Cassandra Telenko

A comparison of the energy efficiency of selective laser sintering and injection molding of nylon parts

Purpose – The purpose of this paper is to evaluate the energy consumed to fabricate nylon parts using selective laser sintering (SLS) and to compare it with the energy consumed for injection molding (IM) the same parts.Design/methodology/approach – Estimates of energy consumption include the energy consumed for nylon material refinement, adjusted for SLS and IM process yields. Estimates also include the energy consumed by the SLS and IM equipment for part fabrication and the energy consumed to machine the injection mold and refine the metal feedstock required to fabricate it. A representative part is used to size the injection mold and to quantify throughput for the SLS machine per build.Findings – Although SLS uses significantly more energy than IM during part fabrication, this energy consumption is partially offset by the energy consumption associated with production of the injection mold. As a result, the energy consumed per part for IM decreases with the number of parts fabricated while the energy con...

A COMPILATION OF DESIGN FOR ENVIRONMENT PRINCIPLES AND GUIDELINES

Public policy is becoming increasingly stringent with respect to the environmental impacts of modern products. To respond to this tightened scrutiny, product designers must innovate to lower the environmental footprints of their concepts. Design for Environment (DfE) is a field of product design methodology that includes tools, methods and principles to help designers reduce environmental impact. The most powerful and well-known tool within DfE is Life-Cycle Analysis (LCA); however, LCA requires a fully specified design and thus is a retrospective design tool, only applicable as the end of the design process. Because the decisions with the greatest environmental impact are made during earlier design stages, it is important to develop concurrent design tools that can implement DfE principles at conceptual and embodiment design stages, thereby achieving more substantial environmental improvements. The goal of this work is to compile a set of DfE principles that are useful during the design process; explain select principles through examples; and provide an example of applying DfE principles concurrently during the design process.Copyright

A Methodology for Identifying Environmentally Conscious Guidelines for Product Design

A reverse engineering methodology is presented for identifying environmentally conscious design guidelines for use in the conceptual stages of product design. Environmentally conscious principles and guidelines help designers improve environmental impacts of products by making better decisions during conceptual design stages when data for life cycle analysis (LCA) are sometimes scarce. The difficulty in using the current knowledge base of guidelines is that it is not exhaustive and conflicts are not well understood. In response, the authors propose a general method for expanding the current set of guidelines and for understanding potential environmental tradeoffs. The method helps designers extract environmentally conscious design guidelines from a set of functionally related products by combining reverse engineering with LCA. The guidelines and LCA results can then be used to inform subsequent design cycles without repeating the process. Although in environmentally conscious design, reverse engineering is commonly applied to studies of disassembly and recyclability, the methodology and case study herein show how reverse engineering can be applied to the utilization stage of a product’s life cycle as well. The method is applied to an example of electric kettles to demonstrate its utility for uncovering new design guidelines.

A method for developing design for environment guidelines for future product design

Design for environment principles and guidelines help designers create greener products during the early stages of design when life cycle analysis is not feasible. However, the available guidelines are not exhaustive and a general methodology for discovering guidelines has yet to be proposed. In this paper, a method for identifying green design guidelines is presented, which aims to fulfill the need for more comprehensive guidelines. The method combines typical aspects of product design, such as customer needs analysis, with reverse engineering and life cycle analysis. Although reverse engineering is commonly applied to studies of disassembly and recyclability, the methodology and case study herein show how reverse engineering can be applied to areas of product utilization and energy consumption in particular. A general description of the methodology helps readers apply it to their own studies, and a case study of electric kettles shows how each step of the method was applied to reveal four new design guidelines.Copyright

Probabilistic Graphical Modeling of Use Stage Energy Consumption: A Lightweight Vehicle Example

Although energy consumption during product use can lead to significant environmental impacts, the relationship between a products usage context and its environmental performance is rarely considered in design evaluations. Traditional analyses rely on broad, average usage conditions and do not differentiate between contexts for which design decisions are highly beneficial and contexts for which the same decision may offer limited benefits or even penalties in terms of environmental performance. In contrast, probabilistic graphical models (PGMs) provide the capability of modeling usage contexts as variable factors. This research demonstrates a method for representing the usage context as a PGM and illustrates it with a lightweight vehicle design example. Factors such as driver behavior, alternative driving schedules, and residential density are connected by conditional probability distributions derived from publicly available data sources. Unique scenarios are then defined as sets of conditions on these factors to provide insight into sources of variability in lifetime energy use. The vehicle example demonstrates that implementation of realistic usage scenarios via a PGM can provide a much higher fidelity investigation of use stage energy savings than commonly found in the literature and that, even in the case of a universally beneficial design decisions, distinct scenarios can have significantly different implications for the effectiveness of lightweight vehicle designs.

