HNTAS and KPIs

Get to grips with HNTAS and what Ofgem will soon expect from your network. Learn how to measure efficiency, reliability and data quality

HNTAS and the Big 6 (KPIs)

The Heat Network Technical Assurance Scheme (HNTAS) is the technical backbone of Ofgem's consumer protection framework. It sets the standards that make heat networks affordable, reliable and low carbon - turning regulation from principle into practice.

HNTAS establishes minimum technical standards for how networks are designed, built, operated, and maintained, ensuring they deliver on the vision of a fair and efficient energy system.

Its purpose is simple: to raise the bar for performance, transparency and trust.

HNTAS Scheme Objectives & Core Principles

Vision = a fair and efficient energy system
Aims = minimum technical standards.
Objectives = carbon reduction, cost reduction, consumer confidence.
Principles = "designed to be enforceable but also proportionate."

Why this Matters

Drawing on experts and Ofgem's consultation papers, the KPIs are expected to include: (consultation closed October 2025)

Heat Efficiency

Proportion of purchased energy that reaches residents.
Industry benchmark: >60% efficiency (many networks today operate below 45%).

Heat Loss

Targets to reduce distribution losses (often 30–50% today).

Reliability & Availability

Uptime of heat supply to residents (measured in % of hours per year).

Billing & Transparency

Accurate bills based on consumption data.
Clear debt management processes and consumer protection.

Carbon Performance

Alignment with Net Zero trajectory.
Reporting on energy sources, carbon factors, and future decarbonisation plans.

For years, many networks escaped scrutiny - inefficiency was hidden. HNTAS changes that.

A KPI (Key Performance Indicator) is simply a measurable value that shows how well your heat network is performing against agreed standards.

Under HNTAS, KPIs turn raw data from meters and sensors into actionable insights - things like average flow temperature, network efficiency, and system losses. They are the benchmarks Ofgem will expect property managers to monitor, report, and improve against.

Residents gain new rights: They’ll see how their network performs compared to national standards.
Managers gain accountability: If your network scores poorly, you’ll need to demonstrate an action plan to improve.
Costs are on the line: Poor performance equals higher bills, higher complaints, and potential regulatory fines.

What's Been Published

The draft HNTAS technical specifications (published July 2025) now include defined KPIs and monitoring points for each element of a network: A public consultation on the scheme is expected to follow in the near future.

Defined KPIs & Monitoring Points

Energy Centre – boilers, CHP, or heat pumps supplying thermal energy
District Distribution Network – pipework between plant and buildings
Communal Distribution Network – risers and laterals inside buildings
Substations – secondary plant connecting different parts of the network
Customer Connections – interface between the network and individual dwellings
Customer Heat Systems – HIUs and in-home heating/hot water systems

The Big 6 KPIs for HNTAS & Elements within the Scheme

For each of the Defined KPIs & Monitoring Points, the specification sets out:

The KPI itself (e.g., average flow temperature, heat loss percentage).
Where to monitor (e.g., heat source outlet, block entry point).
Data required (flow rate, return temperature, energy use).
Minimum frequency of reads (as tight as every 5 minutes in some cases).
Quality checks (to avoid wild values or negative reads).

Water quality is also a critical factor in meeting network KPIs. Poorly treated or unmonitored systems can lead to corrosion, blockages and inefficiencies that directly affect flow temperatures, heat losses and long-term performance. Maintaining proper water treatment and regular sampling isn’t just good practice - it’s essential for achieving and sustaining compliance under HNTAS.

^{Image source: Guru Systems - Auditing & Improving Metering Training}

The Two Types of KPIs

Data Health KPIs (universal across all elements)

Without data health, performance KPIs can’t be calculated - and the network is automatically non-compliant.

Connectivity – has data been received within the last 24 hours?
Completeness – are all expected reads present?
Quality – do the numbers make sense, or are there errors/outliers?

Auditing & Improving Metering:

Energy Performance KPIs:

Heat loss (the most basic performance KPI - the difference between input and delivered energy).
Flow/return temperature efficiency.
Substation and HIU efficiency.

These metrics form the backbone of Ofgem’s push to bring transparency and accountability into the sector.

Market-Wide Half-Hourly Settlement

Your metering and billing systems are about to face one of the largest upheavals in UK energy markets in decades. Ofgem is introducing Market-Wide Half-Hourly Settlement (MHHS) – a major reform of the UK electricity market that will change how all energy use is measured and billed.

Today, only large commercial sites are settled using half-hourly data. Everyone else is billed using profiles or estimates based on average usage. MHHS will change that.

From 2025, every meter – residential or commercial – will be settled using real half-hourly data. Under MHHS, every meter point (MPAN) will be settled using real data every 30 minutes rather than estimated profiles.

For PMs of communal or district heat networks this change means:
More accurate measurement and billing - reducing resident complaints and protecting trust.
Performance data flows become more granular and timely — giving you insight into when and how heat is used.
Potential opportunities for new tariffs or services (e.g., time-of-use, flexibility) that align with the performance of your network.
A stronger foundation for the regulatory landscape ahead - because accurate data is central to both compliance (e.g., Heat Network Technical Assurance Scheme (HNTAS)) and operational efficiency.

What you should do now

Review your network’s metering and data architecture - ensure each dwelling, HIU and plant room meter is up to standard and capable of supporting high-resolution data flows.
Engage with your M&B partner: ask how their platform will integrate half-hourly data, support billing transparency and align with MHHS timelines.
Communicate with residents: make clear how change in data reporting and measurement might affect their bills, tariffs or consumption visibility.
Link this initiative back to your compliance story: more accurate data = fewer surprises = smoother audits.

The Bottom Line: MHHS isn’t optional. It’s not simply an electricity supplier matter. For heat network PMs, it’s part of the wider shift towards transparency, fairness and performance-based operation. Get ahead of it, and you protect your network, your residents and your compliance journey.

Key Dates

Industry code changes live: 22 September 2025.
Migration window begins: October 2025 – April 2027.
Full migration / shortened settlement cycle: ~July 2027.

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