).
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Abstract
Incentive/disincentive (I/D) and cost-plus-time (A+B) are two of the most widely used alternative contracting methods (ACMs) for accelerating the construction of highway infrastructure improvement projects. However, little is known about the effects of trade-offs in terms of project schedule and cost performance. This study addresses this problem by creating and testing a stochastic decision support model called accelerated alternative contracting cost-time trade-off (ACT(2)). This model was developed by a second-order polynomial regression analysis and validated by the predicted error sum of square statistic and paired comparison tests. The results of a descriptive trend analysis based on a rich set of high-confidence project data show that I/D is effective at reducing project duration but results in higher cost compared to pure A+B and conventional methods. This cost-time trade-off effect was confirmed by the ACT(2) model, which determines the level of cost-time trade-off for different ACMs. This study will help state transportation agencies promote more effective application of ACMs by providing data-driven performance benchmarking results when evaluating competing acceleration strategies and techniques. (C) 2020 American Society of Civil Engineers.
Keywords
Highway; Construction; Model; Alternative Contracting Methods; Cost-plus-time; A Plus B; Incentive; Infrastructure Trend; Time-cost Trade-off
Shakouri, Mahmoud; Lee, Hyun Woo. (2016). Mean-Variance Portfolio Analysis Data For Optimizing Community-Based Photovoltaic Investment. Data In Brief, 6, 840 – 842.
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Abstract
The amount of electricity generated by Photovoltaic (PV) systems is affected by factors such as shading, building orientation and roof slope. To increase electricity generation and reduce volatility in generation of PV systems, a portfolio of PV systems can be made which takes advantages of the potential synergy among neighboring buildings. This paper contains data supporting the research article entitled: PACPIM: new decision-support model of optimized portfolio analysis for community-based photovoltaic investment [1]. We present a set of data relating to physical properties of 24 houses in Oregon, USA, along with simulated hourly electricity data for the installed PV systems. The developed Matlab code to construct optimized portfolios is also provided in Supplementary materials. The application of these files can be generalized to variety of communities interested in investing on PV systems. (C) 2016 The Authors. Published by Elsevier Inc.
Keywords
Community Solar; Photovoltaic System; Portfolio Theory; Energy Optimization; Electricity Volatility
Su, Shu; Li, Xiaodong; Zhu, Chen; Lu, Yujie; Lee, Hyun Woo. (2021). Dynamic Life Cycle Assessment: A Review of Research for Temporal Variations in Life Cycle Assessment Studies. Environmental Engineering Science, 38(11), 1013 – 1026.
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Abstract
Life cycle assessment (LCA) is a comprehensive and important environmental management tool around the world. However, lacking temporal information has been a major challenge. In the past decade, dynamic LCA (DLCA), which incorporates temporal variations into assessment, has been an emerging research topic with increasing publications. A timely comprehensive review is needed to present current progress and discuss future directions. This article reviews 144 DLCA articles quantitatively and qualitatively. A bibliometric approach is adopted to conduct co-occurrence analysis and cluster analysis of DLCA studies. The research progress, approaches, and limitations of three temporal variation types (i.e., dynamic life cycle inventory, dynamic characterization factors, and dynamic weighting factors) in DLCA studies are systematically analyzed and discussed. It is concluded that: (1) dynamic inventory analysis is usually conducted by collecting time-differentiated data at each time step. Field monitoring, simulation, scenario analysis, and prediction based on historical data are common approaches. (2) Dynamic characterization studies primarily focus on two impact categories: global warming and toxicity. More studies are in need. (3) Various methods and indicators (i.e., dynamic pollution damage cost, temporal environmental policy targets, and discount rates) are used to solve the dynamic weighting issue, and they have specific limitations. Finally, three interesting topics are discussed: comparison between dynamic and static results, the large data amount issue, and the trend of tools development. This review offers a holistic view on temporal variations in DLCA studies and provides reference and directions for future dynamic studies.
