MHHS is a major Ofgem-led reform that changes how electricity is measured and billed across the UK. From October 2026, every electricity meter in the country will be settled on a half-hourly basis — creating 48 data points per meter, per day, based on your actual consumption.
For UK businesses, this is the most significant change to energy metering in decades. It creates both new obligations and new opportunities — particularly for SMEs that want to reduce costs and demonstrate their environmental credentials.
48
readings per meter per day
4.2TB
data generated annually
Oct 2026
full settlement deadline
The shift
Four fundamental changes to how electricity is measured, billed, and reported.
Most SMEs were previously billed on estimated consumption profiles. MHHS replaces these with empirical half-hourly data from your actual meter.
Where carbon calculations previously relied on annual grid averages, MHHS enables time-specific emission factor calculations for greater accuracy.
MHHS enables innovative time-of-use tariffs that reward businesses for shifting consumption to off-peak periods when grid carbon intensity is lower.
Authorised third parties can access your half-hourly data via APIs — enabling tools like miOhm to automatically calculate your carbon footprint.
Key dates
Migration is already underway. Here is what is coming and when.
September 2025
MHHS migration begins
Elexon begins migrating electricity meters to half-hourly settlement. Migration is now live.
October 2026
Full settlement deadline
All electricity meters must be settled on a half-hourly basis.
⚡ This deadline is approaching — miOhm helps you prepare now
January 2027
CBAM applies
Carbon Border Adjustment Mechanism applies carbon costs to certain imports — increasing the importance of accurate Scope 2 reporting.
May 2027
Migration complete
Full MHHS Target Operating Model in place across all meter types.
For your business
MHHS creates both obligations and opportunities for UK SMEs.
More accurate carbon reporting
Half-hourly data means your Scope 2 carbon calculations are based on your actual consumption, not estimated profiles. This matters when enterprise clients scrutinise your Scope 3 submissions.
New tariff opportunities emerge
Time-of-use tariffs become widely available, rewarding businesses that can shift flexible loads — refrigeration, EV charging, machinery — to off-peak periods with lower carbon intensity.
Procurement pressure increases
As large enterprises face mandatory carbon disclosure, they will increasingly require accurate Scope 3 data from their SME suppliers. MHHS makes this data available — miOhm makes it usable.
Anomaly detection becomes possible
With 48 readings per day, unusual consumption patterns — overnight equipment left running, HVAC faults, unexpected usage — become visible in a way that monthly bills never allowed.
Further reading
Direct links to government bodies and standards organisations.
Ofgem
Market-wide Half Hourly Settlement
Official programme page — policy, objectives, and implementation timeline.
Elexon
MHHS Programme
Technical implementation of the Balancing and Settlement Code.
UK Government / DEFRA
GHG Conversion Factors
Annual emission factors used for carbon reporting — the same factors miOhm uses.
GHG Protocol
Corporate Standard
The international standard for corporate carbon accounting. miOhm reports are aligned to this.
FRC
UK Sustainability Reporting Standards
Published February 2026 — the new mandatory UK framework replacing TCFD and SECR.
FAQ
Everything UK businesses need to know about MHHS.
Market-wide Half Hourly Settlement (MHHS) is an Ofgem-led reform that changes how electricity consumption is measured and billed across the UK. From October 2026, every electricity meter will be settled on a half-hourly basis using actual consumption data rather than estimated profiles.
Yes — if your business has an electricity meter in the UK, MHHS affects you. From October 2026, your meter will automatically generate 48 consumption readings per day. The main impact for SMEs is access to more accurate energy data, new time-of-use tariff options, and increased pressure from enterprise clients to submit accurate carbon data.
You do not need to take technical action — your energy supplier will migrate your meter automatically. However, you should consider how you will use the new half-hourly data. Tools like miOhm connect to your meter data and automatically calculate your carbon footprint and energy costs, so you are ready when enterprise clients ask for Scope 3 submissions.
A half-hourly meter records your electricity consumption in 30-minute intervals, producing 48 data points per day. Previously, only large businesses (above 100kW demand) were required to use half-hourly meters. MHHS extends this to all UK electricity meters regardless of size.
