Findings from a survey on the current use of daylight simulations in building design

This paper presents findings from a web-based survey on the current use of daylight simulations in building design. The survey was administered from December 2nd 2003 to January 19th 2004. One hundred and eighty five individuals from 27 countries completed the survey. The majority of respondents worked in Canada (20%), the United States (20%), and Germany (12%). Most participants were recruited through building simulation mailing lists. Their self-reported professions ranged from energy consultants and engineers (38%) to architects and lighting designers (31%) as well as researchers (23%). They worked predominantly on large and small offices and schools.Ninety one percent of respondents included daylighting aspects in their building design. Those who did not consider daylighting blamed lack of information and unwillingness of clients to pay for this extra service. Among those participants who were considering daylighting 79% used computer simulations. This strong sample bias towards computer simulations reflects that many participants had been recruited through building simulation mailing lists. Participants named tools’ complexity and insufficient program documentation as weaknesses of existing programs. Self-training was the most common training method for daylight simulation tools. Tool usage was significantly higher during design development than during schematic design. Most survey participants used daylighting software for parameter studies and presented the results to their clients as a basis for design decisions.While daylight factor and interior illuminances were the most commonly calculated simulation outputs, shading type and control were the most common design aspects influenced by a daylighting analysis. The use of scale model measurements had rapidly fallen compared to a 1994 survey, whereas, trust in the reliability of daylighting tools has risen. While participants named a total of 42 different daylight simulation programs that they routinely used, over 50% of program selections were for tools that use the RADIANCE simulation engine, revealing the program's predominance within the daylight simulation community.     

虚拟环境模拟工具在可持续发展建筑设计中的应用

可持续发展建筑关注建筑全寿命周期的环境影响,致力于减少建筑对能源和资源的需求、减少污染物和CO2排放、改善环境,是未来的设计趋势。近年来,计算机虚拟环境模拟工具可靠性大大提高,进入实用阶段,在建筑设计,特别是早期方案阶段引入计算机模拟程序,对可持续发展建筑设计有积极意义。本文通过实例分析阐述了能源和环境模拟工具在优化建筑设计中的作用,它不仅帮助建筑师预知建筑的性能和状况,帮助建筑师对不同解决方案进行分析比较,对建筑设计发挥直接影响力,而且还能在建筑使用后研究(POE)中对建筑进行评价,针对设计缺陷提供新的解决方案。     

Co-simulation between ESP-r and TRNSYS

The quest for innovative architectural designs and the development of novel and integrated energy conversion, storage, and distribution technologies presents a challenge for existing building performance simulation (BPS) tools. No single BPS tool offers sufficient capabilities and the flexibility to resolve all the possible design variants of interest. The development of a co-simulation between the ESP-r and TRNSYS simulation tools has been accomplished to address this need by enabling an integrated simulation approach that rigorously treats both building physics and energy systems. The design, verification, and demonstration of this new co-simulation environment are demonstrated in this paper.     

Fundamentals of performance-based building design

The paper formulates some fundamental principles of performance-based design (PBD), suggesting a conceptual framework and systematic approach suitable for application in most areas of building design, and in the development of simulation tools and performance test methods required in the design and assessment processes. A schematic algorithm, which has been developed for the common engineering approach, was helpful in identifying the inter-relation with the required knowledge-based databases and tools that are needed for proper implementation of PBD. It is also shown that this schematic algorithm can serve not only as a conceptual model but also as the basic framework for developing or adapting simulation tools that are intended for PBD and assessment. The last part of the paper demonstrates the application of the fundamental approach in several areas of building performance (fire safety, acoustics, moisture safety, indoor air quality, and durability), outlining in each area the main user needs, ensuing performance requirements, and the most significant capabilities required of adequate simulation tools, with an emphasis on input/output.     

Achieving informed decision-making for net zero energy buildings design using building performance simulation tools

Building performance simulation (BPS) is the basis for informed decision-making of Net Zero Energy Buildings (NZEBs) design. This paper aims to investigate the use of building performance simulation tools as a method of informing the design decision of NZEBs. The aim of this study is to evaluate the effect of a simulation-based decision aid, ZEBO, on informed decision-making using sensitivity analysis. The objective is to assess the effect of ZEBO and other building performance simulation tools on three specific outcomes: (i) knowledge and satisfaction when using simulation for NZEB design; (ii) users’ decision-making attitudes and patterns, and (iii) performance robustness based on an energy analysis. The paper utilizes three design case studies comprising a framework to test the use of BPS tools. The paper provides results that shed light on the effectiveness of sensitivity analysis as an approach for informing the design decisions of NZEBs.     

