Below zero: the fuel saving exceeds the cover cost within ~2 years, so each tonne is abated at negative net cost — cheaper than any other industrial measure, before counting €77/t of avoided allowances.
From our guide: Removable insulation (modular) — 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: