@article {31673, title = {OPEN COMPUTING INFRASTRUCTURE FOR SHARING DATA ANALYTICS TO SUPPORT BUILDING ENERGY SIMULATIONS}, year = {2019}, month = {08/2019}, abstract = {

Building energy simulation plays an increasingly important role in building design and operation. In this paper, we present an open computing infrastructure, Virtual Information Fabric Infrastructure (VIFI), that allows building designers and engineers to enhance their simulations by combining empirical data with diagnostic or prognostic models. Based on the idea of dynamic data-driven application systems (DDDAS), the VIFI infrastructure complements conventional data-centric sharing strategies and addresses key data sharing concerns such as the privacy of building occupants. To demonstrate the potential of the VIFI infrastructure, we simulate an empirically-derived lighting schedule in the U.S. Department of Energy{\textquoteright}s small office building reference model. We use the case study simulation to explore the possibility and potential of integrating data-centric and analytic-centric sharing strategies; the method of combining empirical data with simulations; the creation, sharing, and execution of analytics using VIFI; and the impact of incorporating empirical data on energy simulations. While the case study reveals clear advantages of the VIFI data infrastructure, research questions remain surrounding the motivation and benefits for sharing data, the metadata that are required to support the composition of analytics, and the performance metrics that could be used in assessing the applications of VIFI.

}, author = {Omer T. Karaguzel and Mohammed Elshambakey and Yimin Zhu and Tianzhen Hong} } @article {30490, title = {Comparative Study of Air-Conditioning Energy Use of Four Office Buildings in China and USA}, journal = {Energy and Buildings}, volume = {169}, year = {2018}, abstract = {

Energy use in buildings has great variability. In order to design and operate low energy buildings as well as to establish building energy codes and standards and effective energy policy, it is crucial to understand and quantify key factors influencing building energy performance. This study investigates air-conditioning (AC) energy use of four office buildings in four locations: Beijing, Taiwan, Hong Kong, and Berkeley. Building simulation was employed to quantify the influences of key factors, including climate, building envelope and occupant behavior. Through simulation of various combinations of the three influencing elements, it is found that climate can lead to AC cooling consumption differences by almost two times, while occupant behavior resulted in the greatest differences (of up to three times) in AC cooling consumption. The influence of occupant behavior on AC energy consumption is not homogeneous. Under similar climates, when the occupant behavior in the building differed, the optimized building envelope design also differed. Overall, the optimal building envelope should be determined according to the climate as well as the occupants who use the building.

}, keywords = {Building envelope, climate, energy consumption, occupant behavior, office buildings, technological choice}, doi = {10.1016/j.enbuild.2018.03.073}, author = {Xin Zhou and Da Yan and Jingjing An and Tianzhen Hong and Xing Shi and Xing Jin} } @article {31308, title = {Impact of post-rainfall evaporation from porous roof tiles on building cooling load in subtropical China}, journal = {Applied Thermal Engineering}, volume = {142}, year = {2018}, month = {09/2018}, pages = {391 - 400}, abstract = {

Rainfall occurs frequently in subtropical regions of China, with the subsequent water evaporation from building roofs impacting the thermal performance and the energy consumption of buildings. We proposed a novel simulation method using actual meteorological data to evaluate this impact. New features were developed in EnergyPlus to enable the simulation: (1) an evaporation latent heat flux source term was added to the heat balance equation of the external surface and (2) algorithms for the evaporative cooling module (ECM) were developed and implemented into EnergyPlus. The ECM experimental results showed good agreement with the simulated results. The ECM was used to assess the impact of evaporation from porous roof tiles on the cooling load of a one-floor building in subtropical China. The results show that the evaporation process decreased the maximal values of the external and internal roof surface temperatures by up to 6.4 {\textdegree}C and 3.2 {\textdegree}C, respectively, while the lower internal surface temperature decreased the room accumulated cooling load by up to 14.8\% during the hot summer period. The enhanced EnergyPlus capability can be used to evaluate the evaporative cooling performance of roofs with water-storage mediums, as well as to quantify their impact on building cooling loads.

}, keywords = {Building energy simulation, cooling load, energyplus, Evaporative Cooling, Rainfall event, Subtropical China}, issn = {13594311}, doi = {10.1016/j.applthermaleng.2018.07.033}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1359431117356107https://api.elsevier.com/content/article/PII:S1359431117356107?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S1359431117356107?httpAccept=text/plain}, author = {Lei Zhang and Rongpeng Zhang and Tianzhen Hong and Yu Zhang and Qinglin Meng} } @article {30486, title = {A Novel Variable Refrigerant Flow (VRF) Heat Recovery System Model: Development and Validation}, journal = {Energy and Buildings}, volume = {168}, year = {2018}, abstract = {

As one of the latest emerging HVAC technologies, the Variable Refrigerant Flow (VRF) system with heat recovery (HR) configurations has obtained extensive attention from both the academia and industry. Compared with the conventional VRF systems with heat pump (HP) configurations, VRF-HR is capable of recovering heat from cooling zones to heating zones and providing simultaneous cooling and heating operations. This can further lead to substantial energy saving potential and more flexible zonal control. In this paper, a novel model is developed to simulate the energy performance of VRF-HR systems. It adheres to a more physics-based development with the ability to simulate the refrigerant loop performance and consider the dynamics of more operational parameters, which is essential for representing more advanced control logics. Another key feature of the model is the introduction of component-level curves for indoor units and outdoor units instead of overall performance curves for the entire system, and thus it requires much fewer user-specified performance curves as model inputs. The validation study shows good agreements between the simulated energy use from the new VRF-HR model and the laboratory measurement data across all operational modes at sub-hourly time steps. The model has been adopted in the official release of the EnergyPlus simulation program since Version 8.6, which enables more accurate and robust assessments of VRF-HR systems to support their applications in energy retrofit of existing buildings or design of zero-net-energy buildings.

