This part of ISO 14644 specifies requirements for the design and construction of cleanroom installations but does not prescribe specific technological or contractual means to meet these requirements. It is intended for use by purchasers, suppliers and designers of cleanroom installations and provides a checklist of important parameters of performance. Construction guidance is provided, including requirements for start-up and qualification. Basic elements of design and construction needed to ensure continued satisfactory operation are identified through the consideration of relevant aspects of operation and maintenance.Application of this part of ISO 14644 is restricted in the following:user requirements are represented by purchaser or specifier;specific processes to be accommodated in the cleanroom installation are not specified;fire and safety regulations are not considered specifically; the appropriate national and local requirements should be respected;process media and utility services are only considered with respect to their routing between and in the different zones of cleanliness;regarding initial operation and maintenance, only cleanroom construction-specific requirements are considered.