If you receive only a net-metered bill from your utility, meaning your bill only shows the difference between the energy you imported from the grid minus the energy you exported (N = C – B), then you’ll need to calculate the values for A, B, and C below using your bill and your organization’s internal records.
Three values are required if you have onsite green power:
- A: The energy you generated onsite and used onsite
- B: The energy you generated and exported to the grid
- C: The energy you purchased from the grid
If you have a net metering setup, you may not have access to A, B, and C. However, its expected that you would have access to:
- G (Generated): Total onsite energy generated, G = A + B
- N (Net): Total net energy from the grid, N = C - B
Note that G and N, are not enough to obtain the three required values (A, B, and C). If you can get either A, B, or C – in addition to the net-metered consumption (N) and the total onsite generation (G) – then you will be able to benchmark your property completely and correctly (see example below). If you cannot obtain the necessary values, then you will need to take an alternate approach. If you cannot obtain the necessary values, then you will need to take an alternate approach. Please contact us for further assistance.
Below is an example of calculating A, B, and C, when your energy bills are net-metered. In this example, the utility provides a value for “energy generated onsite and exported offsite” (Flow B). Not all utilities will provide this value alongside the net-metered consumption value. Furthermore, your utility may use other names to indicate these values, compared to the terminology used in Portfolio Manager. If you have any questions about what a specific item on your utility bill means, ask your utility.
Value A: The energy you generated onsite and used onsite. Take value G (Generated) that you obtained from onsite measurements of energy production during the relevant billing period (in this case 1,000 kWh) and subtract B (50 kWh), then enter the result in the “Energy Used Onsite” column of your onsite meter, as shown below (950 kWh).
Value B: The energy you generated onsite and exported to the grid. Get this value from your utility bill (or from your organization’s data logs for the relevant billing period, if appropriate sub-metering is in place), and enter it in the “Energy Exported Offsite” column for your Onsite Green Power meter, as shown below. In this example, the value is 50 kWh and comes from the utility bill.
Value C: The energy you purchased from the grid. Take value N from your utility bill (25 kWh), and add A (50 kWh) to calculate the total amount of energy the building used that was physically supplied by the grid (75 kWh). Input this value in your Electric Grid meter.
Note: It may be helpful to set up formulas to run these calculations within a spreadsheet file so you don’t need to repeat the calculation manually each month.