Thermal neutrality
From Glossary of Meteorology
thermal neutrality
(Also called thermoneutrality.) The condition in which the thermal environment of a homeothermic animal is such that its heat production (metabolism) is not increased either by cold stress or heat stress.
The temperature range in which this minimum occurs is called the zone of thermal neutrality. For humans, this zone is 29°–31°C (84°–88°F).