@article {30728, title = {Dynamic equation-based thermo-hydraulic pipe model for district heating and cooling systems}, journal = {Energy Conversion and Management}, volume = {151}, year = {2017}, abstract = {

Simulation and optimisation of district heating and cooling networks requires efficient and realistic models of the individual network elements in order to correctly represent heat losses or gains, temperature propagation and pressure drops. Due to more recent thermal networks incorporating meshing decentralised heat and cold sources, the system often has to deal with variable temperatures and mass flow rates, with flow reversal occurring more frequently. This paper presents the mathematical derivation and software implementation in Modelica of a thermo-hydraulic model for thermal networks that meets the above requirements and compares it to both experimental data and a commonly used model. Good correspondence between experimental data from a controlled test set-up and simulations using the presented model was found. Compared to measurement data from a real district heating network, the simulation results led to a larger error than in the controlled test set-up, but the general trend is still approximated closely and the model yields results similar to a pipe model from the Modelica Standard Library. However, the presented model simulates 1.7 (for low number of volumes) to 68 (for highly discretized pipes) times faster than a conventional model for a realistic test case. A working implementation of the presented model is made openly available within the IBPSA Modelica Library. The model is robust in the sense that grid size and time step do not need to be adapted to the flow rate, as is the case in finite volume models.

}, doi = {10.1016/j.enconman.2017.08.072}, author = {Brahm van der Heijde and Marcus Fuchs and Carles Ribas Tugores and Gerald Schweiger and Kevin Sartor and Daniele Basciotti and Dirk Muller and Christoph Nytsch-Geusen and Michael Wetter and Lieve Helsen} } @article {30481, title = {IEA EBC Annex 53: Total Energy Use in Buildings {\textendash} Analysis and Evaluation Methods}, journal = {Energy and Buildings}, volume = {152}, year = {2017}, abstract = {

One of the most significant barriers to achieving deep building energy efficiency is a lack of knowledge about the factors determining energy use. In fact, there is often a significant discrepancy between designed and real energy use in buildings, which is poorly understood but are believed to have more to do with the role of human behavior than building design. Building energy use is mainly influenced by six factors: climate, building envelope, building services and energy systems, building operation and maintenance, occupants{\textquoteright} activities and behavior, and indoor environmental quality. In the past, much research focused on the first three factors. However, the next three human-related factors can have an influence as significant as the first three. Annex 53 employed an interdisciplinary approach, integrating building science, architectural engineering, computer modeling and simulation, and social and behavioral science to develop and apply methods to analyze and evaluate the real energy use in buildings considering the six influencing factors. Outcomes from Annex 53 improved understanding and strengthen knowledge regarding the robust prediction of total energy use in buildings, enabling reliable quantitative assessment of energy-savings measures, policies, and techniques.

}, keywords = {energy data definition, energy modeling, energy monitoring, occupant behavior, Performance Evaluation, real energy use}, doi = {10.1016/j.enbuild.2017.07.038}, author = {Hiroshi Yoshino and Tianzhen Hong and Natasa Nord} } @article {60350, title = {Design choices for thermofluid flow components and systems that are exported as Functional Mockup Units}, year = {2015}, abstract = {

This paper discusses design decisions for exporting Modelica thermofluid flow components as Functional Mockup Units. The purpose is to provide guidelines that will allow building energy simulation programs and HVAC equipment manufacturers to effectively use FMUs for modeling of HVAC components and systems. We provide an analysis for direct input-output dependencies of such components and discuss how these dependencies can lead to algebraic loops that are formed when connecting thermofluid flow components. Based on this analysis, we provide recommendations that increase the computing efficiency of such components and systems that are formed by connecting multiple components. We explain what code optimizations are lost when providing thermofluid flow components as FMUs rather than Modelica code. We present an implementation of a package for FMU export of such components, explain the rationale for selecting the connector variables of the FMUs and finally provide computing benchmarks for different design choices. It turns out that selecting temperature rather than specific enthalpy as input and output signals does not lead to a measurable increase in computing time, but selecting nine small FMUs rather than a large FMU increases computing time by 70\%

}, author = {Michael Wetter and Marcus Fuchs and Thierry Stephane Nouidui} } @article {60342, title = {Equation-based languages {\textendash} A new paradigm for building energy modeling, simulation and optimization}, journal = {Energy and Buildings}, volume = {117}, year = {2015}, month = {04/2016}, pages = {290-300}, abstract = {

Most of the state-of-the-art building simulation programs implement models in imperative programming languages. This complicates modeling and excludes the use of certain efficient methods for simulation and optimization. In contrast, equation-based modeling languages declare relations among variables, thereby allowing the use of computer algebra to enable much simpler schematic modeling and to generate efficient code for simulation and optimization.

