Triads are the three half-hour periods of highest system demand between November and February each year, separated by at least ten clear days. The following factors all have an impact on the occurrence of the Triad periods:

  • Temperature
  • When it gets dark
  • Embedded wind generation
  • Overlap of business and domestic demand

Our Triad services

Our dedicated Energy Management team provide a Triad warning service. We will alert you when a Triad is possible so you can prepare and react accordingly.

Each warning comes with:

  • A likelihood scale to help you understand the possibility of it being one of the three triad periods
  • Forecast of peak within day demand to compare to previous peaks in the same season
  • Commentary to explain why the alert has been sent

Click here to sign up to our Triad Alert email/text service

Impact on customers

The National Grid and Scottish equivalents are paid a Transmission Network Use of System (TNUoS) fee in order to finance the cost of maintaining and upgrading the transmission network, this fee/benefit is variable for consumers dependent on line loss factor and which DNO (distribution network operator) you fall under.

Retail customers receiving pass-through charges pay their share based on consumption during Triads. Sign up for our non-commodity costs quarterly webinars to keep up to date with forecasts for future Triad costs.

> Read how Saint-Gobain UK "powered down" to reduce Triad costs

Embedded generators receive TNUoS as a benefit, since by generating power directly onto the distribution network, the workload for the transmission network is reduced. Sign up for our embedded benefits quarterly webinars to keep up to date with forecasts for future Triad benefits.

Winter 2018/19 Triad forecast

Watch the below segment from our October 2018 non-commodity costs webinar for our latest Triad forecast:


Winter 2017/18 results

If you receive SmartestEnergy's Triad Warnings, you'll be pleased to know that all three Triads were predicted correctly. The three Triads all occurred on the following days:

  1. 11th December 2017 (48,582MWh GB demand)
  2. 5th February 2018 (47,099MWh GB demand)
  3. 26th February 2018 (47,123MWh GB demand)

> See the data

Source: National Grid