Because there are over 1 200 000 American commercial/institutional buildings erected prior to World War II, and countless more residential units, there is a need for an ordered assembly of mechanical/electrical specifications especially for these structures. In dealing with their mechanical/electrical services, it is desirable to retain the architectural integrity as well as to provide systems that satisfy both the needs of the occupants and the safety requirements of the regulatory agencies.

Maintaining, repairing, upgrading, and retrofitting equipment in existing spaces may demand more innovation than in new buildings. If not already provided, electric power, air, gas, water, or steam must be brought from the source to this equipment. Poor installations in older buildings have economic implications because they adversely affect the cost of repair, maintenance, and operation. Consequently, this work should not be done without attention to impact on original design and historic fabric, even if it is not an Investment Tax Act Project. There may be irreversible damage to the structure itself, diminishing architectural heritage. Therefore, for both economic and cultural reasons, national standards in this field are essential.