Developing a physical BIM library for building thermal energy simulation

Insufficient interoperability resulting from complex data exchange between architectural design and building energy simulation prevents the efficient use of energy performance analyses in the early design stage. This paper presents the development of a Modelica library for Building Information Modeling (BIM)-based building energy simulation (ModelicaBIM library) using an Object-Oriented Physical Modeling (OOPM) approach and Modelica, an equation-based OOPM language. By using the ModelicaBIM library, our project investigates system interfaces between BIM and energy simulation, which can perform semi-automatic translation from the building models in BIM to building energy modeling (BEM) using a BIM's authoring tool's Application Programming Interface (API).The ModelicaBIM library consists of OOPM-based BIM classes and OOPM-based BIM structure. OOPM-based BIM classes represent building component information. OOPM-based BIM structure consists of test case models that demonstrate (i) how building information in BIM can be transformed to OOPM and (ii) how design operations in BIM, such as changing a building geometry and editing building components, can be translated into BEM. A case study for simulation result comparisons has been conducted using (i) OOPM-based BIM models in the ModelicaBIM library and (ii) LBNL Modelica Buildings library (a Modelica-based building thermal simulation library developed by Lawrence Berkeley National Laboratory). Our implementation shows that the ModelicaBIM library enables (i) objects in BIM to be translated into the OOPM-based energy models and (ii) existing OOPM library to be utilized as a simulation solver for BIM-based energy simulation.     

Optimum lumped parameters for modeling building thermal performance

A least-squares method for choosing optimum lumped parameters for modelling the thermal performance of buildings is presented. A realistic passive solar-heated room is modelled with a one-time constant lumped model to better than 10% accuracy. This technique provides a simple method that can be used in the design or evaluation of the thermal performance of buildings such as those using passive solar heating.     

Integrated energy performance modeling for a retail store building

This paper presents an integrated energy performance modeling approach that considers heat and mass transfer through building envelope, HVAC (heating, ventilation, and air conditioning) and refrigeration systems of a retail store building with limited measured data. The internal heat gains/losses were estimated based on an Extended Kalman Filter. The simulation coupling strategy among room top units (RTUs), refrigeration display cases and zones is based on the ping-pong coupling strategy. The integrated model was validated against measured data from June to August, 2011. The results show that temperature prediction is within the ±1.5°C error band and the RTU electricity energy use prediction is within the ±10% error band. The difference between measured and simulated annual electricity consumption from the refrigeration system is 3%. Based on further analysis and diagnostics, deviations of model predictions from measured data were found to be partially due to the faults in the RTUs. Such deviation accounts for a 4% saving of the total building electrical energy consumption.     

Integrating 4D thermal information with BIM for building envelope thermal performance analysis and thermal comfort evaluation in naturally ventilated environments

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建筑热工设计对建筑节能的要求

本文通过冬季保温设计、夏季防热设计等的论述,指出了建筑热工设计对建筑节能的要求.     

建筑外墙隔热涂料节能效果实测研究

利用室外动态测试设备对建筑外墙隔热涂料在上海实际气候条件下的节能效果进行测试研究.分别在多孔黏土砖和加外保温的多孔黏土砖的基墙外表面涂刷相同颜色的隔热涂料和普通涂料进行室外测试,获取了实际天气条件下的隔热涂料传热系数的修正系数,为隔热涂料的实际节能效果评价提供试验依据.     

A methodology for a thermal energy building audit

The present paper introduces a new method for the certification of the energy consumption of a building recording its “energy behavior”. The method utilizes energy indices such as Index of Thermal Charge or Index of Energy Disposition to simulate the heat losses of the building and the heat flow because of the temperature difference (ΔT) from the inner to outer space.The present method and the algorithm that is implemented could be used as a part of a building energy audit or as a single audit method. Additionally it could be used for the inspection of the energy efficiency in public or municipal buildings. The forenamed method is currently under investigation by the present research team.     

Evaluation of reference modeling for building performance assessment

Lifecycle building performance assessment (LBPA) practices are being increasingly applied on existing buildings to ensure that performance requirements are fulfilled during building service-life. LBPA is a multi-disciplinary and information-intense process that requires computational tools for information management and decision support. We have previously developed a computational reference model (CLIP-Core) that supports various component-based LBPA practices. When CLIP-Core is considered to be used, it needs to be adapted to the specific context it addresses. We developed two such domain models, CLIP EPI-CREM and CLIP-CMU, for two existing LBPA practices. This paper addresses the evaluation of CLIP-Core and its potential in supporting various requirements. Hereto, we first discuss CLIP-Core and the two domain models. Then we present the evaluation results based on the domain models and their development processes. Finally we discuss guidelines for extending CLIP-Core and recommend technologies and alternative architectures that can increase CLIP-Core’s usability.     

