Reading type is the format in which points record and report data. An accurate reading type is required for correctly processing data being sent to Atrius.

Atrius supports five reading types:

Before proceeding, make sure you have a solid understanding of kilowatts (kW) versus kilowatt-hours (kWh). If you need a refresher, see Understand kW vs. kWh.

Sometimes you have a choice of reading types when exporting data from a point. If so, obtain data using one of the reading types in the 100% accurate list below:

100% accurate reading types:

Less-than-100% accurate reading types:

Points with a totalizer reading type, also known as an accumulator reading type, behave the same way that car odometers do: they only go up and they generally report the total amount consumed since they were installed. Car odometers report total miles ever driven, and points with a totalizer reading type report total kWh of electricity ever consumed, or total gallons of water ever consumed, etc. Some totalizer points may "turn over" periodically, meaning that they reset to 0, then start counting up again.

Here is what data from a point with a totalizer reading type might look like:

As you can see, the totalizer values are always increasing. To calculate the amount of electricity consumed between two readings, you simply subtract the earlier reading from the later one. This is often referred to as calculating the delta, and produces a value that is referred to as an interval consumption value.

For data with a totalizer reading type, only the totalized value needs to be sent to Atrius (or entered via a form, or uploaded via Batch Point Data Upload). Atrius automatically calculates the interval consumption value.

Points with an interval demand reading type report the average rate of consumption (or production) during a specific interval of time.

Here is what data from a point with an interval demand reading type might look like:

If you look at the data closely, you might notice that the kW values are exactly four times higher than the interval electricity consumption (measured in kWh) values given in the second table, above. That’s because the interval electricity consumption value (measured in kW), for a one-hour period will be equivalent to the total amount of electricity consumed during that hour, expressed in kWh. For example:

50 kW x 1 hour = 50 kWh

We can now easily see why the kW values in the table above are four times larger than the interval electricity consumption kWh values given in the second table:

44 kW x 1/4 hour = 11 kWh

Points with an interval consumption reading type report the total amount consumed (or produced) during a specific interval of time.

Here is what data from a point with an interval consumption reading type might look like:

Although the example data set above shows consumption for 15-minute periods, data from a point with an interval consumption reading type could also be reported at other frequencies, such as 1-minute, 5-minute, hourly, daily, weekly, or even monthly or yearly.

Energy management systems most commonly report data every 15 minutes.

Data with an instantaneous measurement reading type report measurements at a particular instant in time. Typically, the value being measured is the rate of consumption.

Here is what data from a point with an instantaneous measurement reading type might look like:

These measurements are, as their name suggests, instantaneous, and so only provide a snapshot of what is happening at that exact moment.

Total consumption is estimated from the instantaneous measurement values by assuming that consumption during the period preceding the measurement is the same as it was when the measurement was taken. However, since the actual consumption between snapshots can be very different from the measurement the snapshot captured, points with instantaneous measurement reading types are not as accurate as the other point reading types listed above.

Here’s an example to illustrate why instantaneous measurement reading types are less-than-ideal and only provide an estimate of actual consumption:

Assume that the actual consumption of your building is shown by the orange line in the graph below, and that your point with an instantaneous consumption reading type records a reading every hour, shown by the vertical red lines in the graph below:

Using only the information we have from our point (i.e., the kW values at each of the timestamps with a red line), we estimate the total kWh consumed in the one-hour periods preceding each red line to be equivalent to the area of the red shaded regions below:

As you can see, the red shaded regions—the kWh consumption estimate for 6am to 9am that can be produced when the only available data is instantaneous demand values—is significantly different than the yellow shaded region between 6am and 9am, which is the actual amount of electricity that was consumed during that time period.

Here is what data from a point with a totalizer reading type might look like:

As you can see, the totalizer values are not always increasing (in comparison to a standard totalizer point).

However, just like with a standard totalizer point, to calculate the amount of electricity consumed or produced between two readings, you simply subtract the earlier reading from the later one. This is often referred to as calculating the delta, and produces a value that is referred to as an interval consumption value.

For data with a bi-directional totalizer reading type, only the totalized value needs to be sent to Atrius (or entered via a form, or uploaded via Batch Point Data Upload). Atrius automatically calculates the interval consumption value.