An addendum that revises requirements for the use of natural ventilation for theAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers'(ASHRAE) ventilation standard has been approved for publication.

ANSI/ASHRAE Standard 62-1999, Ventilation for Acceptable Indoor Air Quality, sets minimum ventilation rates and other requirements for commercial and institutional buildings.

While the standard currently allows natural ventilation, more guidance is needed on the design of natural ventilation systems. Addendum j changes the language to be more prescriptive, simpler and in line with most building codes.

"The language in the addendum is similar to many model building codes," Andrew Persily, chairman of the Standard 62 committee, said. "The new language makes it easier for designers to understand and use and easier to enforce."

Addenda related to construction and startup and operation and maintenance also were approved for publication at the Society's 2001 Annual Meeting held in Cincinnati June 23-27.

While the design of an HVAC system affects indoor air quality, the installation, operation and maintenance of the system and the building it has a significant impact as well, according to Persily.

"If the design is not properly implemented during construction or the building is not operated consistent with the design intent, indoor air quality can suffer," he said.

Addendum l, which creates a new section on construction and ventilation system start-up, and addendum m, which creates a section on operations and maintenance, address those issues through requirements for changing filters, cleaning heating and cooling coils, keeping sensors calibrated and other maintenance procedures.