Demand Estimation

We provide the analytical support for the daily estimation of demand and billing responsibilities of Great Britain’s Gas Industry.

The Role of Demand Estimation

The Demand Estimation team create parameters for delivering critical processes to Britain’s gas industry, including:

  • Non-Daily Metered Nominations and Allocations
  • Capacity and Commodity Invoicing
  • Annual Quantity Calculation
  • Opening Read Estimation

The DESC parameters are reviewed and approved by the gas industry each summer. They are then loaded into our systems ahead of the upcoming gas year.

This information is then provided for authorised industry use.

Key Demand Estimation parameters

What we do...


In order to...


Represented by...


For use in...


Estimate how consumers typically use their gas during a year

Develop consumer consumption profiles

The Annual Load
Profile (ALP)

Demand Attribution, AQ and opening read estimation

Estimate how gas consumers usage reacts to changes in weather

Understand and define weather sensitivity profiles

The Daily Adjustment Factor (DAF)


Demand Attribution, AQ and opening read estimation

Understand how gas consumers will react in the event of extremely cold weather

Understand and estimate peak day demand


The Peak Load Factor (PLF)



Capacity invoicing



Categorise gas consumers by their different usage patterns


Ensure profiles are available for a wide range of consumer types

The End User Category (EUC)



Demand Attribution, AQ, Capacity invoicing and opening read estimation

Understand and explain the relationship between weather and gas consumption

Produce a variable which we can depend upon as a ‘building block’ for modelling

The Composite Weather Variable (CWV)


Demand Attribution, AQ and opening read estimation


Define a basis for ‘seasonal normal’ weather



Enable profiles to be represented at ‘average’ conditions which creates stability for industry

The Seasonal Normal Composite Weather Variable (SNCWV)

Demand Attribution, AQ and opening read estimation



Typical timetable for producing Demand Estimation parameters

Consumption data is collected each April for the previous 12 months, together with actual weather and seasonal normal weather variables. It is this data that is used to create the parameters for the next gas year, which runs from 1st October every year.

Date Activity
Jan / Feb Produce a document which describes how demand models will be formed for upcoming analysis – known as Spring Approach document
Feb Industry Checkpoint: DESC review and approve Spring Approach document
March / April Collect and collate sample data for analysis period (typically 1st April to 31st March) and summarise supply meter points counts by End User Category (EUC)
April Industry Checkpoint: DESC TWG approve sample data aggregations for modelling
April / May Perform modelling using agreed sample data aggregations. Summarise results
May Industry Checkpoint: DESC TWG review and approve modelling results
May / June Using the approved modelling results produce and publish a first draft of all Demand Estimation parameters (ALPs, DAFs, PLFs)
June / July Industry Checkpoint: DESC TWG / DESC and industry review and approve parameters
August Prepare system interface files containing new and approved parameters Update Gemini and UK Link
October New parameters GO LIVE for gas day 1st October
October / December Analyse performance of parameters for previous gas year.
Carry out adhoc analysis in order to improve modelling for the next cycle


The Demand Estimation Sub Committee

The Demand Estimation Sub Committee (DESC) oversees the production of parameters and provides its approval for wider industry review.

The DESC is made up of both gas Shippers and Transporters. Its responsibilities are described in Section H of the Uniform Network Code (UNC).

The meetings of DESC are coordinated by the Joint Office of Gas Transporters and can be attended by any industry party. To vote on Demand Estimation matters you will need to be a member of DESC.

Contact us

Our Demand Estimation Team is responsible for the analytical activities necessary to produce the parameters on behalf of the DESC.

Email the Demand Estimation Team with any queries, questions or comments.

NDM Nomination Accuracy Report

This report shows the national Non-Daily Metered (NDM) nomination energy values and the D+1 (initial view) and D+5 (close-out) NDM allocation positions.

A percentage value is provided to display the difference between the NDM nomination and NDM allocation figures. 

This document is prepared by Xoserve as the Central Data Service Provider (CDSP) and published on behalf of National Grid.

NDM Nomination Accuracy Report 2020-2021

Last updated on 30 Dec 2021

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