Vanessa Valentin

Decision-making life-cycle cost analysis model for energy-efficient housing retrofits

Housing retrofit can reduce energy consumption and decrease long-term costs associated with the operation of a building. The objective of this study is to introduce an approach for evaluating energy-efficient housing retrofit alternatives, using data from a real case. A detailed life-cycle cost analysis (LCCA) of possible retrofitting strategies is performed for the case of a house built in the 1960s in Albuquerque, New Mexico, USA. Based on this case study, an approach is developed to illustrate the impact trend of retrofitting costs on energy consumption savings. By defining three separate cost evaluation zones, comprising of a cost effective zone, an energy efficient zone, and an improvement needed zone, the results of this study can potentially be used not only in decision-making for retrofitting, but also in the evaluation of projects related to energy retrofits. Then, using the proposed methodology for the case study, a normalised model is developed to evaluate the effectiveness of retrofitting effo...

Five ways to support interdisciplinary work before tenure

Academic institutions often claim to promote interdisciplinary teaching and research. Prescriptions for successfully engaging in interdisciplinary efforts, however, are usually directed at the individuals doing the work rather than the institutions evaluating them for the purpose of tenure and promotion. Where institutional recommendations do exist, they are often general in nature and lacking concrete guidance. Here, we draw on our experiences as students and faculty participating in three interdisciplinary water resource management programs in the USA to propose five practices that academic institutions can adopt to effectively support interdisciplinary work. We focus on reforms that will support pre-tenure faculty because we believe that an investment in interdisciplinary work early in one’s career is both particularly challenging and seldom rewarded. Recommended reforms include (1) creating metrics that reward interdisciplinary scholarship, (2) allowing faculty to “count” teaching and advising loads in interdisciplinary programs, (3) creating a “safe fail” for interdisciplinary research proposals and projects, (4) creating appropriate academic homes for interdisciplinary programs, and (5) rethinking “advancement of the discipline” as a basis for promotion and tenure.

Extracting Pavement Surface Distress Conditions Based on High Spatial Resolution Multispectral Digital Aerial Photography

Abstract State transportation agencies regularly collect data on pavement surface distresses. These data are used to assess overall pavement conditions and to make maintenance and repair decisions. Routinely-acquired and publically-available high spatial resolution (hsr) multispectral digital aerial photography provides a potential method for collecting distress information that can supplement or replace currently-used technologies. Principal component analysis and linear least squares regression models were used to evaluate the potential of using HSR multispectral digital aerial photographs to estimate pavement surface overall distress conditions. Various models were developed using HSR multispectral digital aerial photographs of different spatial resolution (6-inch, 12-inch, and 24-inch) and reference pavement surface distress data collected manually at multiple sample sites using standard protocols. The results show that the spectral response of HSR multispectral digital aerial photographs correlate strongly with reference distress rates at all tested spatial resolutions, but the 6-inch aerial photos exhibit the strongest correlation (R 2 > 0.95), even when using only half of the sample sites (R 2 > 0.92). These results indicate that straightforward analysis of HSR multispectral digital aerial photographs, routinely acquired by most municipalities and states, can permit assessment of pavement surface distress conditions as well as current manual evaluation protocols.

Estimating the Economic Value of Energy Improvements in U.S. Residential Housing

AbstractResidential buildings are one of the major consumers of energy in the United States. The existing housing stock can be targeted for energy-efficient interventions through energy retrofits. ...

Public Opinion As an Indicator of the Social Sustainability of Construction Projects

Increasing the use of social sustainability in the decision-making process of construction projects requires that it be defined such that it can be evaluated objectively. One potential indicator of social sustainability in construction projects is public opinion, which can provide a means to evaluate the level of social sustainability on a construction project in normative ways. In this study, the causes for public opposition to a construction project are investigated using a framework that incorporates social principles of sustainability (as defined in current literature). The framework is demonstrated using two case studies: (1) California Delta (Sacramento-San Joaquin River Delta), and (2) the Yucca Mountain Nuclear Waste Repository. Key observations are summarized using grounded theory. Preliminary analysis indicated that the public perception of unfulfilled social sustainability principles related to providing human basic needs, are common triggers of public opposition in construction infrastructure projects. This study provides the basis for research considering social sustainability principles and public opinion in construction projects. An improved understanding of the correlation of these factors could enable decision makers to better incorporate them during the planning phase of the project.

ASSESSMENT OF PUBLIC OPPOSITION TO INFRASTRUCTURE DEVELOPMENTS: THE CASE OF NUCLEAR POWER PROJECTS

Infrastructure projects are complex undertakings that capture public attention because of their magnitude and effect on society, the economy and the environment. Public opinion presents a source of great uncertainty in infrastructure development projects. For instance, a project might experience disruptions if there is public opposition due to project location or environmental impacts. In this study, a survey was deployed to quantify how project characteristics (reactor size, type of technology, experience of utility company, number of reactor units, etc.) could gear public opinion related to new nuclear power plant projects. A logit model was developed for each project characteristic considering variables such as: (1) staterelated characteristics (region in Nuclear Regulatory Commission, number of nuclear power plants operating in the state, etc.), (2) perceived risk of nuclear power pertaining to safety and to environmental aspects, and (3) the respondents’ attributes (age, level of education, electricity consumption per month, etc.). The probability of individuals opposing a project with a specific set of characteristics was calculated using these models. The project characteristics that lead to higher probabilities of opposition were found to be (1) larger reactor size, (2) lack of experience of the utility company with nuclear power, and (3) presence of financial support from the government. The results of this research provide decision-makers with information that could be used to define the project characteristics during the planning phase in a way so as to mitigate public opposition.

Evaluation of the Visibility of Workers’ Safety Garments during Nighttime Highway-Maintenance Operations

To reduce traffic congestion in the United States, roadway maintenance and construction operations are widely performed during nighttime hours. This makes visibility a critical issue as workers need to be visible to oncoming traffic and heavy equipment operators in order to ensure their safety. A variety of high-visibility safety garments are available to increase the visibility of workers at night. The study presented in this paper assesses some of these garments from the perspective of drivers. The approach adopted includes the design of a field test setup in which eight safety garment assemblies were displayed in a replicated maintenance work zone. A video was created for each safety garment assembly being worn by workers to capture the approaching view of a driver entering the work zone. The videos were shown to drivers, who evaluated the visibility of the garments in pairwise comparisons. Two random effects binary probit models were estimated. One model was used to understand the characteristics that...

Assessment of the Impact of Inter-Organizational Interactions on Project Metrics

The scale and complexity of capital intensive projects, along with the presence of multiple organizations and stakeholders with conflicting objectives, often cause expensive delays and cost overruns in such projects. This study develops a framework to measure the impact of organizational and stakeholder interactions on the performance metrics of the construction process of capital intensive projects. First, an inter-organizational network is developed to identify the key organizations involved in a specific project phase using social network analysis. Then, potential interactions between these key entities having a negative impact on the performance metrics of the projects are identified and simulated. A Monte Carlo simulation is used to identify significant interactions and to determine their overall impact on the time metric. Nuclear power plant projects, with a history of actual costs of more than 200% the estimated cost, is used as a test bed to verify and validate the research framework. The regulatory agency, the utility company, financing entities, designer and directly affected parties were identified as key entities for these types of projects. In addition, interactions between the utility company and financial entities were found to be significant.

Optimal construction site conditions for concrete operations

Concrete usually undergoes stringent quality controls during its fabrication in a batching plant or when made in situ. However, there are several conditions in the construction site that may affect concrete quality and operations. Reduction in compressive strength, increment in costs of concrete fabrication and low productivity are among the consequences of adverse jobsite conditions. In this study, construction site conditions including crew experience, compaction method, mixing time, curing humidity, and curing temperature were selected as variables to conduct a full 2 factorial experimental design for quantifying their effect on concrete. Cylindrical concrete samples were fabricated and evaluated under each factor combination. Concrete compressive strength as a quality metric, costs, and production rates were measured as the experimental responses. Significant affecting factors and their effects on concrete were identified through the analysis of variance (ANOVA) and used to predict concrete compressive strength, cost, and production effects. A multi-objective optimization problem based on compromised solutions was formulated to maximize both concrete quality and production rates, and to minimize operation costs. The results show that high curing humidity and temperature have a positive effect on compressive strength while high mixing times increases concrete cost and reduces productivity. The proposed optimization model provides construction managers with a tool that allows finding in-situ construction conditions to reach desired goals. Further, understanding the possible impacts of these site conditions on concrete allows taking preventive actions.

Risk of wildfires with known ignition points : case of residential buildings

Wildfire is considered the dominant disaster in many regions of the world including the United States, Australia, Canada and parts of Europe. However, unlike other natural disasters, such as flooding, earthquakes and hurricanes, the risk of wildfire to the built environment is not vigorously studied. Most of the research in the wildfire risk management area is limited to the study and management of wildfire within the wildland. On the other hand, there is an increasing progress of housing projects towards the natural lands. The Wildland Urban Interface (WUI) is where the developed and undeveloped areas meet. Because of high vulnerability of the WUIs to wildfires, there is a need to identify, quantify and manage the expected damage of wildfires to the WUIs. This study calculates the risk of wildfires to residential buildings considering a specific ignition point. The model inputs include the spatial distribution of the buildings, an absolute or proxy value for the damage from wildfire, and atmospheric and landscape attributes needed to simulate the fire propagation on a specific land. The model outputs are the distribution of damage at each time interval from the initial ignition and total risk of a fire with a given ignition point.