We contrast the two approaches in this paper. We explain how such manipulations support new use cases. In the first of two examples, we couple models of the electrical grid, multiple buildings, HVAC systems and controllers to test a controller that adjusts building room temperatures and PV inverter reactive power to maintain power quality. In the second example, we contrast the computing time for solving an optimal control problem for a room-level model predictive controller with and without symbolic manipulations. Exploiting the equation-based language led to 2200 times faster solution.

}, keywords = {Equation-based modeling, modelica, Multi-physics simulation, Optimal control, smart grid}, doi = {10.1016/j.enbuild.2015.10.017}, author = {Michael Wetter and Marco Bonvini and Thierry Stephane Nouidui} } @article {60932, title = {Green, Clean, \& Mean: Pushing the Energy Envelope in Tech Industry Buildings}, year = {2015}, month = {05/2015}, publisher = {Lawrence Berkeley National Laboratory}, abstract = {

When it comes to innovation in energy and building performance, one can expect leading-edge activity from the technology sector. As front-line innovators in design, materials science, and information management, developing and operating high-performance buildings is a natural extension of their core business.

The energy choices made by technology companies have broad importance given their influence on society at large as well as the extent of their own energy footprint. Microsoft, for example, has approximately 250 facilities around the world (30 million square feet of floor area), with significant aggregate energy use of approximately 4 million kilowatt-hours per day.

There is a degree of existing documentation of efforts to design, build, and operate facilities in the technology sector. However, the material is fragmented and typically looks only at a single company, or discrete projects within a company.Yet, there is no single resource for corporate planners and decision makers that takes stock of the opportunities and documents sector-specific case studies in a structured manner. This report seeks to fill that gap, doing so through a combination of generalized technology assessments ({\textquotedblleft}Key Strategies{\textquotedblright}) and case studies ({\textquotedblleft}Flagship Projects{\textquotedblright}).

}, author = {Evan Mills and Jessica Granderson and Wanyu R. Chan and Richard C. Diamond and Philip Haves and Bruce Nordman and Paul A. Mathew and Mary Ann Piette and Gerald Robinson and Stephen E. Selkowitz} } @article {60352, title = {Modelica Buildings Library}, year = {2015}, author = {Michael Wetter and Wangda Zuo and Thierry Stephane Nouidui and Xiufeng Pang} } @proceedings {57000, title = {Functional Mock-Up Unit Import in EnergyPlus For Co-Simulation}, journal = {13th Conference of International Building Performance Simulation}, year = {2013}, month = {08/2013}, address = {Chambery, France}, abstract = {

This paper describes how to use the recently implemented Functional Mock-up Unit (FMU) for co-simulation import interface in EnergyPlus to link EnergyPlus with simulation tools packaged as FMUs. The interface complies with the Functional Mock-up Interface (FMI) for co-simulation standard version 1.0, which is an open standard designed to enable links between different simulation tools that are packaged as FMUs. This article starts with an introduction of the FMI and FMU concepts. We then discuss the implementation of the FMU import interface in EnergyPlus. After that, we present two use cases. The first use case is to model a HVAC system in Modelica, export it as an FMU, and link it to a room model in EnergyPlus. The second use case is an extension of the first case where a shading controller is modeled in Modelica, exported as an FMU, and used in the EnergyPlus room model to control the shading device of one of its windows. In both cases, the FMUs are imported into EnergyPlus which models the building envelope and manages the data-exchange between the envelope and the systems in the FMUs during run-time.

}, author = {Thierry Stephane Nouidui and Michael Wetter and Wangda Zuo} } @proceedings {3408, title = {Validation and Application of the Room Model of the Modelica Buildings Library}, journal = {Proc. of the 9th International Modelica Conference}, year = {2012}, month = {09/2012}, address = {Munich, Germany}, abstract = {

The Modelica Buildings library contains a package with a model for a thermal zone that computes heat transfer through the building envelope and within a room. It considers various heat transfer phenomena of a room, including conduction, convection, short-wave and long-wave radiation. The first part of this paper describes the physical phenomena considered in the room model. The second part validates the room model by using a standard test suite provided by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). The third part focuses on an application where the room model is used for simulation-based controls of a window shading device to reduce building energy consumption.

}, author = {Thierry Stephane Nouidui and Phalak, Kaustubh and Wangda Zuo and Michael Wetter} } @article {3182, title = {Validation of the Window Model of the Modelica Buildings Library}, year = {2012}, month = {07/2012}, abstract = {

This paper describes the validation of the window model of the free open-source Modelica Buildings library. This paper starts by describing the physical modeling assumptions of the window model. The window model can be used to calculate the thermal and angular properties of glazing systems. It can also be used for steady-state simulation of heat transfer mechanism in glazing systems. We present simulation results obtained by comparing the window model with WINDOW 6 the well established simulation tool for steady-state heat transfer in glazing systems. We also present results obtained by comparing the window model with measurements carried out in a test cell at the Lawrence Berkeley National Laboratory.

