When businesses consider strategies to increase energy efficiency, they look for the sweet spots where actions that shrink their company’s energy use also lead to boosting the bottom line. The key is to find upgrades and retrofits that will achieve a quick payback by lowering energy costs, qualifying for rebates and taking advantage of utility programs for free energy audits and innovative payment options.
Commercial buildings use almost 20 percent of all energy in the United States, and more than a third of them are due for retrofitting that could reduce energy costs from 10 to 50 percent, according to a report published in July 2010 by Pike Research on energy efficiency for commercial and public buildings. One problem is that businesses often put off such projects because managers think the efforts will not be worth the trouble for the savings produced, especially if occupants or clients might be inconvenienced by work in progress.
Energy Engineer Mike Bigelow, LEED-AP, is on a mission to get business owners and building managers to understand the power and payback of energy efficiency and self-generation. As a member of the engineering team at the California Center for Sustainable Energy in San Diego, Bigelow specializes in commercial, government and industrial building energy audits and retrofits. During a recent workshop titled “Boost Your Bottom Line and Shrink Your Eco Waistline,” he demonstrated how improving the performance of building systems and producing energy onsite can far outweighed the costs involved.
Optimizing energy performance
The process begins with retro-commissioning, a systematic approach to restoring building systems to their optimal performance and making low-cost improvements. Bigelow compares a poorly functioning building to driving a car with one foot on the gas and one on the brake – after retro-commissioning, the brake’s off.
The first step is a comprehensive energy audit compiled from past utility bills, system inspections and interviews of facility personnel. This benchmarking of energy performance provides a baseline of current use and supplies a means to track and analyze actions as fixes are made. The EPA’s online Portfolio Manager is a superior self assessment tool.
Bigelow used an existing 130,000-square-foot, four-story, mixed-use building in San Diego to illustrate some of the finer points of building energy upgrading. The building’s annual energy consumption was 2,540,000 kilowatt-hours (kWh) of electricity and 36,600 therms of natural gas at a cost of $486,500. To calculate the impacts of improvements, he employed energy simulation software called eQuest and proprietary CCSE modeling tools. In this example, annual savings are calculated over 13 years (except for self generation) and energy costs are escalated at 3.4% annually.
Focusing on controls and equipment
- Improperly set thermostats were simultaneously heating and cooling certain interior spaces, adding nearly four percent to energy costs. Proper set points yielded reductions of 95,000 kWh and 2,000 therms. Annual savings estimate: $22,000
- Incorrect settings in the building management system kept the fan override switch constantly on and required the heating and cooling coils always at the ready, resulting in a cost increase of 45 percent. Rescheduling controls reduced 1,840,000 kWh and 86,000 therms. Annual savings estimate : $230,000
- Equipment upgrades and replacements offered energy efficiency. Adding variable frequency drives to fans cost $5,000, replacing T-8 32 watt fluorescent lamps with T-8 28 watt cost $279,500 and two new chillers with higher ratings for the central plant $1,000,000. Annual savings estimate: $66,000
Adding self generation
- Install a 75-kW solar photovoltaic rooftop system at a cost of $390,000. Eligible for state rebates, allows access to advantageous rate tariff and qualifies for two federal tax benefits. Nominal annual savings: $24,000
- Install 60-kW natural gas fuel cells at a cost of $558,000. Eligible for federal tax credits, qualifies for IOU tariffs and may receive a state rebate. Heat recovery supplements water heating. Nominal annual savings: $60,000
The complete package
The result is a commercial building that consumes the minimum amount of energy for the maximum efficiency and comfort of occupants with annual energy savings of nearly $400,000 a year. Self-generated clean power adds positive environmental affects, and with benchmarking in place there will be opportunities to maintain high-performance operations.