Simulation and visualization of energy-related occupant behavior in office buildings

In current building performance simulation programs, occupant presence and interactions with building systems are over-simplified and less indicative of real world scenarios, contributing to the discrepancies between simulated and actual energy use in buildings. Simulation results are normally presented using various types of charts. However, using those charts, it is difficult to visualize and communicate the importance of occupants’ behavior to building energy performance. This study introduced a new approach to simulating and visualizing energy-related occupant behavior in office buildings. First, the Occupancy Simulator was used to simulate the occupant presence and movement and generate occupant schedules for each space as well as for each occupant. Then an occupant behavior functional mockup unit (obFMU) was used to model occupant behavior and analyze their impact on building energy use through co-simulation with EnergyPlus. Finally, an agent-based model built upon AnyLogic was applied to visualize the simulation results of the occupant movement and interactions with building systems, as well as the related energy performance. A case study using a small office building in Miami, FL was presented to demonstrate the process and application of the Occupancy Simulator, the obFMU and EnergyPlus, and the AnyLogic module in simulation and visualization of energy-related occupant behaviors in office buildings. The presented approach provides a new detailed and visual way for policy makers, architects, engineers and building operators to better understand occupant energy behavior and their impact on energy use in buildings, which can improve the design and operation of low energy buildings.     

Überlegenheit moderner,innovativer Planungswerkzeuge in der Gebäudeplanung

Superiority of advanced, innovative design tools. In Germany, standard building design is often determined in the traditional way that is, solely according to the HOAI (Official Scale of Fees for Services by Architects and Engineers) [1]. This means that in most cases only simplistic design tools are used by default. However, with high‐class complex buildings these are not always an adequate means of ensuring that the often stringent requirements their use places on the indoor climate conditions are met once they are in operation. In ambitious buildings featuring numerous open areas inside and open exits leading outdoors or to adjacent buildings but still place stringent requirements on the indoor climate conditions, the interactions between the individual areas inside and between these and ambient air are extremely important. Such buildings often appear transparent so as to look attractive to visitors: keeping entrance doors open helps to attract the attention of passers‐by and to make the buildings seem more inviting. The resulting streams of visitors necessitate a multiple open doorways, resulting in more or less strong airflow within the buildings. The effects of this wind‐ and buoyancy‐induced airflow on the indoor climate conditions proposed for a particular building can only be evaluated by means of advanced innovative design methods in the form of simulation technology. The airflow inside the buildings raises a number of very different issues regarding their design which can only be resolved by means of different simulation techniques. Using the new entrance building (NEG) on Berlin's Museum Island as an example, typical design issues are exemplified and the corresponding simulation techniques presented here. In this way the – urgently needed – transparency concerning the application of building simulation technology is encouraged.     

基于BIM的小型节能建筑生命周期环境影响和成本分析

被动式超低能耗建筑通过被动式设计策略、高性能的围护结构和高效的设备体系降低其使用阶段能耗。零能耗建筑在此基础上,采用太阳能光伏发电等可再生能源系统,进一步降低不可再生能源消耗。这两类节能建筑的材料和设备系统的隐含能耗、环境影响和成本通常高于一般建筑,同时对构件的后期维护和替换提出了更高的要求。因此,有必要从生命周期的范畴分析其环境和经济效益。建筑信息模型（BIM）能够为建筑项目的建造、运行和拆解等阶段提供多专业共享的数据平台。本文基于BIM,通过LCA和LCC方法对一座小型住宅建筑在不同节能目标情景下的生命周期全球变暖潜势值（GWP）、一次能耗（PE）和成本（LCC）进行分析和比较。结果表明,零能耗乃至正能源建筑在降低一次能耗和GWP方面具有明显优势,被动式超低能耗建筑也具有良好的环境效益。在经济效益方面,由于住宅建筑能源价格较低,如果按近年的价格指数计算,零能耗建筑和被动式超低能耗建筑的初建成本和后期构件替换成本增量将抵消其使用阶段节约的能耗成本,因此生命周期成本高于普通节能建筑。如果未来50年能源价格涨幅超过建筑安装价格涨幅,那么零能耗建筑在生命周期成本方面将具有优势。     