An instructional design for building energy simulation e-learning: an interdisciplinary approach

This article describes the development of a new instructional design (ISD) to promote building energy simulation (BES) education. The study is based upon education fundamentals combined with computer-based learning and hypermedia to enable the development of a BES-based distance learning system. Some cognitive tools are established such as: (i) an interdisciplinary knowledge tree of BES that can be used by professionals with different backgrounds; (ii) a hypermedia navigational aid to understand the simulation software, called the BES tool graphic organizer; (iii) a concept map with an overview of building energy performance and (iv) a cooperative problem-based learning (CPBL) environment. Furthermore, the paper also brings an analysis of the students’ comprehension – from a course applied across Brazil – by means of concept network graphs from text mining provided by the CPBL environment, showing a significant potential to develop interdisciplinary e-learning related to building energy efficiency.     

A new approach to performance-based building design exploration using linear inverse modeling

Despite the development of a large number of building performance simulation tools, designers still need a systematic framework appropriate for energy-oriented decision-making in the early stages of design. While the current workflow follows a “forward” modelling procedure in which simulation tools predict the performance of a design, this study proposes an “inverse” procedure that entails a performance objective that estimates design parameters. Using linear inverse modelling, this approach generates plausible ranges for design parameters given a preferred thermal performance. The paper begins by demonstrating that thermal demand in a particular building operation-and-climate condition can be expressed as a linear regression model and then, in two case-studies, uses the regression model to develop an inverse algorithm. After defining energy performance targets as input, users obtain a probabilistic estimate of design parameters as output that represents a large “menu” of feasible design solutions, provides confidence, and embodies the iterative nature of design.     

Comparison of HVAC system modeling in EnergyPlus, DeST and DOE-2.1E

Building energy modeling programs (BEMPs) are effective tools for evaluating the energy savings potential of building technologies and optimizing building design. However, large discrepancies in simulated results from different BEMPs have raised wide concern. Therefore, it is strongly needed to identify, understand, and quantify the main elements that contribute towards the discrepancies in simulation results. ASHRAE Standard 140 provides methods and test cases for building thermal load simulations. This article describes a new process with various methods to look inside and outside the HVAC models of three BEMPs—EnergyPlus, DeST, and DOE-2.1E—and compare them in depth to ascertain their similarities and differences. The article summarizes methodologies, processes, and the main modeling assumptions of the three BEMPs in HVAC calculations. Test cases of energy models are designed to capture and analyze the calculation process in detail. The main findings are: (1) the three BEMPs are capable of simulating conventional HVAC systems, (2) matching user inputs is key to reducing discrepancies in simulation results, (3) different HVAC models can be used and sometimes there is no way to directly map between them, and (4) different HVAC control strategies are often used in different BEMPs, which is a driving factor of some major discrepancies in simulation results from various BEMPs. The findings of this article shed some light on how to compare HVAC calculations and how to control key factors in order to obtain consistent results from various BEMPs. This directly serves building energy modelers and policy makers in selecting BEMPs for building design, retrofit, code development, code compliance, and performance ratings.     

Thermal simulation: Response factor analysis using three-dimensional CFD in the simulation of air conditioning control

The heat generated from an air-conditioning equipment or other thermal loads is distributed throughout a room by a three-dimensional airflow. This three-dimensional airflow creates a three-dimensional heat distribution in a room. To better understand building performance, we must integrate this spatial distribution into building simulations. Thus, three-dimensional computational fluid dynamics (CFD) analysis is necessary in design process because most conventional building energy simulations still employ a temperature that is averaged across the space of a room. However, usually only a few cases of CFD analyses are executable in real design process because of the large computational load they require. This paper presents a new, simplified method to calculate heat transport phenomena in rooms, based on a few cases of CFD analysis, and to integrate data into a nodal analysis. This method can be used to calculate an indoor environment, including the spatial distribution of temperature, with a computational load that is much lighter than it is in a simulation using CFD alone. Furthermore, in terms of precision, it is a far more reliable method than the conventional simulation, which assumes the perfect mixing of heat in a room. In the paper, we apply this method to simulate the control of air conditioning. Ordinarily, the reproduction of the phenomena shown in the calculation examples requires substantial manpower and costly computing resources for experimentation or CFD analysis. With our calculation method, it is possible to reproduce the same calculation results in a very short time with a PC. And we checked the potential to the practical use through a verification calculation with CFD analysis.     

