Análisis de Proyectos en el mercado

The results of studies from seven projects related to commissioning, either in new or existing buildings, have been discussed, with the major conclusions drawn from each. These studies represent the extent of research that has been performed with regard to the persistence of commissioning benefits over time. These studies together provide a foundation for helping to understand how savings persist or degrade over time, and how to maintain savings. The current study builds upon the findings and information presented in these seven projects.

The savings in the buildings that were retro-commissioned generally showed some degradation with time, with specific findings as detailed below. For the ten buildings studied at Texas A&M, the cooling energy savings obtained from retro-commissioning degraded from 44.8% to 35.1% during the period from 1997 to 2000. The heating energy savings decreased 79.7% in 1998 to 49.7 % in year 2000. In spite of these decreases,

cost savings from retro-commissioning in these 10 buildings were still $985,626/year compared with original savings of $1,192,884/year. As noted, 3/4 of the decrease was in two buildings in which component failures occurred. For the additional three buildings at Texas A&M, aggregate site savings increased with time. One building saw an increase from 6.9% savings the first year after commissioning to 15.6% the most recent year, another from 10.5% to 21.7%, and the third from 11.9% to 26.7%. For the eight buildings in California, peak aggregate savings occurred in years two and three with about 1/4 of the savings disappearing in year four for the four buildings for which that much data was available. 89% of the electric savings and none of the gas savings in three of the Oregon buildings persisted four years later. The persistence in the other five Oregon buildings was not quantified. The building in Colorado was still saving 86+% as much after seven years as after the initial retro-commissioning. Savings were also not quantified in the two utility retro-commissioning program office buildings, though less than 40% of the measures implemented persisted.

For the new buildings, well over half of the fifty-six commissioning fixes persisted. Hardware fixes, such as moving a sensor or adding a valve, and control algorithm changes that were reprogrammed generally persisted. Control strategies that could easily be changed, such as occupancy schedules, reset schedules, and chiller staging tended not to persist. It was also found that the extent to which persistence occurs is also related to operator training.

As is evident, the number of buildings studied in all of the papers described here represents a very small portion of commercial buildings that have undergone commissioning or retro-commissioning. Much more research is needed to verify the conclusions made in these studies, as well as to continue to provide practical solutions to building owners and operators as to how to best maintain commissioning savings, and how these methods may be better integrated in the commissioning process.

Useful work for the future would be to attempt to consolidate all the data and findings from each of these studies, along with the current study, to see what further conclusions,

models, or correlations could be developed based on the entire set of data. Part of this would include presenting the results of each of these studies in a consistent format so that persistence of savings could be visually and mathematically compared more easily.

CHAPTER III

METHODOLOGY

The development of procedures for calculating energy savings in buildings is directly linked to the development of procedures to measure and verify energy consumption. Haberl and Culp (2003) trace the history of energy consumption measurement and verification (M&V) from the earliest days of electricity consumption (circa 1890) to the 2003 industry standards for savings calculations. Table 3-1 below lists major events in this history beginning with the first energy simulations in the 1960s.

2003 – IPMVP-2003 Volume III (new construction) 2002 – ASHRAE Guideline 14-2002

2001 - IPMVP-2001 Volume I & II (revised and expanded IPMVP) 1998 - Texas State Performance Contracting Guidelines

1997 - IPMVP (revised NEMVP) 1996 - FEMP Guidelines

1996 - NEMVP

1995 - ASHRAE Handbook - Ch. 37 “Building Energy Monitoring” 1994 - PG&E Power Saving Partner “Blue Book”

1993 - NAESCO M&V Protocols

1993 - New England AEE M&V Protocols 1992 - California CPUC M&V Protocols 1989 - Texas LoanSTAR Program 1988 - New Jersey M&V Protocols

1985 - First Utility Sponsored Large Scale Programs to Include M&V

The 1980s saw a surge in the number of programs designed to utilize measurement and verification, as the ability to monitor energy savings precisely became increasingly important. The early to mid 1990s witnessed the beginnings of state and federal guidelines for measurement. In 1996, the North American Energy Measurement and Verification Protocol (NEMVP) was published, and was later expanded and republished as the International Performance Measurement and Verification Protocols (IPMVP) in 1997 and again in 2001. Meanwhile, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) had been working simultaneously on the development of a guideline, although it was not published until 2002. This document is called ASHRAE Guideline 14-2002, Measurement of Energy and Demand Savings, and provided more technical basis for the procedures described in the IPMVP. The IPMVP was subsequently updated and revised, and republished in 2007. The 2007 IPMVP was used as the basis for savings analysis calculations performed in this study, although ASHRAE Guideline 14 also served as a valuable reference. One of the statistical tests required by Guideline 14, the mean bias test, could not be met with the data from this study. This test may be removed from the Guideline in future editions, but is currently not required by IPMVP 2007.

3.2 IPMVP 2007

The 2007 IPMVP explains that energy savings cannot be directly measured, but are determined by comparing measured consumption before and after an energy program has been implemented and making adjustments for changes in conditions. This is summarized in Equation 3.1 below:

( –