TY - JOUR T1 - The Squeaky wheel: Machine learning for anomaly detection in subjective thermal comfort votes JF - Building and Environment Y1 - 2019 A1 - Zhe Wang A1 - Thomas Parkinson A1 - Peixian Li A1 - Borong Lin A1 - Tianzhen Hong KW - anomaly detection KW - ASHRAE global thermal comfort database KW - K-nearest neighbors KW - Multivariate Gaussian KW - Occupancy responsive controls KW - Subjective votes KW - thermal comfort AB -

Anomalous patterns in subjective votes can bias thermal comfort models built using data-driven approaches. A stochastic-based two-step framework to detect outliers in subjective thermal comfort data is proposed to address this problem. The anomaly detection technique involves defining similar conditions using a k-Nearest Neighbor (KNN) method and then quantifying the dissimilarity of the occupants' votes from their peers under similar thermal conditions through a Multivariate Gaussian approach. This framework is used to detect outliers in the ASHRAE Global Thermal Comfort Database I & II. The resulting anomaly-free dataset produced more robust comfort models avoiding dubious predictions. The proposed method has been proven to effectively distinguish outliers from inter-individual variabilities in thermal demand. The proposed anomaly detection framework could easily be applied to other applications with different variables or subjective metrics. Such a tool holds great promise for use in the development of occupancy responsive controls for automated building HVAC systems.

VL - 151 UR - https://linkinghub.elsevier.com/retrieve/pii/S0360132319300861 JO - Building and Environment ER - TY - JOUR T1 - Simplifications for hydronic system models in Modelica JF - Journal of Building Performance Simulation Y1 - 2018 A1 - Filip Jorissen A1 - Michael Wetter A1 - Lieve Helsen AB -

Building systems and their heating, ventilation and air conditioning ow networks, are becoming increasingly complex. Some building energy simulation tools simulate these ow networks using pressure drop equations. These ow network models typically generate coupled algebraic nonlinear systems of equations, which become increasingly more difficult to solve as their sizes increase. This leads to longer computation times and can cause the solver to fail. These problems also arise when using the equation-based modelling language Modelica and Annex 60 based libraries. This may limit the applicability of the library to relatively small problems unless problems are restructured. This paper discusses two algebraic loop types and presents an approach that decouples algebraic loops into smaller parts, or removes them completely. The approach is applied to a case study model where an algebraic loop of 86 iteration variables is decoupled into smaller parts with a maximum of 5 iteration variables.

ER - TY - JOUR T1 - Simulation and visualization of energy-related occupant behavior in office buildings JF - Building Simulation Y1 - 2017 A1 - Yixing Chen A1 - Xin Liang A1 - Tianzhen Hong A1 - Xuan Luo KW - Behavior Modeling KW - building performance KW - building simulation KW - energyplus KW - occupant behavior KW - visualization AB -

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.

VL - 10 IS - 6 ER - TY - RPRT T1 - Small and Medium Building Efficiency Toolkit and Community Demonstration Program Y1 - 2017 A1 - Mary Ann Piette A1 - Tianzhen Hong A1 - William J. Fisk A1 - Norman Bourassa A1 - Wanyu R. Chan A1 - Yixing Chen A1 - H.Y. Iris Cheung A1 - Toshifumi Hotchi A1 - Margarita Kloss A1 - Sang Hoon Lee A1 - Phillip N. Price A1 - Oren Schetrit A1 - Kaiyu Sun A1 - Sarah C. Taylor-Lange A1 - Rongpeng Zhang KW - CBES KW - commercial buildings KW - energy efficiency KW - energy modeling KW - energy savings KW - indoor air quality KW - indoor environmental quality KW - outdoor air measurement technology KW - outdoor airflow intake rate KW - retrofit KW - ventilation rate AB -

Small commercial buildings in the United States consume 47 percent of all primary energy consumed in the building sector. Retrofitting small and medium commercial buildings may pose a steep challenge for owners, as many lack the expertise and resources to identify and evaluate cost-effective energy retrofit strategies. To address this problem, this project developed the Commercial Building Energy Saver (CBES), an energy retrofit analysis toolkit that calculates the energy use of a building, identifies and evaluates retrofit measures based on energy savings, energy cost savings, and payback. The CBES Toolkit includes a web app for end users and the CBES Application Programming Interface for integrating CBES with other energy software tools. The toolkit provides a rich feature set, including the following:

  1. Energy Benchmarking providing an Energy Star score
  2. Load Shape Analysis to identify potential building operation improvements
  3. Preliminary Retrofit Analysis which uses a custom developed pre-simulated database
  4. Detailed Retrofit Analysis which utilizes real time EnergyPlus simulations

In a parallel effort the project team developed technologies to measure outdoor airflow rate; commercialization and use would avoid both excess energy use from over ventilation and poor indoor air quality resulting from under ventilation.

If CBES is adopted by California’s statewide small office and retail buildings, by 2030 the state can anticipate 1,587 gigawatt hours of electricity savings, 356 megawatts of non-coincident peak demand savings, 30.2 megatherms of natural gas savings, $227 million of energy-related cost savings, and reduction of emissions by 757,866 metric tons of carbon dioxide equivalent. In addition, consultant costs will be reduced in the retrofit analysis process.

CBES contributes to the energy savings retrofit field by enabling a straightforward and uncomplicated decision-making process for small and medium business owners and leveraging different levels of assessment to match user background, preference, and data availability.