}, keywords = {building performance simulation, controls, energy modeling, heat recovery, validation, Variable refrigerant flow}, doi = {10.1016/j.enbuild.2018.03.028}, author = {Rongpeng Zhang and Kaiyu Sun and Tianzhen Hong and Yoshinori Yura and Ryohei Hinokuma} } @article {31304, title = {Occupancy prediction through Markov based feedback recurrent neural network (M-FRNN) algorithm with WiFi probe technology}, journal = {Building and Environment}, volume = {138}, year = {2018}, month = {06/2018}, pages = {160 - 170}, abstract = {

Accurate occupancy prediction can improve facility control and energy efficiency of buildings. In recent years, buildings{\textquoteright} exiting WiFi infrastructures have been widely studied in the research of occupancy and energy conservation. However, using WiFi to assess occupancy is challenging due to that occupancy information is often characterized stochastically and varies with time and easily disturbed by building components. To overcome such limitations, this study utilizes WiFi probe technology to actively scan WiFi connection requests and responses between access points and network devices of building occupants. With captured signals, this study proposed a Markov based feedback recurrent neural network (M-FRNN) algorithm to model and predict the occupancy profiles. One on-site experiment was conducted to collect ground truth data using camera-based video analysis and the results were used to validate the M-FRNN occupancy prediction model over a 9-day measurement period. From the results, the M-FRNN based occupancy model using WiFi probes shows best accuracies can reach 80.9\%, 89.6\%, and 93.9\% with a tolerance of 2, 3, and 4 occupants respectively. This study demonstrated that WiFi data coupled with stochastic machine learning system can provide a viable alternative to determine a building{\textquoteright}s occupancy profile.

}, issn = {03601323}, doi = {10.1016/j.buildenv.2018.04.034}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0360132318302464https://api.elsevier.com/content/article/PII:S0360132318302464?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0360132318302464?httpAccept=text/plain}, author = {Wei Wang and Jiayu Chen and Tianzhen Hong and Na Zhu} } @article {30301, title = {Comparison of typical year and multiyear building simulations using a 55-year actual weather data set from China}, journal = {Applied Energy}, volume = {195}, year = {2017}, month = {06/2017}, pages = {890-904}, abstract = {

Weather has significant impacts on the thermal environment and energy use in buildings. Thus, accurate weather data are crucial for building performance evaluations. Traditionally, typical year data inputs are used to represent long-term weather data. However, there is no guarantee that a single year represents the changing climate well. In this study, the long-term representation of a typical year was assessed by comparing it to a 55-year actual weather data set. To investigate the weather impact on building energy use, 559 simulation runs of a prototype office building were performed for 10 large cities covering all climate zones in China. The analysis results demonstrated that the weather data varied significantly from year to year. Hence, a typical year cannot reflect the variation range of weather fluctuations. Typical year simulations overestimated or underestimated the energy use and peak load in many cases. With the increase in computational power of personal computers, it is feasible and essential to adopt multiyear simulations for full assessments of long-term building performance, as this will improve decision-making by allowing for the full consideration of variations in building energy use.

}, keywords = {Actual weather data, building simulation, energy use, Multiyear simulation, Peak load , Typical year}, doi = {10.1016/j.apenergy.2017.03.113}, author = {Ying Cui and Da Yan and Tianzhen Hong and Chan Xiao and Xuan Luo and Qi Zhang} } @article {30031, title = {Modeling of HVAC Operational Faults in Building Performance Simulation}, year = {2017}, abstract = {

Operational faults are common in the heating, ventilating, and air conditioning (HVAC) systems of existing buildings, leading to a decrease in energy efficiency and occupant comfort. Various fault detection and diagnostic methods have been developed to identify and analyze HVAC operational faults at the component or subsystem level. However, current methods lack a holistic approach to predicting the overall impacts of faults at the building level{\textemdash}an approach that adequately addresses the coupling between various operational components, the synchronized effect between simultaneous faults, and the dynamic nature of fault severity. This study introduces the novel development of a fault-modeling feature in EnergyPlus which fills in the knowledge gap left by previous studies. This paper presents the design and implementation of the new feature in EnergyPlus and discusses in detail the fault-modeling challenges faced. The new fault-modeling feature enables EnergyPlus to quantify the impacts of faults on building energy use and occupant comfort, thus supporting the decision making of timely fault corrections. Including actual building operational faults in energy models also improves the accuracy of the baseline model, which is critical in the measurement and verification of retrofit or commissioning projects. As an example, EnergyPlus version 8.6 was used to investigate the impacts of a number of typical operational faults in an office building across several U.S. climate zones. The results demonstrate that the faults have significant impacts on building energy performance as well as on occupant thermal comfort. Finally, the paper introduces future development plans for EnergyPlus fault-modeling capability.

