What are Triads?

In the UK, National Grid determines the three highest half hour periods of demand during the winter months. These are termed “Triads” and are used to calculate your Transmission charges.

To be recognised as a Triad these three half hour periods must:

✔ Fall between 1st November and 28th/29th February
✔ Be separated by a clear window of at least ten days

If you are charged for Transmission separately, your average demand during the three Triad periods is multiplied by your regional tariff to determine how much you pay each year.

The Triads are only announced at the end of the season by National Grid, this happened at the end of last week.

History repeats itself – trends are hard to change.

Two of the three Triads this year fell on a Monday.

As well as being possibly the worst day of the week, Mondays are the most common day for a Triad period to occur with around 40% of Triads falling on this day.

Both of these Monday Triads also took place between 17:00-17:30, this is a classic time slot for Triads, as it is typically when commercial and residential demand coincides.

However, one of the Triads fell between 16:30-17:00, this has not happened since the 1997/98 Triad season.

This season’s Triad periods are shown below:


Want to know more about Triads?

Read our handy guide on Transmission costs and the complicated Triad charging methodology.

Three in the same year – a first!

For the first time since National Grid records began in 1990, all three of this season’s Triads fell within the same year (2019). In every other previous Triad season, we have seen at least one Triad fall after the turn of the year. However, no Triads took place in 2020 this season.

Consequently, this year saw the earliest final Triad on record (December 17th). This shows the importance of being ready for the Triad season.


What should you do next?

Use our FREE Cost Reporting tool to review your site’s Transmission costs

Sign in to Stark ID now, and:

  • Audit your Triad charges where necessary
  • Find out which of your sites successfully shifted load
  • Determine which sites cost you the most

To unlock Stark ID’s FREE Cost Reporting, you will need to provide us with some information about your tariff. Download a form here.

If you have Cost Reporting unlocked already, then go to Static Reports > Cost and select an Actual Triad report to see how your sites performed.

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Check out the full range of Stark’s cost analytics here.

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