@conference {59967, title = {A New Model to Simulate Energy Performance of VRF Systems}, year = {2014}, abstract = {

This paper presents a new model to simulate energy performance of variable refrigerant flow (VRF) systems in heat pump operation mode (either cooling or heating is provided but not simultaneously). The main improvement of the new model is the introduction of the evaporating and condensing temperature in the indoor and outdoor unit capacity modifier functions. The independent variables in the capacity modifier functions of the existing VRF model in EnergyPlus are mainly room wet-bulb temperature and outdoor dry-bulb temperature in cooling mode and room dry-bulb temperature and outdoor wet-bulb temperature in heating mode. The new approach allows compliance with different specifications of each indoor unit so that the modeling accuracy is improved. The new VRF model was implemented in a custom version of EnergyPlus 7.2. This paper first describes the algorithm for the new VRF model, which is then used to simulate the energy performance of a VRF system in a Prototype House in California that complies with the requirements of Title 24 {\textendash} the California Building Energy Efficiency Standards. The VRF system performance is then compared with three other types of HVAC systems: the Title 24-2005 Baseline system, the traditional High Efficiency system, and the EnergyStar Heat Pump system in three typical California climates: Sunnyvale, Pasadena and Fresno. Calculated energy savings from the VRF systems are significant. The HVAC site energy savings range from 51 to 85\%, while the TDV (Time Dependent Valuation) energy savings range from 31 to 66\% compared to the Title 24 Baseline Systems across the three climates. The largest energy savings are in Fresno climate followed by Sunnyvale and Pasadena. The paper discusses various characteristics of the VRF systems contributing to the energy savings. It should be noted that these savings are calculated using the Title 24 prototype House D under standard operating conditions. Actual performance of the VRF systems for real houses under real operating conditions will vary.

}, author = {Tianzhen Hong and Xiufeng Pang and Oren Schetrit and Liping Wang and Shinichi Kasahara and Yoshinori Yura and Ryohei Hinokuma} } @conference {3407, title = {The Energy Saving Potential of Membrane-Based Enthalpy Recovery in VAV System for Commercial Office Buildings}, booktitle = {SimBuild 2012}, year = {2012}, month = {08/2012}, address = {Madison, Wisconsin}, author = {Liping Wang and Philip Haves and John Breshears} } @conference {3444, title = {The Energy Saving Potential of Membrane-Based Enthalpy Recovery in Vav Systems for Commercial Office Buildings}, booktitle = {SimBuild 2012 IBPSA Conference}, year = {2012}, abstract = {

A design tool to evaluate the heat and mass transfer effectiveness and pressure drop of a membrane-based enthalpy exchanger was developed and then used to optimize the configuration of an enthalpy exchanger for minimum pressure drop and maximum heat recovery effectiveness. Simulation was used in a parametric study to investigate the energy saving potential of the enthalpy recovery system. The case without energy recovery and air side economizer was used as a baseline. Two comparison cases for the implementation of enthalpy recovery with and without air side economizer were simulated in EnergyPlus. A case using a desiccant wheel for energy recovery was also investigated for comparison purposes. The simulation results show significant energy saving benefits from applying a low pressure drop, high effectiveness enthalpy exchanger in two US cities representing a range of humid climates. The sensitivity of the energy savings potential to pressure drop and heat and mass transfer effectivenesses is also presented.

}, author = {Liping Wang and Philip Haves and John Breshears} } @conference {3442, title = {An Improved Simple Chilled Water Cooling Coil Model}, booktitle = {SimBuild 2012 IBPSA Conference}, year = {2012}, month = {08/2012}, abstract = {

The accurate prediction of cooling and dehumidification coil performance is important in model-based fault detection and in the prediction of HVAC system energy consumption for support of both design and operations. It is frequently desirable to use a simple cooling coil model that does not require detailed specification of coil geometry and material properties. The approach adopted is to match the overall UA of the coil to the rating conditions and to estimate the air-side and water-side components of the UA using correlations developed by Holmes (1982). This approach requires some geometrical information about the coil and the paper investigates the sensitivity of the overall performance prediction to uncertainties in this information, including assuming a fixed ratio of air-side to water-side UA at the rating condition. Finally, simulation results from different coil models are compared, and experimental data are used to validate the improved cooling coil model.

}, author = {Liping Wang and Philip Haves and Walter F. Buhl} } @article {3414, title = {Monitoring-based HVAC Commissioning of an Existing Office Building for Energy Efficiency}, year = {2012}, month = {10/2012}, abstract = {

The performance of Heating, Ventilation and Air Conditioning (HVAC) systems may fail to satisfy design expectations due to improper equipment installation, equipment degradation, sensor failures, or incorrect control sequences. Commissioning identifies and implements cost-effective operational and maintenance measures in buildings to bring them up to the design intent or optimum operation. An existing office building is used as a case study to demonstrate the process of commissioning. Building energy benchmarking tools are applied to evaluate the energy performance for screening opportunities at the whole building level. A large natural gas saving potential was indicated by the building benchmarking results. Faulty operations in the HVAC systems, such as improper operations of air-side economizers, simultaneous heating and cooling, and ineffective optimal start, were identified through trend data analyses and functional testing. The energy saving potential for each commissioning measure is quantified with a calibrated building simulation model. An actual energy saving of 10\% was realized after the implementations of cost-effective measures.

}, keywords = {benchmarking, commissioning, energyplus, fault detection and diagnostics, functional testing, trend data}, author = {Shankar Earni and Spencer Woodworth and Xiufeng Pang and Jorge Hernandez-Maldonado and Rongxin Yin and Liping Wang and Steve E. Greenberg and John Fiegel and Alma Rubalcava} } @article {57517, title = {Uncertainties in energy consumption introduced by building operations and weather for a medium-size office building}, journal = {Energy and Buildings}, volume = {53}, year = {2012}, month = {10/2012}, pages = {152 - 158}, keywords = {Building Operations, energyplus, Monte Carlo Analysis, Uncertainties}, issn = {03787788}, doi = {10.1016/j.enbuild.2012.06.017}, author = {Liping Wang and Paul A. Mathew and Xiufeng Pang} } @conference {2672, title = {Modeling and simulation of HVAC faults in EnergyPlus}, booktitle = {Building Simulation 2011}, year = {2011}, month = {11/2011}, address = {Australia}, keywords = {advanced building software: energyplus, building simulation, energyplus, faults, fouling, modeling, sensor offset, simulation research group}, author = {Mangesh Basarkar and Philip Haves and Xiufeng Pang and Liping Wang and Tianzhen Hong} } @article {3179, title = {Modeling and simulation of HVAC Results in EnergyPlus}, year = {2011}, month = {11/2011}, author = {Mangesh Basarkar and Xiufeng Pang and Liping Wang and Tianzhen Hong} } @article {237, title = {Case study of zero energy house design in UK}, journal = {Energy and Buildings}, volume = {41}, year = {2009}, month = {11/2009}, pages = {1215-1222}, author = {Liping Wang and Julie Gwilliam and Phillip Jones} } @article {274, title = {Coupled simulations for naturally ventilated rooms between building simulation (BS) and computational fluid dynamics (CFD) for better prediction of indoor thermal environment}, journal = {Building and Environment}, volume = {44}, year = {2009}, month = {01/2009}, pages = {95-112}, author = {Liping Wang and Nyuk Hien Wong} } @article {262, title = {Coupled simulations for naturally ventilated residential buildings}, journal = {Automation in Construction}, volume = {17}, year = {2008}, month = {05/2008}, pages = {386-398}, author = {Liping Wang and Nyuk Hien Wong} } @conference {284, title = {A convenient coupled simulation method for thermal environment prediction in naturally ventilated buildings}, booktitle = {2nd PALENC conference and 28th AIVC conference, 27-29 September}, year = {2007}, month = {09/2007}, author = {Liping Wang and Nyuk Hien Wong} } @conference {283, title = {Discussion of strategies for UK zero energy building design}, booktitle = {2nd PALENC conference and 