Compare Design Options Research Articles

BUILDING LIFE CYCLE ASSESSMENT OF A COLLECTIVE HOUSING BUILDING IN PORTUGAL CONSIDERING DIFFERENT STRUCTURAL MATERIALS

AbstractIn recent years, the focus on reducing the environmental impact of construction has shifted from operational carbon emissions to embodied carbon or materials due to the constant decarbonization of the energy sector. This paper compares the life‐cycle assessment (LCA) of a collective housing building in Portugal, examining four structural solutions: composite steel and concrete, light steel framing, prefabricated reinforced concrete, and cross‐laminated timber load‐bearing walls. This study aims to aid construction professionals in making environmentally informed decisions by comparing design options composed of different materials and highlighting potential improvements in environmental performance.

Making sense of LCA results when evaluating multiple building designs – comparison of interpretation concepts

ABSTRACT Identifying environmental hotspots and comparing design options are the most common goals in building life cycle assessment (LCA). Our paper focuses on the latter by identifying and evaluating various concepts for interpreting LCA results that can be applied when comparing multiple design options. The term LCA interpretation concept is introduced. Eight approaches were analysed and classified into three groups; (i) raw LCA data, (ii) benchmarking and (iii) single score indicator interpretation concepts. Features and attributes for making sense of LCA data were defined and used to evaluate how the investigated LCA interpretation concepts support decision-making. Finally, the results were compared and evaluated whether the applied LCA interpretation concepts could influence the designer's perception of environmental superiority. The outcomes show substantial differences in the ability of LCA interpretation concepts to support the decision-making process. Benchmarking, weighting and normalization are essential to making environmental decisions when comparing multiple design options coupled with multiple environmental indicators. Otherwise, the risk of decision-making dilemmas due to data overflow is high. Our case study with 21 design options showed that the perception of environmental superiority and inferiority may be conditioned by the selection of the LCA interpretation concept.

Validation of spectral simulation tools in the context of ipRGC-influenced light responses of building occupants

With the growing awareness about ipRGC-influenced light (IIL) responses, design applications related to these responses are flourishing. To compare design options and optimize lighting conditions for building occupants, lighting simulations are typically used. However, as our IIL responses depend on the spectral characteristics of light, spectral simulations are required. The goal of this study is to validate two spectral simulation tools, ALFA and Lark, for the study of indoor spaces in relation to occupants’ IIL responses. Indicators associated with IIL responses derived from ALFA- and Lark-simulated data are compared against indicators derived from data measured under indoor daylighting and electric lighting conditions. The results show that Lark outperforms ALFA in most cases, with a simulation error in the ±20% range for point-in-time indicators. When accounting for time dynamics of light exposure, at least 9% of the daylight exposures simulated for a 6-h period in Lark lead to a significant error.

Reliability-Informed Life Cycle Warranty Cost and Life Cycle Analysis of Newly Manufactured and Remanufactured Units

Abstract Standard life cycle techniques such as life cycle warranty cost (LCWC) analysis and life cycle analysis (LCA) are used to respectively quantify the relative economical and environmental advantages of remanufactured goods while simultaneously identifying avenues for improvement. In this paper, we contribute to the literature on life cycle studies by incorporating reliability into LCWC analysis and LCA with the goal of improving long-term/multiple life cycle decision making. We develop a branched power-law model to incorporate the physical degradation mechanisms leading to reduced reuse rates of system parts over multiple life cycles. We then follow a standard LCA protocol to quantify the difference between a new unit and its remanufactured version in terms of environmental impact items such as abiotic depletion potential, global warming potential, and energy consumption. We then devise four practical warranty policies that vary in the choice of replacement and/or provision for extended warranty. All possible replacement scenarios for multiple life cycles are explored for each policy and a mathematically rigorous framework is provided, where the reliability information is used to calculate probabilistic LCWC and life cycle impact items. This reliability-informed LCWC analysis and LCA framework enables design engineers to compare design options and warranty policies by quantifying both economical and environmental impacts to aid in decision making. Although the framework is presented in a general form applicable to any engineered system, we demonstrate the utility of this framework by using a case study of an infinitely variable transmission used in agricultural equipment.

Effect of LCA Data Sources on GBRS Reference Values: The Envelope of an Italian Passive House

Scientific literature provides evidence that mitigating the effects of a building’s operation does not in itself ensure an overall improvement in its environmental performance. A Life Cycle Assessment (LCA) plays a key role in gauging the overall environmental performance of a building although several authors argue that the lack of LCA threshold values makes it difficult to compare design options or measure whether reduced impact targets are achieved. This has led the Green Building Rating Systems (GBRS) to include the LCA within their evaluation criteria and, in like Active House (AH), establish threshold values of the main impact categories to quantify the level of performance achieved. Since the reliability of the data sources is a crucial issue for applying the LCA method, the effectiveness of their implementation within the GBRS also strictly depends on the origin of the impact values. To quantify the extent to which the source affects the impacts calculated by the LCA threshold value in AH, the present study compared the outcomes of two assessments carried out in parallel using two different data sources: AH–LCA evaluation tool v.1.6 and the Environmental Product Declaration (EPD). A Passive House (PH)-compliant, small residential building was selected as a case study, as this is a standard that excels in ultra-low-energy performance. Moreover, given the crucial role that the envelope plays in the PH standard, the analysis was undertaken on the envelope of a PH-compliant building located in Northern Italy. To stress the influence of embedded effects in a Passive House, the assessment focused on the production and end-of-life stages of building materials. The comparison showed a relevant difference between the two scenarios for all the environmental indicators: e.g., deviations of 10% for Global Warming Potential, 20% for Acidification Potential and Eutrophication Potential, and 40–50% for Renewable Primary Energy.

Principles for the application of mixed reality as pre-occupancy evaluation tools (P-OET) at the early design stages

The implementation of two pre-occupancy evaluation tools (P-OET) demonstrating the feasibility of using mixed reality are documented. The focus is on the early design stages, where relative merits of distinct options are being considered. For proof-of-concept, a simple architectural design context was used – the simulation of a typical commercial office environment. Four principles underpin the specification of a Virtual Reality (VR) prototype: (1) quasi-realistic graphics and low geometry models; (2) a multi-sensory approach (3) the capacity to evaluate changes in temporal context (4) evaluation via a task-based approach, combined with voice recordings and activity tracking. The second prototype uses Augmented Reality (AR) technology to compare design options where interactive virtual models appear on a conference table. Evaluation of the prototype applications is discussed: VR POET proved highly feasible and demonstrated the effectiveness of the four principles above; AR POET showed potential but is constrained by the functionality of available hardware.

Dose Finding in Late-Phase Drug Development.

A drug may fail or raise concerns that must be addressed in later-phase trials because of an unacceptable toxicity profile, even if the drug meets expectations for efficacy. The problem could be due to the late onset of unacceptable toxicities that were not observed in early-phase trials. We explore methodologies to find appropriate doses in situations where a drug meets the primary efficacy objective but concerns about toxicity remain. In this manuscript, we propose a general framework to design a good phase IV trial that is designed to optimize the treatment regimen. In the first step, we learn from the existing data about the dose-response and dose-toxicity relationships and further to explore and establish the relationship using a statistical model. Noting the limitations of the exploratory analyses, these analyses are not sufficient to allow us to make definitive conclusions. However, the prediction obtained from the model, either estimated efficacy metrics or safety parameters for some doses, can be incorporated in the design of the phase IV trial. In the second step, we further propose and compare design options, including options that could effectively incorporate information from these exploratory analyses, for clinical trials to find optimal doses, including trials to fulfill postmarketing commitments or requirements.

Characterizing variations in variable air volume system controls

The variable air volume (VAV) system is the most popular form of heating, ventilation, and air-conditioning (HVAC) system used in commercial buildings. Researchers and engineers often use VAV systems as a reference when evaluating new technologies and systems or comparing design options. However, VAV system performance varies significantly, in part because of variations among VAV system controls, so, when analyzing use cases, it is critical to accurately represent system controls in order to accurately define system performance. Unfortunately, no existing literature documents standard VAV system controls for this purpose. This paper aims to remedy this omission by characterizing the variations in VAV system controls and proposing an approach to representing VAV system baseline performance. We used EnergyPlus to model variation among VAV system controls. We use the medium-size office reference-building model developed by the U.S. Department of Energy to demonstrate the impact of variations among controls in two U.S. climate zones and sort system performance into “good,” “average,” and “poor” categories.

Efficiency versus Equality: Comparing Design Options for Indirect Emissions Accounting in the Korean Emissions Trading Scheme

The Korean emissions trading scheme (ETS) has one special characteristic that makes it different from other schemes, such as the EU ETS. While the other schemes consider only direct emissions from fossil fuels, the Korean ETS also regulates indirect emissions arising from the consumption of electricity. The problem of double counting arises under this setting, in which emissions from the power sector can be accounted for twice, when electricity is produced and consumed. This study aims to compare design options on indirect emissions accounting for the Korean ETS using a computable general equilibrium model. Four scenarios are generated for options accounting for direct and/or indirect emissions and are evaluated in terms of efficiency and equality. The result shows that the ETS operates most efficiently when only direct emissions are considered. However, the option that includes both direct and indirect emissions produces a competent result in terms of equality by spreading the economic burden of emissions reduction among industries. We conclude that this option can be an alternative to meet the key purposes of the Korean ETS.

A 6D CAD Model for the Automatic Assessment of Building Sustainability

Current building assessment methods limit themselves in their environmental impact by failing to consider the other two aspects of sustainability: the economic and the social. They tend to be complex and costly to run, and therefore are of limited value in comparing design options. This paper proposes and develops a model for the automatic assessment of a building's sustainability life cycle with the building information modelling (BIM) approach and its enabling technologies. A 6D CAD model is developed which could be used as a design aid instead of as a post-construction evaluation tool. 6D CAD includes 3D design as well as a fourth dimension (schedule), a fifth dimension (cost) and a sixth dimension (sustainability). The model can automatically derive quantities (5D), calculate economic (5D and 6D), environmental and social impacts (6D), and evaluate the sustainability performance of alternative design options. The sustainability assessment covers the life cycle stages of a building, namely material production, construction, operation, maintenance, demolition and disposal.

Assessing creativity of design projects: criteria for the service engineering field

An emerging thread of research is represented by the attempt of quantitatively assessing creativity, its dimensions, and how it influences the design process. The purpose of the task is to compare design options, thus allowing to select the most innovative and supposedly profitable alternative. The endeavor of previous works has consisted in the assessment of creativity concerning designers, methodologies, concepts, and products. As the scope of engineering design is expanding so to include not traditional aspects of the product development process, the paper proposes metrics tailored to evaluate the creativity of services. Such metrics are built as a result of the extension and adaptation of previously formulated criteria, including the evaluation of novelty and usefulness. A sample of successful innovative services is considered, giving rise to a considerable variability of creativity scores. The outcomes may represent a starting point for a wider discussion about which dimensions of creativity majorly impact the success of products and services in the marketplace.

Uncertainty quantification for combined building performance and cost-benefit analyses

Building performance simulation is most often used to improve the design and at times the operation of buildings. Within a building model, the thermal characteristics of the envelope and the HVAC (heating, ventilation, and air conditioning) equipment are described by parameters that often cannot be estimated with high accuracy (e.g., occupant behavior, building envelope and HVAC equipment performance). Another common part of the design process of a building is a cost-benefit analysis to compare design options and different scenarios. The results are also heavily dependent on assumptions about uncertain economic parameters (e.g., future inflation rates and energy costs). In this paper a Monte Carlo based methodology for uncertainty quantification that combines the building simulation and the cost-benefit calculation is developed and demonstrated. Furthermore, Monte Carlo filtering is applied to determine the model inputs (e.g., design specifications and boundary conditions) that lead to the desired model output (e.g., a positive net present value of the investment). The aim is to propose a methodology that helps to enhance the design process or building operation and supports related decision-making.

