ISO/TS 5660-4:2016 specifies a method for evaluating materials and products that produce low levels of heat release when exposed to high irradiance levels typical of fully developed fires. It differs from ISO 5660‑1 by prescribing items such as specific specimen size, specimen holder, specimen orientation, volumetric flow rate for O₂ analyses and irradiance levels at which testing is conducted.

The test method described in this document is intended for use on products and materials that contain only small amounts of combustible elements, e.g. test specimens that yield a total heat release of 0,75 MJ/m² to 15 MJ/m².