}, keywords = {energy performance, energyplus, hvac system, Modeling and simulation, Operational fault, Thermal comfort }, author = {Rongpeng Zhang and Tianzhen Hong} } @article {29854, title = {Small and Medium Building Efficiency Toolkit and Community Demonstration Program}, year = {2017}, month = {03/2017}, abstract = {

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{\textquoteright}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.

}, keywords = {CBES, commercial buildings, energy efficiency, energy modeling, energy savings, indoor air quality, indoor environmental quality, outdoor air measurement technology, outdoor airflow intake rate, retrofit, ventilation rate}, doi = {10.7941/S93P70}, author = {Mary Ann Piette and Tianzhen Hong and William J. Fisk and Norman Bourassa and Wanyu R. Chan and Yixing Chen and H.Y. Iris Cheung and Toshifumi Hotchi and Margarita Kloss and Sang Hoon Lee and Phillip N. Price and Oren Schetrit and Kaiyu Sun and Sarah C. Taylor-Lange and Rongpeng Zhang} } @article {30312, title = {Spatial Distribution of Internal Heat Gains: A Probabilistic Representation and Evaluation of Its Influence on Cooling Equipment Sizing in Large Office Buildings}, journal = {Energy and Buildings}, year = {2017}, abstract = {

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.

}, keywords = {air handling unit, chiller plant, equipment sizing, internal heat gain, spatial distribution, spatial diversity, stochastic}, doi = {10.1016/j.enbuild.2017.01.044}, author = {Qi Zhang and Da Yan and Jingjing An and Tianzhen Hong and Wei Tian and Kaiyu Sun} } @article {30303, title = {A Thorough Assessment of China{\textquoteright}s Standard for Energy Consumption of Buildings}, journal = {Energy and Buildings}, year = {2017}, month = {03/2017}, abstract = {

China{\textquoteright}s Design Standard for Energy Efficiency of Public Buildings (the Design Standard) is widely used in the design phase to regulate the energy efficiency of physical assets (envelope, lighting, HVAC) in buildings. However, the standard does not consider many important factors that influence the actual energy use in buildings, and this can lead to gaps between the design estimates and actual energy consumption. To achieve the national energy savings targets defined in the strategic 12th Five-Year Plan, China developed the first standard for energy consumption of buildings GB/T51161-2016 (the Consumption Standard). This study provides an overview of the Consumption Standard, identifies its strengths and weaknesses, and recommends future improvements. The analysis and discussion of the constraint value and the leading value, two key indicators of the energy use intensity, provide insight into the intent and effectiveness of the Consumption Standard. The results indicated that consistency between China{\textquoteright}s Design Standard GB 50189-2015 and the Consumption Standard GB/T51161-2016 could be achieved if the Design Standard used the actual building operations and occupant behavior in calculating the energy use in Chinese buildings. The development of an outcome-based code in the U.S. was discussed in comparison with China{\textquoteright}s Consumption Standard, and this revealed the strengths and challenges associated with implementing a new compliance method based on actual energy use in buildings in the U.S. Overall, this study provides important insights into the latest developments of actual consumption-based building energy standards, and this information should be valuable to building designers and energy policy makers in China and the U.S.

}, keywords = {China, code and standard, energy consumption, energy efficiency, Energy Use Intensity, outcome-based code}, doi = {10.1016/j.enbuild.2017.03.019}, author = {Da Yan and Tianzhen Hong and Cheng Li and Qi Zhang and Jingjing An and shan Hu} } @article {30300, title = {A Comparative Study on Energy Performance of Variable Refrigerant Flow Systems and Variable Air Volume Systems in Office Buildings}, journal = {Applied Energy}, year = {2016}, abstract = {

Variable air volume (VAV) systems and variable refrigerant flow (VRF) systems are popularly used in office buildings. This study investigated VAV and VRF systems in five typical office buildings in China, and compared their air conditioning energy use. Site survey and field measurements were conducted to collect data of building characteristics and operation. Measured cooling electricity use was collected from sub-metering in the five buildings. The sub-metering data, normalized by climate and operating hours, show that VRF systems consumed much less air conditioning energy by up to 70\% than VAV systems. This is mainly due to the different operation modes of both system types leading to much fewer operating hours of the VRF systems. Building simulation was used to quantify the impact of operation modes of VRF and VAV systems on cooling loads using a prototype office building in China. Simulated results show the VRF operation mode leads to much less cooling loads than the VAV operation mode, by 42\% in Hong Kong and 53\% in Qingdao. The VRF systems operated in the part-time-part-space mode enabling occupants to turn on air-conditioning only when needed and when spaces were occupied, while the VAV systems operated in the full-time-full-space mode limiting occupants{\textquoteright} control of operation. The findings provide insights into VRF systems operation and controls as well as its energy performance, which can inform HVAC designers on system selection and building operators or facility managers on improving VRF system operations.\  \ \ 