BuildOpt—a new building energy simulation program that is built on smooth models

Building energy simulation programs compute numerical approximations to physical phenomena that can be modeled by a system of differential algebraic equations (DAE). For a large class of building energy analysis problems, one can prove that the DAE system has unique solution that is once continuously differentiable in the building design parameters. Consequently, if building simulation programs are built on models that satisfy the smoothness assumptions required to prove existence of a unique smooth solution, and if their numerical solvers allow controlling the approximation error, one can use such programs with generalized pattern search optimization algorithms that adaptively control the precision of the solutions of the DAE system. Those optimization algorithms construct sequences of iterates with stationary accumulation points and have been shown to yield a significant reduction in computation time compared to algorithms that use fixed precision cost function evaluations.In this paper, we state the required smoothness assumptions and present the theorems that state existence of a unique smooth solution of the DAE system. We present BuildOpt, a detailed thermal and daylighting building energy simulation program. We discuss examples that explain the smoothing techniques used in BuildOpt. We present numerical experiments that compare the computation time for an annual simulation with the smoothing techniques applied to different parts of the models. The experiments show that high precision approximate solutions can only be computed if smooth models are used. This is significant because today's building simulation programs do not use such smoothing techniques and their solvers frequently fail to obtain a numerical solution if the solver tolerances are tight. We also present how BuildOpt's approximate solutions converge to a smooth function as the precision parameter of the numerical solver is tightened.     

A cost effective approach to design of energy efficient residential buildings

The objective of this study is to identify cost-optimal efficiency packages at several levels of building energy savings. A two-story residential building located in Jordan is selected as a case study. DesignBuilder software is used to predict the annual energy usage of a two-story residence in Irbid, Jordan. Real-time experimental data from a single isolated controlled room was used to verify the proposed model. In addition to energy analysis, the economic, environmental, and social benefits of the proposed design have been investigated. The sequential search optimization approach is used to estimate the minimum cost of the building while considering various design scenarios. In addition, the impact of various energy conservation techniques on residential buildings is assessed, and the payback period for each program is calculated. Ultimately, the optimal combination of design to achieve energy efficiency measures has been identified in several climate regions. The simulations results predict that the annual electricity consumption can be reduced up to 50% if the proper combinations of energy conservation measures are selected at the lowest cost. The payback period is 9.3 years. Finally, energy efficiency measures can lead to a total of 9470 jobs/year job opportunities.The study provide practical framework to link between energy performance criteria and economic goals of building. Linking the energy performance requirements to economic targets provides guidelines for homeowners, contractors, and policymakers for making a suitable decision regarding the retrofitting of existing residential buildings. The study focuses on developing new methodologies that support minimizing costs during a building's lifecycle while maximizing environmental benefits which can not be identified by a series of parametric analyses using individual energy-efficient measures.     

Computational intelligence techniques for HVAC systems: A review

Buildings are responsible for 40% of global energy use and contribute towards 30% of the total CO2 emissions. The drive to reduce energy use and associated greenhouse gas emissions from buildings has acted as a catalyst in the development of advanced computational methods for energy efficient design, management and control of buildings and systems. Heating, ventilation and air-conditioning (HVAC) systems are the major source of energy consumption in buildings and ideal candidates for substantial reductions in energy demand. Significant advances have been made in the past decades on the application of computational intelligence (CI) techniques for HVAC design, control, management, optimization, and fault detection and diagnosis. This article presents a comprehensive and critical review on the theory and applications of CI techniques for prediction, optimization, control and diagnosis of HVAC systems. The analysis of trends reveals that the minimisation of energy consumption was the key optimization objective in the reviewed research, closely followed by the optimization of thermal comfort, indoor air quality and occupant preferences. Hardcoded Matlab program was the most widely used simulation tool, followed by TRNSYS, EnergyPlus, DOE-2, HVACSim+ and ESP-r. Metaheuristic algorithms were the preferred CI method for solving HVAC related problems and in particular genetic algorithms were applied in most of the studies. Despite the low number of studies focussing on multi-agent systems (MAS), as compared to the other CI techniques, interest in the technique is increasing due to their ability of dividing and conquering an HVAC optimization problem with enhanced overall performance. The paper also identifies prospective future advancements and research directions.     