U2 - LBNL-2001054 ER - TY - JOUR T1 - Smart Building Management vs. Intuitive Human Control — Lessons learnt from an office building in Hungary JF - Building Simulation Y1 - 2017 A1 - Zsofia Belafi A1 - Tianzhen Hong A1 - Andras Reith KW - building operation KW - building performance simulation KW - case study KW - Occupant Behaviour KW - optimization AB -

Smart building management and control are adopted nowadays to achieve zero-net energy use in buildings. However, without considering the human dimension, technologies alone do not necessarily guarantee high performance in buildings. An office building was designed and built according to state-of-the-art design and energy management principles in 2008. Despite the expectations of high performance, the owner was facing high utility bills and low user comfort in the building located in Budapest, Hungary. The objective of the project was to evaluate the energy performance and comfort indices of the building, to identify the causes of malfunction and to elaborate a comprehensive energy concept. Firstly, current building conditions and operation parameters were evaluated. Our investigation found that the state-of-the-art building management system was in good conditions but it was operated by building operators and occupants who are not aware of the building management practice. The energy consumption patterns of the building were simulated with energy modelling software. The baseline model was calibrated to annual measured energy consumption, using actual occupant behaviour and presence, based on results of self-reported surveys, occupancy sensors and fan-coil usage data. Realistic occupant behaviour models can capture diversity of occupant behaviour and better represent the real energy use of the building. This way our findings and the effect of our proposed improvements could be more reliable. As part of our final comprehensive energy concept, we proposed intervention measures that would increase indoor thermal comfort and decrease energy consumption of the building. A parametric study was carried out to evaluate and quantify energy, comfort and return on investment of each measure. It was found that in the best case the building could save 23% of annual energy use. Future work includes the follow-up of: occupant reactions to intervention measures, the realized energy savings, the measurement of occupant satisfaction and behavioural changes.

VL - 10 IS - 6 ER - TY - JOUR T1 - Spatial Distribution of Internal Heat Gains: A Probabilistic Representation and Evaluation of Its Influence on Cooling Equipment Sizing in Large Office Buildings JF - Energy and Buildings Y1 - 2017 A1 - Qi Zhang A1 - Da Yan A1 - Jingjing An A1 - Tianzhen Hong A1 - Wei Tian A1 - Kaiyu Sun KW - air handling unit KW - chiller plant KW - equipment sizing KW - internal heat gain KW - spatial distribution KW - spatial diversity KW - stochastic AB -

Internal heat gains from occupants, lighting, and plug loads are significant components of the space cooling load in an office building. Internal heat gains vary with time and space. The spatial diversity is significant, even for spaces with the same function in the same building. The stochastic nature of internal heat gains makes determining the peak cooling load to size air-conditioning systems a challenge. The traditional conservative practice of considering the largest internal heat gain among spaces and applying safety factors overestimates the space cooling load, which leads to oversized air-conditioning equipment and chiller plants. In this study, a field investigation of several large office buildings in China led to the development of a new probabilistic approach that represents the spatial diversity of the design internal heat gain of each tenant as a probability distribution function. In a large office building, a central chiller plant serves all air handling units (AHUs), with each AHU serving one or more floors of the building. Therefore, the spatial diversity should be considered differently when the peak cooling loads to size the AHUs and chillers are calculated. The proposed approach considers two different levels of internal heat gains to calculate the peak cooling loads and size the AHUs and chillers in order to avoid oversizing, improve the overall operating efficiency, and thus reduce energy use.

ER - TY - RPRT T1 - Synthesizing building physics with social psychology: An interdisciplinary framework for context and occupant behavior in office buildings Y1 - 2017 A1 - Simona D'Oca A1 - Chien-Fen Chen A1 - Tianzhen Hong A1 - Zsofia Belafi AB -

This study introduces an interdisciplinary framework for investigating building-user interaction in office spaces. The framework is a synthesis of theories from building physics and social psychology including social cognitive theory, the theory of planned behavior, and the drivers-needs-actions-systems ontology for energy-related behaviors. The goal of the research framework is to investigate the effects of various behavioral adaptations and building controls (i.e., adjusting thermostats, operating windows, blinds and shades, and switching on/off artificial lights) to determine impacts on occupant comfort and energy-related operational costs in the office environment. This study attempts to expand state-of-the-art understanding of: (1) the environmental, personal, and behavioral drivers motivating occupants to interact with building control systems across four seasons, (2) how occupants’ intention to share controls is influenced by social-psychological variables such as attitudes, subjective norms, and perceived behavioral control in group negotiation dynamic, (3) the perceived ease of usage and knowledge of building technologies, and (4) perceived satisfaction and productivity. To ground the validation of the theoretical framework in diverse office settings and contexts at the international scale, an online survey was designed to collect cross-country responses from office occupants among 14 universities and research centers within the United States, Europe, China, and Australia.

