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Written by Alan Pong, Greeniac168   
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Friday, 08 May 2009

Understanding Your Commercial Building’s Metrics
My last article provided a simple way to measure your utility consumption by calculating your building’s kilowatt hours per square feet per year (http://www.greeniacs.com/Commercial-Green-Building/Determining-Your-Commercial-Buildings-Energy-Efficiency.html). One tip to help make the process of gathering your utility information easier is to use the free tools found at most utility companies. As an example, Pacific Gas & Electric provides free commercial access to your building’s meter information that can be saved as an excel file.1 That will make gathering the last 12 months of data easy and a breeze to calculate.

So now you have converted your utility bills to kilowatt hours per square feet per year, what do the numbers mean? Just like miles per gallon for an automobile, kilowatt hours per square feet (kwh/sq.ft./yr.) is the best way to see if your building is energy efficient and create a plan to improve your efficiency.

Commercial buildings are in a way like having a custom car without anyone giving you any information as to how much gas the car should use to operate normally. In a typical commercial office or headquarter type space that operates say 6 days a week, it might have up to 10% of the space used for computer rooms that support computers and telephones. It is easy to know if the kwh/sq.ft./yr. is a good number or not. On the West Coast, a typical commercial office building should operate under 16 kwh/sq.ft/yr. That number is what I would consider a reasonably efficient building. In fact, the EPA Energy Star award level for that same building on the West coast would need to be about 17 kwh/sq/ft./yr. to be certified as an Energy Star award level building.

Do not be alarmed if your numbers are higher, as most commercial buildings are often operating well above 16-17 kwh/sq.ft./yr. A very efficient commercial building can be as low as 11-12 kwh/sq.ft.yr., and most buildings that are not efficient can be brought to those levels without replacing the mechanical HVAC heating/ventilation/air-conditioning systems, lighting or other parts of the infrastructure. When a building is operating somewhere between the 17 and 19 level, the problems may be corrected with simple adjustments of the systems. Those types of issues often can be solved with a knowledgeable HVAC service person, or with the help of your local utility company without much cost.

If you are more than a few kwh/sq.ft.yr. above the 16-17 kwh/sq.ft./yr. level, then some type of audit should be performed on your building. As cited in the Flex Your Power best practice guide, audits generally fall into several categories:2 The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) identify three levels of energy audits:3

• Walk-through Assessment: energy bills are analyzed and, possibly, a brief visual survey of the facility is conducted. The subsequent report identifies no-cost and low-cost opportunities. This is the least costly of the three levels.

• Energy Survey and Analysis: a more detailed analysis is conducted, including a breakdown of how energy is used within the building. Recommendations consider an owner's operations and maintenance, constraints, and economic criteria. Potential capital-intensive opportunities are identified in the final report for further research and analysis. This is the typical level of audit.

• Detailed Analysis of Capital-Intensive Modifications (Investment-grade Audit): this analysis focuses on capital-intensive opportunities and provides a higher degree of monitoring, data collection, and engineering analysis. The report includes detailed cost and savings information with a high-level of confidence sufficient for major capital investment decisions, and may include a reasonable timeline for implementation of each recommendation.

The typical energy audits that you will find often are only at the first or at best second levels of audits described above. Those type of audits even the ones performed by your utility company only give an estimate and do not provide you with enough detail to make a sound investment decision to optimize the building.

Most commercial buildings are often more than 20% higher than they should be on electricity. When a building is operating that far away from the proper metrics, an investment grade audit is usually the best strategy to identify all of the available energy waste. When you are looking at companies to perform a detailed investment grade type energy audit, you should review their track record/references, get examples of their typical projects showing the metrics they achieved, and find out if they have the ability to guarantee the results.

Remember, you are looking for not just the lowest price. Rather, the goal must be to achieve energy savings that you can measure at your utility meter level. If there are no measurable performance metrics used in your process to audit the building and implement energy efficiency improvements, there is an extremely high probability that you will NOT achieve the savings you were expecting. The advantage of a having a detailed energy audit is that companies who are knowledgeable in performing energy management should all be able to guarantee the savings that they will produce. The savings should be measured and verified at your utility meter level as that is the point where your charges are determined. Whoever can identify the most energy savings that are guaranteed at your utility meter should be the company you choose to help you bring your commercial building to an energy efficient level.

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1 Most commercial buildings have the ability have electronic access as PG&E has installed upgraded meters to most of their commercial accounts: http://www.pge.com/mybusiness/myaccount/analysis/.
2 http://www.fypower.org/bpg/index.html?b=offices.
3http://www.fypower.org/bpg/module.html?b=offices&m=Planning_an_Energy_Program&s=Energy_Audits.




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