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CHAPTER 4
VENTILATION
SECTION 401
GENERAL
401.1 Scope. This chapter shall govern the ventilation of
spaces within a building intended to be occupied. This chapter does not govern the requirements for smoke control systems.
401.2 Ventilation required. Every occupied space shall be
ventilated by natural means in accordance with Section 402
or by mechanical means in accordance with Section 403.
401.3 When required. Ventilation shall be provided during
the periods that the room or space is occupied.
401.4 Vestibule ventilation. Vestibule ventilation for smokeproof enclosures shall be in accordance with the Florida
Building Code, Building.
401.5 Opening location. Outside air exhaust and intake
openings shall be located a minimum of 10 feet (3048 mm)
from lot lines or buildings on the same lot. Where openings
front on a street or public way, the distance shall be measured
to the centerline of the street or public way.
Exception: Use Group R-3.
401.5.1 Intake openings. Mechanical and gravity outside
air intake openings shall be located a minimum of 10 feet
(3048 mm) from any hazardous or noxious contaminant,
such as vents, chimneys, plumbing vents, streets, alleys,
parking lots and loading docks, except as otherwise specified in this code. Fresh air intakes shall not be located
closer than 10 ft (3048 mm) from any chimney or vent
outlet, or sanitary sewer vent outlet.
401.5.2 Exhaust openings. Outside exhaust openings
shall be located so as not to create a nuisance. Exhaust air
shall not be directed onto walkways.
401.6 Outdoor opening protection. Air exhaust and intake
openings that terminate outdoors shall be protected with corrosion-resistant screens, louvers or grilles. Openings in louvers, grilles and screens shall be sized in accordance with
Table 401.6. Openings shall be protected against local weather conditions. Outdoor air exhaust and intake openings located in exterior walls shall meet the provisions for exterior wall
opening protectives in accordance with the Florida Building
Code, Building.
FLORIDA BUILDING CODE — MECHANICAL
TABLE 401.6
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE OPENINGS
OUTDOOR OPENING
Exhaust openings
Intake openings in residential
occupancies
Intake openings in other than
residential occupancies
MINIMUM AND MAXIMUM OPENING
SIZES IN LOUVERS, GRILLES
AND SCREENS MEASURED IN
ANY DIRECTION
Not < 1/4 inch and not > 1/2 inch
Not < 1/4 inch and not > 1 / 2 inch
> 1/4 inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.7 Contaminant sources. Stationary local sources producing air-borne particulates, heat, odors, fumes, spray,
vapors, smoke or gases in such quantities as to be irritating or
injurious to health shall be provided with an exhaust system
in accordance with Chapter 5 or a means of collection and
removal of the contaminants. Such exhaust shall discharge
directly to an approved location at the exterior of the building.
SECTION 402
NATURAL VENTILATION
402.1 General. Natural ventilation of an occupied space
shall be through windows, doors, louvers or other openings
to the outdoors.
402.2 Ventilation area required. The minimum openable area to
the outdoors shall be 4 percent of the floor area being ventilated.
402.2.1 Adjoining spaces. Where rooms and spaces without openings to the outdoors are ventilated through an
adjoining room, the opening to the adjoining rooms shall
be unobstructed and shall have an area not less than 8 percent of the floor area of the interior room or space, but not
less than 25 square feet (2.3 m 2 ). The minimum openable
area to the outdoors shall be based on the total floor area
being ventilated.
402.2.2 Openings below grade. Where openings below
grade provide required natural ventilation, the outside horizontal clear space measured perpendicular to the opening
shall be one and one-half times the depth of the opening.
The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
402.3 Contaminants exhausted. Naturally ventilated spaces
having contaminant sources as covered in Section 401.7 shall
be provided with an exhaust system in accordance with
Chapter 5 or an approved means of collection and removal of
the contaminants.
4.1
402.3.1 - TABLE 403.3
402.3.1 Bathrooms. Rooms containing bathtubs, showers, spas and similar bathing fixtures shall be mechanically ventilated in accordance with Section 403.
402.4 Openings on yards or courts. Where natural ventilation
is to be provided by openings onto yards or courts, such yards or
courts shall comply with the requirements of the Florida
Building Code, Building.
SECTION 403
MECHANICAL VENTILATION
403.1 Ventilation system. Mechanical ventilation shall be
provided by a method of supply air and return or exhaust air.
The amount of supply air shall be approximately equal to the
amount of return and exhaust air. The system shall not be
prohibited from producing a negative or positive pressure.
The system to convey the ventilation air shall be designed
and installed in accordance with Chapter 6.