}, keywords = {building simulation, comparative analysis, energy performance, field measurement, Variable Air Volume (VAV) Systems, Variable Refrigerant Flow (VRF) Systems}, author = {Xinqiao Yu and Da Yan and Kaiyu Sun and Tianzhen Hong and Dandan Zhu} } @article {30297, title = {The Impact of Evaporation Process on Thermal Performance of Roofs - Model Development and Numerical Analysis}, journal = {Energy and Buildings}, year = {2016}, keywords = {Evaporative Cooling, model development, Net zero energy building, Numerical analysis, Passive techniques, Porous building material, Roof thermal performance}, author = {Lei Zhang and Rongpeng Zhang and Yu Zhang and Tianzhen Hong and Qinglin Meng and Yanshan Feng} } @conference {60961, title = {Modeling and Simulation of Operational Faults of HVAC Systems Using Energyplus}, year = {2016}, abstract = {

HVAC operations play a significant role among various driving factors to improve energy performance of buildings. Extensive researches have been conducted on the design efficiencies and control strategies of HVAC system, but very few focused on the impacts of its operational faults on the building energy efficiency. Modeling and simulation of operational faults can lead to better understandings of the fault impacts and thus support decision making of timely fault corrections which can further benefit the efficient system operation, improve the indoor thermal comfort, and prolong the equipment service life. Fault modeling is also critical to achieve more accurate and reliable model calibrations. This paper introduces the modeling and simulation of operational faults using EnergyPlus, a comprehensive whole building performance simulation tool. The paper discusses the challenges of operational fault modeling, and compares three approaches to simulate operational faults using EnergyPlus. The paper also introduces the latest development of native fault objects within EnergyPlus. As an example, EnergyPlus version 8.4 is used to investigate the impacts of the integrated thermostat and humidistat faults in a typical office building across several U.S. climate zones. The results demonstrate that the faults create significant impacts on the building energy performance as well as occupant thermal comfort. At last, the paper introduces the future development plan of EnergyPlus for the further improvement of its fault modeling capability.

}, author = {Rongpeng Zhang and Tianzhen Hong} } @article {61107, title = {Commercial Building Energy Saver: An energy retrofit analysis toolkit}, journal = {Applied Energy}, volume = {159}, year = {2015}, month = {9/2015}, chapter = {298}, abstract = {

Small commercial buildings in the United States consume 47\% of the total primary energy of the buildings sector. Retrofitting small and medium commercial buildings poses a huge challenge for owners because they usually lack the expertise and resources to identify and evaluate cost-effective energy retrofit strategies. This paper presents the Commercial Building Energy Saver (CBES), an energy retrofit analysis toolkit, which calculates the energy use of a building, identifies and evaluates retrofit measures in terms of energy savings, energy cost savings and payback. The CBES Toolkit includes a web app (APP) for end users and the CBES Application Programming Interface (API) for integrating CBES with other energy software tools. The toolkit provides a rich set of features including: (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 and, (4) Detailed Retrofit Analysis which utilizes real-time EnergyPlus simulations. CBES includes 100 configurable energy conservation measures (ECMs) that encompass IAQ, technical performance and cost data, for assessing 7 different prototype buildings in 16 climate zones in California and 6 vintages. A case study of a small office building demonstrates the use of the toolkit for retrofit analysis. The development of CBES provides a new contribution to the field by providing a straightforward and uncomplicated decision making process for small and medium business owners, leveraging different levels of assessment dependent upon user background, preference and data availability.

}, keywords = {Building Technologies Department, Building Technology and Urban Systems Division, buildings, buildings energy efficiency, Commercial Building Systems, conservation measures, energy efficiency, energy use, energyplus, External, Retrofit Energy, simulation research}, doi = {10.1016/j.apenergy.2015.09.002}, author = {Tianzhen Hong and Mary Ann Piette and Yixing Chen and Sang Hoon Lee and Sarah C. Taylor-Lange and Rongpeng Zhang and Kaiyu Sun and Phillip N. Price} } @article {59960, title = {Data Analysis and Stochastic Modeling of Lighting Energy Use in Large Office Buildings in China}, journal = {Energy and Buildings}, volume = {86}, year = {2015}, month = {01/2015}, pages = {275-287}, abstract = {

Lighting consumes about 20\% to 40\% of the total electricity use in large office buildings in China. Commonly in building simulations, static time schedules for typical weekdays, weekends and holidays are assumed to represent the dynamics of lighting energy use in buildings. This approach does not address the stochastic nature of lighting energy use, which can be influenced by occupant behavior in buildings. This study analyzes the main characteristics of lighting energy use over various timescales, based on the statistical analysis of measured lighting energy use data from 15 large office buildings in Beijing and Hong Kong. It was found that in these large office buildings, the 24-hourly variation in lighting energy use was mainly driven by the schedules of the building occupants. Outdoor illuminance levels had little impact on lighting energy use due to the lack of automatic daylighting controls (an effective retrofit measure to reduce lighting energy use) and the relatively small perimeter area exposed to natural daylight. A stochastic lighting energy use model for large office buildings was further developed to represent diverse occupant activities, at six different time periods throughout a day, and also the annual distribution of lighting power across these periods. The model was verified using measured lighting energy use from the 15 buildings. The developed stochastic lighting model can generate more accurate lighting schedules for use in building energy simulations, improving the simulation accuracy of lighting energy use in real buildings.