Keywords
Literature Reviews; Cluster Analysis (statistics); Global Warming; Environmental Management; Discount Prices; Emission Inventories; Dynamic Characterization; Dynamic Inventory Analysis; Dynamic Weighting; Environmental Impact; Life Cycle Assessment; Temporal Variation; Cluster Analysis; Life Cycle; 'current; Dynamic Inventory Analyse; Dynamic Lca; Environmental Management Tool; Inventory Analysis; Research Topics; Temporal Information; Dependent Climate Impact; Greenhouse-gas Emission; Biogenic Carbon; Assessment Framework; Fresh-water; Electricity-generation; Energy Efficiency; Wheat Production; Embodied Energy; Time
Gambatese, John A.; Pestana, Catarina; Lee, Hyun Woo. (2017). Alignment between Lean Principles and Practices and Worker Safety Behavior. Journal Of Construction Engineering And Management, 143(1).
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Abstract
Alignment and synergy between the areas of lean construction and safety management are expected because all near misses and injury incidents represent waste from the lean perspective. This paper describes a research study of lean and safety principles and practices with regards to worker behavior and safety practices. Specifically, the study aimed to investigate the extent of alignment between lean construction principles/practices and worker behaviors associated with construction safety. To conduct the study, the researchers used a multistep process involving a comprehensive literature review, document content analyses by an expert panel, and a survey of industry practitioners knowledgeable about lean construction. The findings support the perspective that many similarities exist between the application and impacts of lean and safety principles and practices. Lean practitioners surveyed believe that implementation of the last planner system as a lean practice is most beneficial to the following safety practices: management commitment, preproject planning, and pretask planning. The present study revealed that lean principles and practices can provide a valuable opportunity to further improve construction worker safety; however, the findings show that there is a difference between lean construction and safety management practices, revealing a gap with respect to worker behavior. Understanding and eliminating this gap is important for the industry to realize the full benefit that lean principles and practices can have on worker safety. To do so, the authors suggest expanding lean practices to further directly engage field workers and address worker behavior issues along with carefully communicating the lean message to construction personnel. (C) 2016 American Society of Civil Engineers.
Keywords
Construction Industry; Injuries; Lean Production; Occupational Safety; Planning; Lean Principles; Lean Construction; Safety Management Practices; Injury Incidents; Worker Behaviors; Construction Safety; Document Content Analysis; Management Commitment; Preproject Planning; Pretask Planning; Construction Worker Safety Behavior; Construction Accident Causality; Risk; Lean Design; Worker Behavior; Safety; Labor And Personnel Issues
Choi, Suji; Kim, Soyeon; Kwak, Mingi; Park, Jaewan; Park, Subin; Kwak, Dongjoon; Lee, Hyun Woo; Lee, Sangwon. (2022). Would You Trust Driverless Service? Formation Of Pedestrian’s Trust And Attitude Using Non-verbal Social Cues. Sensors (14248220), 22(7).
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Abstract
Despite the widespread application of Autonomous Vehicles (AV) to various services, there has been relatively little research carried out on pedestrian-AV interaction and trust within the context of service provided by AV. This study explores the communication design strategy promoting a pedestrian's trust and positive attitude to driverless services within the context of pedestrian-AV interaction using non-verbal social cues. An empirical study was conducted with an experimental VR environment to measure participants' intimacy, trust, and brand attitude toward AV. Further understanding of their social interaction experiences was explored through semi-structured interviews. As a result of the study, the interaction effect of social cues was found, and it was revealed that brand attitude was formed by the direct effects of intimacy and trust as well as the indirect effects of intimacy through trust's mediation. Furthermore, 'Conceptual Definition of Space' was identified to generate differences in the interplay among intimacy, trust, and brand attitude according to social cues. Quantitative and qualitative results were synthesized to discuss implications considering the service context. Practical implications were also addressed suggesting specific design strategies for utilizing the sociality of AV.
Keywords
Pedestrians; Nonverbal Cues; Consumer Attitudes; Social Attitudes; Social Interaction; Attitude (psychology); Autonomous Vehicles; Brand Attitude; Driverless Service; Intimacy; Pedestrian–av Interaction; Social Cues; Trust; Pedestrian-av Interaction; Conversational Agent; Brand Experience; Impact; Automation; Perception; Disclosure; Style; Gaze