Taking stock
Using the BEPI to organize your energy management plan By Matthew Redekopp, P.Eng., CEM, LEED AP Getting started with an energy management program in your district or across your campuses can be a daunting task. Of your many buildings, on which do you begin focusing your efforts? What improvements do you make and which do you start with? The simple and straightforward starting point is to organize your efforts and benchmark your facilities using a metric called the Building Energy Performance Index (BEPI), a.k.a. the Energy Utilization value (EU). The BEPI uses the units of energy divided by area and is commonly seen in the form ekWh/m2, ekWh/ft2, and eGJ/m2. Provincially you can expect to see the first, and federally the last. The “e” prefix identifies the energy unit as encompassing many energy types including electricity and fuels (e.g., natural gas). It is shorthand for “equivalent” and it tells the reader that one energy type’s units of measure has been converted into that of another for the purpose of comparison. By this approach you can speak of kilowatts of propane without ofDGMAd_D.G. MacLachlan Ltd_ad.qxd 12-03-30 9:44 Page fending the convention of measuring propane in litres orAM cubic feet.1
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There are two types of information embodied in the BEPI – total energy and total size. The recipe is simple: for each building under your care, gather all the energy records for a sample year, convert all units to a common equivalent unit, combine them, and divide the result by the total conditioned floor area. The result is a number that is rendered independent of building size and therefore useful for comparison. Thus your largest and smallest buildings now share common ground. Building a BEPI chart is a simple task if you are a fluent in spreadsheets. You first order the data, then sort it, and lastly combine the sorted data into a graphic. Recognizing that spreadsheets are foreign to some readers, I will provide a brief overview of the process and have gone so far as to host a sample file for download at tinyurl.com/8xxvcm9. Step 1 - Open your earliest SMART tool Excel file and save it as a new file. Open each successive SMART file and copy/paste the rows from below the header down into this new file. Once complete, you should have a spreadsheet listing every building for two to three years of monthly records. Step 2 - Highlight the building name column and copy/paste it to a blank column. Highlight this new column and select the function “Remove Duplicates” from the data ribbon menu. Sort the remaining list of building names alphabetically with the “A-Z” button. Step 3 - Create a table on the same sheet as the data from the list of names. Add, as headers to the table, the number of years for which data
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is available and each type of energy unit (see Figure 3). Use the “Sumifs” Excel function (a multiple-condition sum function) to add up all the entries based on the building name, year and unit.
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Step 4 - Convert the non-kWh units to ekWhs using the conversion
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factors listed in the Toolbox (Figure 4). For example, natural gas is con-
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PrecisionAirQuality_Ad_PrecisionAirQuality.qxd 12-03-30 verted to ekWhs by multiplying the total GJs by a factor of 278.9:58 AM Page 1
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