}, keywords = {building simulation, energy use, Lighting modeling, occupant behavior, office buildings, Poisson distribution, stochastic modeling}, doi = {10.1016/j.enbuild.2014.09.071}, author = {Xin Zhou and Da Yan and Tianzhen Hong and Xiaoxin Ren} } @article {60960, title = {Development and validation of a new variable refrigerant flow systemmodel in EnergyPlus}, journal = {Energy and Buildings}, volume = {117}, year = {2015}, month = {9/2015}, chapter = {399}, abstract = {

Variable refrigerant flow (VRF) systems vary the refrigerant flow to meet the dynamic zone thermalloads, leading to more efficient operations than other system types. This paper introduces a new modelthat simulates the energy performance of VRF systems in the heat pump (HP) operation mode. Com-pared with the current VRF-HP models implemented in EnergyPlus, the new VRF system model has morecomponent models based on physics and thus has significant innovations in: (1) enabling advanced con-trols, including variable evaporating and condensing temperatures in the indoor and outdoor units, andvariable fan speeds based on the temperature and zone load in the indoor units, (2) adding a detailedrefrigerant pipe heat loss calculation using refrigerant flow rate, operational conditions, pipe length, andpipe insulation materials, (3) improving accuracy of simulation especially in partial load conditions, and(4) improving the usability of the model by significantly reducing the number of user input performancecurves. The VRF-HP model is implemented in EnergyPlus and validated with measured data from fieldtests. Results show that the new VRF-HP model provides more accurate estimate of the VRF-HP systemperformance, which is key to determining code compliance credits as well as utilities incentive for VRFtechnologies.

}, keywords = {building simulation, energy modeling, energyplus, Heat pump, model validation, Variable refrigerant flow}, doi = {10.1016/j.enbuild.2015.09.023}, author = {Tianzhen Hong and Kaiyu Sun and Rongpeng Zhang and Ryohei Hinokuma and Shinichi Kasahara and Yoshinori Yura} } @article {60352, title = {Modelica Buildings Library}, year = {2015}, author = {Michael Wetter and Wangda Zuo and Thierry Stephane Nouidui and Xiufeng Pang} } @article {59969, title = {Integrated Design for High Performance Buildings}, year = {2014}, author = {Tianzhen Hong and Cheng Li and Richard C. Diamond and Da Yan and Qi Zhang and Xin Zhou and Siyue Guo and Kaiyu Sun and Jingyi Wang} } @article {56246, title = {Building energy modeling programs comparison Research on HVAC systems simulation part}, year = {2013}, abstract = {

Building energy simulation programs are effective tools for the evaluation of building energy saving and optimization of design. The fact that large discrepancies exist in simulated results when different BEMPs are used to model the same building has caused wide concern. Urgent research is needed to identify the main elements that contribute towards the simulation results. This technical report summarizes methodologies, processes, and the main assumptions of three building energy modeling programs (BEMPs) for HVAC calculations: EnergyPlus, DeST, and DOE-2.1E, and test cases are designed to analyze the calculation process in detail. This will help users to get a better understanding of BEMPs and the research methodology of building simulation. This will also help build a foundation for building energy code development and energy labeling programs.

}, keywords = {Building energy modeling programs, comparison tests, HVAC system simulation, theory analysis}, author = {Xin Zhou and Da Yan and Tianzhen Hong and Dandan Zhu} } @article {57084, title = {Comparison of Building Energy Modeling Programs: HVAC Systems}, year = {2013}, month = {08/2013}, author = {Xin Zhou and Tianzhen Hong and Da Yan} } @article {56249, title = {Data Analysis and Modeling of Lighting Energy Use in Large Office Buildings}, year = {2013}, abstract = {

Lighting consumes about 20 to 40\% of total electricity use in large office buildings in the U.S. and China. In order to develop better lighting simulation models it is crucial to understand the characteristics of lighting energy use. This paper analyzes the main characteristics of lighting energy use over various time scales, based on the statistical analysis of measured lighting energy use of 17 large office buildings in Beijing and Hong Kong. It was found that the daily 24-hour variations of lighting energy use were mainly driven by the schedule of the building occupants. Outdoor illumination levels have little impact on lighting energy use in large office buildings due to the lack of automatic daylighting controls and relatively small perimeter areas. A stochastic lighting energy use model was developed based on different occupant activities during six time periods throughout a day, and the annual distribution of lighting power across those periods. The model was verified using measured lighting energy use of one selected building. This study demonstrates how statistical analysis and stochastic modeling can be applied to lighting energy use. The developed lighting model can be adopted by building energy modeling programs to improve the simulation accuracy of lighting energy use.

}, keywords = {building simulation, energy use, lighting, modeling, occupant behavior, office buildings, Poisson distribution}, author = {Xin Zhou and Da Yan and Xiaoxin Ren and Tianzhen Hong} } @article {56245, title = {A Detailed Loads Comparison of Three Building Energy Modeling Programs: EnergyPlus, DeST and DOE-2.1E}, journal = {Building Simulation}, volume = {6}, year = {2013}, month = {09/2013}, pages = {323-335}, publisher = {Tsinghua University Press}, chapter = {323}, abstract = {