Partnership in building energy performance contracting

Building energy performance contracting is a business strategy to assist building owners overcome the financial barriers for improving the energy performance of their buildings. In return for the investments made into the energy-saving measures, the energy service contractors would share with the building owners the energy cost saving. Although the contractual arrangement is meant to create a win–win situation, disappointments could arise due to mismatches between the expected and actual outcomes. From a micro-economics viewpoint, the key factors contributing to the failure of a building energy performance contract are reviewed. To solve the commonly encountered problems in building energy performance contracting, it is proposed the conventional performance contract is replaced with a partnership formed jointly by the building owner and the energy service contractor, with the latter assuming the role of the performance contractor. This would unite the goals of the two parties and cultivate genuine cooperation between them. The key features for this new contractual arrangement are described along with how this arrangement could resolve typical energy performance contracting problems.     

Partnership in building energy performance contracting

Building energy performance contracting is a business strategy to assist building owners overcome the financial barriers for improving the energy performance of their buildings. In return for the investments made into the energy-saving measures, the energy service contractors would share with the building owners the energy cost saving. Although the contractual arrangement is meant to create a win-win situation, disappointments could arise due to mismatches between the expected and actual outcomes. From a micro-economics viewpoint, the key factors contributing to the failure of a building energy performance contract are reviewed. To solve the commonly encountered problems in building energy performance contracting, it is proposed the conventional performance contract is replaced with a partnership formed jointly by the building owner and the energy service contractor, with the latter assuming the role of the performance contractor. This would unite the goals of the two parties and cultivate genuine cooperation between them. The key features for this new contractual arrangement are described along with how this arrangement could resolve typical energy performance contracting problems.     

A decision tree method for building energy demand modeling

This paper reports the development of a building energy demand predictive model based on the decision tree method. This method is able to classify and predict categorical variables: its competitive advantage over other widely used modeling techniques, such as regression method and ANN method, lies in the ability to generate accurate predictive models with interpretable flowchart-like tree structures that enable users to quickly extract useful information. To demonstrate its applicability, the method is applied to estimate residential building energy performance indexes by modeling building energy use intensity (EUI) levels. The results demonstrate that the use of decision tree method can classify and predict building energy demand levels accurately (93% for training data and 92% for test data), identify and rank significant factors of building EUI automatically. The method can provide the combination of significant factors as well as the threshold values that will lead to high building energy performance. Moreover, the average EUI value of data records in each classified data subsets can be used for reference when performing prediction. One crucial benefit is improving building energy performance and reducing energy consumption. Another advantage of this methodology is that it can be utilized by users without requiring much computation knowledge.     

节能量保证型合同能源管理在建筑节能中的应用

阐述了节能量保证型合同能源管理的实施流程、财务模式,给出了常用的节能解决方案,并针对节能解决方案介绍了节能量的测量与验证方法及节能量的修正方法,对节能量保证型合同能源管理的节能收益进行了分析。     

建筑外墙热工性能和节能设计分析

本文介绍福建省常用外墙材料的隔热保温构造形式和热工性能试验分析结果,并对我省建筑外墙的墙体节能提出看法和建议。     

Using building energy simulation and geospatial modeling techniques to determine high resolution building sector energy consumption profiles

A technique is presented for estimating hourly and seasonal energy consumption profiles in the building sector at spatial scales down to the individual taxlot or parcel. The method combines annual building energy simulations for city-specific prototypical buildings and commonly available geospatial data in a Geographical Information System (GIS) framework. Hourly results can be extracted for any day and exported as a raster output at spatial scales as fine as an individual parcel (<100 m). This method can be applied to virtually any large U.S. city to obtain day-specific estimates of electricity and natural gas consumption within the residential and commercial sectors. As a demonstration this method has been applied to Houston TX. When the resulting profiles were averaged over 1.33 km grid cells, the resulting peak energy consumption within the urban core was found to be greater than 100 W/m². The resulting profiles can be used to estimate anthropogenic sensible and latent waste heat emissions associated with building energy consumption. The target application for this approach is urban scale atmospheric modeling in support of urban heat island and air quality studies. In such applications the inclusion of high spatial and temporal resolution waste heat data represents a significant advancement.     

