Note: Bill summaries and detailed variance reports are available for each of your billed utility services. Variance reports require at least 13 months of billing history so Gridium can compare each period to the same period one year ago. Cost data isn’t available for submeters, since they aren’t subject to utility tariffs. To see costs for a submeter’s energy, select the associated utility meter.
You’ll find individual bills in the Energy costs tab, where you can dig into the drivers of variance for each billing period.
Key headline metrics
This is what a utility bill should look like: all of the most important data right up top, placed in context against the same billing period one year ago. The comparison period dates likely won’t line up day for day, but that’s expected. Gridium searches your bill history for the most comparable bill available.
- Total cost: Copied straight from your utility bill online, including all taxes and fees (unless your bill is Direct Access without generation charges).
- Billed use: Also straight from the utility bill online.
- Billed demand peak: Again, copied directly from the bill.
- Cost per kWh: Total cost divided by total use.
- Cost per day: Total cost divided by the number of days in the bill period (found in the operational factors table below).
Variance drivers
This is Gridium’s most detailed breakdown of what’s driving the difference between this bill and last year’s.
- Operational energy use: The daily operations and baseload components of your load curve, measured in and compared with kWh.
- Demand: The peak kW reading during the bill period, converted to dollars based on your tariff, and compared to the same peak demand charge dollar figure from the comparison period bill.
- Time of energy use: Gridium buckets your load curve into the time-of-use categories from your rate tariff: on hours, off hours, partial peak, summer peak, etc. It then compares the kWh allocation across the differently priced buckets. Two load curves can total the same kWh, but if one spends more time in a more expensive bucket of the day, the cost will differ.
- Temperature response: This is one of two weather-related variance components (the other is Weather conditions, below).Gridium calculates a temperature response curve for the billing period last year and a second curve for the current billing period, then returns the difference between those two curves as the change in temperature response.If you upgrade the efficiency of HVAC hardware in your building, you’ll see an improvement in the temperature response curve. The weather effect will still be there, but the amount of energy your building uses in response to weather will be lower. Refinements to BMS scripts can have similar results. This calculation isolates the change in energy use due to conditions internal to the building.
- Weather conditions: This is the second weather-related variance component.Weather conditions variance holds your building’s temperature response constant: Gridium draws an average temperature response curve and applies that single curve to both the current billing period and the billing period from last year.With one average temperature response curve, Gridium can calculate the change in energy use associated only with the change in temperature. For example, if weekday average temperature in September last year was 88°F and this September was 84°F, the single response curve produces an energy use estimate at each temperature, and the difference between those two estimates is the weather conditions variance. This calculation isolates the change in energy use due to conditions external to your building.
- Rate changes: Once all other drivers of variance are quantified, the remaining portion is assigned to rate changes. Keep an eye on this one; suspiciously high rate variances can be signs of utility billing errors.
- Bill period length: More than just the difference in number of days between bill periods. Gridium groups types of days together: weekdays, weekends, and holidays. It calculates the average kWh and dollar costs for each type of day, and then compares them.
- Total: The bottom line total dollar change.
Operational factors
This table adds another layer of detail to the difference between your selected bill and its comparison period.
- Peak demand: The highest kW demand set by your meter during the current bill and the comparison period bill.
- Heating degree days: One heating degree day means the average outdoor temperature for that day was one degree below 65°F. The colder it is, the more heating degree days add up: 60°F for one calendar day equals 5 heating degree days. This metric is particularly relevant for meters connected to human-occupied space, and is not used in Gridium’s quantitative models or analytics.
- Cooling degree days: The opposite of a heating degree day. If the average temperature for the day is 66°F, that’s one cooling degree day. Like heating degree days, this is relevant for human-occupied space and is not used in the quantitative models or analytics.
- Bill period: The raw, unadjusted difference in calendar days.