Changing Conversations and Perceptions: The Research and Practice of Design Science

Although design science is a relatively young field, the impact of design research upon industry is evident in the literature, in the practice of design by academics, and in the experience set of the authors. This chapter provides evidence of impact from three sources, two studies of design literature, and one survey of design researchers. It is found that more than one third of design research articles, despite focusing on theory, include engagements with industry, and, complementarily, a majority of design researchers have patents, industry experience, or both. These studies of design literature and design researchers change our perceptions of the impact of design research on practice and initiate a new conversation. In the context of research findings and models of transferring general fields of research to practice, design research impacts practice in a variety of tangible and long-lasting ways. Building upon these analyses, we develop a first set of guidelines for transferring design research to practice. These guidelines are illustrated by selected examples and outcomes from the authors’ experiences. The frontier of design science, especially the impact on practice, is exciting and filled with unlimited potential. Changing conversations and perceptions is a critical first step in building the community’s tremendous past successes. Through proven guidelines, we may realize our potential and create a sustainable ecosystem of transferring design research to practice.

How Does Modularity Affect Green Design

Product architecture significantly influences environmental impact. Modular architectures aid manufacture and reuse, thereby reducing manufacturing-related impacts and diverting usable waste from landfills. In contrast, modular product architectures may also sacrifice product performance or lead to over-designed products. These side-effects can increase environmental impact. The Black and Decker Firestorm and G5 George Foreman Griddle were studied to uncover and understand the effects of product architecture on energy and material efficiency. Both products incorporate component sharing for fulfilling multiple functions and incur environmental tradeoffs as a result. Experimentation, reverse engineering, and life cycle analysis of these products were used to inspire a number of guidelines for green design of modular product architectures. Difficulties involved the design of interfaces and selection of components for shared modules.Copyright

Designettes: New Approaches to Multidisciplinary Engineering Design Education

Teaching of engineering design and other fundamental engineering topics is often isolated to dedicated courses, missing an opportunity to foster a culture of engineering design and multidisciplinary problem solving throughout the curriculum. Designettes, defined as brief, vignette-like design challenges, provide the opportunity to integrate design learning experiences in class, across courses, across terms, and across disciplines. When fundamental engineering courses join together in a designette, a multidisciplinary learning activity occurs, demonstrating how subjects are integrated and applied to open-ended problems and grand challenges. The development of designettes helps foster a culture of design, and enables the introduction of multidisciplinary design challenges across all core courses in each semester. These challenges combine problem clarification, concept generation and prototyping with subject content from curricula such as biology, thermodynamics, differential equations, and software with controls. This paper provides examples and investigates the use of single and multidisciplinary designettes over a two-year history of designettes at SUTD. From pre- and post-surveys of junior college students, designettes were found to increase students’ awareness of applications and the learning of content. From 321 third-semester students across six cohorts, designettes were found to increase students’ self-perceptions of their ability to solve multidisciplinary problems.

Scoping Usage Contexts and Scenarios in Eco-Design

Descriptions of a product’s usage context are easily understood and often provide useful information for reducing energy consumption of products. Such descriptions help inspire concept generation, explore operational issues, and evaluate prototypes. Nevertheless, characterizing the usage context as a concise but comprehensive set of factors is not a trivial task. This paper presents a taxonomy and method for characterizing the usage context and its various scenarios as sets of factors relevant to energy consumption. The taxonomy defines a general usage context as a set of human, product and situational factors that can be specified individually to create unique scenarios. The method for identifying relevant factors is grounded by first assessing variables in the fundamental physical equations that govern product operation. Then, activity diagrams reveal the elements influencing user habits and procedures. The method is demonstrated through the example of an automobile and the results are compared with existing automobile studies.Copyright

A Review of Intervention Studies Aimed at Domestic Water Conservation

We must overhaul how we view and use water to ensure that there is enough potable water to meet the rising global demand. To achieve such changes, many researchers have developed intervention methods aimed at promoting water conservation in the home. Single or combined styles of intervention, applied from a range of a few days to eight months, achieve a wide range (2 % to 28 %) of water savings. However, what factors play the biggest roles in achieving such savings remain as of yet unclear. Two factors are highlighted in this review: an intervention’s visibility and the climate context in which the intervention was conducted. This paper provides a comprehensive review of intervention methods; in doing so it summarizes findings of current research and provides recommendations for future work.