Benchmarking Hong Kong and China energy codes for residential buildings

Mandatory energy codes to curb energy use of residential buildings have been formally launched in China for more than two decades but little has been publicized in literature. Similar codes are not available for residential buildings in Hong Kong, but most residential buildings in Hong Kong, especially public housing estates, are HK-BEAM certified to demonstrate their compliance with regulatory and basic design requirements. Given HK-BEAM is internationally recognized and there are doubts about the effectiveness of the China codes, how the energy efficiency of the HK-BEAM certified buildings compare with buildings in compliance with the China codes is of interest to most building designers and policy makers. This paper describes how the energy efficiency of a case study building in compliance with the China codes compare with the one in compliance with HK-BEAM. The energy simulation by HTB2 and BECRES reveal that the case study building in compliance with the China codes is 51.1% better in energy use. In the study, the relative impact of each compliance criterion on energy use and cooling load has been quantified by sensitivity analysis. The sensitivity values indicate that energy use is most sensitive to air-conditioning operation hours, indoor design temperature, coefficient of performance (COP) of the room air-conditioners (RAC) units, and the envelop characteristics. The results of this study indicate that a HK-BEAM certified building cannot satisfy the China codes requirements. This provides good reference to the policy makers, the building owners, and to the China and Hong Kong Governments when considering reciprocal recognition of building energy codes.     

A parametric approach for performance optimization of residential building design in Beijing

During the early design stage of green residential buildings, there are tremendous potential of using parametric optimization to achieve preferable green performance, such as building energy consumption efficiency, daylighting, ventilation and thermal comfort. Taking residential design features into consideration, this paper presents an optimization workflow and effects based on a case study of a residential building project in Beijing. Firstly, 27 design parameters related to residential spatial form and building envelope were selected for the optimization. The simulation results of the cooling and heating load were taken as the optimization objects. Secondly, optimized schemes were obtained from 6246 simulation results, with 1925 verified simulation results proving that the optimized result is reliable. Finally, analysis was performed to establish the correlations between design parameters and performance in order to create the easy access for architects to determine design parameters depending on the performance sensitivity of each parameter. Analysis results showed that parametric optimization of spatial form and building envelope at the design stage is a feasible approach to reducing energy consumption in residential building design.

     

高能效建筑设计策略

随着国民经济的快速发展和人民生活水平的不断提高,能量消耗和温室气体排放也愈来愈高。同时,我国建筑能耗也占到总能耗的约28%。可持续建筑(绿色建筑)的不断发展对整个建筑业提出了新的要求和机遇。该文提出了以高能效设计为核心的绿色建筑设计策略。     

住区规划节能设计研究——以南京为例

目前对住宅节能的研究大多集中在单体层面,倒如对围护结构热工物理性能展开研究通过对住宅单体进行充分的节能设计,显然可以取得良好的节能效果。但在另一方面,住宅单体几乎总是位于特定的住区建筑群之中,而住区的微环境会对其中的住宅单体能耗带来直接的影响。因此,除在单体层面研究住宅节能外,还需要在群体层面研究住区节能。该文运用EnergyPlus能耗模拟软件对住区能耗影响因子进行了定量研究,分析了建筑密度、建筑间距、建筑朝向和景观对住区能耗的影响规律。     

住宅建筑采暖空调能耗模拟方法的研究

住宅建筑的采暖空调能耗受室内居住人员行为方式的影响,在调查研究基础上,确定了两种反映室内居住人员行为方式的计算模式。在两种不同计算模式下,利用建筑热环境模拟工具DeST对上海地区同一住宅建筑能耗进行模拟,并将模拟结果与调研结果进行比较,分析计算模式对上海地区住宅建筑采暖空调能耗大小的影响,从而获得能正确反映上海地区住宅建筑采暖空调能耗大小的模拟计算方法。此方法可用于上海地区住宅建筑采暖空调的能耗分析与评价,并正确指导住宅建筑的节能设计。     

Needs and trends in integrated building and HVAC thermal design tools

Buildings are responsible for approximately 40% of the total energy consumption in developed countries. More than half of this is used to condition the indoor environment. Studies have shown that savings of between 30 and 70% may be realized through improved design and retrofit procedures for buildings and air conditioning equipment.

Designing for energy efficiency requires a system approach that includes the building, the HVAC system and the controller. Traditional design philosophy based on load calculations is inadequate. New user-friendly design tools allowing an integrated simulation of the complete system are needed.

