ISO 5660-1 specifies the cone calorimeter method: a small specimen is exposed to a controlled radiant heat flux and ignited, and the heat it releases is calculated from the oxygen consumed in the exhaust gases. It is the reference bench-scale method for heat release in product standards and regulations on several continents, and its data - heat release rate, total heat release, smoke production, mass loss - are the most complete small-scale fire record available for a material.
What the test measures
The method reports heat release rate per unit area (kW/m²), total heat release, effective heat of combustion, mass loss rate, smoke production rate and total smoke, and ignition time. Because all of these come from the same run, ISO 5660 data serve both regulation (as an input, with the SBI, to Euroclass decisions for some products) and development work where engineers compare formulations.
How a test runs
The specimen, up to 100 x 100 mm, is conditioned and wrapped, placed on the load cell under the cone heater at the chosen irradiance (commonly 25, 35 or 50 kW/m² depending on the end use being modelled), and exposed with spark ignition. Exhaust products are collected completely; oxygen concentration and flow give heat release through the oxygen-consumption relationship, while a laser across the duct gives smoke. A test typically runs until flaming ceases or a set period elapses.
Where ISO 5660 sits among the standards
ASTM E1354 is the North American counterpart method on the same apparatus. In Europe, ISO 5660 data are used in product development, in the marine and railway regimes, and as supporting evidence; the construction classification decision itself is made on SBI results. Choosing between them is a question of which document your report must cite - the instrument is common to both. See the cone calorimeter product page for the Motis CCT configuration and the ASTM E1354 explainer for the US method.