}, author = {Thierry Stephane Nouidui and Michael Wetter and Wangda Zuo} } @article {3181, title = {BacNet and Analog/Digital Interfaces of the Building Controls Virtual Testbed}, year = {2011}, month = {11/2011}, abstract = {

This paper gives an overview of recent developments in the Building Controls Virtual Test Bed (BCVTB), a framework for co-simulation and hardware-in-the-loop.

First, a general overview of the BCVTB is presented. Second, we describe the BACnet interface, a link which has been implemented to couple BACnet devices to the BCVTB. We present a case study where the interface was used to couple a whole building simulation program to a building control system to assess in real-time the performance of a real building. Third, we present the ADInterfaceMCC, an analog/digital interface that allows a USB-based analog/digital converter to be linked to the BCVTB. In a case study, we show how the link was used to couple the analog/digital converter to a building simulation model for local loop control.

}, author = {Philip Haves and Prajesh Bhattacharya and Thierry Stephane Nouidui and Michael Wetter and Zhengwei Li and Xiufeng Pang} } @proceedings {2785, title = {BACnet and Analog/Digital Interfaces of the Building Controls Virtual Test Bed}, journal = {Proc. of the 12th IBPSA Conference}, year = {2011}, month = {11/2011}, pages = {p. 294-301}, address = {Sydney, Australia}, author = {Thierry Stephane Nouidui and Michael Wetter and Zhengwei Li and Xiufeng Pang and Prajesh Bhattacharya and Philip Haves} } @proceedings {2786, title = {Modeling of Heat Transfer in Rooms in the Modelica "Buildings" Library}, journal = {12th Conference of International Building Performance Ssimulation Association}, year = {2011}, month = {11/2011}, pages = {1096-1103}, address = {Sydney, Australia}, author = {Michael Wetter and Wangda Zuo and Thierry Stephane Nouidui} } @proceedings {2782, title = {Recent developments of the Modelica Buildings library for building energy and control systems}, journal = {the 8th International Modelica Conference}, year = {2011}, address = {Dresden, Germany}, abstract = {

At the Modelica 2009 conference, we introduced the Buildings library, a freely available Modelica library for building energy and control systems [16]. This paper reports the updates of the library and presents example applications for a range of heating, ventilation and air conditioning (HVAC) systems. Over the past two years, the library has been further developed. The number of HVAC components models has been doubled and various components have been revised to increase numerical robustness. The paper starts with an overview of the library architecture and a description of the main packages. To demonstrate the features of the Buildings library, applications that include multizone airow simulation as well as supervisory and local loop control of a variable air volume (VAV) system are briey described. The paper closes with a discussion of the current development.

}, keywords = {building energy systems, heating}, url = {https://www.modelica.org/events/modelica2011/Proceedings/pages/papers/12_1_ID_113_a_fv.pdf}, author = {Michael Wetter and Wangda Zuo and Thierry Stephane Nouidui} } @conference {224, title = {Development of an isothermal 2D zonal air volume model with impulse conservation}, booktitle = {Clima 2010, 10th Rehva World Congress "Sustainable Energy Use in Buildings"}, year = {2010}, address = {Antalya, Turkey}, abstract = {

This paper presents a new approach to model air flows with a zonal model. The aim of zonal models is to perform quick simulations of the air distribution in rooms. Therefore an air volume is subdivided into several discrete zones, typically 10 to 100. The zones are connected with flow elements computing the amount of air exchanged between them. In terms of complexity and needed computational time zonal models are a compromise between CFD calculations and the approximation of perfect mixing. In our approach the air flow velocity is used as property of the zones. Thus the distinction between normal zones and jet or plume influenced zones becomes obsolete. The model is implemented in the object oriented and equation based language Modelica. A drawback of the new formulation is that the calculated flow pattern depends on the discretization. Nevertheless, the results show that the new zonal model performs well and is a useful extension to existing models.