Building energy simulation is widely used to help design energy efficient building envelopes and HVAC systems, develop and demonstrate compliance of building energy codes, and implement building energy rating programs. However, large discrepancies exist between simulation results from different building energy modeling programs (BEMPs). This leads many users and stakeholders to lack confidence in the results from BEMPs and building simulation methods. This paper compared the building thermal load modeling capabilities and simulation results of three BEMPs: EnergyPlus, DeST and DOE-2.1E. Test cases, based upon the ASHRAE Standard 140 tests, were designed to isolate and evaluate the key influencing factors responsible for the discrepancies in results between EnergyPlus and DeST. This included the load algorithms and some of the default input parameters. It was concluded that there is little difference between the results from EnergyPlus and DeST if the input values are the same or equivalent despite there being many discrepancies between the heat balance algorithms. DOE-2.1E can produce large errors for cases when adjacent zones have very different conditions, or if a zone is conditioned part-time while adjacent zones are unconditioned. This was due to the lack of a strict zonal heat balance routine in DOE-2.1E, and the steady state handling of heat flow through interior walls and partitions. This comparison study did not produce another test suite, but rather a methodology to design tests that can be used to identify and isolate key influencing factors that drive the building thermal loads, and a process with which to carry them out.

}, keywords = {building energy modeling program, building thermal loads, comparison, dest, DOE-2.1E, energyplus}, issn = {Print: 1996-3599; Online 1996-8744}, doi = {10.1007/s12273-013-0126-7}, author = {Dandan Zhu and Tianzhen Hong and Da Yan and Chuang Wang} } @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} } @conference {57409, title = {Application of a stochastic window use model in EnergyPlus}, booktitle = {SimBuild 2012, 5th National Conference of IBPSA-USA, August 1-3, 2012}, year = {2012}, month = {08/2012}, address = {Madison, WI}, abstract = {

Natural ventilation, used appropriately, has the potential to provide both significant HVAC energy savings, and improvements in occupant satisfaction.

Central to the development of natural ventilation models is the need to accurately represent the behavior of building occupants. The work covered in this paper describes a method of implementing a stochastic window model in EnergyPlus. Simulated window use data from three stochastic window opening models was then compared to measured window opening behavior, collected in a naturally-ventilated office in California. Recommendations regarding the selection of stochastic window use models, and their implementation in EnergyPlus, are presented.

}, url = {https://escholarship.org/uc/item/2gm7r783}, author = {Spencer M. Dutton and Hui Zhang and Yongchao Zhai and Edward A. Arens and Youness Bennani Smires and Samuel L. Brunswick and Kyle S. Konis and Philip Haves} } @conference {2673, title = {Comparative research in building energy modeling programs}, booktitle = {China Annual HVACR Conference}, year = {2012}, month = {06/2011}, address = {China (in Chinese)}, keywords = {advanced building software: energyplus, building energy modeling program, building simulation, comparison, dest, doe-2, energyplus, simulation research group, test}, author = {Dandan Zhu and Tianzhen Hong and Da Yan and Chuang Wang} } @article {3445, title = {Comparison of Building Energy Modeling Programs: Building Loads}, year = {2012}, month = {06/2012}, author = {Dandan Zhu and Tianzhen Hong and Chuang Wang} } @article {2581, title = {Reduction of numerical viscosity in FFD model}, journal = {Engineering Applications of Computational Fluid Mechanics}, volume = {6}, year = {2012}, pages = {234-247}, author = {Wangda Zuo and Mingang Jin and Qingyan Chen} } @conference {2671, title = {A Retrofit Tool for Improving Energy Efficiency of Commercial Buildings}, booktitle = {ACEEE 2012 Summer Study}, year = {2012}, month = {08/2012}, address = {Asilomar, CA}, abstract = {

Existing buildings will dominate energy use in commercial buildings in the United States for three decades or longer and even in China for the about two decades. Retrofitting these buildings to improve energy efficiency and reduce energy use is thus critical to achieving the target of reducing energy use in the buildings sector. However there are few evaluation tools that can quickly identify and evaluate energy savings and cost effectiveness of energy conservation measures (ECMs) for retrofits, especially for buildings in China. This paper discusses methods used to develop such a tool and demonstrates an application of the tool for a retrofit analysis. The tool builds on a building performance database with pre-calculated energy consumption of ECMs for selected commercial prototype buildings using the EnergyPlus program. The tool allows users to evaluate individual ECMs or a package of ECMs. It covers building envelope, lighting and daylighting, HVAC, plug loads, service hot water, and renewable energy. The prototype building can be customized to represent an actual building with some limitations. Energy consumption from utility bills can be entered into the tool to compare and calibrate the energy use of the prototype building. The tool currently can evaluate energy savings and payback of ECMs for shopping malls in China. We have used the tool to assess energy and cost savings for retrofit of the prototype shopping mall in Shanghai. Future work on the tool will simplify its use and expand it to cover other commercial building types and other countries.\ 