MPAN stands for Meter Point Administration Number. It is a unique 13-digit reference number that identifies your electricity supply point. You can find your MPAN on your electricity bill. miOhm uses your MPAN to retrieve your half-hourly consumption data from your meter.
MHHS significantly improves the accuracy of Scope 2 carbon reporting for UK businesses. Previously, carbon calculations relied on estimated consumption profiles and annual grid average emission factors. With MHHS, your Scope 2 emissions can be calculated from real half-hourly data using time-specific DEFRA emission factors — the most accurate method available.
SMETS1 (Smart Metering Equipment Technical Specification version 1) meters were the first generation of UK smart meters, installed from around 2012. SMETS2 meters are the second generation, installed from 2018 onwards, and communicate via the national DCC network. Both types will be migrated under MHHS, though SMETS2 meters provide more reliable data access for third-party tools like miOhm.
CBAM — the Carbon Border Adjustment Mechanism — applies carbon costs to certain goods imported into the UK from January 2027. Businesses involved in importing or exporting regulated goods will need accurate Scope 2 carbon figures to calculate their CBAM liability. MHHS provides the underlying consumption data that makes those figures accurate.
MHHS itself does not directly change your bill — it changes how your consumption is measured. However, it opens up time-of-use tariffs that were previously unavailable to most SMEs. If you can shift flexible energy use to off-peak periods, you may be able to reduce your bills significantly.
miOhm connects to your half-hourly meter data via your energy supplier API or a CSV export. It automatically calculates your Scope 2 carbon emissions using DEFRA grid emission factors, identifies peak usage patterns, flags consumption anomalies, and generates a GHG Protocol-aligned carbon report you can submit to enterprise clients or use for regulatory compliance.
Glossary
Plain-English definitions of the terms you will encounter in MHHS documentation.
MHHS
Market-wide Half Hourly Settlement. The Ofgem reform requiring all UK electricity meters to be settled on a half-hourly basis from October 2026.
MPAN
Meter Point Administration Number. The unique 13-digit number identifying your electricity supply point. Found on your electricity bill.
Settlement period
A 30-minute block of time used to measure electricity consumption. There are 48 settlement periods in each day, numbered 1 to 48.
Elexon
The organisation responsible for operating the Balancing and Settlement Code (BSC) — the legal framework governing how electricity is settled in the UK.
DCC
Data Communications Company. The organisation that manages the national smart metering infrastructure, connecting smart meters to energy suppliers and authorised third parties.
SMETS2
Smart Metering Equipment Technical Specification version 2. The second-generation UK smart meter standard, communicating via the DCC network for reliable data access.
AMR meter
Automated Meter Reading meter. Advanced business meters that record half-hourly consumption data. Common in commercial premises above a certain size.
Scope 2 emissions
Indirect greenhouse gas emissions from purchased electricity. Calculated by multiplying electricity consumption (kWh) by a grid emission factor (kgCO2e/kWh).
DEFRA grid factor
The UK Government emission factor for grid electricity, published annually by DEFRA. Currently 0.21233 kgCO2e/kWh. Used by miOhm to calculate your Scope 2 emissions.
GHG Protocol
The Greenhouse Gas Protocol. The international standard for corporate carbon accounting. miOhm reports are aligned to the GHG Protocol Corporate Accounting and Reporting Standard.
CBAM
Carbon Border Adjustment Mechanism. Applies carbon costs to certain goods imported into the UK from January 2027. Requires accurate Scope 2 carbon figures.
ESOS
Energy Savings Opportunity Scheme. A mandatory UK energy assessment programme for large organisations. Phase 4 deadlines are currently approaching.
UK SRS
UK Sustainability Reporting Standards. Published February 2026, replacing TCFD, SECR, and voluntary frameworks as the mandatory UK climate disclosure standard.
MDR
Meter Data Retriever. A new role created under MHHS responsible for connecting to the DCC and retrieving smart metering data for settlement purposes.
miOhm connects to your smart meter and turns half-hourly data into carbon reports, cost insights, and procurement-ready documentation.
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