Ventilation supply systems shall be designed to deliver the
required rate of supply air to the occupied zone within an occupied space. The occupied zone shall have boundaries measured
at 3 inches (76 mm) and 72 inches (1829 mm) above the floor
and 24 inches (610 mm) from the enclosing walls.
403.2 Outdoor air required. The minimum ventilation rate
of required outdoor air shall be determined in accordance
with Section 403.3.
Exception: Where the registered design professional
demonstrates that an engineered ventilation system design
will prevent the maximum concentration of contaminants
from exceeding that obtainable by the rate of outdoor air
ventilation determined in accordance with Section 403.3,
the minimum required rate of outdoor air shall be reduced
in accordance with such engineered system design.
403.2.1 Recirculation of air. The air required by Section
403.3 shall not be recirculated. Air in excess of that
required by Section 403.3 shall not be prohibited from
being recirculated as a component of supply air to building spaces, except that:
1. Ventilation air shall not be recirculated from one
dwelling to another or to dissimilar occupancies.
2. Supply air to a swimming pool and associated deck
areas shall not be recirculated unless such air is
dehumidified to maintain the relative humidity of
the area at 60 percent or less. Air from this area shall
not be recirculated to other spaces.
403.2.2 Transfer air. Except where recirculation from
such spaces is prohibited by Table 403.3, air transferred
from occupied spaces is not prohibited from serving as
makeup air for required exhaust systems in such spaces as
kitchens, baths, toilet rooms, elevators and smoking
lounges. The amount of transfer air and exhaust air shall
be sufficient to provide the flow rates as specified in
Sections 403.3 and 403.3.1.
403.3 Ventilation rate. Ventilation systems shall be designed
to have the capacity to supply the minimum outdoor air flow
rate determined in accordance with Table 403.3 based on the
occupancy of the space and the occupant load or other
parameter as stated therein. The occupant load utilized for
design of the ventilation system shall not be less than the
number determined from the estimated maximum occupant
load rate indicated in Table 403.3. Where peak occupancies
of less than three hours duration occur, the outside air flow
rate may be determined on the basis of average occupancy
for the space for the duration of the system, provided the
average occupancy used is not less than one-half the maximum. Ventilation rates for occupancies not represented in
Table 403.3 shall be determined by an approved engineering
analysis. The ventilation system shall be designed to supply
the required rate of ventilation air continuously during the
period the space is occupied, except as otherwise stated in
other provisions of the code.
Exception: The occupant load is not required to be determined, based on the estimated maximum occupant load
rate indicated in Table 403.3 where approved statistical
data document the accuracy of an alternate anticipated
occupant density.
TABLE 403.3
REQUIRED OUTDOOR VENTILATION AIR
ESTIMATED
MAXIMUM
OCCUPANT LOAD,
PERSONS PER
1,000 SQUARE
FEET'
OCCUPANCY CLASSIFICATION
Correctional facilities
Cells
Dining halls
Guard station
Dry cleaners, laundries
Coin-operated dry cleaner
Coin-operated laundries
Commercial dry cleaner
Commercial laundry
Storage, pick up
Education
Auditoriums
Classroom
Corridors
Laboratories
Libraries
Locker rooms
Music rooms
Smoking loungesb
Training shops
20
100
40
20
15
15
20
20
30
10
30
15
15
30
25
35
150
50
50
70
30
15
15
0.10cfm/ft2
20
15
0.50 cfm/ft2
15
60
20
100
100
70
20
30
20
20
15
—
30
20
—
Food and beverage service
Bars, cocktail lounges
Cafeteria, fast food
Dining room
Kitchens (cooking)f
Hospitals, nursing and convalescent
homes
Autopsy roomsb
Medical procedure rooms
Operating rooms
Patient rooms
Physical therapy
Recovery and ICU
OUTDOOR AIR
[cubic feet per
minute (cfm) per
person] UNLESS
NOTED*
—
20
20
10
20
20
0.50 cfm/.ft2
15
30
25
15
15
(continued)
4.2
FLORIDA BUILDING CODE — MECHANICAL
TABLE 403.3
TABLE 403.3 (continued)
REQUIRED OUTDOOR VENTILATION AIR
TABLE 403.3 (continued)
REQUIRED OUTDOOR VENTILATION AIR
ESTIMATED
MAXIMUM
OCCUPANT LOAD,
PERSONS PER
1,000 SQUARE
OCCUPANCY CLASSIFICATION
Hotels, motels, resorts and
dormitories
Assembly rooms
Bathroomsb
Bedrooms
Conference rooms
Dormitory sleeping areas
Gambling casinos
Living rooms
Lobbies
Offices
Conference rooms
Office spaces
Reception areas
Telecommunication
centers and data entry
Private dwelling single
and multiple
Living areasc
FEET*
120
—
—
50
20
120
30
NOTED*
20
20
15
60
20
Garages, separate for
each dwelling
—
Garages, common for
multiple unitsb
—
1.5 cfm/ft2
Toilet rooms and
bathrooms
Public spaces
Corridors and utilities
Elevatorsg
Locker and dressing
roomsb
Toilet roomsb,g
Smoking loungesb
Retail stores, sales floors
and showroom floors
Basement and street
Dressing rooms
Malls and arcades
Shipping and receiving
Smoking loungesb
Storage rooms
Upper floors
Warehouses
—
—
—
—
0.05 cfm/ft2
1.00 cfm/ft2
0.5 cfm/ft2
70
50 cfm per
water closet
or urinal
60
—
—
—
—
70
—
—
—
(continued)
FLORIDA BUILDING CODE — MECHANICAL
Specialty shops
Automotive service
stations
Barber
Beauty
Clothiers, furniture
Florists
Hardware, drugs, fabrics
Pet shops
Reducing salons
Supermarkets
0.35 air changes
per houra or 15
cfm per person.
whichever is
greater
100 cfm
intermittent or
25 cfm
continuous
Mechanical
exhaust capacity
of 50 cfm
intermittent or
20 cfm
continuous
100 cfm per car
Kitchens
OCCUPANCY CLASSIFICATION
15
35 cfm per room
30 cfm per room
20
15
30
30 cfm per room
15
50
7
60
Based upon
number of
bedrooms
First bedroom: 2;
each additional
bedroom: 1
ESTIMATED
MAXIMUM
OCCUPANT LOAD,
PERSONS PER
1,000 SQUARE
OUTDOOR AIR
[cubic feet per
minute (cfm) per
person] UNLESS
cfm/ft2
cfm/ft2
cfm/ft2
cfm/ft2
60
0.15 cfm/ft2
0.20 cfm/ft2
0.05 cfm/ft2
0.30
0.20
0.20
0.15
OUTDOOR AIR
[cubic feet per
minute (cfm) per
person] UNLESS
FEET*
NOTED*
—
1.5 cfm/ft2
15
25
0.30 cfm/ft2
15
15
1.00 cfm/ft2
15
15
25
25
—
8
8
—
20
8
Theaters
Auditoriums
Lobbies
Stages, studios
Ticket booth
150
150
70
60
15
20
15
20
Transportation
Platforms
Vehicles
Waiting rooms
100
150
100
15
15
15
Workrooms
Bank vaults
Darkrooms
Duplicating, printing
Meat processingc
Pharmacy
Photo studios
Sports and amusement
Ballrooms and discos
Bowling alleys (seating
areas)
Game rooms
Ice arenas
Playing floors
(gymnasiums)
Spectator areas
Swimming pools (pool
and deck area)
Storage
Repair garages, public
garages (enclosed)d
Warehouses
5
—
—
15
0.50 cfm/ft2
0.50 cfm/ft2
10
20
10
100
70
70
25
30
25
25
0.50 cfm/ft2
20
150
15
—
—
0.50 cfm/ft2
—
—
1.5 cfm/ft2
0.05 cfm/ft2
For SI: 1 cubic foot per minute = 0.0004719 m3/s,
1 cubic foot per minute per square foot = 0.00508 m3
°C = [(°F)-32]/1.8.
'
Based upon net occupied heated or conditioned space.
b
Mechanical exhaust required and recirculation is prohibited.
c
Spaces unheated or maintained below 50°F are not covered by these requirements
unless the occupancy is continuous.
d
e
f
g
Public parking garages shall be ventilated in accordance with Section 403.4 where
the ventilation system is operated by an automatic carbon monoxide detection
device.
Where the ventilation rate is expressed in cfm/ft2' such rate is based upon cubic feet
per minute per square foot of the floor area being ventilated.
The sum of the outdoor and transfer air from adjacent spaces shall be sufficient to
provide an exhaust rate of not less than 1.5 cfm/ft2.
Transfer air permitted in accordance with Section 403.2.2.
4.3
403.3.1 - 403.6.2
403.3.1 System operation. The minimum flow rate of
outdoor air that the ventilation system must be capable of
supplying during its operation shall be permitted to be
based on the rate per person indicated in Table 403.3 and
the actual number of occupants present.
403.4.1 Minimum ventilation. Automatic operation of
the system shall not reduce the ventilation rate below 5
cfm (0.0024 m3/s) per person and the system shall be
capable of producing a ventilation rate of 1.5 cfm per
square foot (0.0076 m3/s m2) of floor area.
403.3.2 Common ventilation system. Where spaces having different ventilation rate requirements are served by a
common ventilation system, the ratio of outdoor air to total
supply air for the system shall be determined based on the
space having the largest outdoor air requirement or shall be
determined in accordance with the following formula:
403.5 ASHRAE 62 Alternative. In lieu of compliance with
Section 403.1 through 403.4, mechanical ventilation may be
implemented in compliance with ASHRAE 62 including
approved addenda.
where:
Y = Vot /Vst = Corrected fraction of outdoor air in
system supply.
X = Von /Vst = Uncorrected fraction of outdoor air
in system supply.
Z = Voc /Vsc - Fraction of outdoor air in critical
space.
The critical space is that space with
the greatest required fraction of outdoor air in the supply to this space.
Vot =
Corrected total outdoor airflow rate.
Vst =
Total supply flow rate, i.e., the sum
of all supply for all branches of the
system.
Von =
Sum of outdoor airflow rates for all
branches on system.
Voc=
Outdoor airflow rate required in critical
spaces.
Vsc=
Supply flow rate in critical space.
403.3.3 Variable air volume system control. Variable air
volume air distribution systems, other than those designed
to supply only 100-percent outdoor air, shall be provided
with controls to regulate the flow of outdoor air. Such control system shall be designed to maintain the flow of outdoor air at a rate of not less than that required by Section
403 over the entire range of supply air operating rates.
403.4 Public garages. Mechanical ventilation systems for
public garages are not required to operate continuously
where the system is arranged to operate automatically upon
detection of a concentration of carbon monoxide of 25 parts
per million (ppm) by approved automatic detection devices.
4.4
403.6 Smoke control. Smoke control systems for selected
occupancies shall comply with Sections 403.6.1 through
403.6.7.
403.6.1 Stages. Emergency ventilation shall be provided for
all stage areas greater than 1,000 sq ft (92.9m 2) or with a
stage height of greater than 50 ft (15.2 m) to provide a means
of removing smoke and combustion gases directly to the
outside in the event of a fire. Ventilation shall be by one or a
combination of the following methods:
1. Smoke control: A means shall be provided to maintain the smoke level not less than 6 ft (1829 mm)
above the highest level of assembly seating or above
the top of the proscenium opening where a proscenium wall and opening protection is provided. The
system shall be activated independently by each of
the following: (1) Activation of the sprinkler system
in the stage area and (2) by a manually operated
switch at an approved location. The emergency ventilation system shall be connected to both normal
and standby power. Fan power wiring and ducts
shall be located and properly protected to assure a
minimum 20 minutes of operation in the event of
activation.
2. Roof vents: Two or more vents shall be located near
the center of and above the highest part of the stage
area. They shall be raised above the roof and provide a net free vent area equal to 5% of the stage
area. Vents shall be constructed to open automatically by approved heat-activated devices.
Supplemental means shall be provided for manual
operation of the ventilator from the stage floor.
Vents shall be labeled by an approved agency.
403.6.2 Special hazardous occupancies. Areas within
hazardous occupancies storing liquid and solid oxidizers,
organic peroxides, unstable (reactive) materials or water
reactive materials shall be provided with means to vent
smoke and heat in a fire or other emergency. Smoke and
heat venting shall be designed in accordance with the
Florida Fire Prevention Code.
FLORIDA BUILDING CODE — MECHANICAL
403.6.3 - 403.6.6.6
403.6.3 Institutional restrained occupancies.
Windowless Group I restrained buildings shall be provided with vent openings, smoke shafts, or an engineered
smoke control system approved by the building official to
provide ventilation, mechanical or natural, for each windowless smoke compartment.
403.6.4 Group B and Group R high rise buildings. Natural
or mechanical ventilation for the removal of products of combustion shall be provided in every story of a Group R or
Group B high rise building and shall consist of one of the following:
1. Panels or windows in the exterior walls which can
be opened remotely from an approved location other
than the fire floor. Such venting facilities shall be
provided at the rate of 20 sq ft per 50 linear ft (1.86
m2 per 15 m) of exterior wall in each story and shall
be distributed around the perimeter at not more than
50 ft (15 m) intervals. Such windows or panels and
their controls shall be clearly identified.
