This part of ISO 14269 specifies a uniform test method for measuring the contribution to operator environmental temperature and humidity provided by an air-conditioning, heating and ventilation system operating in a specific ambient environment for tractors and self-propelled machines for agriculture and forestry. The method may not determine the complete climatic environment of the operator since this is also affected by heat load from sources other than those on the machine, for example solar heating. It is recommended that part 3 of ISO 14269 be used in conjunction with this part to determine more accurately the complete heat loading on the operator enclosure. Minimum performance levels for the machine's operator enclosure air conditioning, heating and ventilation systems are established in this part.