Interpretation #6547
Published June 23, 2010
Original Request
- Code Version
- 2007
- Code
- BUILDING
- Code Description
- Building
- Chapter
- 13
- Section
- 13-407.AB.2.1
- Topic
- Zone Controls
Question
Is it the intent of the Florida Building Code - Building Section 13-407.AB.2.1, Exception B, to allow simultaneous heating and cooling for makeup air systems for 20 percent of kitchen hood exhaust air in Cafeterias and Dining Halls where the same air handling system also provides thermal comfort to occupied dining areas?
Answer Published 06/23/2010 at 11:14 AM
Although a definitive answer cannot be provided without a
full review of the proposed design, based upon the limited
information provided, the answer would be no. Please
consider the following: The ASHRAE 90.1-2004 User's Manual
states the following regarding Exception B: "Zones where
special pressurization relationships, cross-contamination
requirements, or code-required minimum circulation rates are
such that variable air volume systems are impractical. This
exception might apply to some areas of hospitals, such as
operating rooms, and to laboratories that must be maintained
at positive (or negative) pressures to prevent
contaminates from entering (or escaping). VAV systems have
been successfully used in these applications to reduce
energy costs, but control is very complicated and requires
precise airflow-measuring and/or pressure-measuring
instruments. The risk of a failure of these controls, such
as the possible release of dangerous chemicals or bacteria,
must be balanced against the potential energy savings."
As such, it does not appear that the use of Exception B
would be permitted in the design of restaurant kitchens and
/ or dining areas.
full review of the proposed design, based upon the limited
information provided, the answer would be no. Please
consider the following: The ASHRAE 90.1-2004 User's Manual
states the following regarding Exception B: "Zones where
special pressurization relationships, cross-contamination
requirements, or code-required minimum circulation rates are
such that variable air volume systems are impractical. This
exception might apply to some areas of hospitals, such as
operating rooms, and to laboratories that must be maintained
at positive (or negative) pressures to prevent
contaminates from entering (or escaping). VAV systems have
been successfully used in these applications to reduce
energy costs, but control is very complicated and requires
precise airflow-measuring and/or pressure-measuring
instruments. The risk of a failure of these controls, such
as the possible release of dangerous chemicals or bacteria,
must be balanced against the potential energy savings."
As such, it does not appear that the use of Exception B
would be permitted in the design of restaurant kitchens and
/ or dining areas.
Commentary
It is also important to note that the Florida Energy Code
requires a building to pressurized relative to the outdoors
and also requires the kitchen areas to be slightly negative
in pressure relative to the rest of the space. The Florida
Building Code - Mechanical prohibits return air to be drawn
from a kitchen unless it's from a dedicated kitchen system.
Additionally, transfer air from the dining room may be used
as the additional make-up air for the kitchen, however, the
building must maintain a slight positive pressure relative
to the outdoors, so some sort of control process will have
to be in place. If the unit installed has multiple stages
and a hot-gas bypass then some reheating is permitted.