2. In a building which is equipped with an approved
complete automatic sprinkler system, windows or
panels manually openable from the fire floor or panels of approved, fixed, fully tempered glass may be
substituted for the remotely operated openable panels or windows. Such manually openable windows
or fixed tempered panels shall be clearly identified
and shall be of the size and spacing required in
403.6.4(1).
3. In a building which is equipped with an approved
complete automatic sprinkler system, properly
designed mechanical air handling equipment may
be substituted for the natural ventilation described
in 403.6.4(1) and 403.6.4(2), provided that the air
handling equipment is connected to the standby
power and light system. Under fire conditions, the
return and exhaust air shall be moved directly to the
outside without recirculation to other sections of the
building. The air handling system shall have the
capability of providing a minimum of one exhaust
air change every 10 minutes for any area which
might be involved.
4. Any other design which will produce equivalent
results may be considered by the building official.
403.6.5 Covered mall buildings.
403.6.5.1 Smoke detectors shall be provided within an
air conditioning system in accordance with Section 606
of this code. Actuation of either a smoke detector or the
sprinkler system shall cause the air supply to the air
conditioning zone in which the fire occurs to shut
down.
FLORIDA BUILDING CODE — MECHANICAL
403.6.5.2 The mall shall have smoke removal capability installed in or near the roof. Such facility may be
either natural or mechanical.
403.6.5.3 Before the systems are accepted by the building official, they shall be tested in his presence to confirm that they are operating in compliance with the
requirements of this section.
403.6.6 Atriums. A smoke control system shall be
designed to control the migration of products of combustion in the atrium space. Upon detection of a fire, the system shall shut down the air supply to the fire floor and the
return air from all nonfire floors. Any other approved
design which will achieve the same level of smoke control
as described in this section may be used in lieu of these
requirements.
403.6.6.1 In atriums 55ft (16.8 m) or less in height with
a volume of 600,000 cu ft (16992 m3) or less, a smoke
exhaust system shall be located at the ceiling of the
atrium. Such systems shall exhaust 40,000 cfm
(18.93/s). When the volume of the atrium exceeds
600,000 cu ft (16992 m3) the exhaust system shall be
sized to provide a minimum of four air changes per
hour.
403.6.6.2 Supply air inlets may be provided at the lowest level of the atrium. These inlets shall be sized to
provide 75% of the exhaust.
403.6.6.3 For purposes of this section, the volume of
the atrium shall include all spaces not separated from
the atrium as provided in 414.5 of the Florida Building
Code, Building.
403.6.6.4 When the height of the atrium exceeds 55ft (16.8
m), an exhaust system shall be provided as required in
403.6.6.1; however, supply air shall be introduced
mechanically from the floor of the atrium and shall be
directed vertically at the exhaust outlet above. The capacity of the supply shall be 75% of the exhaust.
403.6.6.5 Manual controls shall be provided for the
atrium smoke control system. When the smoke control
system in other than the atrium is provided by mechanical ventilation in accordance with 403.6.6.6, manual
controls shall also be provided as described above for
the atrium system. The manual controls shall be provided in a location approved by the building official.
403.6.6.6 In any building containing an atrium, occupied space that does not open directly to the atrium
shall be designed to provide natural or mechanical ventilation in accordance with 403.6.4.
4.5
403.6.7 - 404.1
403.6.7 Underground buildings. Where compartmentation is required, each compartment shall have an independent, automatically activated smoke exhaust system
capable of manual operation. The system shall have an air
supply and smoke exhaust capability which will provide a
minimum of six air changes per hour.
403.6.7.1 The smoke exhaust system shall be operated
in the compartment of origin by the following independently of each other:
1. Two cross-zoned smoke detectors within a single
protected area or a single smoke detector monitored by an alarm verification zone or an
approved equivalent method.
2. The automatic fire sprinkler system.
3. Manual controls that are readily accessible to the
fire department.
403.6.7.2 Activation of the smoke exhaust system shall
activate an audible alarm at a constantly attended location.
SECTION 404
VENTILATION OF UNINHABITED SPACES
404.1 General. Uninhabited spaces, such as crawl spaces and
attics, shall be provided with natural ventilation openings as
required by the Florida Building Code, Building or shall be
provided with a mechanical exhaust and supply air system.
The mechanical exhaust rate shall be not less than 0.02 cfm
per square foot (0.00001 m3/s m2) of horizontal area and
shall be automatically controlled to operate when the relative
humidity in the space served exceeds 60 percent.
4.6
FLORIDA BUILDING CODE —MECHANICAL