HNTAS 2026: What Heat Network Technical Standards Mean for Pipe Insulation, Cladding and Valve Jackets
July 20, 2026Heat networks are moving into a more regulated environment.
On 27 January 2026, Ofgem launched new consumer protection rules for heat networks in Great Britain, covering customers in England, Scotland and Wales.
Alongside that wider regulatory shift, the Heat Network Technical Assurance Scheme, known as HNTAS, is being developed to improve the technical performance of communal and district heat networks.
For M&E contractors, heat network operators, ESCos, specifiers and facilities managers, this matters because heat network performance is not only about boilers, HIUs, substations and controls. It also depends on the pipework.
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Insulation & More supplies pipe insulation, valve jackets, cladding, trace heating and insulation accessories for communal heating, district heating, plant rooms and mechanical services projects.
What is HNTAS?
HNTAS stands for Heat Network Technical Assurance Scheme. It is the forthcoming technical assurance scheme being developed to help heat network operators demonstrate compliance with technical requirements for heat networks in Great Britain.The scheme is being developed by the Department for Energy Security and Net Zero, with technical input from FairHeat and industry stakeholders.
The aim is to move heat networks from voluntary best-practice guidance into a more formal technical assurance environment.
HNTAS is expected to build on the principles already familiar to many heat network designers and contractors through CIBSE CP1: Heat Networks Code of Practice.
Design and Operation
The draft standards cover how heat networks are designed, operated, monitored and maintained.
Heat Losses
Pipework insulation, distribution losses and system performance are becoming more visible.
Evidence Records
Projects should expect greater focus on what has been installed and how performance is demonstrated.
For insulation contractors and M&E teams, the key point is simple: pipework insulation is no longer just a finishing detail. It is part of how a heat network demonstrates long-term technical performance.
Is HNTAS already in force?
Ofgem heat network consumer regulation began on 27 January 2026 in Great Britain, but HNTAS technical standards are still being finalised and are planned to be phased in from 2027.This distinction is important.
Ofgem regulation is focused first on consumer protection, billing, service standards, complaints and supplier obligations. HNTAS is the technical assurance side.
That means HNTAS is concerned with how heat networks are designed, built, operated and evidenced.
The final HNTAS requirements are still subject to government response and finalisation, so contractors should avoid treating draft documents as final law. However, the direction of travel is clear enough that project teams should start reviewing insulation standards now.
Does HNTAS apply to existing heat networks?
Yes, HNTAS is being developed for both new and existing heat networks, although the route to compliance is expected to be phased and proportionate.New-build heat networks are expected to be assessed through design, construction, commissioning and operation stages.
Existing networks are expected to work toward compliance through staged requirements, milestones and evidence of technical performance.
That matters because many existing communal and district heating systems contain insulation issues that are easy to overlook.
- Under-insulated risers
- Damaged cladding
- Missing valve jackets
- Bare flanges
- Poorly finished bends and fittings
- Insulation gaps in plant rooms
- External pipework with weather damage
- Limited insulation records
- Incomplete as-built information
For heat network operators and maintenance contractors, the best starting point is often a practical insulation audit.
Where insulation fits into HNTAS
HNTAS is expected to make insulation performance more visible and evidence-based, especially on mains, risers, laterals, valves, fittings and exposed pipework.For this article, it is useful to think about HNTAS preparation across four practical areas.
Temperature and hydraulics
Lower operating temperatures, stable flow rates and good control strategies depend on the network being maintained properly.
Insulation and losses
Poor insulation increases heat loss from pipework and can create unwanted heat gains in risers and plant areas.
Monitoring and evidence
Technical assurance depends on being able to show what has been installed and how the system performs.
Lifecycle performance
Insulation, cladding and valve coverage need to remain effective throughout the network’s operating life.
The practical implication is that “it looks insulated” is no longer a strong enough standard. Heat network pipework should be specified, installed and recorded in a way that can support future assessment.
