Generate BESA Heat Interface Unit Testing Regime v3.1-aligned commissioning reports in minutes. Document HIU performance against VWART thresholds, populate your material assets register for Ofgem Authorisation Condition A12, and build the evidence base for Security of Supply (AC C2) compliance ahead of the 26 January 2027 registration deadline.
The HIU Commissioning Tool produces BESA v3.1-aligned commissioning reports against the four core performance criteria: Volume-Weighted Average Return Temperature (VWART), differential pressure response, modulation behaviour, and DHW preparation. Reports include the threshold tests required for compliance evidence — 37°C SH return, DHW priority, valve authority — and produce a board-ready PDF that can be filed against the operator's material assets register and referenced in C2 (Security of Supply) compliance evidence.
Each report is self-contained: the operator records as-installed readings, the tool evaluates against BESA thresholds, and the output is an auditor-ready PDF with pass/fail flags, narrative explanation, and signed-off commissioning sign-off lines.
Free
For operators evaluating the tool or with very low commissioning volume.
Try freeSingle Network
For operators commissioning a single small-to-medium network.
Buy Single NetworkBest Value Pack
For operators commissioning multiple networks or working with a portfolio.
Buy Best Value PackHIU performance is the largest single determinant of heat network reliability at the consumer connection. Poorly-commissioned or drifting HIUs cause persistent high primary return temperatures, which reduce network efficiency, increase fuel costs, increase consumer complaints, and ultimately drive C2 (Security of Supply) non-compliance.
Under the Heat Networks (Market Framework) Regulations 2025, operators have a positive duty under AC C2 to operate their networks in a manner intended to ensure a reliable and consistent supply, minimise outages, periodically review network reliability, and report on performance. Under AC A12, operators must maintain a register of material assets including condition and function information for physical assets. HIU commissioning reports are the canonical evidence source for both obligations.
Operators relying on consultancy reports for individual HIUs face two problems: cost (typically £200–£500 per HIU), and the lack of a consistent format that maps cleanly to AC C2 and A12 evidence requirements. The Commissioning Tool produces a consistent, auditor-ready format at a tier appropriate to the operator's volume.
The tool's output is designed for direct use as evidence under the following Ofgem Authorisation Conditions:
Populates the material assets register with HIU condition and function information at installation and recommissioning.
Provides the periodic review and performance monitoring evidence required by C2.1.2 and C2.1.3, with clear pass/fail flags against industry-standard thresholds.
Supports the duty to treat consumers fairly by demonstrating that HIU performance is monitored and remediated proactively, not only after consumer complaints.
Supports accurate billing by documenting that the metering arrangements at the consumer connection are functioning to industry standard.
The reports also align with BESA Heat Interface Unit Testing Regime v3.1, CIBSE CP1 (Heat Networks: Code of Practice), and HNTAS technical assessment requirements.
Used by operators preparing for Ofgem authorisation across the UK.
References available on request.
Yes — under AC C2 (Security of Supply), operators have a duty to operate the network to ensure reliable supply, which depends on every HIU performing to specification. BESA v3.1 sets the industry standard for HIU performance testing, and the tool generates reports against the same thresholds. For a first-time authorisation submission, evidence of commissioning across the network demonstrates that the operator has discharged the C2 periodic review duty.
AC A12 requires operators to maintain a register of material assets including condition and function information. HIU commissioning reports populate exactly that field for the most operationally important assets at the consumer connection. The PDF output can be filed against the material assets register and referenced in any A12-related submission to Ofgem.
Free reports are watermarked PDF output and limited to one per calendar month. Paid reports (Single Network at £50 for 10 reports, or Best Value Pack at £150 for 50 reports) produce clean, unwatermarked output suitable for board approval, Ofgem submission, or inclusion in a consumer complaint response. Free reports are appropriate for evaluation or very low commissioning volume.
No — the tool does not replace physical performance testing or BESA certification of the HIU hardware itself. It produces the commissioning report that documents an as-installed or re-commissioning performance check against BESA v3.1 thresholds. For a hardware-level BESA test (the manufacturer's certification), operators should engage a BESA-accredited testing laboratory.
The Heat Networks (Market Framework) Regulations 2025 commenced on 27 January 2026. Registration with Ofgem opens Spring 2026 via a digital service, with a deadline of 26 January 2027. Operators who can demonstrate active HIU commissioning documentation at registration are evidencing both AC A12 (material assets) and AC C2 (security of supply) compliance from day one.
Open the HIU Commissioning Tool to generate your first report — the free tier is available without registration. Operators preparing a portfolio of HIU evidence ahead of the 26 January 2027 deadline typically choose the Best Value Pack to cover a year of commissioning work at consistent cost.
Open the HIU Commissioning ToolNeed policy documentation alongside the commissioning evidence? See the Heat Network Compliance Policy Generator for the documentation set covering all 29 Authorisation Conditions.
Need tariff modelling alongside your commissioning evidence? Try the free Heat Network Tariff Calculator.