HNTAS and KPIs

Get to grips with HNTAS and what Ofgem will soon expect from your network. Find out why efficiency, reliability and data quality is important.

HNTAS, KPIs and the Big 6 (Elements)

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.

Performance outcomes of a heat network can be measured using Key Performance Indicators (KPIs), which can be assessed against a target level to determine compliance. 28 KPIs have been determined and categorised into 6 Elements.

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."

Types & Categories of KPIs:

Types of KPIs:

Assessed KPIs: These are measured against predetermined targets during commissioning and operation to achieve and maintain HNTAS certification.
Reported KPIs: These are valuable metrics that are reported even if they are not directly linked to a performance target.

Categories:

Category	Aim
Monitoring and data capture	To ensure heat networks have adequate provision for data monitoring and capture. This will ensure accurate monitoring of heat networks, which improves performance monitoring, issue diagnosis and issue rectification.
Reliability	To improve heat network reliability and ensure the heat network operates to provide a stable heat supply to consumers.
Heat Losses	To prevent heat networks from being designed, commissioned, and operated with high heat losses, as high heat losses lead to poor efficiency, high costs, and overheating.
Performance	To ensure heat networks are designed, installed, commissioned, and operated in a way that ensures system longevity and reduces operational costs.
Domestic consumer outcomes	To ensure domestic Consumer Connections and domestic Consumer Heat Systems are designed, installed, and commissioned to provide a suitable service level for heat network consumers.
Water quality	To ensure heat networks are filled, cleaned, treated, and maintained at suitable water quality standards. This will aim to ensure longevity of heat network pipework and equipment, and reduce operating and maintenance costs.

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, differential pressure and heat 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.

The Elements within the HNTAS Scheme

Heat networks are made up of six key elements, each playing a different role in generating, distributing and delivering heat to residents. HNTAS uses these six elements to create structure and consistency, helping heat network operators understand where responsibilities lie, what each part of the system should deliver, and how any issues can affect overall performance and compliance.

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

The Big Six HNTAS Elements

KPI	Purpose	Covers	KPIs focus
Energy Centre (EC)	Ensure heat is generated safely, reliably, and efficiently.	Boilers, CHP, heat pumps, thermal stores Commissioning + ongoing O&M standards Safety systems, control logic, redundancy Monitoring points for flow/return temps, pressures, plant run hours	Plant availability, correct documentation, performance against design.
2. District Distribution Network (DDN)	Ensure heat is transported efficiently from energy centre to buildings.	Primary pipework routes, valves, insulation Network hydraulics and balancing Monitoring at network boundary points Temperature, pressure and flow integrity	Network condition, integrity, monitoring completeness.
3. Substation (SS)	Ensure efficient heat transfer from district network into a building.	Plate heat exchangers, pumps, controls Substation metering + 5-min data capture Flow/return stability, pressure control Access, safety, documentation	Flow/return temperature performance, stability, asset condition.
4. Communal Distribution Network (CDN)	Ensure heat is delivered through internal risers/laterals effectively.	Building-level pipework, insulation, balancing HIU feed pipework, branch valves Operational access + documentation	Pipework condition, performance, insulation compliance.
5. Consumer Connection (CC)	Ensure each dwelling receives heat efficiently, safely, and consistently.	HIUs (or direct connections), meters, controls Data quality + ARMS connectivity Return temperature and efficiency standards Standing heat loss performance	VWART / VWATD, standing losses, generation efficiency, data completeness.
6. Consumer Heat System (CH)	Ensure the in-home heating system delivers comfort as intended.	Radiators, UFH, thermostats, TRVs Room temperature performance tests Commissioning and documentation	Comfort delivery, temperature control, system responsiveness.

Data Health KPIs

Monitoring is the backbone of every heat network – it’s what makes accurate assessment, optimisation and compliance possible.

Data Health KPIs apply across all six HNTAS elements and determine whether the information coming from the network is reliable enough to support meaningful performance analysis.

Without strong data health, performance KPIs cannot be calculated and the network is automatically considered 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?

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

What's Been Published

Draft versions of the new-build assessment procedures have already been released, outlining the KPIs for each of the six HNTAS elements. More recently, in November 2025, the draft TS1 document was published. TS1 acts as the technical rulebook, setting out the minimum requirements a heat network must meet across design, installation, commissioning, operation, maintenance and performance. In effect, it elevates what was previously CP1-style best practice into mandatory technical standards.

Next Steps

Although the HNTAS requirements are not yet formally published, there are practical steps you can take now.

The most important is to review your network’s current efficiency and ensure you are compliant with existing Metering and Billing Regulations. By confirming that your meters are functioning correctly, your data is reliable, and your billing processes are accurate, you build a strong foundation for future Ofgem compliance.