Energy data
How energy data flows through the GB system, and why the 2026 MHHS rollout changes everything.
Thirty million smart meters generate about 2.7 billion readings a day. Six DNO groups publish real-time network data. Elexon runs the settlement of every half hour. By 2026, Market-wide Half-Hourly Settlement will put every GB meter on 30-minute settlement, and the Data Integration Platform will route messages the 1998 protocol could not. This is the biggest data architecture change in GB energy since the Central Settlement System was built in 1990.
08Route 8 of 12 · Data and standardsAfter this route you will be able to
- Name the five stages of the GB energy data journey and the actor responsible for each.
- Explain what CIM, MHHS and DIP are, and how they interlock.
- Identify the public APIs that every GB energy analyst can use today.
- Describe the LTDS v2-1-0 release and what Ofgem requires every DNO to publish.
- Make a reasoned call on the 2025 data-sharing framework.
21 March 2024MHHS Programme Update 38 · 12-month delay announced
The market-wide settlement reform slipped twelve months, and the reason was data.
Market-wide Half-Hourly Settlement is the biggest operational change to GB retail energy in a generation. Every meter in GB would move from one reading per month (for non-half-hourly customers) to one reading per half hour. Half-hourly settlement would enable time-of-use tariffs, smart demand response and cost reflectivity. The original go-live was October 2025.
On 21 March 2024, Elexon as Programme Party published
The headline cost is several hundred million pounds of additional programme spend and a year of delayed consumer benefit. The systemic lesson is that the hardest part of energy-system data reform is not the code. It is getting 60 organisations to agree on what the fields mean.
Smart meters have been rolled out for a decade. Settlement has been defined for 30 years. Why does it take another 18 months to put them on the same page, and what does that tell us about data governance across the rest of the energy system?
The answer sits in the journey a single data point takes. From a meter, through ten intermediaries, to a settlement figure that changes what a supplier charges.
Section 01 · The data journey
Five stages, five accountable actors.
The simplest way to read GB energy data is to follow one reading from generation to bill. Each step has a defined custodian, a defined protocol, and a defined time budget.
Stage 01
Generate
The reading happens: a smart meter logs consumption, an AMR logs generation, a SCADA point logs network flow.
Stage 02
Collect
DCC retrieves smart-meter data. Meter operators poll non-smart and industrial meters. Network operators collect SCADA telemetry.
Stage 03
Validate
Data passes quality rules: range, continuity, revision history. Gaps are flagged. Disputes are raised.
Stage 04
Settle
Energy consumed in each half hour is reconciled against energy supplied. Imbalance prices apply. Money moves.
Stage 05
Share
Aggregate data is published via BMRS, carbon APIs, NESO operational data. Consumer data flows to suppliers and, with consent, to third parties.
Source: DESNZ Energy Data Strategy 2025; Elexon MHHS Interface Specification December 2025.
Section 02 · The data stack
CIM, MHHS, DIP are the three load-bearing standards.
Every large data programme in GB energy maps to at least one of these three. Understanding what each one is makes every data reform debate legible.
CIM. Common Information Model (IEC 61968/61970). A data model for describing power system assets, topology, ratings and limits. Used by the Long Term Development Statement (LTDS) that every DNO publishes annually under Ofgem rules. LTDS v2-1-0 uses four CIM profiles: Equipment (EQ v7), ShortCircuitResult (SCR v3), SYSCAP v5, Header v1. Files are RDF/Turtle, validated by SHACL constraints.
MHHS. Market-wide Half-Hourly Settlement. The Elexon-led programme to move every GB meter onto half-hourly settlement. Requires coordinated change across settlement, suppliers, DNOs, meter operators, and the DCC. Go-live now expected late 2026. The payoff: full cost reflectivity, time-of-use tariffs at scale, smart demand response.
DIP. Data Integration Platform. A new shared platform that routes messages between MHHS parties. Replaces bilateral integration: every supplier used to build interfaces to every DNO, a quadratic cost. DIP is a hub-and-spoke. Messages follow
All three standards interlock. LTDS (CIM) feeds DNO network models. DNO network models feed NESO's Future Energy Scenarios. NESO's FES drives policy decisions at DESNZ. MHHS settles the transactions those decisions shape. DIP is the plumbing.