}, author = {Norrefeldt Victor and Thierry Stephane Nouidui and Gunnar Gruen} } @article {240, title = {Modeling and Measurement Constraints in Fault Diagnostics for HVAC Systems}, journal = {ASME Journal of Dynamic Systems, Measurement, and Controls}, year = {2010}, abstract = {Many studies have shown that energy savings of five to fifteen percent are achievable in commercial buildings by detecting and correcting building faults, and optimizing building control systems. However,in spite of good progress in developing tools for determining HVAC diagnostics, methods to detect faults in HVAC systems are still generally undeveloped. Most approaches use numerical filtering or parameter estimation methods to compare data from energy meters and building sensors to predictions from mathematical or statistical models. They are effective when models are relatively accurate and data contain few errors. In this paper, we address the case where models are imperfect and data are variable, uncertain, and can contain error. We apply a Bayesian updating approach that is systematic in managing and accounting for most forms of model and data errors. The proposed method uses both knowledge of first principle modeling and empirical results to analyze the system performance within the boundaries defined by practical constraints. We demonstrate the approach by detecting faults in commercial building air handling units. We find that the limitations that exist in air handling unit diagnostics due to practical constraints can generally be effectively addressed through the proposed approach.}, author = {Massieh Najafi and David M. Auslander and Peter L. Bartlett and Philip Haves and Michael D. Sohn} } @article {242, title = {A Statistical Pattern Analysis Framework for Rooftop Unit Diagnostics}, journal = {International Journal of Heating, Ventilating, Air-Conditioning and Refrigeration Research}, year = {2010}, author = {Massieh Najafi and David M. Auslander and Philip Haves and Michael D. Sohn} } @proceedings {243, title = {Systems Approach to Energy Efficient Building Operation: Case Studies and Lessons Learned in a University Campus}, journal = {2010 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2010}, publisher = {Omnipress}, address = {Asilomar, California, USA}, abstract = {

This paper reviews findings from research conducted at a university campus to develop a robust systems approach to monitor and continually optimize building energy performance. The field analysis, comprising three projects, included detailed monitoring, model-based analysis of system energy performance, and implementation of optimized control strategies for both district and building-scale systems. One project used models of the central cooling plant and campus building loads, and weather forecasts to analyze and optimize the energy performance of a district cooling system, comprising chillers, pumps and a thermal energy storage system. Fullscale implementation of policies devised with a model predictive control approach produced energy savings of about 5\%, while demonstrating that the heuristic policies implemented by the operators were close to optimal during peak cooling season and loads. Research was also conducted to evaluate whole building monitoring and control methods. A second project performed in a campus building combined sub-metered end-use data, performance benchmarks, energy simulations and thermal load estimators to create a web-based energy performance visualization tool prototype. This tool provides actionable energy usage information to aid in facility operation and to enable performance improvement. In a third project, an alternative to demand controlled ventilation enabled by direct measurements of building occupancy levels was assessed. Simulations were used to show 5-15\% reduction in building HVAC system energy usage when using estimates of actual occupancy levels.

}, isbn = {0-918249-60-0}, author = {Satish Narayanan and Michael G. Apte and Philip Haves and Mary Ann Piette and John Elliott} } @conference {233, title = {Application of software tools for moisture protection of buildings in different climate zones}, booktitle = {6th International Conference on Cold Climate, Heating, Ventilating and Air-Conditioning}, year = {2009}, address = {Sisimiut, Groenland}, abstract = {

The application of software tools for moisture protection of buildings in different climatic zones is demonstrated in this paper. The basics of the programs are presented together with a typical application for a problem specific for the chosen climatic zone. A 1-D calculation has been performed for tropical climate zone with the improvement of a flat roof in Bangkok as an example. For half timbered buildings, which are common in the temperate zone with the 2-D model an infill insulation and its benefits are demonstrated. Finally the combined appliance of the whole building model and the mould risk prognosis model is shown in detail as a special case for the cold climate zone: In heated buildings of cold climate zones the internal climate with its low relative humidity in wintertime often causes discomfort and health problems for the occupants. In case of using air humidifier the risk of mould growth increases. Instead of an uncontrolled humidifying of the dry air an innovativecontrol system using a thermal bridge, which switches the humidifier off when condensation occurs is presented. To quantify the improvement in the comfort while preventing the risk of mould growth for a typical building comparative calculations of the resulting inner climates and its consequences on comfort have been performed.