The main features of a suitable design tool are identified. It should allow dynamic analysis of the passive performance of the building combined with pseudo-steady HVAC system simulation. HVAC component models should be based on simplified fundamental principle analysis to ensure flexibility. The tool should allow for a fully integrated simulation of the building, its HVAC system and controller.

A flexible icon-based graphical interface must be complemented be expandable databases for all components to ensure user-friendly operation. The software must run on a personal computer and should also allow standard system design calculations, life-cycle cost analysis, automatic optimization features and data exchange with CAD software. No tool could be found that provided all of these needs.

The use of such a tool will result in more energy-efficient solutions when designing, managing and retrofitting buildings. This will help to reduce the burden on the environment. The tool will make commissioning of new systems more precise and less laborious. The ability of the designer to guarantee desired comfort conditions will also be enhanced.     

Ancient vernacular architecture: characteristics categorization and energy performance evaluation

Building has significant impacts on the environment and natural resources. The emerging world energy and environment challenges demand a substantial revolution of building design philosophies, strategies, technologies, and construction methods. Vernacular architectures, built by people whose design decisions are influenced by traditions in their culture, have been gleaned through a long period of trial and error and the ingenuity of local builders who possess specific knowledge about their place on the planet, and thus are valuable in promoting climate-specific passive building technologies to modern buildings. This study introduced an approach to categorizing distinct vernacular regions and evaluating energy performance of ancient vernacular homes as well as identifying optimal constructions using vernacular building techniques. The research conducted an extensive computer energy modeling for a number of representative ancient vernacular architectural characteristics observed for different climatic regions. The vernacular test subjects were compared against those established according to the International Energy Conservation Code and those generated by the optimization software. The simulation results of the energy models suggest that considering traditions seen in ancient vernacular architecture as an approach to improving building energy performance is a worthwhile endeavor and a scientific guidance can help enhance the performance. The study indicates that, although many vernacular dwells exist in the world, it is challenging (but desired) to package vernacular architecture traditions and quantitative design knowledge to modern building designers. This project is the first part of a much larger project that intends to create a knowledge base of vernacular building traditions that will include information about not only the energy performance of traditional building techniques, but also address areas of cost, material availability and cultural traditions.     

Thermoeconomic analysis and optimization of high efficiency solar heating and cooling systems for different Italian school buildings and climates

The paper investigates the energetic and economic feasibility of a solar-assisted heating and cooling system (SHC) for different types of school buildings and Italian climates. The SHC system under investigation is based on the coupling of evacuated solar collectors with a single-stage LiBr-H₂O absorption chiller; auxiliary energy for both heating and cooling is supplied by an electric-driven reversible heat pump. The SHC system was coupled with different types of school buildings located in three different Italian climatic zones. The analysis is carried out by means of a zero-dimensional transient simulation model, developed using the TRNSYS software; the analysis of the dynamic behaviour of the building was also included. An economic model is proposed, in order to assess the operating and capital costs of the systems under analysis. Furthermore, a parametric analysis and a subsequent mixed heuristic-deterministic optimization algorithm was implemented, in order to determine the set of the synthesis/design variables that maximize system profitability. The results are encouraging, as for the potential of energy saving. On the contrary, the SHC economic profitability can be achieved only in case of public funding policies (e.g. feed-in tariffs), as always happens for the great majority of renewable energy systems.     

Genetic-algorithm based approach to optimize building envelope design for residential buildings

A simulation–optimization tool is developed and applied to optimize building shape and building envelope features. The simulation–optimization tool couples a genetic algorithm to a building energy simulation engine to select optimal values of a comprehensive list of parameters associated with the envelope to minimize energy use for residential buildings. Different building shapes were investigated as part of the envelope optimization, including rectangle, L, T, cross, U, H, and trapezoid. Moreover, building envelope features were considered in the optimization analysis including wall and roof constructions, foundation types, insulation levels, and window types and areas. The results of the optimization indicate rectangular and trapezoidal shaped buildings consistently have the best performance (lowest life-cycle cost) across five different climates. It was also found that rectangle and trapezoid exhibit the least variability from best to worst within the shape.     