Why under-insulated pipework is a performance risk
Under-insulated heat network pipework can increase distribution losses, raise operating costs and undermine the performance case for the network.On a heat network, distribution losses can occur across long pipe runs, risers, laterals, plant rooms and communal areas.
Bare valves and flanges
Repeated exposed components can create avoidable heat-loss points across the system.
Damaged insulation
Wet, damaged or missing insulation can reduce the effectiveness of the pipework system.
Missing evidence
Unrecorded repairs and unclear product information can make future assessment harder.
For contractors, this creates an opportunity. A contractor who can identify, price and install the complete insulation system, not just the straight pipe lengths, is better placed to support heat network operators preparing for future HNTAS requirements.
Best product route by heat network area
The right insulation product depends on pipe size, service temperature, location, space constraints, exposure, specification and installation method.
| Heat network area | Suggested product route |
|---|---|
| Energy centre / plant room pipework | Mineral wool or fibreglass pipe insulation with suitable cladding where required. |
| Primary distribution pipework | Mineral wool, fibreglass or phenolic pipe insulation depending on temperature, space and specification. |
| Risers and laterals | Phenolic, fibreglass, mineral wool or rubber pipe insulation depending on space and temperature. |
| Valves and flanges | Internal or external valve and flange insulation jackets. |
| External pipework | Pipe insulation with PIB, aluminium or Aluzinc cladding. |
| Frost-risk sections | Pipe insulation with trace heating where required. |
| Secondary or lower-temperature circuits | Rubber or closed-cell insulation where suitable for the application. |
| Plant-room protection | Pipe insulation with protective cladding, labels and finishing accessories. |
Useful heat network product routes
Use these product routes when reviewing heat network insulation schedules, maintenance upgrades or tender packages.
Mineral Wool / Stone Pipe Insulation
Common route for higher-temperature mechanical and heat network pipework.
View CollectionFibreglass Pipe Insulation
Practical foil-faced insulation route for internal heating and hot-water pipework.
View FibreglassPhenolic Foam Pipe Insulation
Useful where thermal performance is required but available space is limited.
View PhenolicRubber Pipe Insulation
Closed-cell route for lower-temperature and condensation-risk services where suitable.
View RubberValve & Flange Insulation Jackets
Removable insulation jackets for valves, flanges and fittings requiring maintenance access.
View JacketsInsulation Cladding
PIB, aluminium, Aluzinc, Isogenopak and protective covering routes.
View CladdingTrace Heating
Heating cables, controls and accessories for frost-risk pipework sections.
View Trace HeatingInsulation Accessories
Tapes, adhesives, labels, fixings and finishing products for insulation projects.
View AccessoriesSpecifying pipe insulation for heat networks
Heat network pipe insulation should be specified as a complete system, not just as straight pipe sections.The insulation schedule should consider the pipe diameter, service temperature, location, ambient conditions, insulation thickness, thermal conductivity, fire performance, cladding, valve coverage and evidence requirements.
Mineral wool pipe insulation for heat networks
Mineral wool and stone wool pipe sections are commonly used for thermal insulation on mechanical and heat network pipework.They are often selected for primary distribution pipework, plant room pipework, higher-temperature heating circuits, mechanical services and fire-performance considerations.
Mineral wool pipe insulation is commonly paired with an appropriate outer finish, depending on location and exposure. For plant rooms and exposed areas, insulation may need additional protection from mechanical damage, moisture, UV exposure or general site conditions.
Fibreglass pipe insulation for risers and laterals
Fibreglass pipe insulation can be a practical option for heating and hot-water pipework, including risers and lateral distribution pipework where suitable for the specification.For heat network projects, fibreglass pipe insulation may be relevant to risers, plant rooms, laterals and internal distribution pipework, subject to temperature and project specification.
Phenolic pipe insulation where space is limited
Phenolic pipe insulation can be useful where thermal performance is required but available space is limited.Heat network risers and service cupboards can be tight. In those situations, the insulation specification may need a product route that helps achieve the required performance within limited space.
