Daylighting: appraisal at the early design stages

For a building design team concerned with the quality of the internal environment of buildings the percentage area of glazing on a building facade is one of the most useful criteria for judging the building envelope as a modifier of climate at early design stages since it is at the window that the various environmental parameters (heat, light and sound) remain only minimally modified. The percentage area of glazing can be used to relate the numerous and often conflicting functions of the window such as the provision of daylight, summer time teperatures, sound insulation, energy efficiency and view satisfaction

Reliability prediction in early design stages

In the past, reliability is usually quantified with sufficient information available. This is not only time-consuming and cost-expensive, but also too late for occurred failures and losses. For solving this problem, the objective of this dissertation is to predict product reliability in early design stages with limited information. The current research of early reliability prediction is far from mature. Inspired by methodologies for the detail design stage, this research uses statistics-based and physics-based methodologies by providing general models with quantitative results, which could help design for reliability and decision making during the early design stage. New methodologies which accommodate component dependence, time dependence, and limited information are developed in this research to help early accurate reliability assessment. The component dependence is considered implicitly and automatically without knowing component design details by constructing a strength-stress interference model. The time-dependent reliability analysis is converted into its time-independent counterpart with the use of the extreme value of the system load by simulation. The effect of dependent interval distribution parameters estimated from limited point and interval samples are also considered to obtain more accurate system reliability. Optimization is used to obtain narrower system reliability bounds compared to those from the traditional method with independent component assumption or independent distribution parameter assumption. With new methodologies, it is possible to obtain narrower time-dependent system reliability bounds with limited information during early design stages by considering component dependence and distribution parameter dependence. Examples are provided to demonstrate the proposed methodologies --Abstract, page iv

Modelling bus contention during system early design stages

Reliably upperbounding contention in multicore shared resources is of prominent importance in the early design phases of critical real-time systems to properly allocate time budgets to applications. However, during early stages applications are not yet consolidated and IP constraints may prevent sharing them across providers, challenging the estimation of contention bounds. In this paper, we propose a model to estimate the increase in applications' execution time due to on-chip bus sharing when they simultaneously execute in a multicore. The model works with information derived from the execution of each application in isolation, hence, without the need to actually run applications simultaneously. The model improves inaccuracy with respect to the existing model, and tends to over-estimate. The latter, is very important to prevent that, during late design stages, applications miss their deadline when consolidated into the same multicore, causing costly system redesign.This work has been supported by the Spanish Ministry of Science and Innovation grant TIN2015-65316-P. Jaume Abella has been partially supported by the MINECO under Ramon y Cajal postdoctoral fellowship number RYC-2013-14717. Carles Hernández is jointly funded by the Spanish Ministry of Economy and Competitiveness and FEDER funds through grant TIN2014-60404-JIN.Peer ReviewedPostprint (author's final draft

GENERALIZED CRITERIA OF ENERGY PERFORMANCE EVALUATION IN EARLY DESIGN STAGES OF NEARLY ZERO-ENERGY BUILDINGS

According to Directive 2010/31/EC the member states of the EU shall ensure that by 31 December 2020 all new buildings will be nearly zero-energy buildings (nZEB). They are characterized with very high energy performance, but they still need to meet the energy demand associated with their typical use, which includes energy for heating, cooling, ventilation, hot water and lighting. This energy should be covered to a significant extent by renewable energy. In the early design stages the generalized criteria of the energy performance of the building have to be used. The performance of the building envelope could be evaluated with the Form Factor as a measure of the compactness of the building and the average thermal transmittance U-value of the building envelope. A grid of roses of solar radiation is recommended as a method to evaluate the distribution of solar resources for a plot, situated in a complex urban environment and to guide the architect about the best exposure of the main facades of the building or the group of buildings. The solar potential of a variant building shape could be evaluated with the building shading factor.According to Directive 2010/31/EC the member states of the EU shall ensure that by 31 December 2020 all new buildings will be nearly zero-energy buildings (nZEB). They are characterized with very high energy performance, but they still need to meet the energy demand associated with their typical use, which includes energy for heating, cooling, ventilation, hot water and lighting. This energy should be covered to a significant extent by renewable energy. In the early design stages the generalized criteria of the energy performance of the building have to be used. The performance of the building envelope could be evaluated with the Form Factor as a measure of the compactness of the building and the average thermal transmittance U-value of the building envelope. A grid of roses of solar radiation is recommended as a method to evaluate the distribution of solar resources for a plot, situated in a complex urban environment and to guide the architect about the best exposure of the main facades of the building or the group of buildings. The solar potential of a variant building shape could be evaluated with the building shading factor