28th AIVC conference, 27-29 September}, year = {2007}, month = {09/2007}, author = {Liping Wang and Julie Gwilliam} } @article {238, title = {Facade design optimization for naturally ventilated residential buildings in Singapore}, journal = {Energy and Buildings}, volume = {39}, year = {2007}, month = {08/2007}, pages = {954-961}, author = {Liping Wang and Nyuk Hien Wong and Shuo Li} } @article {261, title = {The impacts of facade and ventilation strategies on indoor thermal environment for a naturally ventilated residential building in Singapore}, journal = {Building and Environment}, volume = {42}, year = {2007}, month = {12/2007}, pages = {4006-4015}, author = {Liping Wang and Nyuk Hien Wong} } @article {275, title = {Investigation of the possibility of applying natural ventilation for thermal comfort in residential buildings in Singapore}, journal = {Architectural Science Review}, volume = {50}, year = {2007}, month = {2007}, pages = {190-199}, author = {Liping Wang and Nyuk Hien Wong} } @conference {290, title = {Coupling between the CFD simulation and building simulation for better prediction of natural ventilation}, booktitle = {the 2nd International conference on sustainable architecture and urban design in tropical regions, Jogjakarta}, year = {2006}, month = {04/2006}, author = {Liping Wang and Nyuk Hien Wong} } @conference {291, title = {A coupling method to increase the accuracy of natural ventilation prediction in thermal simulation program}, booktitle = {the 2nd International conference on sustainable architecture and urban design in tropical regions, Jogjakarta}, year = {2006}, month = {04/2006}, author = {Liping Wang and Nyuk Hien Wong} } @conference {286, title = {The impacts of facade designs: orientations, window to wall ratios and shading devices on indoor environment for naturally ventilated residential buildings in Singapore}, booktitle = {the 23st International conference on Passive and Low energy architecture, Geneva}, year = {2006}, month = {09/2006}, author = {Liping Wang and Nyuk Hien Wong} } @conference {287, title = {Natural ventilation simulation by using coupling building simulation and CFD simulation program for accurate prediction of indoor thermal environment}, booktitle = {the 23st International conference on Passive and Low energy architecture , Geneva}, year = {2006}, month = {09/2006}, author = {Liping Wang and Nyuk Hien Wong} } @conference {289, title = {A numerical study of Trombe wall for enhancing stack ventilation in buildings}, booktitle = {The 23rd International Conference on Passive and Low Energy Architecture, Geneva}, year = {2006}, month = {09/2006}, author = {Liping Wang and Angui Li} } @article {277, title = {Effects of double glazed fa{\c c}ade on energy consumption, thermal comfort and condensation for a typical office building in Singapore}, journal = {Energy and Buildings}, volume = {37}, year = {2005}, month = {06/2005}, author = {Nyuk Hien Wong and Liping Wang and Aida Noplie Chandra and Anupama Rana Pandey and Xiaolin Wei} } @conference {292, title = {The impacts of facade and ventilation strategies on indoor thermal environment for a naturally ventilated residential building in Singapore}, booktitle = {the 10th International conference on Indoor Air Quality and Climate, Beijing}, year = {2005}, month = {2005}, author = {Liping Wang and Nyuk Hien Wong} } @conference {295, title = {Thermal analysis of climate environments based on weather data in Singapore for naturally ventilated buildings}, booktitle = {the 10th International conference on Indoor Air Quality and Climate,Beijing}, year = {2005}, month = {2005}, author = {Liping Wang and Nyuk Hien Wong} } @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} } @conference {296, title = {A numerical study of vertical solar chimney for Enhancing stack ventilation in buildings}, booktitle = {The 21st International Conference on Passive and Low Energy Architecture, The Netherlands}, year = {2004}, month = {09/2004}, author = {Liping Wang and Angui Li} }