Interpretation #7947
Published July 11, 2017
Original Request
- Code Version
- 2014
- Code
- MECHANIC
- Code Description
- Chapter
- 4
- Section
- 401.2
- Topic
- Ventilation in Dwelling Units
Question
Is the intent of section 401.2 to permit only mechanical ventilation in accordance with Section 403 as the means for compliance in the dwelling units of a multifamily building greater than three stories?
Answer Published 07/11/2017 at 1:32 PM
To the question, Yes.
FMC 401.2 indicates that an occupied space must be ventilated by (402) natural or (403) mechanical means. Natural ventilation may not be suited for all situations, such as climates with very high humidities, or sites with excessive levels of outside noise or pollution. Unlike natural ventilation, mechanical ventilation does not depend on unpredictable air pressure differentials between the indoors and outdoors to create a flow. Mechanical ventilation must be activated whenever conditions preclude operation of the natural ventilation system. FMC, Table 403 indicates occupancies where mechanical ventilation must be provided. Additionally, FMC 405 which applies to both natural, or mechanical ventilation systems requires that ventilation be provided whenever spaces are occupied. ASHRAE 62.1, which is the base document for Table 403 reinforces the concept that the minimum outdoor air flow must be maintained whenever a space is occupied under any load condition
FMC 401.2 indicates that an occupied space must be ventilated by (402) natural or (403) mechanical means. Natural ventilation may not be suited for all situations, such as climates with very high humidities, or sites with excessive levels of outside noise or pollution. Unlike natural ventilation, mechanical ventilation does not depend on unpredictable air pressure differentials between the indoors and outdoors to create a flow. Mechanical ventilation must be activated whenever conditions preclude operation of the natural ventilation system. FMC, Table 403 indicates occupancies where mechanical ventilation must be provided. Additionally, FMC 405 which applies to both natural, or mechanical ventilation systems requires that ventilation be provided whenever spaces are occupied. ASHRAE 62.1, which is the base document for Table 403 reinforces the concept that the minimum outdoor air flow must be maintained whenever a space is occupied under any load condition
Commentary
See previous report # 7222