ER - TY - JOUR T1 - A Simulation Approach to Estimate Energy Savings Potential of Occupant Behavior Measures JF - Energy and Buildings Y1 - 2016 A1 - Kaiyu Sun A1 - Tianzhen Hong KW - behavior measure KW - Behavior Modeling KW - building performance simulation KW - energy savings KW - energyplus KW - occupant behavior AB -

Occupant behavior in buildings is a leading factor influencing energy use in buildings. Low-cost behavioral solutions have demonstrated significant potential energy savings. Estimating the behavioral savings potential is important for a more effective design of behavior change interventions, which in turn will support more effective energy-efficiency policies. This study introduces a simulation approach to estimate the energy savings potential of occupant behavior measures. First it defines five typical occupant behavior measures in office buildings, then simulates and analyzes their individual and integrated impact on energy use in buildings. The energy performance of the five behavior measures was evaluated using EnergyPlus simulation for a real office building across four typical U.S. climates and two vintages. The Occupancy Simulator was used to simulate the occupant movement in each zone with inputs from the site survey of the case building. Based on the simulation results, the occupant behavior measures can achieve overall site energy savings as high as 22.9% for individual measures and up to 41.0% for integrated measures. Although energy savings of behavior measures would vary depending upon many factors, the presented simulation approach is robust and can be adopted for other studies aiming to quantify occupant behavior impact on building performance.

ER - TY - JOUR T1 - Simulation of Occupancy in Buildings JF - Energy and Buildings Y1 - 2015 A1 - Xiaohang Feng A1 - Da Yan A1 - Tianzhen Hong KW - building simulation KW - co-simulation KW - occupancy KW - occupant behavior KW - software module KW - stochastic modeling AB -

Occupants are involved in a variety of activities in buildings, which drive them to move among rooms, enter or leave a building. In this study, occupancy is defined at four levels and varies with time: (1) the number of occupants in a building, (2) occupancy status of a space, (3) the number of occupants in a space, and (4) the space location of an occupant. Occupancy has a great influence on internal loads and ventilation requirement, thus building energy consumption. Based on a comprehensive review and comparison of literature on occupancy modeling, three representative occupancy models, corresponding to the levels 2–4, are selected and implemented in a software module. Main contributions of our study include: (1) new methods to classify occupancy models, (2) the review and selection of various levels of occupancy models, and (3) new methods to integrate these model into a tool that can be used in different ways for different applications and by different audiences. The software can simulate more detailed occupancy in buildings to improve the simulation of energy use, and better evaluate building technologies in buildings. The occupancy of an office building is simulated as an example to demonstrate the use of the software module.

VL - 87 U2 - LBNL-180424 ER - TY - JOUR T1 - Simulation Speed Analysis and Improvements of Modelica Models for Building Energy Simulation Y1 - 2015 A1 - Filip Jorissen A1 - Michael Wetter A1 - Lieve Helsen AB -

This paper presents an approach for speeding up Modelica models. Insight is provided into how Modelica models are solved and what determines the tool’s computational speed. Aspects such as algebraic loops, code efficiency and integrator choice are discussed. This is illustrated using simple building simulation examples and Dymola. The generality of the work is in some cases verified using OpenModelica. Using this approach, a medium sized office building including building envelope, heating ventilation and air conditioning (HVAC) systems and control strategy can be simulated at a speed five hundred times faster than real time.

U2 - LBNL-1002904 ER - TY - JOUR T1 - Stochastic Modeling of Overtime Occupancy and Its Application in Building Energy Simulation and Calibration Y1 - 2014 A1 - Kaiyu Sun A1 - Tianzhen Hong A1 - Siyue Guo KW - building energy use KW - building simulation KW - model calibration KW - occupant behavior KW - overtime occupancy KW - stochastic modeling AB -

Overtime is a common phenomenon around the world. Overtime drives both internal heat gains from occupants, lighting and plug-loads, and HVAC operation during overtime periods. Overtime leads to longer occupancy hours and extended operation of building services systems beyond normal working hours, thus overtime impacts total building energy use. Current literature lacks methods to model overtime occupancy because overtime is stochastic in nature and varies by individual occupants and by time. To address this gap in the literature, this study aims to develop a new stochastic model based on the statistical analysis of measured overtime occupancy data from an office building. A binomial distribution is used to represent the total number of occupants working overtime, while an exponential distribution is used to represent the duration of overtime periods. The overtime model is used to generate overtime occupancy schedules as an input to the energy model of a second office building. The measured and simulated cooling energy use during the overtime period is compared in order to validate the overtime model. A hybrid approach to energy model calibration is proposed and tested, which combines ASHRAE Guideline 14 for the calibration of the energy model during normal working hours, and a proposed KS test for the calibration of the energy model during overtime. The developed stochastic overtime model and the hybrid calibration approach can be used in building energy simulations to improve the accuracy of results, and better understand the characteristics of overtime in office buildings.

U2 - LBNL-6670E ER - TY - JOUR T1 - Statistical Analysis and Modeling of Occupancy Patterns in Open-Plan Offices using Measured Lighting-Switch Data JF - Building Simulation Y1 - 2013 A1 - Wen-Kuei Chang A1 - Tianzhen Hong KW - building simulation KW - occupancy model KW - occupancy pattern KW - occupant schedule KW - office buildings KW - statistical analysis AB -

Occupancy profile is one of the driving factors behind discrepancies between the measured and simulated energy consumption of buildings. The frequencies of occupants leaving their offices and the corresponding durations of absences have significant impact on energy use and the operational controls of buildings. This study used statistical methods to analyze the occupancy status, based on measured lighting-switch data in five-minute intervals, for a total of 200 open-plan (cubicle) offices. Five typical occupancy patterns were identified based on the average daily 24-hour profiles of the presence of occupants in their cubicles. These statistical patterns were represented by a one-square curve, a one-valley curve, a two-valley curve, a variable curve, and a flat curve. The key parameters that define the occupancy model are the average occupancy profile together with probability distributions of absence duration, and the number of times an occupant is absent from the cubicle. The statistical results also reveal that the number of absence occurrences decreases as total daily presence hours decrease, and the duration of absence from the cubicle decreases as the frequency of absence increases. The developed occupancy model captures the stochastic nature of occupants moving in and out of cubicles, and can be used to generate a more realistic occupancy schedule. This is crucial for improving the evaluation of the energy saving potential of occupancy based technologies and controls using building simulations. Finally, to demonstrate the use of the occupancy model, weekday occupant schedules were generated and discussed.

VL - 6 IS - 1 U2 - LBNL-6080E ER - TY - CONF T1 - Sustainable Campus with PEV and Microgrid T2 - 2012 ACEEE Summer Study on Energy Efficiency in Buildings Y1 - 2012 A1 - K. Nandha Kumar A1 - B. Sivaneasan A1 - P.L. So A1 - H.B. Gooi A1 - Nilesh Jadhav A1 - Reshma Singh A1 - Chris Marnay KW - buildings KW - campus KW - electric vehicles KW - energy KW - loads KW - microgrids KW - renewable energy KW - transport AB -

Market penetration of electric vehicles (EVs) is gaining momentum, as is the move
towards increasingly distributed, clean and renewable electricity sources. EV charging shifts a
significant portion of transportation energy use onto building electricity meters. Hence,
integration strategies for energy-efficiency in buildings and transport sectors are of increasing
importance. This paper focuses on a portion of that integration: the analysis of an optimal
interaction of EVs with a building-serving transformer, and coupling it to a microgrid that
includes PV, a fuel cell and a natural gas micro-turbine. The test-case is the Nanyang
Technological University (NTU), Singapore campus. The system under study is the Laboratory
of Clean Energy Research (LaCER) Lab that houses the award winning Microgrid Energy
Management System (MG-EMS) project. The paper analyses three different case scenarios to
estimate the number of EVs that can be supported by the building transformer serving LaCER.
An approximation of the actual load data collected for the building into different time intervals is
performed for a transformer loss of life (LOL) calculation. The additional EV loads that can be
supported by the transformer with and without the microgrid are analyzed. The numbers of
possible EVs that can be charged at any given time under the three scenarios are also determined.
The possibility of using EV fleet at NTU campus to achieve demand response capability and
intermittent PV output leveling through vehicle to grid (V2G) technology and building energy
management systems is also explored.

JF - 2012 ACEEE Summer Study on Energy Efficiency in Buildings CY - Pacific Grove, CA UR - https://aceee.org/files/proceedings/2012/data/papers/0193-000363.pdf ER - TY - CONF T1 - SimModel: A domain data model for whole building energy simulation T2 - IBPSA Building Simulation 2011 Y1 - 2011 A1 - James O'Donnell A1 - Richard See A1 - Cody Rose A1 - Tobias Maile A1 - Vladimir Bazjanac A1 - Philip Haves AB -

Many inadequacies exist within industry-standard data models as used by present-day whole-building energy simulation software. Tools such as EnergyPlus and DOE-2 use custom schema definitions (IDD and BDL respectively) as opposed to standardized schema definitions (defined in XSD, EXPRESS, etc.). Non-standard data modes lead to a requirement for application developers to develop bespoke interfaces. Such tools have proven to be error prone in their implementation – typically resulting in information loss.

This paper presents a Simulation Domain Model (SimModel) - a new interoperable XML-based data model for the building simulation domain. SimModel provides a consistent data model across all aspects of the building simulation process, thus preventing information loss. The model accounts for new simulation tool architectures, existing and future systems, components and features. In addition, it is a multi-representation model that enables integrated geometric and MEP simulation configuration data. The SimModel objects ontology moves away from tool-specific, non-standard nomenclature by implementing an industry-validated terminology aligned with Industry Foundation Classes (IFC).

The first implementation of SimModel supports translations from IDD, Open Studio IDD, gbXML and IFC. In addition, the EnergyPlus Graphic User Interface (GUI) employs SimModel as its internal data model. Ultimately, SimModel will form the basis for a new IFC Model View Definition (MVD) that will enable data exchange from HVAC Design applications to Energy Analysis applications. Extensions to SimModel could easily support other data formats and simulations (e.g. Radiance, COMFEN, etc.).

JF - IBPSA Building Simulation 2011 U2 - LBNL-5566E ER - TY - CONF T1 - A software tool to compare measured and simulated building energy performance data T2 - IBPSA Building Simulation 2011 Y1 - 2011 A1 - Tobias Maile A1 - Vladimir Bazjanac A1 - James O'Donnell A1 - Matthew Garr AB -

Building energy performance is often inadequate when compared to design goals. To link design goals to actual operation one can compare measured with simulated energy performance data. Our previously developed comparison approach is the Energy Performance Comparison Methodology (EPCM), which enables the identification of performance problems based on a comparison of measured and simulated performance data. In context of this method, we developed a software tool that provides graphing and data processing capabilities of the two performance data sets. The software tool called SEE IT (Stanford Energy Efficiency Information Tool) eliminates the need for manual generation of data plots and data reformatting. SEE IT makes the generation of time series, scatter and carpet plots independent of the source of data (measured or simulated) and provides a valuable tool for comparing measurements with simulation results. SEE IT also allows assigning data points on a predefined building object hierarchy and supports different versions of simulated performance data. This paper briefly introduces the EPCM, describes the SEE IT tool and illustrates its use in the context of a building case study.