Simulation of coupled heat and moisture transfer in air-conditioned buildings

The simultaneous heat and moisture transfer in the building envelope has an important influence on the indoor environment and the overall performance of buildings. In this paper, a model for predicting whole building heat and moisture transfer was presented. Both heat and moisture transfer in the building envelope and indoor air were simultaneously considered; their interactions were modeled. The coupled model takes into account most of the main hygrothermal effects in buildings. The coupled system model was implemented in MATLAB-Simulink, and validated by using a series of published testing tools. The new program was applied to investigate the moisture transfer effect on indoor air humidity and building energy consumption under different climates. The results show that the use of more detailed simulation routines can result in improvements to the building's design for energy optimisation through the choice of proper hygroscopic materials, which would not be indicated by simpler calculation techniques.     

Building simulation: Ten challenges

Buildings consume more than one-third of the world’s primary energy. Reducing energy use and greenhouse-gas emissions in the buildings sector through energy conservation and efficiency improvements constitutes a key strategy for achieving global energy and environmental goals. Building performance simulation has been increasingly used as a tool for designing, operating and retrofitting buildings to save energy and utility costs. However, opportunities remain for researchers, software developers, practitioners and policymakers to maximize the value of building performance simulation in the design and operation of low energy buildings and communities that leverage interdisciplinary approaches to integrate humans, buildings, and the power grid at a large scale. This paper presents ten challenges that highlight some of the most important issues in building performance simulation, covering the full building life cycle and a wide range of modeling scales. The formulation and discussion of each challenge aims to provide insights into the state-of-the-art and future research opportunities for each topic, and to inspire new questions from young researchers in this field.     

可持续设计方法在产能房设计中的应用——以甘肃河畔小学为例

可持续设计方法是基于当地气候条件分析,以被动节能优先、主动节能优化的设计策略,通过降低能量需求、提高用能效率,以及优化用能策略来最大可能地降低建筑能源消耗。以甘肃会宁河畔小学为例,通过建筑朝向、采光、通风及光伏板安装角度等方面的优化,高效新风热回收系统的设计,以及对当地旱厕的改造,使用当地生土砖等设计措施,使建筑在节能、舒适及环境影响之间达到平衡,为可持续设计方法在产能房中的应用提供参考。     

上海地区住宅围护结构性能对全年空调采暖能耗的分析

将根据《夏热冬冷地区居住建筑节能设计标准》,采用逐时能耗分析软件Equest-3.6(DOE-2.2)建立基本模型,采用上海典型气象年8760h气象参数进行能耗模拟,在能耗模拟的基础上对建筑的全年能耗进行分析。据此提出各项围护结构优化设计方案,并对各方案的经济性和可行性进行分析。最后对各优化方案进行合理的组合,建立一个综合优化模型。结果表明在住宅建筑中,用于制冷和供热的能耗占住宅总能耗的60%～70%;围护结构的性能对住宅的室内热环境和能耗有较大的影响,围护结构的优化可大幅降低建筑的空调和制冷能耗。     

Building energy efficiency and thermal comfort in tropical climates: Presentation of a numerical approach for predicting the percentage of well-ventilated living spaces in buildings using natural ventilation

The paper deals with the optimization of building energy efficiency in tropical climates by reducing the period of air-conditioning thanks to natural ventilation and a better bioclimatic design. A bioclimatic approach to designing comfortable buildings in hot and humid tropical regions requires, firstly, some preliminary, important work on the building envelope to limit the energy contributions, and secondly, an airflow optimization based on the analysis of natural ventilation airflow networks. For the first step, tools such as nodal or zonal models have been largely implemented in building energy codes to evaluate energy transport between indoor and outdoor. For the second step, the assessment of air velocities, in three dimensions and in a large space, can only be performed through the use of detailed models such as with CFD. A new modelling approach based on the derivation of a new quantity—i.e. the well-ventilated percentage of a living space is proposed. The well-ventilated percentage of a space allows a time analysis of the air motion behaviour of the building in its environment. These percentages can be over a period such as 1 day, a season or a year. Twelve living spaces with different configuration of openings have been studied to compare the performance of ventilation function of the opening distribution. Results and discussion are presented in the paper. This method is helpful for an architect to design the rooms according to their use, and their environment. Finally, the developed models can be used in building projects to estimate the period of the natural ventilation and to reduce the energy consumption due to air-conditioning.