Interpretation #7222
Published July 31, 2013
Original Request
- Code Version
- 2010
- Code
- MECHANIC
- Code Description
- Mechanical
- Chapter
- 4
- Section
- 402
- Topic
- Natural Ventilation
Question
Is it the intent of chapter 402 to allow natural ventilation in all commercial buildings in lieu of mechanical ventilation regardless of occupant density, activity level, or space usage? For example, in a church setting which is an assembly occupancy, this would normally require several hundred CFM of outside air for a typical size church, would it be acceptable to omit the ventilation completely if you have greater then 4% glass to floor ratio given that the building was kept at positive pressure?
Answer Published 07/31/2013 at 12:54 PM
Natural ventilation is acceptible for most circumstances.
However, where Table 403.3 indicates mechanical ventilation
required then mechanical ventilation shall be provided (see
footnotes of Table 403.3). Keep in mind, Section 402
requires the openable area of windows and doors to be at
least 4 percent of the floor area served by the openings.
one must bear in mind that the 4% is not the glazed area,
but the openable area which can be through windows, doors,
louvers or other openings to the outdoors and not fixed
glazing.
However, where Table 403.3 indicates mechanical ventilation
required then mechanical ventilation shall be provided (see
footnotes of Table 403.3). Keep in mind, Section 402
requires the openable area of windows and doors to be at
least 4 percent of the floor area served by the openings.
one must bear in mind that the 4% is not the glazed area,
but the openable area which can be through windows, doors,
louvers or other openings to the outdoors and not fixed
glazing.
Commentary
FEC 503.2.10.6 requires the building be pressurized with
respect to outdoors and is only applicable to mechanical
ventilation