Last month this column described the design intent document (DID) and how it is the backbone of the commissioning process. A good DID, however, can have great value beyond the life of the design and construction project. It can be an invaluable operations and maintenance (O&M) reference throughout the life of the systems.
Either by direct inclusion or by indirect exclusion, the DID can also be used to document what the systems are not intended to do. For example, if offices are to be cooled to 75˚F, it can be assumed that no one should expect them to be able to cool to 72˚ under design conditions. Similarly, if a space is to be ventilated at the rate of 0.25 cfm/sq ft, it should be understood that the systems cannot provide 0.5 cfm/sq ft of outside air.