Rubber pipe insulation for lower-temperature and condensation-risk areas
Rubber pipe insulation is commonly used where closed-cell performance and vapour resistance are important.For heat network projects, rubber pipe insulation may be relevant to lower-temperature secondary circuits, cooling pipework, plant room services and areas where condensation control is required.
Valve and flange jackets: the detail that often gets missed
Valves, flanges and fittings are often the weakest points in a heat network insulation system.Straight pipe sections are usually easy to identify and price. The problems often appear around isolation valves, control valves, flanges, strainers, pumps, unions, meter sets, bends, tees and equipment connections.
Leaving these exposed creates repeated heat-loss points across the system. Valve and flange insulation jackets help close those gaps while still allowing access for inspection and maintenance.
Cladding for external and exposed pipework
Insulation performance can deteriorate if the insulation is left exposed to weather, moisture or mechanical damage.This matters on heat networks because external pipework and plant areas may be inspected or assessed long after the original installation.
Cladding helps protect the insulation and maintain a cleaner, more durable finish.
- PIB cladding
- Aluminium cladding
- Aluzinc cladding
- Isogenopak
- Self-adhesive cladding systems
- Protective tapes and finishes
Frost protection and trace heating on heat network pipework
Insulation slows heat loss, but it does not generate heat. Where exposed pipework may be at risk of freezing, trace heating may also be required.This is particularly relevant where pipework is external, intermittently used, in unheated areas, exposed to low temperatures or serving vulnerable systems.
Trace heating should be coordinated with insulation thickness, cable route, controls, thermostats, warning labels, fixings, cladding, power supply and maintenance access.
What about duct insulation?
HNTAS is primarily concerned with heat network technical performance, so pipework, distribution losses, temperatures, plant rooms and network operation are the main focus.Duct insulation may still be relevant to the wider mechanical package, particularly in energy centres, plant rooms and associated building-services areas.
However, duct insulation should not be presented as a core HNTAS pipework requirement unless the project specification clearly requires it.
Practical checklist for contractors and specifiers
Before ordering insulation for a heat network project, check the following:
- Are all mains, risers and laterals included?
- Are pipe sizes and service temperatures confirmed?
- Is the insulation material specified?
- Is the required insulation thickness confirmed?
- Are flow and return pipes both covered?
- Are valves, flanges, unions and fittings included?
- Are jackets required for access and maintenance?
- Is external pipework protected with suitable cladding?
- Are bends, tees, brackets and supports allowed for?
- Is trace heating required for exposed or frost-risk pipework?
- Are tapes, adhesives, labels and finishing accessories included?
- Are data sheets and product records required for evidence?
- Has product availability been checked before the order is placed?
- Are existing insulation defects recorded for maintenance works?
- Does the schedule separate internal, external and plant-room pipework?
Common heat network insulation mistakes
The most common problems are usually caused by missing details rather than the main pipe insulation itself.
- Straight pipe sections priced, but valves and flanges missed
- Riser pipework insulated, but laterals ignored
- Plant room pipework installed without removable valve jackets
- External insulation left without suitable cladding
- Damaged cladding not repaired
- Trace heating specified without controls or warning labels
- Frost-risk pipework treated as insulation-only
- No record of insulation thickness or product type
- Old pipe schedules reused without checking current service temperatures
- Poor access planning around valves and equipment
For heat network operators preparing for HNTAS, these details are worth checking now.
Send us your heat network insulation schedule
If you are pricing, reviewing or upgrading a heat network, send us your pipework schedule before you order.
Insulation & More can help identify suitable product routes for pipe insulation, valve jackets, PIB cladding, aluminium cladding, Aluzinc cladding, trace heating, tapes, labels and accessories.
Pipe sizes, pipe lengths, service temperatures and internal or external location.
Valve counts, flange quantities, bends, supports and access requirements.