Formal Verification Toolkit for Requirements and Early Design Stages

Efficient flight software development from natural language requirements needs an effective way to test designs earlier in the software design cycle. A method to automatically derive logical safety constraints and the design state space from natural language requirements is described. The constraints can then be checked using a logical consistency checker and also be used in a symbolic model checker to verify the early design of the system. This method was used to verify a hybrid control design for the suit ports on NASA Johnson Space Center's Space Exploration Vehicle against safety requirements

BIM-based LCSA application in early design stages using IFC

Life Cycle Sustainability Assessment (LCSA) is an integrated method that combines environmental, economic, and social assessments. Its methodological development remains under discussion, mainly regarding the building design. This paper aims to provide a systematic, interoperable, and open-source approach towards implementing LCSA in Building Information Modelling (BIM) in five steps. A harmonized data structure that enriches BIM objects is proposed. Automation in the principal evaluation step is provided by integrating new parameters into the current Industry Foundation Classes (IFC4). A Dynamo script verifies its utility in a case study in Spain using real-time calculations and visualizations. Two alternative structural systems are assessed, and identification is made of the lowest CO2 emitter, the lowest cost, and the most beneficial system for local employment. The approach can be employed to evaluate other indicators and building systems in other countries. Challenges and limitations in the standardization and harmonization of the three dimensions are identified

An Urban-Conscious Rapid Wind Downscaling Model for Early Design Stages

Assessments of urban contexts using existing microclimate models mostly fall short, when considering topographies along with complex layouts of buildings and streets, regardless of their significant influences on building performances and outdoor environments. The challenge exists mainly due to modelâ??s inherent complexities and the associated high computational costs. This becomes especially challenging at early design stages when time, expertise, and computational resources are limited, even though the opportunities for performance enhancement are greater than at later stages. This dissertation develops a wind downscaling model that can rapidly assess urban contexts to relate climate data in a large spatial resolution for a smaller-scale site. Surrounding slopes and terrains, up to a few kilometers in diameter, are considered to predict wind pressure on the volumetric boundary of a neighborhood and local wind speed. The new model strives for prediction accuracy and computational efficiency by employing the capacities of a computational fluid dynamics (CFD) simulation and of an existing mathematical method. The proposed model is composed of three parts: pressure database, speed database, and interpolation. The databases store wind data for existing urban contexts that are generated with CFD simulations. Using the databases, the interpolation approximates the pressure outcomes for a new urban context; thus, real-time CFD runs can be avoided for the model users. Independent development of data for pressure and speed facilitates the flexibility and expandability of the model. The proposed model showed an acceptable prediction accuracy, with average errors of less than 10%, compared to the full-scale CFD simulation for the same territorial scope. An exceptional computational efficiency is also shown, with a runtime in 0.308 seconds, which is 16568 times faster than the CFD simulation. This rate allows creation of a yearlong prediction in a few tens of minutes with a personal desktop computer. For non-experts, the pertinence of the model is enhanced with a limited number of parameters, making it easily adaptable during early design stages of buildings and urban design scales. Geometric sensitivities are embedded for incremental study, which is crucial to finding optimal solutions, toward more efficient, yet healthier, urban environments

Quantification of Construction Waste in Early Design Stages Using Bim-Based Tool

Construction and demolition waste represents a growing environmental, social, and economic problem, and has become a priority for European and worldwide policies. The early quantification of construction waste is essential for the minimisation of its production and the improvement of waste management. This requires the development of design-based tools that enable a better understanding of the expected waste produced during the construction phase. Building Information Modelling (BIM) methodologies have gained recognition in the Architecture, Engineering, Construction, and Operations (AECO) sector, largely due to their capacity for data simulation, storage, and management during the building design phase. This study presents a software application, called WE-BIM Add-in, to quantify construction waste (CW) while designing the BIM model in Revit. A validated CW quantification model which enables waste types and quantities per building element to be predicted in detail according to the European List of Waste (LoW) is integrated into the Revit workflow. Design alternatives could be effortlessly simulated in real time to assist practitioners in decision-making during the early design stages. Two alternative structural systems of a Spanish residential building were compared: a reinforced concrete structure, Option 1 (O1), and a steel structure, Option 2 (O2). The results were obtained automatically: O2, in addition to reducing 56% of O1′s waste, would have increased the waste recycling rate by 49%; and displayed in Revit, thereby remaining consistent with those of other studies that compare prefabricated systems with in situ systems. This work provides a basis for future research into the automated estimation of construction waste in BIM which could become a useful tool in waste-prevention policies