A study of the effectiveness of different control strategies in double skin facades in warm and humid climates

Thermal building simulations were linked to nodal airflow network simulations for a detailed ventilated facade calculation of performance.The validated simulation model can be used to optimize airflow window design in respect to reducing the solar heat gains during the summer period by controlling the exhaust airflow. This may result in significant energy savings and a reduction in systems cooling size. This work evaluates different control strategies of internally ventilated facade designs in respect to energy consumption savings. It further proposes a new type of airflow window to control the exhaust airflow that can help to reduce cooling load of an office up to almost 40%. An important factor was the development of a climate sensitive regulator that helps to take advantage of the hot and humid climate.     

Linking BIM and Design of Experiments to balance architectural and technical design factors for energy performance

To transform the existing energy systems towards renewable energy sources, buildings need to use less energy, use energy more efficiently and harness local renewable energy sources. For the design of energy-efficient buildings, building energy simulation of varying sophistication is commonly employed. Types of simulations range from simple, static calculations to sophisticated dynamic simulation. Especially for building retrofit many assumptions on construction, material etc. have to be taken, which increases the uncertainty of simulation results. In conjunction with simulation, methods of Building Performance Optimization are increasingly employed. They are able to identify best performing designs however do not provide insights on the mechanisms and interdependencies of the different design factors, which are most valuable to make informed design decisions. We present a methodology that aims to provide a better understanding and create knowledge about the influence and interactions of different architectural and technical design factors on building energy performance of a specific design task. For this purpose, we introduce Design of Experiments (DoE) in an integrated design workflow using the Design Performance Viewer (DPV) toolset, combining Building Information Modeling (BIM), distributed dynamic simulation and statistical analysis of the extensive simulation results. The experiments created using the methodology allow to identify the strength of effects and interactions of different design factors on selected performance indicators. We apply the methodology on an office retrofit case, introducing a factor scatterplot for result visualization, development and comparison of retrofit strategies. We further evaluate its potential to identify high performing strategies while balancing architectural and technical factors and their impact on energy performance.     

Tools for quality control in simulation

This research examines the nature of environmental design information used by building designers. The goal is to identify commonality in the types of information that design tools should produce. It presumes that improving the use of design tools will lead to improved building performance. Through practitioner interviews, it investigates application of design decision support tools by building designers. It proposes a means of increasing designers’ use of these tools. This proposal derives from observation that systematic quality assurance (QA) systems are seldom used with simulation-based tools. The proposal is a QA system comprising (a) a simulation veracity test akin to the Turing test of computer intelligence; (b) an internet database of building performance information; (c) post-analysis tools that define the reliability of design tool output.     

绿色建筑设计中被动设计与性能工具的应用思路与策略研究

研究立足于绿色建筑被动设计手法,关注性能工具与绿色设计相结合的设计思路,以及相关性能工具所涉及的热环境、光环境、风环境等环境性能。着重探讨这三类环境性能在进行绿色建筑设计时对建筑各个层面的影响,如立面设计、造型设计、空间组织等。同时,研究绿色建筑设计性能工具由手工模拟逐步转为计算机动态模拟技术势态。其发展趋势让建筑师直观并准确了解环境性能作用于建筑的影响结果,给绿色建筑设计带来全新的变革。通过对大量国内外案例分析比较,同时结合项目实践的经验,对绿色建筑的性能设计加以分析研究,试图启发基于气候因素的绿色建筑被动设计策略与方法的新思路。     

The application of building performance simulation in the writing of architectural history: Analysing climatic design in 1960s Israel

This article presents a methodology for the integration of building performance simulation (BPS) into the writing of architectural history. While BPS tools have been developed mainly for design purposes, their current maturity enables to reliably apply them in simulating the performance of past buildings, even when these buildings have been significantly modified or demolished. The possibility to virtually reconstruct the performance of past buildings can help us to overcome the existing knowledge gap in the understanding of the role played by building performance and building performance research through the history of architecture and can therefore promote the intelligent and successful application of environmental features in contemporary architecture. The potential of the proposed methodology is presented here using a historical case study from 1960s Israel (a university building in Tel Aviv), in which climatic considerations were anexplicit part of the entire design process. The original thermal performance of the building was analysed by employing the EnergyPlus simulation engine, and the simulation results were used for evaluating the climatic impact of certain design decisions, comparing them with the proclaimed design goals and the original intentions of the architects.     

Dem Himmel entgegen – Klimadesign für den Federation Tower Moskau

Skywards – climate design for the Moscow Federation Tower. Advanced simulation tools were used in developing the climate design for the roof covering the taller of the two blocks at Moscow's Federation Tower. The all‐glass roof space at a height of 365 m is designed to accommodate the finest and most exclusive hotel areas. Several restaurants, bars and lounges and a Sky Dance Club will offer entertainment and fabulous views across the whole city. Simulations were used to develop and verify a design that ensures thermal comfort taking into account architectural, climate and utilisation requirements. The structure and the building services were simulated based on a 3D model, and simulations were carried out for summer and winter scenarios. This paper describes the design process including load calculations and the development and assessment of the climate design by means of simulation.     

