Soolyeon Cho

Is Commissioning Once Enough

ABSTRACT Over the last decade, the Energy Systems Laboratory has developed a commissioning process called Continuous Commissioning®. This process is used to resolve operating problems, improve comfort, optimize energy use, and sometimes to recommend retrofits. The process has produced average energy savings of about 20 percent without significant capital investment in over 150 large buildings in which it has been implemented. Payback has virtually always been under 3 years, with two years or less in most buildings. This article describes the process and presents a case study that explicitly shows the value of follow-up consumption tracking and commissioning. Examination of 20 building-years of heating and cooling consumption data from commissioned buildings found an overall increase in heating and cooling of 12.1 percent over two years. Almost 75 percent of this increase was caused by significant component failures and/or control changes that did not compromise comfort, but caused large changes in consump...

A Study on the Evaluation of the Annual Energy Consumption for a Geothermal Heat Pump System with Open Loop and Closed Loop Ground Heat Exchangers

Heating and cooling systems contribute greatly to the energy consumption and CO2 emissions of many countries. Ground source heat pumps (GSHP) are promising energy saving systems for residential, commercial or industrial heating or cooling purposes. A method to estimate the energy consumption and CO2 emission of GSHPs is therefore very eminent. This paper reviews the methodology to calculate the energy consumption and CO2 emission of GSHPs. The discussed methodology is then used to compare the energy consumption and CO2 emission of an open-loop and closed-loop GSHP using data from field test. It is observed that the open-loop GSHP saves 28% energy and reduces CO2 by 28% than the closed-loop GSHP in the cooling season. When used for both cooling and heating purposes in the year, the open-loop GSHP saves about 6% energy and reduces about 6% of CO2 emission than the closed-loop GSHP.

Network-based energy supply optimal system in the condition where both heating and cooling are required simultaneously in a swing season

ABSTRACT Recent building control models have adopted advanced algorithms to replace conventional controllers to improve the performance of plant or system levels. However, most models used to optimize fuel use or fan speed have several disadvantages to respond to, accurately and promptly, zone-scaled level. This paper proposes network-based controllers utilizing Artificial Neural Network (ANN) in space cooling and heating through the simultaneous control of the amount of supply air and its temperature. Two controllers are developed to evaluate the optimum of supply air conditions for a swing season that requires both moderate heating and cooling and they are compared to conventional thermostat on/off model by using the total control errors and energy consumption for operating damper and resistance coil. The result describes the advantage of the ANN simultaneous control that control errors reduce by 61.5% and energy consumption decreases by 3.5% in comparison with on/off controller. The ANN controller effectively optimizes the supply air conditions to reduce control errors and energy consumption, as they relate to human comfort and energy savings in a swing season.

Application priority of GSHP systems in the climate conditions of the United States

ABSTRACT Building energy-performance simulation programs are powerful tools for many aspects of feasibility studies regarding ground source heat pump (GSHP). However, the understanding of the limitations of the energy modelling programs, their capability of predicting energy performance early in the design process, and the complicated functionality of these programs makes the software programs harder to use and less practical. The interactive tool developed in this study seeks to provide analysis information in a straightforward manner that is inexpensive, convenient, and sophisticated. This tool uses an inclusive approach to assess the feasibility of GSHPs by prescreening critical factors such as climate conditions, ground temperatures, energy use, and cost savings. It is interactive and enables the user to do a feasibility analysis with a weighting factor for each feasibility criterion based on the user’s preference and interests. The application of the tool explains feasibility scores of 15 representative cities in various climatic conditions across the US. Results for commercial buildings show that the GSHP systems are more feasible in cold and dry, cool and humid, and very cold areas than warm and dry, very hot and humid, and mixed marine areas, and that most feasibility levels are located on good and moderate.

Methodology to Develop the Airport Terminal Building Energy Use Intensity (ATB-EUI) Benchmarking Tool

The report outlines the overall data collection and analysis process for developing airport terminal building energy use intensity (ATB-EUI) benchmarks. Individual chapters highlight: defining annual EUI per ATB zone; annual EU calculation per ATB system; estimation of ATB’s measured annual EU based on utility information; the complete ATB annual EU/EUI table; the input form; and site visits. The report complements CD-ROM 178: Airport Terminal Building Energy Use Intensity (ATB-EUI) Benchmarking Tool.