Generally voluntary, but it satisfies the EU Energy Efficiency Directive's audit obligation (Art. 8) for large enterprises in many member states, and large energy users increasingly face it in tenders.
From our guide: Gestión de la energía ISO 50001 — full context, charts and sources there.
Boilers, kilns, heat exchangers, valves and steam lines lose energy continuously. Inzonex makes patented (UK GB2508992.1) removable modular insulation — snap-fastened covers engineered per temperature tier, not generic off-the-shelf jackets:
Every tonne you stop emitting is a tonne you don't have to report: cutting heat loss is a measurable, auditable Scope 1 reduction that flows straight into EU ETS, CBAM and your ESG / CSRD disclosures — not an offset, an actual emission cut.