Send drawings, cladding notes, trace heating requirements and project schedules.
Phone: 01792 209987
Email: info@insulation-more.co.uk
Website: https://insulation-more.co.uk/
Where Insulation & More fits in
Insulation & More supplies insulation products and accessories for trade, commercial and industrial pipework projects across the UK.
Mineral Wool / Stone Pipe Insulation
Rockwool, PAROC and stone wool pipe lagging sections.
View CollectionFibreglass Pipe Insulation
Foil-faced pipe lagging for internal mechanical services.
View CollectionPhenolic Foam
Pipe insulation route for constrained spaces and specification-led projects.
View CollectionRubber Pipe Insulation
Closed-cell insulation for suitable lower-temperature and condensation-risk areas.
View CollectionValve & Flange Jackets
Removable jackets for valves, flanges, strainers and fittings.
View CollectionInsulation Cladding
PIB, aluminium, Aluzinc, Isogenopak and protective finishes.
View CollectionTrace Heating
Cables, controls and accessories for frost-risk pipework sections.
View CollectionInsulation Accessories
Tapes, adhesives, labels, fixings and finishing accessories.
View CollectionFAQs: HNTAS and heat network insulation
What is HNTAS?
HNTAS stands for Heat Network Technical Assurance Scheme. It is the forthcoming technical assurance scheme being developed to help heat network operators demonstrate compliance with technical requirements for heat networks in Great Britain.
Is HNTAS the same as Ofgem heat network regulation?
No. Ofgem heat network regulation began with consumer protection rules. HNTAS is the separate technical assurance scheme being developed for the physical performance of heat networks, including areas such as temperatures, heat losses, monitoring and pipe insulation.
Is HNTAS already in force?
Ofgem heat network regulation began on 27 January 2026 in Great Britain, but HNTAS technical standards are still being finalised and are planned to be phased in from 2027.
Does HNTAS apply to existing heat networks?
Yes, HNTAS is being developed for both new and existing heat networks. Existing networks are expected to work toward compliance through phased and proportionate requirements.
Why does pipe insulation matter for HNTAS?
Pipe insulation affects distribution heat losses, operating performance, comfort, plant efficiency and long-term network performance. Under HNTAS, insulation is expected to become a more visible and evidence-based part of demonstrating technical compliance.
What insulation products are used on heat network pipework?
Common product routes include mineral wool pipe insulation, fibreglass pipe insulation, phenolic pipe insulation, rubber pipe insulation, valve and flange jackets, cladding and trace heating. The correct product depends on temperature, pipe size, exposure, space constraints and the project specification.
Do heat network valves and flanges need insulation?
Valves, flanges and fittings should be reviewed as part of the full insulation system. Leaving them bare can create repeated heat-loss points and may undermine the performance of the insulated pipework.
When should cladding be used?
Cladding should be considered where insulation needs protection from weather, moisture, impact, UV exposure or plant-room conditions. External pipework and exposed services are common examples.
When should trace heating be considered?
Trace heating may be required where exposed or intermittently used pipework could be at risk of freezing. It should be coordinated with the insulation thickness, controls, labels, fixings and cladding.
What should I send to Insulation & More for a heat network product check?
Send pipe sizes, lengths, service temperatures, drawings, insulation notes, valve and flange quantities, internal or external location, cladding requirements and any trace heating requirements.
Technical and regulatory disclaimer
This article is provided for general information and product-selection guidance only. It is not legal, engineering, regulatory or building-control advice.
The HNTAS technical standards are still being finalised and are expected to be phased in over time. Requirements may change as the government response, final technical standards and scheme documents are published.
Product suitability depends on the final specification, service temperature, pipe size, insulation thickness, thermal conductivity, facing, vapour-control requirements, exposure, cladding, installation quality and site conditions.
Always refer to the latest DESNZ, Ofgem, HNTAS and project-specific guidance, and seek advice from a competent designer, heat network specialist or installer before ordering or installing materials.