Each Distribution Network Operator shall publish, by 31 December each year, a Long Term Development Statement. The statement shall provide sufficient technical information for interested parties to assess connection opportunities and plan operational decisions.
Distribution Licence Standard Condition 25 (Ofgem)
Section 03 · Public APIs
Anyone can query GB energy data. Start with BMRS and Carbon Intensity.
A striking feature of GB energy is how much operational data is public. Most other large economies keep their system-operator telemetry behind a commercial licence. GB does not.
BMRS (Elexon). The primary operational data feed: generation by fuel type, demand, imbalance prices, balancing actions, system margin. Updated every few minutes. Free and open. REST and SOAP interfaces. Essential for any operational analysis.
Carbon Intensity API (National Grid / NESO). GB carbon intensity at 30-minute granularity, with regional variations and 48-hour forecasts. Used by consumer apps, EV chargers, time-of-use tariffs. Free and open.
NESO Data Portal. Historic and near-real-time operational data, including constraint actions, system inertia, frequency response procurement, Future Energy Scenarios datasets. Free and open under OGL.
DCC (Data Communications Company). Smart meter communications. Access is not public; it is consent-based for suppliers and their authorised agents. The private-to-public boundary sits at aggregated DNO/NESO data.
Ofgem compliance data. Price controls, consumer complaints, ECO scheme data, network reliability indicators. Published alongside decisions.
Section 04 · Privacy and governance
Half-hourly data is personal data. The 2025 framework draws the line.
A 30-minute consumption reading is enough to infer when a household is home, whether it has a baby, when it watches television. UK GDPR classifies half-hourly consumption as personal data. How it can be shared, and with whom, is a live regulatory question.
The 2025 DESNZ Smart Energy Data Strategy introduced tiered consent categories. Tier 1 is aggregate data, shared freely. Tier 2 is individual consumption, shared with explicit consent. Tier 3 is individual consumption with device-level disaggregation, requiring opt-in and purpose limitation.
The Information Commissioner's Office and Ofgem jointly oversee the regime. The Smart Energy Code includes specific duties on the DCC, suppliers, and third-party access providers. Third parties wanting to use smart-meter data for innovation must accredit through the
Common misconception
Smart-meter data belongs to the supplier.
The data belongs to the consumer under UK GDPR. Suppliers are the controller for settlement purposes. For any wider use (research, innovation, product offers), the consumer must give explicit, purpose-specific consent. Breach of this principle would be an ICO enforcement matter.
Section 05 · The sharing call
Open by default, or consent-first? Pick a data-sharing posture.
The tension runs through every smart-meter debate. Innovation wants data. Privacy advocates want consent. The posture you pick shapes what is possible.
Check your understanding
Three questions on what you have just read.
Key takeaways
- Five stages: generate, collect, validate, settle, share. Each stage has a named accountable actor.
- CIM, MHHS and DIP are the three load-bearing standards. They interlock.
- GB is unusual in how much operational data is public. BMRS, Carbon Intensity API and NESO Data Portal are the three primary sources.
- Half-hourly data is personal data under UK GDPR. The 2025 tiered framework is the working governance model.
- The 12-month MHHS delay was a data governance failure, not a technology failure. Getting 60 organisations to agree is the hard part.
References
- Elexon: Market-wide Half-Hourly Settlement programme
MHHS programme governance, schedule, interface specification.
Primary source for MHHS reform.
- Elexon BMRS
Real-time GB generation, demand, balancing and price data.
Operational data authority.
- National Grid / NESO: Carbon Intensity API
30-minute grid carbon intensity with regional breakdown.
Widely-used public API reference.
- Ofgem: Long Term Development Statement (LTDS)
LTDS v2-1-0 requirements, CIM profile definitions, SHACL validation.
Regulatory source for DNO data publication duties.
- Smart Energy Code Company
Smart Energy Code, DCC obligations, third-party access rules.
Data governance authority.
- Information Commissioner's Office
UK GDPR guidance and enforcement.
Privacy regulator of record.
The next route goes deeper on LTDS and CIM. What the DNOs actually publish, and how you can validate it.