AEC Market Education - Module #6
How to Read Your Interval / IDR / SMT Data.
Part 1
Your bill tells you what you spent. Interval data tells you the story.
Every commercial electric meter in ERCOT above a certain size records your usage every 15 minutes. That’s 96 data points every single day — 2,880 or more per month. Your monthly bill collapses all of that into a handful of line items. Interval data is what’s underneath.
What you see on your bill
Monthly total
One number. 46,428 kWh. That’s everything your building consumed for the entire month, collapsed into a single figure. Useful for paying the bill. Not useful for understanding your building.
What interval data shows you
2,880 data points
The same month, broken into 15-minute slices. You can see when your building wakes up, when it peaks, what runs overnight, and where the anomalies are. This is where the story lives.
The core idea
“A flat load is cheap to serve. A spiky, unpredictable load is expensive. Your interval data is proof of which one you are — and your REP already knows.”
When a REP prices your electricity contract, they don’t just look at your total kWh. They look at your load shape — when you use power, how much it varies, and how predictable your peaks are. Interval data is the source of that analysis. Understanding your own data before you go to market is one of the few genuine information advantages a buyer can have.
Part 2
How to read the file
When you download your interval data from Smart Meter Texas, you get a CSV file — a plain spreadsheet that opens in Excel or Google Sheets. At first glance it looks like a wall of numbers. Here’s what those columns actually mean.
Smart Meter Texas — Green Button CSV format (sample rows)
| Date | Start Time | End Time | Usage (kWh) | Estimated |
|---|
kWh ÷ 0.25 = kW
How to calculate demand from a 15-minute interval: Each row covers a quarter-hour (0.25 hours). Divide the kWh reading by 0.25 to get the average kilowatt demand during that interval. A reading of 11.25 kWh ÷ 0.25 = 45 kW demand. That single number — your highest kW in any 15-minute window all month — is what sets your demand charge.
The demand charge trap
Your demand charge for the entire month is set by a single 15-minute window — your highest read. It doesn’t matter if that peak was a one-time event. A compressor that kicked on during an unusual moment, an extra piece of equipment that ran at the wrong time, a maintenance crew that fired up everything at once. The meter doesn’t care. One bad interval can cost you hundreds of dollars in demand charges for the full month.
Part 3
The four things worth looking for in your data
Once you can see your interval data, you’re looking for four signals. Each one tells you something different about your building and your energy costs.
Part 4
What your load shape actually looks like
The most useful way to visualize a month of interval data is a heat map — each column is a day, each row is a time of day, and the color shows how much power was being used. Darker means more usage. The pattern that emerges tells you more about your building than any single number on your bill. Toggle between building types below.
Monthly load shape — 30 days × 24 hours
Day 1Day 10Day 20Day 30
Low
High
Hover over any cell to see the usage at that time
Load factor: the number that summarizes your load shape in one figure
Load factor
Office building
72%
0% — pure spike50% — typical commercial100% — perfectly flat
Above 70% is generally favorable for pricing. The more consistent your usage, the less risk premium a REP needs to build into your rate.
Part 5
How to get your data from Smart Meter Texas
Smart Meter Texas is the free, state-run portal where every ERCOT customer can access their own interval data going back up to two years. Here’s exactly how to download the file you need.
You’ll need your ESI ID
Your ESI ID is a 17 - 22 digit number that uniquely identifies your meter. It’s on every deregulated electricity bill, usually near the top near your account number or on the meter bar. If you can’t find it, your REP or your TDU can look it up by address. You’ll need it to register on Smart Meter Texas.
Part 6
Now explore your own data
Built for this purpose
Utility Data Explorer — upload your SMT file and see it come to life
Upload the CSV you downloaded from Smart Meter Texas and the app will instantly produce the same kind of visualizations you’ve seen in this module — a line chart of your usage over time, a daily pattern chart, a weekly summary, and a heat map showing your load shape. No account needed. Your data never leaves your browser.
Free to use
No account required
Works with SMT Green Button CSV
Line chart
Daily pattern
Heat map
Weekly summary
▶ Demo mode available — try it without uploading anything first
What to do after you see your data
If your heat map looks spiky and unpredictable, or if you can see large peaks that seem out of proportion to your overall usage, that’s worth a conversation. A broker who understands interval data can help you identify whether those peaks are driving excess demand charges, whether your load factor is affecting your contract pricing, and whether there are operational changes that could meaningfully reduce your bill before you even shop for a new rate. Reach out any time →