An appraisal of the level of application of life cycle costing within the construction industry in the UK

PurposeLife cycle costing (LCC) is a means of comparing design options on the basis of their whole life cost with the objective of providing value for money for the life of the asset. The process involves estimating all the cost elements of the particular subject and translating them into a cost at a particular point in time, the present, enabling comparison. Despite being in theory, a useful tool LCC appears to experience varied levels of usage. Varied opinions have been expressed about the level to which LCC is used but there is no doubt that private finance initiatives and public‐private partnerships procurement routes have seen an increase in the use of the technique. The paper aims to appraise levels of application within the construction industry, in particular the paper will evaluate the existence of motivators and barriers which affect the decision to undertake LCC analysis in order to identify what actions can be taken to increase usage levels.Design/methodology/approachFollowing a literature review, empirical research was undertaken to collect data from construction professionals regarding their views, opinions and experiences of LCC. In total, 100 questionnaires were sent to construction and professionals in the North West of England.FindingsThe paper suggests that whilst just over 50 per cent of the sample implemented LCC the data also identified the lack of understanding of the technique and the absence of a standardised methodology as key limiting factors to wider implementation.Research limitations/implicationsLimitations in both the data collection strategy and sample size raise the issue that the results obtained cannot necessarily be deemed to be representative of the construction industry as a whole but merely of the sample and further research is recommended.Originality/valueThe paper concludes that continued professional development for construction professionals and clients alike together with the development of standardised procedures may enhance usage levels.

Comparing design options for allocating communication media in cooperative safety-critical contexts

In this article we present a method for evaluating and comparing design options for allocating communication media. The method pays particular attention to how such options support cooperation in an interactive safety-critical system. The comparison is performed using three sets of criteria based on task performance, analysis of user deviations and consequent hazards, and coordination. The explicit emphasis on hazards and communication issues, using actual tasks to guide the evaluation, ensures that designers attention is focused on the interactions where problems are likely to occur. We describe an application of the method to the design of access to new communication technology in an air traffic control environment.

The Design and Analysis of 2 k-p × s Prototype Experiments

Israel Prototype testing and experimentation play a key role in the development of new products. It is common practice to build a single prototype product and then test it at specified operating conditions. It is often beneficial, however, to make several variants of a prototype according to a fractional factorial design. The information obtained can be important in comparing design options and improving product performance and quality. In such experiments the response of interest is often not a single number but a performance curve over the test conditions. In this article we develop a general method for the design and analysis of prototype experiments that combines orthogonal polynomials with two-level fractional factorials. The proposed method is simple to use and has wide applicability. We explain our ideas by reference to an experiment reported by Taguchi on carbon monoxide exhaust of combustion engines. We then apply them to an experiment on a prototype fluid-flow controller.

The Design and Analysis of 2 k—P × s Prototype Experiments

Israel Prototype testing and experimentation play a key role in the development of new products. It is common practice to build a single prototype product and then test it at specified operating conditions. It is often beneficial, however, to make several variants of a prototype according to a fractional factorial design. The information obtained can be important in comparing design options and improving product performance and quality. In such experiments the response of interest is often not a single number but a performance curve over the test conditions. In this article we develop a general method for the design and analysis of prototype experiments that combines orthogonal polynomials with two-level fractional factorials. The proposed method is simple to use and has wide applicability. We explain our ideas by reference to an experiment reported by Taguchi on carbon monoxide exhaust of combustion engines. We then apply them to an experiment on a prototype fluid-flow controller.