Simulation of ventilated facades in hot and humid climates

The Hong Kong climate is sub-tropical with hot and humid weather from May to September and temperate climate for the remaining 7 months period. A mechanical ventilation and air-conditioning (MVAC) system is usually operated to avoid the high temperatures resulting in high peak cooling loads. The facade design has a significant influence on the energy performance of office buildings. This work evaluates different ventilated facade designs in respect to energy savings.Thermal building simulations (TRNSYS) were linked to nodal airflow network simulations (COMIS) for detailed ventilated double-skin facade performance. In order to validate the model, simulations were carried out for an office building in Lisboa; the results were compared with measured data from the same building. The simulation results of surface and air temperatures show good agreement with the measurements. The results of the study can be used to reduce surface temperatures by using different materials for the roller blind that is positioned in the cavity of the double-skin facade. The results can further be used to reduce the high peak cooling loads during the summer period. This may result in significant energy savings and a reduction in the system's cooling capacity. It proved that a careful facade design can play an important role in highly glazed buildings and provides potential for energy efficiency.     

Effects of real-time simulation feedback on design for visual comfort

Building performance simulations and models of human visual comfort allow us to predict daylight-caused glare using digital building models and climate data. Unfortunately, the simulation tools currently available cannot produce results fast enough for interactive use during design ideation. We developed software with the ability to predict visual discomfort in real time. However, we know little about how users react to simulation feedback presented in real time. In our study, 40 subjects with backgrounds in building design and technology completed two shading design exercises to balance glare reduction and annual daylight availability in two open office arrangements using two simulation tools with differing system response times. Subjects with access to real-time simulation feedback tested more design options, reported higher confidence in design performance and increased satisfaction with the design task, and produced better-performing final designs with respect to spatial daylight autonomy and enhanced simplified daylight glare probability.     

Optimizing building form for energy performance based on hierarchical geometry relation

Most current research using optimization with building performance was restricted to simple geometry. It considered the building form as a box, polygonal shape, or simple curvature, restricting its applicability and integration with the design process. Generally, geometry variables including length, height, and depth usually control the objective values such as the area and volume of the building. Using these variables, the energy consumption data or simulation results per area or volume are compared to find the optimal form of the building. In addition, the algorithms used to predict performance in most of optimization studies are rather unsophisticated.There are technical constraints that are caused by specific problems that building simulation and optimization tools currently pose. For example, one major constraint can be lack of automated comparisons between different conditions and sharing geometry and boundaries with ease of operability. If the technical constraints can be overcome, building performance will much more easily be integrated into the design process.This paper introduces new method to control building forms by defining hierarchical relationship between geometry points to allow the user to explore the building geometry without being restricted to a box or simple form. It illustrates how the methodology allows the generation of optimized site-specific building form by integrating advanced simulation and optimization algorithm.     

Thermal comparison between ceiling diffusers and fabric ductwork diffusers for green buildings

Continuously increasing energy standards have driven the need for increasing the efficiency of buildings. Most enhancements to building efficiency have been a result of changes to the heating/cooling systems, improvements in construction materials, or building design code improvements. These approaches neglect the way in which air is dispersed into individual rooms or in a building – i.e., the ducting system. This opens up the possibility of significant energy savings by making ductwork systems lighter and better insulating while ensuring cost effectiveness.The current study explores this idea by comparing the performance of conventional ductwork with recent advancements in fabric-based ductwork. We focus on the transient behavior of an on/off control system, as well as the steady state behavior of the two ductwork systems. Transient, fully three dimensional validated computational (CFD) simulations are performed to determine flow patterns and thermal evolution in rooms containing either conventional or fabric ductwork. This analysis is used to construct metrics on efficiency. A number of different flow rates are examined to determine the performance over a range of operating conditions. Transient finite volume simulations consisted of over 13 million degrees of freedom for over 10,000 time steps. The simulations utilized HPC (High Performance Computing) for the large scale analysis.The results conclusively show that fabric ducting systems are superior to the conventional systems in terms of efficiency. Observations from the data show that fabric ducting systems heat the room faster, more uniformly, and more efficiently. The increase in performance demonstrates the potential benefits of moving away from conventional systems to fabric systems for the construction of green buildings: particularly in conjunction with adaptive control systems.