JF - IBPSA Building Simulation 2011 CY - Sydney, Australia U2 - LBNL-6184E ER - TY - CONF T1 - Systematic Development of an Operational BIM Utilising Simulation and Performance Data in Building Operation T2 - IBPSA Building Simulation 2011 Y1 - 2011 A1 - Edward Corry A1 - Marcus Keane A1 - James O'Donnell A1 - Andrea Costa JF - IBPSA Building Simulation 2011 CY - Sydney, Australia ER - TY - JOUR T1 - Simulations of air distribution in buildings by FFD on GPU JF - HVAC&R Research Y1 - 2010 A1 - Wangda Zuo A1 - Qingyan Chen VL - 16 IS - 6 ER - TY - JOUR T1 - A Statistical Pattern Analysis Framework for Rooftop Unit Diagnostics JF - International Journal of Heating, Ventilating, Air-Conditioning and Refrigeration Research Y1 - 2010 A1 - Massieh Najafi A1 - David M. Auslander A1 - Philip Haves A1 - Michael D. Sohn ER - TY - Generic T1 - Systems Approach to Energy Efficient Building Operation: Case Studies and Lessons Learned in a University Campus T2 - 2010 ACEEE Summer Study on Energy Efficiency in Buildings Y1 - 2010 A1 - Satish Narayanan A1 - Michael G. Apte A1 - Philip Haves A1 - Mary Ann Piette A1 - John Elliott AB -

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.

JF - 2010 ACEEE Summer Study on Energy Efficiency in Buildings PB - Omnipress CY - Asilomar, California, USA SN - 0-918249-60-0 ER - TY - JOUR T1 - Simulation-based assessment of the energy savings benefits of integrated control in office buildings JF - Building Simulation Y1 - 2009 A1 - Eric Shen A1 - Tianzhen Hong KW - daylighting KW - energy conservation KW - energy consumption KW - energy efficiency KW - energy management systems KW - lighting control systems AB -

The purpose of this study is to use existing simulation tools to quantify the energy savings benefits of integrated control in office buildings. An EnergyPlus medium office benchmark simulation model (V1.0_3.0) developed by the Department of Energy (DOE) was used as a baseline model for this study. The baseline model was modified to examine the energy savings benefits of three possible control strategies compared to a benchmark case across 16 DOE climate zones. Two controllable subsystems were examined: (1) dimming of electric lighting, and (2) controllable window transmission. Simulation cases were run in EnergyPlus V3.0.0 for building window-to-wall ratios (WWR) of 33% and 66%. All three strategies employed electric lighting dimming resulting in lighting energy savings in building perimeter zones ranging from 64% to 84%. Integrated control of electric lighting and window transmission resulted in heating, ventilation, and air conditioning (HVAC) energy savings ranging from –1% to 40%. Control of electric lighting and window transmission with HVAC integration (seasonal schedule of window transmission control) resulted in HVAC energy savings ranging from 3% to 43%. HVAC energy savings decreased moving from warm climates to cold climates and increased when moving from humid, to dry, to marine climates.

VL - 2 IS - 4 ER - TY - Generic T1 - Standardization of thermo-fluid modeling in Modelica.Fluid 1.0 T2 - Proc. of the 7th International Modelica Conference Y1 - 2009 A1 - Rüdiger Franke A1 - Francesco Casella A1 - Martin Otter A1 - Katrin Proelss A1 - Michael Sielemann A1 - Michael Wetter KW - modelica AB -

This article discusses the Modelica.Fluid library that has been included in the Modelica Standard Library 3.1. Modelica.Fluid provides interfaces and basic components for the device-oriented modeling of one dimensional thermo-fluid flow in networks containing vessels; pipes; fluid machines; valves and fittings.

A unique feature of Modelica.Fluid is that the component equations and the media models as well as pressure loss and heat transfer correlations are decoupled from each other. All components are implemented such that they can be used for media from the Modelica.Media library. This means that an incompressible or compressible medium; a single or a multiple substance medium with one or more phases might be used with one and the same model as long as the modeling assumptions made hold. Furthermore;

trace substances are supported. Modeling assumptions can be configured globally in an outer System object. This covers in particular the initialization; uni- or bi-directional flow; and dynamic or steady-state formulation of mass; energy; and momentum balance. All assumptions can be locally refined for every component.

While Modelica.Fluid contains a reasonable set of component models; the goal of the library is not to provide a comprehensive set of models; but rather to provide interfaces and best practices for the treatment of issues such as connector design and implementation of energy; mass and momentum balances. Applications from various domains are presented.

JF - Proc. of the 7th International Modelica Conference PB - Linköping University Electronic Press CY - Como, Italy VL - 43 SN - 978-91-7393-513-5 UR - http://www.ep.liu.se/ecp_article/index.en.aspx?issue=043;article=13 ER - TY - CONF T1 - Specification of an Information Delivery Tool to Support Optimal Holistic Environmental and Energy Management in Buildings T2 - SimBuild 2008 Y1 - 2008 A1 - James O'Donnell A1 - Marcus Keane A1 - Vladimir Bazjanac JF - SimBuild 2008 CY - Berkeley, CA, USA U2 - LBNL-918E ER - TY - JOUR T1 - A Semi-automated Commissioning Tool for VAV Air Handling Units: Functional Test Analyzer JF - ASHRAE Transactions Y1 - 2007 A1 - Philip Haves A1 - Moosung Kim A1 - Massieh Najafi A1 - Peng Xu AB -

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.

