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Development of New Methodologies for Evaluating the Energy Performance of New Commercial Buildings

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Title: Development of New Methodologies for Evaluating the Energy Performance of New Commercial Buildings
Author: Song, Suwon
Abstract: During the past decade, utility companies and others have offered new construction programs to promote energy savings based on energy-efficient design, which maximize design flexibility as well as energy savings. For such programs, the concept of Measurement and Verification (M&V) of a new building continues to become more important because efficient design alone is often not sufficient to deliver an efficient building. Simulation models that are calibrated to measured data can be used to evaluate the energy performance of new buildings if it is compared to energy baselines such as similar buildings, energy codes, and design standards (IPMVP 2003; Torcellini et. 2004). Unfortunately, there is a lack of detailed M&V methods and analysis methods to measure energy savings from new buildings that would have hypothetical energy baselines. In addition, many important questions remain, for example: how to simulate and calibrate a simulation with measured data, how to develop energy baselines for comparison to the new building, and how to calculate energy savings compared to energy baselines. Therefore, this study developed and demonstrated several methodologies for evaluating the energy performance of new commercial buildings using a case-study building in Austin, Texas, in terms of: 1) Whole-building energy metering with in-situ measurements, 2) Simulation and calibration methods applicable to new buildings, and 3) Building energy baselines and savings assessments. Consequently, three new M&V methods were developed in this study to enhance the generic M&V framework (IPMVP 2003) for new buildings, including: 1) The development of a procedure to synthesize weather-normalized cooling energy use (i.e., Btu cooling production) from a correlation of MCC electricity use when chilled water use is unavailable, 2) The development of an improved method to analyze measured solar transmittance against incidence angle for sample glazing using different solar sensor types, including an Eppley PSP and Li-Cor sensor, and 3) The development of an improved method to analyze chiller efficiency and operation at part-load conditions. Second, three new methods were also developed and analyzed in the process of the as-built model simulation and calibration, including: 1) A new percentile analysis to the previous signature method (Wei et al. 1998) for use with a DOE-2 calibration, 2) A new analysis to account for undocumented exhaust air in DOE-2 calibration, and 3) An analysis of the impact of synthesized direct normal solar radiation using the Erbs correlation (Duffie and Beckman 1991) on DOE-2 simulation. Third, an analysis of the actual energy savings compared to three different energy baselines was performed, including: 1) Energy Use Index (EUI) comparisons with sub-metered data, 2) New comparisons against Standards 90.1-1989 and 90.1-2001, and 3) A new evaluation of the performance of selected ECDMs. Finally, potential energy savings were also simulated from selected improvements, including minimum supply air flow, undocumented exhaust air, and daylighting. As a result, the calibrated models were determined to have an overall 20.38% CV(RMSE) and a 0.63% MBE for the 2001 model and an overall 23.82% CV(RMSE) and a 0.61% MBE for the 2004 model, which compares well with the previous research (Kreider and Haberl 1994; Bou-Saada 1994; ASHRAE 2002). It was found that the end-use EUIs, such as cooling, heating, and Motor Control Center (MCC) electricity use can begin to provide information about the building’s heating and cooling efficiencies compared to similar buildings in a control groups. It was also determined that the REJ building is 20.79% more efficient than the Standard 90.1-1989 and approximately equal to the Standard 90.1-2001. Using an ECDM-subtraction method, the REJ building was shown to use approximately 67% less energy than the base-case building without the ECDMs. Potential savings were simulated to be 7,053.3 MMBtu (19.26%) from the combined improvements when compared to the 2004 as-built simulation.
URI: http://hdl.handle.net/1969.1/6056
Date: 2007-09-25

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