}, author = {Martin Krus and Thierry Stephane Nouidui and Klaus Sedlbauer} } @proceedings {394, title = {{\textquotedblleft}The Monitoring,{\textquotedblright} Panel: Chill-Off}, journal = {Silicon Valley Leadership Group Data Center Energy Efficiency Summit}, year = {2009}, month = {10/2009}, address = {Sunnyvale, CA}, author = {Dean Nelson and Brian Day and Geoffrey C. Bell and Prajesh Bhattacharya and Mike Ryan} } @article {226, title = {Neue objektorientierte hygrothermische Modell-Bibliothek zur Ermittlung des hygrothermischen und hygienischen Komforts in R{\"a}umen}, journal = {Bauphysik}, volume = {31}, number = {5}, year = {2009}, pages = {271-278}, issn = {0171-5445}, doi = {10.1002/bapi.200910036}, author = {Thierry Stephane Nouidui and Klaus Sedlbauer and Christoph Nytsch-Geusen and Kurt Kie{\ss}l} } @proceedings {247, title = {Application of Machine Learning in Fault Diagnostics of Mechanical Systems}, journal = {International Conference on Modeling, Simulation and Control}, year = {2008}, month = {10/2008}, author = {Massieh Najafi and David M. Auslander and Peter L. Bartlett and Philip Haves} } @proceedings {246, title = {Fault Diagnostics and Supervised Testing: How Fault Diagnostic tools can be Proactive?}, journal = {Eleventh International Conference on Intelligent Systems and Controls}, year = {2008}, month = {11/2008}, abstract = {The topic of fault detection and diagnostics (FDD) is studied from the perspective of proactive testing. Unlike most research focus in the diagnosis area in which system outputs are analyzed for diagnosis purposes, in this paper the focus is on the other side of the problem: manipulating system inputs for better diagnosis reasoning. In other words, the question of how diagnostic mechanisms can direct system inputs for better diagnosis analysis is addressed here. It is shown how the problem can be formulated as decision making problem coupled with a Bayesian Network based diagnostic mechanism. The developed mechanism is applied to the problem of supervised testing in HVAC systems.}, url = {http://www.actapress.com/Content_of_Proceeding.aspx?proceedingID=503}, author = {Massieh Najafi and David M. Auslander and Peter L. Bartlett and Philip Haves} } @proceedings {236, title = {Geb{\"a}udesimulation mit adaptiven Modellierungsans{\"a}tzen}, journal = {BAUSIM 2008}, year = {2008}, address = {Kassel, Germany}, author = {Christoph Nytsch-Geusen and Thierry Stephane Nouidui} } @proceedings {227, title = {Object-oriented hygrothermal building physics library as a tool to predict and to ensure a thermal and hygric indoor comfort in building construction by using a Predicted-Mean-Vote (PMV) control ventilation system}, journal = {8th Nordic Symposium on Building Physics in the Nordic Countries 2008}, volume = {2}, year = {2008}, pages = {pp.825-832}, address = {Copenhagen, Denmark}, abstract = {

The indoor temperature and humidity conditions of the building envelope are important parameters for the evaluation of the thermal and hygric indoor comfort. In the research project GENSIM a new hygrothermal building library, based on the object- and equation-oriented model description language Modelica{\textregistered} has been developed by the Fraunhofer Institutes IBP and FIRST. This library includes many models as for instance a hygrothermal wall model, an air volume model, a zone model, a window model and an environment model. Due to the object-oriented modelling approach, some models of this library can be configured to a complex hygrothermal room model, which can predict the time dependent indoor temperature and humidity conditions in a building construction. In this paper we will introduce in a first step the object-oriented hygrothermal room model of this library. In a second step, the validation of the room model with some field experiments will be shown. In a third step we willpresent some simulation results, we obtained by coupling the room model with an implemented Predicted-Mean-Vote (PMV) control ventilation system to predict and to ensure a thermal and hygric indoor comfort in one case study. In the conclusion, the possible range of future applications of this new hygrothermal building physics library and demands for further research are indicated.

}, issn = {978-87-7877-265-7}, author = {Thierry Stephane Nouidui and Christoph Nytsch-Geusen and Andreas Holm and Klaus Sedlbauer} } @proceedings {245, title = {Overcoming the Complexity of Diagnostic Problems due to Sensor Network Architecture}, journal = {Eleventh International Conference on Intelligent Systems and Controls}, year = {2008}, month = {11/08}, abstract = {

In fault detection and diagnostics, limitations coming from the sensor network architecture are one of the main challenges in evaluating a system{\textquoteright}s health status. Usually the design of the sensor network architecture is not solely based on diagnostic purposes, other factors like controls, financial constraints, and practical limitations are also involved. As a result, it quite common to have one sensor (or one set of sensors) monitoring the behaviour of two or more components. This can significantly extend the complexity of diagnostic problems. In this paper a systematic approach is presented to deal with such complexities. It is shown how the problem can be formulated as a Bayesian network based diagnostic mechanism with latent variables. The developed approach is also applied to the problem of fault diagnosis in HVAC systems, an application area with considerable modeling and measurement constraints.

}, url = {https://www.actapress.com/Content_Of_Proceeding.aspx?ProceedingID=503}, author = {Massieh Najafi and David M. Auslander and Peter L. Bartlett and Philip Haves} } @article {2923, title = {A Semi-automated Commissioning Tool for VAV Air Handling Units: Functional Test Analyzer}, journal = {ASHRAE Transactions}, volume = {113}, number = {Part 1}, year = {2007}, month = {01/2007}, pages = {380-391}, abstract = {

A software tool that automates the analysis of functional tests for air-handling units is described. The tool compares the performance observed during manual tests with the performance predicted by simple models of the components under test that are configured using design information and catalog data. Significant differences between observed and expected performance indicate the presence of faults. Fault diagnosis is performed by analyzing the variation of these differences with operating point using expert rules and fuzzy inferencing.

The tool has a convenient user interface to facilitate manual entry of measurements made during a test. A graphical display compares the measured and expected performance, highlighting significant differences that indicate the presence of faults. The tool is designed to be used by commissioning providers conducting functional tests as part of either new building commissioning or retro-commissioning, as well as by building owners and operators conducting routine tests to check the performance of their HVAC systems. The paper describes the input data requirements of the tool, the software structure, the graphical interface, and summarizes the development and testing process used.

}, url = {http://gaia.lbl.gov/btech/papers/60979.pdf}, author = {Philip Haves and Moosung Kim and Massieh Najafi and Peng Xu} } @conference {2658, title = {Use of Simulation Tools for Managing Buildings Energy Demand}, booktitle = {Proc. Building Simulation 2007}, year = {2007}, month = {09/2007}, address = {Beijing, China}, author = {Alberto Hernandez and Fl{\'a}vio Neto and Augusto Sanzovo Fiorelli} } @proceedings {229, title = {Advanced modeling and simulation techniques in MOSILAB: A system development case study}, journal = {5th International Modelica Conference}, year = {2006}, pages = {pp.63-72}, author = {Christoph Nytsch-Geusen and Thilo Ernst and Peter Schwarz and Mathias Vetter and Andreas Holm and Juergen Leopold and Alexander Mattes and Andre Nordwig and Peter Schneider and Christoph Wittwer and Thierry Stephane Nouidui and Gerhardt Schmidt} } @article {378, title = {Characterization of the Temperature Oscillation Technique to Measure the Thermal Conductivity of Fluids}, journal = {International Journal of Heat and Mass Transfer}, volume = {49}, year = {2006}, month = {08/2006}, pages = {2950-2956}, chapter = {2950}, abstract = {

The temperature oscillation technique to measure the thermal diffusivity of a fluid consists of filling a cylindrical volume with the fluid, applying an oscillating temperature boundary condition at the two ends of the cylinder, measuring the amplitude and phase of the temperature oscillation at any point inside the cylinder, and finally calculating the fluid thermal diffusivity from the amplitude and phase values of the temperature oscillations at the ends and at the point inside the cylinder. Although this experimental technique was introduced by Santucci and co-workers nearly two decades ago, its application is still limited, perhaps because of the perceived difficulties in obtaining accurate results. Here, we attempt to clarify this approach by first estimating the maximum size of the liquid{\textquoteright}s cylindrical volume, performing a systematic series of experiments to find the allowable amplitude and frequency of the imposed temperature oscillations, and then validating our experimental setup and the characterization method by measuring the thermal conductivity of pure water at different temperatures and comparing our results with previously published work.

}, keywords = {Temperature oscillation technique, Thermal conductivity, thermal diffusivity}, url = {http://www.sciencedirect.com/science/article/pii/S001793100600144X}, author = {Prajesh Bhattacharya and S. Nara and P. Vijayan and Tang, T. and W. Lai and Patrick E. Phelan and Ravi S. Prasher and David W. Song and J. Wang} } @article {378, title = {Characterization of the Temperature Oscillation Technique to Measure the Thermal Conductivity of Fluids}, journal = {International Journal of Heat and Mass Transfer}, volume = {49}, year = {2006}, month = {08/2006}, pages = {2950-2956}, chapter = {2950}, abstract = {

The temperature oscillation technique to measure the thermal diffusivity of a fluid consists of filling a cylindrical volume with the fluid, applying an oscillating temperature boundary condition at the two ends of the cylinder, measuring the amplitude and phase of the temperature oscillation at any point inside the cylinder, and finally calculating the fluid thermal diffusivity from the amplitude and phase values of the temperature oscillations at the ends and at the point inside the cylinder. Although this experimental technique was introduced by Santucci and co-workers nearly two decades ago, its application is still limited, perhaps because of the perceived difficulties in obtaining accurate results. Here, we attempt to clarify this approach by first estimating the maximum size of the liquid{\textquoteright}s cylindrical volume, performing a systematic series of experiments to find the allowable amplitude and frequency of the imposed temperature oscillations, and then validating our experimental setup and the characterization method by measuring the thermal conductivity of pure water at different temperatures and comparing our results with previously published work.