VL - 113 UR - http://gaia.lbl.gov/btech/papers/60979.pdf IS - Pt. 1 U2 - LBNL-60979 U5 -

Design and Retrofit Tools

ER - TY - CONF T1 - A Simplified Hot Water Distribution System Model (DOE-2) T2 - Proc. Building Simulation 2007 Y1 - 2007 A1 - Lixing Gu JF - Proc. Building Simulation 2007 CY - Beijing, China ER - TY - CONF T1 - Simulation Enhanced Prototyping of an Experimental Solar House T2 - Proc. Building Simulation 2007 Y1 - 2007 A1 - Ruchi Choudhary A1 - Godfried Augenbroe A1 - Russell Gentry A1 - Huafen Hu JF - Proc. Building Simulation 2007 CY - Beijing, China ER - TY - CONF T1 - Simulation of Energy Management Systems in EnergyPlus T2 - Proc. Building Simulation 2007 Y1 - 2007 A1 - Peter G. Ellis A1 - Paul A. Torcellini A1 - Drury B. Crawley JF - Proc. Building Simulation 2007 CY - Beijing, China ER - TY - CONF T1 - The Study of a Simple HVAC Interface of EnergyPlus in the Chinese Language T2 - Proc. Building Simulation 2007 Y1 - 2007 A1 - Junjie Liu A1 - Wenshen Li A1 - Xiaojie Zhou JF - Proc. Building Simulation 2007 CY - Beijing, China ER - TY - Generic T1 - Simulation Strategies for Healthcare Design to Achieve Comfort and Optimize Building Energy Use T2 - SimBuild 2006 Y1 - 2006 A1 - Shruti Narayan A1 - Isabelle Lavedrine A1 - Maurya McClintock JF - SimBuild 2006 CY - Cambridge, MA, USA ER - TY - CONF T1 - A Semi-Automated Functional Test Data Analysis Tool T2 - 13th National Conference on Building Commissioning Y1 - 2005 A1 - Peng Xu A1 - Philip Haves A1 - Moosung Kim AB -

The growing interest in commissioning is creating a demand that will increasingly be met by mechanical contractors and less experienced commissioning agents. They will need tools to help them perform commissioning effectively and efficiently. The widespread availability of standardized procedures, accessible in the field, will allow commissioning to be specified with greater certainty as to what will be delivered, enhancing the acceptance and credibility of commissioning. In response, a functional test data analysis tool is being developed to analyze the data collected during functional tests for air-handling units.

The functional test data analysis tool is designed to analyze test data, assess performance of the unit under test and identify the likely causes of the failure. The tool has a convenient user interface to facilitate manual entry of measurements made during a test. A graphical display shows the measured performance versus the expected performance, highlighting significant differences that indicate the unit is not able to pass the test. The tool is described as semi-automated because the measured data need to be entered manually, instead of being passed from the building control system automatically. However, the data analysis and visualization are fully automated. 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 building owners and operators interested in conducting routine tests periodically to check the performance of their HVAC systems.

JF - 13th National Conference on Building Commissioning T3 - Proceedings of the 13th National Conference on Building Commissioning CY - New York City, NY U2 - LBNL-58648 U4 -

May 4-6, 2005

U5 -

CD

ER - TY - Generic T1 - Simulating Tall Buildings Using EnergyPlus T2 - IBPSA Building Simulation 2005 Y1 - 2005 A1 - Peter G. Ellis A1 - Paul A. Torcellini JF - IBPSA Building Simulation 2005 CY - Montreal, Canada ER - TY - CONF T1 - A Simulation-Based Testing and Training Environment for Building Controls T2 - SimBuild 2004, Building Sustainability and Performance Through Simulation Y1 - 2005 A1 - Peng Xu A1 - Philip Haves A1 - Joseph J Deringer AB -

A hybrid simulation environment for controls testing and training is described. A real-time simulation of a building and HVAC system is coupled to a real building control system using a hardware interface. A prototype has been constructed and tested in which the dynamic performance of both the HVAC equipment and the building envelope is simulated using SPARK (Simulation Problem Analysis and Research Kernel). A low cost hardware interface between the simulation and the real control system is implemented using plug-in analog-to-digital and digital-to-analog cards in a personal computer. The design and implementation of the hardware interface in SPARK are described. The development of a variant of this environment that uses a derivative of EnergyPlus to test the implementation of a natural ventilation control strategy in real control hardware is also described.

Various applications of the hybrid simulation environment are briefly described, including the development of control algorithms and strategies, control system product testing and the pre-commissioning of building control system installations. The application to the education and training of building operators and HVAC service technicians is discussed in more detail, including the development of a community college curriculum that includes the use of the hybrid simulation environment to teach both control system configuration and HVAC troubleshooting.

JF - SimBuild 2004, Building Sustainability and Performance Through Simulation CY - Boulder, CO U2 - LBNL-55801 ER - TY - Generic T1 - Specifiction of an IFC-Based Intelligent Graphical User Interface to Support Building Energy Simulation T2 - IBPSA Building Simulation 2005 Y1 - 2005 A1 - Barry O'Sullivan A1 - Marcus Keane JF - IBPSA Building Simulation 2005 CY - Montreal, Canada ER - TY - Generic T1 - Simulation of Tubular Daylighting Devices and Daylighting Shelves in EnergyPlus T2 - SimBuild 2004, Building Sustainability and Performance Through Simulation Y1 - 2004 A1 - Peter G. Ellis A1 - Richard K. Strand A1 - Kurt T. Baumgartner JF - SimBuild 2004, Building Sustainability and Performance Through Simulation CY - Boulder, Colorado, USA ER - TY - ABST T1 - Simulation-based building energy optimization Y1 - 2004 A1 - Michael Wetter KW - dissertation AB -

This dissertation presents computational techniques for simulation-based design optimization of buildings and heating, ventilation, air-conditioning and lighting systems in which the cost function is smooth. In such problems, the evaluation of the cost function involves the numerical solution of systems of differential algebraic equations (DAE). Since the termination criteria of the iterative solvers often depend on the design parameters, a computer code for solving such systems usually defines a numerical approximation to the cost function that is discontinuous in the design parameters. The discontinuities can be large in cost functions that are evaluated by commercial building energy simulation programs, and optimization algorithms that require smoothness frequently fail if used with such programs. Furthermore, controlling the numerical approximation error is often not possible with commercial building energy simulation programs.

In this dissertation, we present BuildOpt, a new detailed thermal building and daylighting simulation program. BuildOpt's simulation models dene a DAE system that is smooth in the state variables, in time and in the design parameters. This allows proving that the DAE system has a unique solution that is smooth in the design parameters, and it is required to compute high precision approximating cost functions that converge to a cost function that is smooth in the design parameters as the DAE solver tolerance is tightened.

For simulation programs that allow such a precision control, we constructed subprocedures for Generalized Pattern Search (GPS) optimization algorithms that adaptively control the precision of the cost function evaluations: coarse precision for the early iterations,with precision progressively increasing as a stationary point is approached. This scheme significantly reduces the computation time, and it allows to prove that the sequence of iterates contains stationary accumulation points. For optimization problems in which commercial building energy simulation programs are used to evaluate the cost function, we compared by numerical experiment several deterministic and probabilistic optimization algorithms.

ER - TY - THES T1 - Simulation-Based Building Energy Optimization T2 - Mechanical Engineering Y1 - 2004 A1 - Michael Wetter JF - Mechanical Engineering PB - University of California, Berkeley CY - Berkeley, CA, USA VL - Ph.D. ER - TY - Generic T1 - A simulation-based testing and training environment for building controls T2 - Simbuild 2004 Y1 - 2004 A1 - Peng Xu A1 - Philip Haves A1 - Joseph J Deringer AB -

A hybrid simulation environment for controls testing and training is described. A real-time simulation of a building and HVAC system is coupled to a real building control system using a hardware interface. A prototype has been constructed and tested in which the dynamic performance of both the HVAC equipment and the building envelope is simulated using SPARK (Simulation Problem Analysis and Research Kernel). A low cost hardware interface between the simulation and the real control system is implemented using plug-in analog-to-digital and digital-to-analog cards in a personal computer. The design and implementation of the hardware interface in SPARK are described. The development of a variant of this environment that uses a derivative of EnergyPlus to test the implementation of a natural ventilation control strategy in real control hardware is also described. Various applications of the hybrid simulation environment are briefly described, including the development of control algorithms and strategies, control system product testing and the pre-commissioning of building control system installations. The application to the education and training of building operators and HVAC service technicians is discussed in more detail, including the development of a community college curriculum that includes the use of the hybrid simulation environment to teach both control system configuration and HVAC troubleshooting.

JF - Simbuild 2004 CY - Boulder, CO U2 - LBNL-55801 ER - TY - CONF T1 - Specification and Implementation of IFC Based Performance Metrics to Support Building Life Cycle Assessment of Hybrid Energy Systems T2 - SimBuild 2004: Building Sustainability and Performance Through Simulation Y1 - 2004 A1 - Elmer Morrissey A1 - James O'Donnell A1 - Marcus Keane A1 - Vladimir Bazjanac JF - SimBuild 2004: Building Sustainability and Performance Through Simulation CY - Boulder, CO U1 -

Simulation Research Group

U2 - LBNL/PUB-906 ER - TY - Generic T1 - Specification and Implementation of IFC Based Performance Metrics to Support Building Life Cycle Assessment of Hybrid Energy Systems T2 - SimBuild 2004, Building Sustainability and Performance Through Simulation Y1 - 2004 A1 - Elmer Morrissey A1 - James O'Donnell A1 - Marcus Keane A1 - Vladimir Bazjanac JF - SimBuild 2004, Building Sustainability and Performance Through Simulation CY - Boulder, Colorado, USA ER - TY - Generic T1 - Specification and Implementation of IFC-Based Performance Metrics to Support Building Life Cycle Assessment of Hybrid Energy Systems T2 - SimBuild 2004, Building Sustainability and Performance Through Simulation Y1 - 2004 A1 - Elmer Morrissey A1 - James O'Donnell A1 - Marcus Keane A1 - Vladimir Bazjanac JF - SimBuild 2004, Building Sustainability and Performance Through Simulation CY - Boulder, Colorado, USA ER - TY - CONF T1 - Specification of IFC Based Performance Metrics to Support Building Life Cycle Analysis of Hybrid Energy Systems T2 - SimBuild 2004 1st International Conference of IBPSA-USA Y1 - 2004 A1 - Elmer Morrissey A1 - James O'Donnell A1 - Marcus Keane A1 - Vladimir Bazjanac JF - SimBuild 2004 1st International Conference of IBPSA-USA CY - Boulder, Colorado, USA ER - TY - CONF T1 - Strategies for Coupling Energy Simulation Programs and Computational Fluid Dynamics Programs T2 - Building Sim 2001 Y1 - 2001 A1 - Zhiqiang Zhai A1 - Qingyan Chen A1 - Joseph H. Klems A1 - Philip Haves AB -

Energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing complementary information about the buildings' environmental performance. However, separate applications of ES and CFD are usually unable to give an accurate prediction of building performance due to the assumptions involved in the separate calculations. Integration of ES and CFD eliminates many of these assumptions since the information provided by the models is complementary. Several different approaches to integrating ES and CFD are described. In order to bridge the discontinuities of time-scale, spatial resolution and computing speed between ES and CFD programs, a staged coupling strategy for different problems is proposed. The paper illustrates a typical dynamic coupling process by means of an example implemented using the EnergyPlus and MIT-CFD programs.

JF - Building Sim 2001 CY - Rio de Janeiro, Brazil VL - 1 U1 -

Simulation Research Group

U2 - LBNL-48286 ER - TY - JOUR T1 - A Standard Simulation Testbed for the Evaluation of Control Algorithms & Strategies JF - ASHRAE Transactions Y1 - 1998 A1 - Philip Haves A1 - Leslie K. Norford A1 - Mark DeSimone AB -

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'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'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.

VL - 104 IS - Pt. 1A ER - TY - JOUR T1 - Stochastic weather model for building HVAC systems JF - Building and Environment Y1 - 1995 A1 - Tianzhen Hong A1 - Yi Jiang AB -

The weather is a multi-dimensional stochastic process; the traditional typical or standard meteorological year is not enough to describe the random behaviour of weather. The model presented in this paper is based on the vector auto-regressive (VAR) time series method. From the validation results, it can be seen that the stochastic weather model is essential to describe real climate behaviour, and the accuracy obtained is sufficient for the application of the stochastic weather model in the simulation and stochastic analysis of building HVAC systems.

VL - 30 IS - 4 ER - TY - JOUR T1 - Stochastic analysis of building thermal processes JF - Building and Environment Y1 - 1993 A1 - Yi Jiang A1 - Tianzhen Hong AB -

A methodology is presented for investigating the uncertainty properties of the building thermal processes caused by the random behaviour of the meteorological processes and the casual gains. A detailed building thermal model is used with a stochastic weather model and a random casual gain model. The probability distribution of the zone temperature of the building is calculated directly from these models. The overheating risk has been analysed as an example. The probability distribution of the periods when the zone temperature is higher than the demand temperature is calculated. The result shows all the possible situations rather than only a sample as would be obtained by running a normal simulation using given weather data. The influence of different building components on the overheating risk has been studied. The result shows that the most likely component for overheating risk in a residential building in Beijing is the window size. The thermal mass of the internal walls and the placing of windows have little effect on overheating risk.

VL - 28 IS - 4 ER - TY - CONF T1 - Stochastic analysis of overheating risk in buildings T2 - CLIMA 2000 Y1 - 1993 A1 - Yi Jiang A1 - Tianzhen Hong JF - CLIMA 2000 CY - London, UK ER - TY - Generic T1 - Self-tuning Control with Fuzzy Rule-Based Supervision for HVAC Applications T2 - ITAC 91 Y1 - 1991 A1 - Keck-Voon Ling A1 - Arthur L. Dexter A1 - Geng, G. A1 - Philip Haves JF - ITAC 91 T3 - International Symposium on Intelligent Tuning and Adapative Control CY - Singapore ER - TY - Generic T1 - Simulation of Local Loop Controls T2 - Building Simulation 89 Y1 - 1989 A1 - Arthur L. Dexter A1 - Philip Haves JF - Building Simulation 89 CY - Vancouver, Canada ER - TY - JOUR T1 - Saving Electricity in Commercial Buildings with Adjustable-Speed Drives JF - IEEE Transactions of Industry Applications Y1 - 1988 A1 - Joseph H. Eto A1 - Anibal T De Almeida AB -

Fan and chiller energy savings achievable in commercial buildings with adjustable-speed drives are described. The savings are estimated with the aid of parametric simulations from a sophisticated, hourly building energy simulation model. Two prototypes-a single-zone retail store and a multizone medium office building-are simulated for five U.S. locations. The model incorporates part-load performance curves for both inlet vane and adjustable-speed drive controls for fans and centrifugal chillers. The results identify economic conditions that justify the added expense of adjustable-speed drives.

PB - IEEE VL - 24 IS - 3 ER - TY - Generic T1 - Selection and Sizing of Low Energy Cooling Systems for More Humid Climates T2 - 2nd International Passive and Low Energy Architecture Conference Y1 - 1983 A1 - Philip Haves JF - 2nd International Passive and Low Energy Architecture Conference CY - Crete, Greece ER - TY - Generic T1 - SERI-RES: a Thermal Simulation Model for Passive Solar and Low Energy Buildings T2 - Design methods for Passive Solar Buildings Conf Y1 - 1983 A1 - Philip Haves JF - Design methods for Passive Solar Buildings Conf T3 - UK-ISES (C34) ER - TY - Generic T1 - Simulated Performance of a Passively Cooled Residence with a Solar Regenerated Desiccant Dehumidifier T2 - 1st International Passive & Hybrid Cooling Conference Y1 - 1981 A1 - Philip Haves JF - 1st International Passive & Hybrid Cooling Conference CY - Miami, FL ER -