Rule of thumb: ~0.35 m³ CH4 per kg COD removed — a brewery's wastewater can supply 10–20% of its heat.
From our guide: Biogas & biomass fuel switch — 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: