Half-hourly data: the foundation of tariff decisions

Half-hourly data is your electricity consumption recorded in half-hour intervals, matching the resolution at which the GB market settles. It is the single most decision-relevant dataset a business energy buyer can hold, and most businesses have never looked at theirs. The market is moving the same way: under market-wide half-hourly settlement, consumption is increasingly settled at this granularity across the board, not just for large sites.

The reason it matters is simple. Electricity does not have one price; it has a price for every half hour, shaped by the wholesale market and by time-banded network charges. Two businesses with identical annual consumption can have very different fair costs, because one consumes overnight and one consumes at the evening peak. Annual consumption tells you how much you buy. Half-hourly data tells you what your consumption should cost.

What the data reveals

A year of interval data shows your load shape: baseload that never switches off, daytime operational load, peaks and their timing, weekend and seasonal patterns. It shows whether your demand coincides with expensive periods, whether your baseload is larger than your operation justifies, and whether your capacity arrangements match reality. Almost every mismatch between a business and its tariff is visible in this one dataset.

A handful of shapes recur often enough to be recognisable on sight. Cold storage, refrigeration and server rooms produce a flat baseload that barely moves across the day or the week, straightforward to model but exposed to any pricing structure that penalises constant consumption. Offices show a sharp weekday ramp from a low overnight floor, peaking mid-morning and again in the early afternoon, then falling away at weekends almost to nothing. Retail sites carry an extended trading-hours plateau that stretches into the evening peak, precisely the window that costs most on both wholesale and network pricing. Manufacturing sites often show shift-pattern steps, distinct plateaus through the day, or a single dominant shift with a long flat tail from equipment left running. None of these shapes is inherently good or bad. What matters is how each one lines up against the times that are expensive to consume, and that alignment differs for every site, which is exactly why a single tariff recommendation across a portfolio is usually wrong for at least some of it.

Getting hold of yours

The data already exists. For half-hourly settled meters, the appointed data collector records it and the supplier settles on it. For smart and advanced meters, the interval reads are captured even where billing does not use them. You are entitled to your own consumption data, and you can authorise an independent party to obtain and analyse it without changing supplier or contract.

There are three practical routes to it. For a half-hourly settled meter, the appointed Meter Operator or Data Collector already holds the data, and a written request, or a Letter of Authority naming a third party to request it on your behalf, should return it without any contract change. For sites with smart or advanced meters not yet settled half-hourly, the interval reads sit with the Data Communications Company and can be requested through the same mechanism. Suppliers can also provide it directly, since they receive the settlement data themselves. In practice, the obstruction is rarely a flat refusal. It is delay: a request routed to the wrong team, a portal that only exposes monthly totals rather than the underlying half-hourly reads, or a response that the data “is not readily available” when what is actually true is that nobody has asked for it in that format before. Persistence and the correct authority paperwork resolve almost all of it. A genuine refusal, as opposed to a slow one, is rare enough to be worth escalating.

From data to decision

The data is the foundation, not the answer. The decision layer is modelling: overlaying your load shape onto candidate tariff structures, network charge bands and, where relevant, generation and storage, to see what each choice would actually have cost you. That is the difference between choosing a tariff and choosing a quote. Every serious energy decision, from a contract renewal to a battery, starts from the same half-hourly baseline.

If you want your half-hourly data collected and read properly, request a benchmark at /benchmark or book a review at /book.