Q：Is constant temperature and humidity in clean room necessary or not?

A：In ASHRAE’s manual, 「Cleanroom」 and 「Clean Space」 are different definitions (See 1-1, related terms 1 and 2); Clean Space only has requirement on cleanliness, without limitations on other conditions like temperature and humidity. Thus, whether clean room requires constant temperature and humidity depending on product requirement. For common air conditioners, the range of temperature should be able to maintain within 24℃±3℃db, but daily range of RH within 60%±20%RH is permissible due to outdoor conditions and indoor load variation; if your product is manufactured or stored within the range of temperature and humidity (Or if no range of RH is required), installation of additional heater and humidifier is unnecessary for the purpose of constant temperature and humidity.
※Note: constant temperature and humidity refers to air conditioner with precision (Or range of variation) of temperature ≤±2℃db and humidity ≤±5%RH.