Best practice guidelines or requirements may be referenced or available from your Accreditation Body (e.g. UKAS) or National Metrology Institute (e.g. NIST). The requirements for environmental conditions will depend on the scope of the laboratory. i.e. what type of calibration or testing is being performed.
Generally the facility and environmental conditions must be suitable for the purpose, be reliable and be consistent. Each laboratory would need to determine the specific requirements from a quality and legal perspective and seek information from:
National legislation and regulatory bodies (e.g. environmental and hazardous substances management, occupational health and safety acts),
Technical criteria of tests to achieve consistent reliable calibration or test results (e.g. suitable operation conditions and controls such as temperature and humidity to preventing damage or deterioration to samples and equipment).