}, keywords = {building simulation, buildings, China, commercial building, energy efficiency measures, retrofit tool, simulation research group}, url = {http://aceee.org/files/proceedings/2012/data/papers/0193-000098.pdf$\#$page=1}, author = {Mark D. Levine and Wei Feng and Jing Ke and Tianzhen Hong and Nan Zhou} } @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} } @proceedings {3405, title = {Validation of three dimensional fast fluid dynamics for indoor airflow simulations}, journal = {the 2nd International Conference on Building Energy and Environment (COBEE2012)}, year = {2012}, pages = {1055-1062}, address = {Boulder, CO}, author = {Mingang Jin and Wangda Zuo and Qingyan Chen} } @proceedings {2783, title = {Advanced simulations of building energy and control systems with an example of chilled water plant modeling}, journal = {the 8th International Forum and Workshop on Combined Heat, Air, Moisture and Pollutant Simulations (CHAMPS 2011)}, year = {2011}, address = {Nanjing, China}, author = {Wangda Zuo and Michael Wetter} } @conference {3404, title = {A Comparison of DeST and EnergyPlus}, booktitle = {China HVAC Simulation Conference}, year = {2011}, month = {2011}, address = {Beijing}, keywords = {building simulation, comparison, dest, energy modeling, energyplus, simulation research, simulation research group, test cases}, author = {Dandan Zhu and Chuang Wang and Da Yan and Tianzhen Hong} } @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} } @proceedings {2784, title = {Validation of a Fast-Fluid-Dynamics Model for Predicting Distribution of Particles with Low Stokes Number}, journal = {12th International Conference on Indoor Air Quality and Climate (Indoor Air 2011)}, year = {2011}, month = {06/2011}, address = {Austin, Texas}, abstract = {To design a healthy indoor environment, it is important to study airborne particle distribution indoors. As an intermediate model between multizone models and computational fluid dynamics (CFD), a fast fluid dynamics (FFD) model can be used to provide temporal and spatial information of particle dispersion in real time. This study evaluated the accuracy of the FFD for predicting transportation of particles with low Stokes number in a duct and in a room with mixed convection. The evaluation was to compare the numerical results calculated by the FFD with the corresponding experimental data and the results obtained by the CFD. The comparison showed that the FFD could capture major pattern of particle dispersion, which is missed in models with well-mixed assumptions. Although the FFD was less accurate than the CFD partially due to its simplification in numeric schemes, it was 53 times faster than the CFD.}, keywords = {cfd, ffd, low stokes number, particle transportation}, author = {Wangda Zuo and Qingyan Chen} } @article {212, title = {Fast and informative flow simulation in a building by using fast fluid dynamics model on graphics processing unit}, journal = {Building and Environment}, volume = {45}, year = {2010}, pages = {747-757}, author = {Wangda Zuo and Qingyan Chen} } @proceedings {216, title = {Fast simulation of smoke transport in buildings}, journal = {the 41st International HVAC\&R congress}, year = {2010}, address = {Beograd, Serbian}, author = {Wangda Zuo and Qingyan Chen} } @proceedings {217, title = {Impact of time-splitting schemes on the accuracy of FFD simulations}, journal = {the 7th International Indoor Air Quality, Ventilation and Energy Conservation in Buildings Conference (IAQVEC 2010)}, year = {2010}, pages = {55-60}, address = {Syracuse, NY}, author = {Jianjun Hu and Wangda Zuo and Qingyan Chen} } @article {249, title = {Impacts of Static Pressure Reset on VAV System Air Leakage, Fan Power, and Thermal Energy}, journal = {ASHRAE Transactions}, volume = {116}, year = {2010}, pages = {428-436}, author = {Mingsheng Liu and Jingjuan Feng and Zhan Wang and Keke Zheng and Xiufeng Pang} } @article {211, title = {Improvements on FFD modeling by using different numerical schemes}, journal = {Numerical Heat Transfer, Part B Fundamentals}, volume = {58}, year = {2010}, pages = {1-16}, author = {Wangda Zuo and Jianjun Hu and Qingyan Chen} } @proceedings {218, title = {Improvements on the fast fluid dynamics model for indoor airflow simulation}, journal = {the 4th National Conference of IBPSA-USA (SimBuild2010)}, year = {2010}, pages = {539-546}, address = {New York, NY}, author = {Wangda Zuo and Qingyan Chen} } @article {210, title = {Simulations of air distribution in buildings by FFD on GPU}, journal = {HVAC\&R Research}, volume = {16}, year = {2010}, pages = {783-796}, author = {Wangda Zuo and Qingyan Chen} } @article {214, title = {Anisotropy invariant Reynolds stress model of turbulence (AIRSM) and its application on attached and separated wall-bounded flows}, journal = {Flow, Turbulence and Combustion}, volume = {83}, year = {2009}, month = {07/2009}, pages = {81-103}, chapter = {81}, abstract = {

Numerical predictions with a differential Reynolds stress closure, which in its original formulation explicitly takes into account possible states of turbulence on the anisotropy-invariant map, are presented. Thus the influence of anisotropy of turbulence on the modeled terms in the governing equations for the Reynolds stresses is accounted for directly. The anisotropy invariant Reynolds stress model (AIRSM) is implemented and validated in different finite-volume codes. The standard wall-function approach is employed as initial step in order to predict simple and complex wall-bounded flows undergoing large separation. Despite the use of simple wall functions, the model performed satisfactory in predicting these flows. The predictions of the AIRSM were also compared with existing Reynolds stress models and it was found that the present model results in improved convergence compared with other models. Numerical issues involved in the implementation and application of the model are also addressed.

}, keywords = {Anisotrpoy, Invariant map, Reynolds stress model, Reynolds-averaged Navier-Stokes, Separated wall-bounded flow, Turbulence, Turbulence modeling}, issn = {1573-1987}, doi = {10.1007/s10494-008-9190-y}, author = {V. Kumar and Bettina Frohnapfel and Jovan Jovanovi{\'c} and Michael Breuer and Wangda Zuo and Ibrahim Hadzi{\'c} and Richard Lechner} } @proceedings {220, title = {Fast parallelized flow simulations on graphic processing units}, journal = {the 11th International Conference on Air Distribution in Rooms (RoomVent 2009)}, year = {2009}, address = {Busan, Korea}, author = {Wangda Zuo and Qingyan Chen} } @proceedings {219, title = {High performance computing for indoor air}, journal = {11th International IBPSA Conference (Building Simulation 2009)}, year = {2009}, pages = {244-249}, address = {Glasgow, U.K.}, author = {Wangda Zuo and Qingyan Chen} } @article {213, title = {Real time or faster-than-real-time simulation of airflow in buildings}, journal = {Indoor Air}, volume = {19}, year = {2009}, pages = {33-44}, author = {Wangda Zuo and Qingyan Chen} } @proceedings {223, title = {Computational fluid dynamics for indoor environment modeling: past, present, and future}, journal = {the 6th International Indoor Air Quality, Ventilation and Energy Conservation in Buildings Conference (IAQVEC 2007)}, year = {2007}, pages = {1-9}, address = {Sendai, Japan}, author = {Qingyan Chen and Zhao Zhang and Wangda Zuo} } @conference {2661, title = {Computer Model of a University Building Using the EnergyPlus Program}, booktitle = {Proc. Building Simulation 2007}, year = {2007}, month = {09/2007}, address = {Beijing, China}, author = {Danielle Monfet and Radu Zmeureanu and Roland Charneux and Nicolas Lemire} } @conference {380, title = {Coverage Problem for Sensors Embedded in Temperature Sensitive Environments}, booktitle = {IEEE Infocom, 2007}, year = {2007}, month = {5/2007}, address = {Anchorage, AL}, author = {Arunabha Sen and Nibedita Das and Ling Zhou and Bao Hong Shen and Sudheendra Murthy and Prajesh Bhattacharya} } @proceedings {221, title = {Real time airflow simulation in buildings}, journal = {the 6th International Indoor Air Quality, Ventilation and Energy Conservation in Buildings Conference (IAQVEC 2007)}, year = {2007}, pages = {459-466}, address = {Sendai, Japan}, author = {Wangda Zuo and Qingyan Chen} } @conference {2653, title = {The Study of a Simple HVAC Interface of EnergyPlus in the Chinese Language}, booktitle = {Proc. Building Simulation 2007}, year = {2007}, month = {09/2007}, address = {Beijing, China}, author = {Junjie Liu and Wenshen Li and Xiaojie Zhou} } @proceedings {222, title = {Validation of fast fluid dynamics for room airflow}, journal = {the 10th International IBPSA Conference (Building Simulation 2007)}, year = {2007}, pages = {980-983}, address = {Beijing, China}, author = {Wangda Zuo and Qingyan Chen} } @conference {255, title = {Case Study of Continuous Commissioning in an Office Building}, booktitle = {the 6th International Conference of Enhanced Building Operations}, year = {2006}, month = {2006}, address = {Shenzhen, China}, author = {Xiufeng Pang and Zheng, B and Mingsheng Liu} } @conference {257, title = {Building Pressure Control in VAV System with Relief Air Fan}, booktitle = {the 5th International Conference of Enhanced Building Operations}, year = {2005}, month = {2005}, address = {Pittsburgh, PA}, author = {Xiufeng Pang and Zheng, B and Mingsheng Liu} } @conference {258, title = {Continuous Commissioning of an Office Building}, booktitle = {the 5th International Conference of Enhanced Building Operations}, year = {2005}, month = {2005}, address = {Pittsburgh, PA}, author = {Zheng, B and Mingsheng Liu and Xiufeng Pang} } @conference {256, title = {Using a Fan Air Flow Station to Control Building Static Pressure in a VAV System}, booktitle = {the 2005 International Solar Energy Conference}, year = {2005}, month = {2005}, address = {Orlando, FL}, author = {Zheng, B and Xiufeng Pang and Mingsheng Liu} } @article {278, title = {Heat transfer and natural ventilation from single-sided heated solar chimney for buildings}, journal = {Journal of Asian Architecture and Building Engineering}, volume = {3}, year = {2004}, author = {Angui Li and Phillip Jones and Pingge Zhao and Liping Wang} } @article {215, title = {Updating traditional CRM system by terminal server}, journal = {Journal of Chongqing University (Natural Science Edition)}, volume = {27}, year = {2004}, pages = {94-95}, author = {Wangda Zuo and Tianyi Yang and Wenyan Zou} } @article {302, title = {On Approaches to Couple Energy Simulation and Computational Fluid Dynamics Programs}, journal = {Building and Environment}, volume = {37}, year = {2002}, chapter = {857}, abstract = {

Energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing complementary information about the buildings{\textquoteright} 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.

}, author = {Zhiqiang Zhai and Qingyan Chen and Philip Haves and Joseph H. Klems} } @conference {1850, title = {Strategies for Coupling Energy Simulation Programs and Computational Fluid Dynamics Programs}, booktitle = {Building Sim 2001}, volume = {1}, year = {2001}, month = {08/2001}, pages = {59-66}, address = {Rio de Janeiro, Brazil}, abstract = {

Energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing complementary information about the buildings{\textquoteright} 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.

}, author = {Zhiqiang Zhai and Qingyan Chen and Joseph H. Klems and Philip Haves} }