}, keywords = {Temperature oscillation technique, Thermal conductivity, thermal diffusivity}, url = {http://www.sciencedirect.com/science/article/pii/S001793100600144X}, author = {Prajesh Bhattacharya and S. Nara and P. Vijayan and Tang, T. and W. Lai and Patrick E. Phelan and Ravi S. Prasher and David W. Song and J. Wang} } @conference {230, title = {MOSILAB: Ein Modelica-Simulationswerkzeug zur energetischen Geb{\"a}ude- und Anlagensimulation}, booktitle = {16. Symposium Thermische Solarenergie}, year = {2006}, address = {Bad Staffelstein, Germany}, isbn = {3-934681-45-X}, author = {Christoph Nytsch-Geusen and Andre Nordwig and Mathias Vetter and Christoph Wittwer and Thierry Stephane Nouidui and Peter Schneider} } @proceedings {2812, title = {Simulation Strategies for Healthcare Design to Achieve Comfort and Optimize Building Energy Use}, journal = {SimBuild 2006}, year = {2006}, month = {08/2006}, address = {Cambridge, MA, USA}, author = {Shruti Narayan and Isabelle Lavedrine and Maurya McClintock} } @proceedings {228, title = {Validierung der eindimensionalen hygrothermischen Wandmodelle der Modelica-Bibliothek "BuildingPhysicsLibrary"}, journal = {BauSIM 2006}, year = {2006}, pages = {pp.144-146}, address = {Munich, Germany}, isbn = {978-3-00-019823-6}, issn = {3-00-019823-7}, author = {Thierry Stephane Nouidui and Christoph Nytsch-Geusen and Andreas Holm} } @conference {388, title = {Effect of Particle Material on the Static Thermal Conductivity of Nanofluids}, booktitle = {Heat Transfer Conference}, year = {2005}, month = {07/2005}, address = {San Francisco, CA}, author = {P. Vijayan and Prajesh Bhattacharya and S. Nara and W. Lai and Patrick E. Phelan and Ravi S. Prasher and David W. Song and J. Wang} } @conference {385, title = {Experimental Determination of the Effect of Varying Base Fluid and Temperature on the Static Thermal Conductivity of Nanofluids}, booktitle = {ASME International Mechanical Engineering Congress and Exposition, November 5-11, 2005}, year = {2005}, month = {11/2005}, publisher = {ASME}, organization = {ASME}, address = {Orlando, FL}, abstract = {

The heat transfer abilities of fluids can be improved by adding small particles of sizes of the order of nanometers. Recently a lot of research has been done in evaluating the thermal conductivity of nanofluids using various nanoparticles. In our present work we address this issue by conducting a series of experiments to determine the effective thermal conductivity of alumina-nanofluids by varying the base fluid with water and antifreeze liquids like ethylene glycol and propylene glycol. Temperature oscillation method is used to find the thermal conductivity of the nanofluid. The results show the thermal conductivity enhancement of nanofluids depends on viscosity of the base fluid. Finally the results are validated with a recently proposed theoretical model.

}, isbn = {0-7918-4221-5}, doi = {10.1115/IMECE2005-81494}, author = {S. Nara and Prajesh Bhattacharya and P. Vijayan and W. Lai and W. Rosenthal and Patrick E. Phelan and Ravi S. Prasher and David W. Song and Jinlin Wang} } @conference {231, title = {A hygrothermal building model based on the object-oriented modeling language Modelica}, booktitle = {Ninth International IBPSA Conference}, year = {2005}, month = {2005}, address = {Montreal, Canada}, isbn = {2-553-01152-0}, author = {Christoph Nytsch-Geusen and Thierry Stephane Nouidui and Andreas Holm and Wolfram Haupt} } @proceedings {232, title = {MOSILAB: Development of a modelica based generic simulation tool supporting modal structural dynamics}, journal = {4th International Modelica Conference}, year = {2005}, pages = {pp.527-534}, address = {Hamburg, Germany}, author = {Christoph Nytsch-Geusen and Thilo Ernst and Peter Schneider and Mathias Vetter and Andreas Holm and Juergen Leopold and Ullrich Doll and Andre Nordwig and Peter Schwarz and Christoph Wittwer and Thierry Stephane Nouidui and Gerhardt Schmidt and Alexander Mattes} } @conference {390, title = {Evaluation of the Temperature Oscillation Technique to Calculate Thermal Conductivity of Water and Systematic Measurement of the Thermal Conductivity of Aluminum Oxide {\textendash} Water Nanofluiids}, booktitle = {International Mechanical Engineering Congress \& Exposition,}, year = {2004}, month = {11/2004}, address = {Anaheim, CA}, author = {Prajesh Bhattacharya and P. Vijayan and Tang, T. and S. Nara and Patrick E. Phelan and Ravi S. Prasher and J. Wang and David W. Song} } @proceedings {50, title = {GenOpt - A Generic Optimization Program}, journal = {Proc. of the 7th IBPSA Conference}, volume = {I}, year = {2001}, pages = {601-608}, address = {Rio de Janeiro}, abstract = {

The potential offered by computer simulation is often not realized: Due to the interaction of system variables, simulation users rarely know how to choose input parameter settings that lead to optimal performance of a given system. Thus, a program called GenOpt{\textregistered} that automatically determines optimal parameter settings has been developed.

GenOpt is a generic optimization program. It minimizes an objective function with respect to multiple parameters. The objective function is evaluated by a simulation program that is iteratively called by GenOpt. In thermal building simulation {\textemdash} which is the main target of GenOpt {\textemdash} the simulation program usually has text-based I/O. The paper shows how GenOpt{\textquoteright}s simulation program interface allows the coupling of any simulation program with text based I/O by simply editing a configuration file, avoiding code modification of the simulation program. By using object-oriented programming, a high-level interface for adding minimization algorithms to GenOpt{\textquoteright}s library has been developed. We show how the algorithm interface separates the minimization algorithms and GenOpt{\textquoteright}s kernel, which allows implementing additional algorithms without being familiar with the kernel or having to recompile it. The algorithms can access utility classes that are commonly used for minimization, such as optimality check, line-search, etc.

GenOpt has successfully solved various optimization problems in thermal building simulation. We show an example of minimizing source energy consumption of an office building using EnergyPlus, and of minimizing auxiliary electric energy of a solar domestic hot water system using TRNSYS. For both examples, the time required to set up the optimization was less than one hour, and the energy savings are about 15\%, together with better daylighting usage or lower investment costs, respectively.

}, url = {http://www.ibpsa.org/proceedings/BS2001/BS01_0601_608.pdf}, author = {Michael Wetter}, editor = {Roberto Lamberts and Cezar O. R. Negr{\~a}o and Jan Hensen} } @article {319, title = {A Standard Simulation Testbed for the Evaluation of Control Algorithms \& Strategies}, journal = {ASHRAE Transactions}, volume = {104}, year = {1998}, abstract = {

This paper, which reports the results of ASHRAE Research Project 825, describes the development of a set of tools and supporting data to facilitate the evaluation of HVAC control algorithms and strategies using computer simulation. The tools consist of a documented set of component models for use in two component-based HVAC simulation programs. New models have been developed to enable explicit simulation of flow rates and pressure drops in ventilation systems, particularly variable-air-volume (VAV) systems, and detailed simulation of algorithms and strategies used in HVAC control systems. A mixed-use building equipped with a VAV HVAC system has been extensively documented, and a detailed model of the fabric, mechanical equipment, and controls has been produced in order to illustrate the capabilities and use of the tools. Values for the parameters in the component models describing the fabric and mechanical equipment are based on construction drawings, manufacturer{\textquoteright}s specifications, surveys, and measurements. Detailed models of the strategies for fan control, supply air temperature control, and room temperature control were developed from the controls manufacturer{\textquoteright}s technical information and the configuration of the actual control system. A simulation model of the whole building was then assembled from the models of the fabric, mechanical equipment, and controls. Results obtained by exercising the test bed in order to demonstrate its use in evaluating the performance of interacting control loops are presented. The paper concludes by discussing possible applications and extensions of the test bed.

}, author = {Philip Haves and Leslie K. Norford and Mark DeSimone} } @article {335, title = {Design, Construction and Commissioning of Building Emulators for EMCS Applications}, journal = {ASHRAE Transactions}, volume = {100}, year = {1994}, author = {Shengwei Wang and Philip Haves and Pierre Nusgens} } @proceedings {341, title = {Use of Building Emulators to Evaluate the Performance of Building Energy Management Systems}, journal = {Building Simulation {\textquoteright}91}, year = {1991}, month = {08/1991}, pages = {209-213}, address = {Nice, France}, abstract = {

Three complementary approaches may be used in the evaluation of the performance of building control systems-simulation, emulation and field testing. In emulation a real-time simulation of the building and HVAC plant is connected to a real building energy management system (BEMS) via a hardware interface. Emulation has the advantage of allowing controlled, repeatable experiments whilst testing real devices that may contain proprietary algorithms. Building emulators have been developed by the authors in the context of lEA Annex 17, which is concerned with the use of simulation to evaluate the performance of BEMS. The paper discusses different approaches to the design of building emulators and describes the different architectures, hardware and software used by the authors. The problem of evaluating the overall performance of BEMS is discussed and results are presented that illustrate the use of emulators to investigate the influence of the tuning of local loop controls on building performance.

}, author = {Hossein Vaezi-Nejad and E. Hutter and Philip Haves and Arthur L. Dexter and George E. Kelly and Pierre Nusgens and Shengwei Wang} } @proceedings {365, title = {Design and Operating Strategies and Sizing Relationships for Solar Regenerated Desiccant Dehumidifiers Used with Passive Cooling Systems}, journal = {1st International Passive \& Hybrid Cooling Conference}, year = {1981}, month = {11/1981}, address = {Miami, FL}, author = {Peter E. Nelson and Philip Haves} } @proceedings {366, title = {Economic Analysis of Desiccant Dehumidifiers in Passive Solar Residences}, journal = {1981 Annual Meeting of ASISE}, year = {1981}, month = {05/1981}, address = {Philadelphia, PA}, author = {Peter E. Nelson and McDougal, G. and Philip Haves} } @proceedings {363, title = {Experimental Validation of a Computer Model of a Solar Regenerated Desiccant Dehumidification System}, journal = {1st International Passive \& Hybrid Cooling Conference}, year = {1981}, month = {11/1981}, address = {Miami, FL}, author = {Peter E. Nelson and Philip Haves} }