ASHRAE Journal - January 2009 - (Page 18) Energy Audits In Large Commercial Office Buildings By Ian Shapiro, P Member ASHRAE .E., O ffice buildings have more floor area (12.2 billion ft2 [1.1 billion m2]) than any other building type in the U.S. and have the highest total energy consump- tion (1.1 quadrillion Btu [1.2 EJ]) of any building type. Furthermore, the largest buildings have a higher energy use intensity (energy consumption per square foot) than any other size of building.1 This scale creates many opportunities for energy savings. A good place to begin is with an energy audit of the building. The challenges of energy audits in large office buildings are many. For example, large HVAC plants and controls can be complex for new energy auditors, and even for experienced engineers. High-rise buildings have unpredictable and uncontrolled airflows, driven by interactions among stack effect, exhaust fans, and higherpressure air-distribution systems. The clients are often seasoned businesspeople, accustomed to hard negotiations who seek to save costs on energy audit fees. The buildings are large, so energy auditors can be swamped with field data. They often find themselves confused back at 18 ASHRAE Journal the office, unable to remember details about individual HVAC components, details on spaces, and potential improvements. The sheer size of the audit can lead to “audit exhaustion,” ending in a limited set of improvements. Sometimes, the exciting technical challenges of advanced improvements, such as demand-controlled ventilation or chiller plant improvements, or solar energy, will draw the attention of enthusiastic energy auditors, leaving other improvements such as envelope (air sealing, windows, and insulation), lighting, and operation/ maintenance inadequately addressed. All ashrae.org of these challenges, led by a concern that building owners might not be willing to pay for comprehensive energy audits, can lead engineering firms to tend towards simpler walkthrough audits. A consensus increasingly has grown that defines three levels of energy audits: walkthrough, general, and investment grade.2 However, requirements for each of these levels can still lack detail, leaving decisions to the energy auditor as to what data to gather and which improvements to evaluate. It has been acknowledged that the three levels do not have distinct boundaries.3 Common mistakes can compound the problems. Simple walkthrough audits can result in a limited set of recommended improvements. Absence of detail in energy audits can lead to unclear recommendations and reports that cannot be easily translated into a work scope or into designs to achieve the energy savings outlined in the audit. A review of 10 comprehensive energy audits identified many common mistakes, including About the Author Ian Shapiro, P is president of Taitem Engineer.E., ing, Ithaca, N.Y. January 2009 http://www.ashrae.org
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