Automated performance measurement for 3D building modeling decisions

Building information modeling (BIM) is instrumental in documenting design, enhancing customer experience, and improving product functionality in capital projects. However, high-quality building models do not happen by accident, but rather because of a managed process that involves several participants from different disciplines and backgrounds. Throughout this process, the different priorities of design modelers often result in conflicts that can negatively impact project outcomes. To prevent such unwanted outcomes from occurring, the modeling process needs to be effectively managed. This effective management requires an ability to closely monitor the modeling process and correctly measure the modelers' performance. Nevertheless, existing methods of performance monitoring in building design practices lack an objective measurement system to quantify modeling progress. The widespread utilization of BIM tools presents a unique opportunity to retrieve granular design process data and conduct accurate performance measurements. This research improves upon previous efforts by presenting a novel application programming interface (API)-enabled approach to (a) automatically collect detailed model development data directly from BIM software packages in real-time, and (b) efficiently calculate several modeling performance measures during schematic and design development phases of building projects. These indicators can be used to properly arrange modeling teams in the quest for high-quality building models. The specific objectives of this study to examine the feasibility of a proposed automated design performance measurement framework, and to identify optimal modeling team configurations using empirical performance information. A passive data recording approach allows for the real-time capture of comprehensive user interface (UI) interaction and model element modification events. The proposed framework is implemented as an Autodesk Revit plugin. Next, an experiment is conducted to capture data using the developed Revit plugin. Experiment participants' individual production rates are estimated to establish the validity of the proposed approach to identify the optimal design team configuration. The presented approach uses the earliest due date (EDD) sequencing rule in combination with the critical path method (CPM) to calculate the maximum lateness for different design team arrangements.     

外墙保温在建筑节能中的作用

通过工程实践,就外墙内保温、夹层保温及外墙外保温分别作了论述,对外墙保温的施工工艺流程作了介绍,并阐述了其施工技术要点,为推广外墙保温技术应用奠定了基础,从而真正实现建筑节能。     

Occupant performance and building energy consumption with different philosophies of determining acceptable thermal conditions

Based on building energy and indoor environment simulations, this study uses a recently developed method relying on Bayesian Network theory to estimate and compare the consequences for occupant performance and energy consumption of applying temperature criteria set according to the adaptive model of thermal comfort and the more conventional PMV model. Simulations were carried out for an example building with two configurations (with and without mechanical cooling) located in tropical, subtropical, and temperate climate regions. Even though indoor temperatures differed significantly between building configurations, especially in the tropical climate, the estimated performance differed only modestly between configurations. However, energy consumption was always lower in buildings without mechanical cooling, particularly so in the tropical climate.     

Beyond the BIM utopia: Approaches to the development and implementation of building information modeling

Building information modeling (BIM) refers to a combination or a set of technologies and organizational solutions that are expected to increase interorganizational and disciplinary collaboration in the construction industry and to improve the productivity and quality of the design, construction, and maintenance of buildings. In this paper we analyze first the rhetorical–promotional dimension of the BIM implementation sometimes characterized as a “BIM utopia.” Second, we analyze the views of the enhancement of BIM implementation. Although BIM visions and promises are needed for BIM implementation, they need to be complemented with a more realistic view of conditions of the implementation. For this we outline an activity–theoretical and evolutionary view by drawing conceptual tools from science and technology studies and other relevant social scientific literature. According to this view, in addition to standards and guidelines underlined by normative approaches, local experimentation and continuous learning play a central role in the implementation of BIM.     

外围护结构常用墙材的热工性能及保温节能效果比较

重庆地处夏热冬冷地区,墙材改革工作滞后,建筑热环境恶劣,建筑能耗惊人。在当前热耗基数中,围护结构夏季负荷占５２．２７％,冬季负荷占８５．０９％,围护结构是现阶段的节能重点。《重庆市民用建筑热环境与节能设计标准》已发布施行,规定外围护墙体材料传热系数不大于１．５W／m２·K,但调查发现,目前我市民用建筑中使用的墙体材料８０％以上不能达到这一要求,９５％以上的民用建筑不是节能建筑。现有墙材与建筑节能的矛盾非常突出。一、不同墙材的热工性能及其优缺点目前重庆地区外围护结构用墙材的品种主要有：烧结页岩实心砖…     

Mandating transparency about building energy performance in use

In 2002, the European Union Energy Performance of Buildings Directive (EPBD) was ratified. This paper uses the lens of one policy measure triggered by the EPBD – Display Energy Certificates (DECs) for non-domestic buildings – to describe the difficulties experienced in capitalizing on a policy intention to use transparency about actual energy performance to drive better energy management and focus energy efficiency investment on things that really work in practice. It reviews the history and precedents of UK Building Regulations and European building energy efficiency policies to identify what helped and hindered progress towards buildings that use less energy in operation; and compares and contrasts building energy certificates based on asset and operational ratings. It also looks at the development paths of operational rating schemes in the US and Australia. It identifies a tendency of regulators to focus on one part of the problem, the so-called ‘regulated loads'; an unhelpful split of government ownership of the topic between various ministries and agencies; a neglect of follow-through, enforcement and feedback; and a political rhetoric that favours an abdication of central government responsibilities to market forces. Based on this evidence, it identifies a number of lessons for improvements to future policy outcomes.