Portfolio Manager Technical Reference: Thermal Conversion Factors

For consistency and comparability, all energy performance metrics in Portfolio Manager reports are expressed in either thousand British thermal units (kBtu) or billion joules (GJ) and are annualized to 12 calendar months. However, in most cases your energy bills are not presented in these units and are not tied to calendar months. Therefore, a series of procedures is applied to make these conversions.

Portfolio Manager offers three main meter types, based on the most common ways buildings receive energy:

  • Metered Delivery. Metered energy is used for products that are supplied by an offsite utility and immediately consumed (i.e., electricity, natural gas, and district steam).
  • Bulk Delivery. Bulk fuels are delivered, stored, and combusted on-site (e.g., fuel oil, propane, wood).
  • Onsite Renewable Electricity. Onsite renewable electricity from solar or wind power is a unique meter type in Portfolio Manager. You should be able to monitor electricity consumption on a continuous basis.

Based on your particular energy suppliers and onsite systems, you may have a variety of different meter types that are reported in different units (e.g., gallons, kWh, therms, kBtu, etc.), which can be difficult to compare. To streamline the process for you, Portfolio Manager enables flexible entry options. You can enter monthly meters and onsite renewable meters with specific start and end dates, as on your bill, and you can also enter bulk purchases with a delivery date and quantity. For all of these fuel types (17 total meter types), Portfolio Manager includes the most common billing units so that you should be able to use the same units as you see on your bill.

To aggregate your consumption across multiple meters and to provide annual metrics in reports, Portfolio Manager will convert all fuels into a standard common unit (kBtu or GJ, whichever you select in your account settings), and will annualize them to whole calendar months. Annualizing data to calendar months enables quantities from different meters to be added together, and also enables weather normalization using monthly average weather conditions. All metrics in Portfolio Manager correspond to annual (12-month) periods. You may select which 12 calendar months you want to evaluate, but you cannot choose periods that start and end in the middle of the month.

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