Rooms or occupied spaces within single-family
homes and multifamily structures of three stories or
less above grade shall be designed to have ventilation (outdoor)
air for occupants in accordance with Section E605.1.1
through Section E605.1.3.2, or the applicable local code.
Naturally ventilated
spaces shall be permanently open to and within 20 feet
(6096 mm) of operable wall or roof openings to the outdoors,
the openable area of which is not less than 5 percent
of the conditioned floor area of the naturally
ventilated space. Where openings are covered with louvers
or otherwise obstructed, openable area shall be
based on the free unobstructed area through the opening.
The means to open required operable openings shall
be readily accessible to building occupants where
the space is occupied.
Each space that
is not naturally ventilated in accordance with Section E605.1.1 shall be ventilated with a mechanical system
capable of providing an outdoor air rate not less than 15
ft3/min (0.007 m3/s) per person times the expected number of occupants. Mechanical ventilation shall comply with this code.
A Mechanical exhaust system, supply system, or combination thereof
shall be installed to operate for each dwelling unit to provide
continuous dwelling-unit ventilation with outdoor air rate not less than the rate specified in Section E605.1.3.1. [ASHRAE 62.2:4.1]
The total
required ventilation rate (Qtot) shall be as specified
in Table E605.1.3.1 or, alternatively, calculated in
accordance with Equation E605.1.3.1.
Where:
For SI units: 1 cubic foot per minute = 0.00047 m3/s, 1 square
foot = 0.0929 m2
For SI units: 1 square foot = 0.0929 m2, 1 cubic foot per minute = 0.00047 m3/s
Qtot = 0.03Afloor + 7.5(Nbr + 1)
(Equation E605.1.3.1)
Where:
| Qtot | = | total required ventilation rate, cubic feet per minute (ft3/min) |
| Afloor | = | dwelling unit square foot (ft2) |
| Nbr | = | number of bedrooms; not to be less than one |
Exceptions: Dwelling-unit mechanical ventilation
systems shall not be required where the Authority
Having Jurisdiction determines that window operation
is a locally permissible method of providing
ventilation and provided one or more of the following
conditions is met:
- The building has no mechanical cooling and is located in zone 1 or 2.
- The building is thermally conditioned for human occupancy for less than 876 hours per year. [ASHRAE 62.2:4.1.1]
| FLOOR AREA(ft2) | BEDROOMS | ||||
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | |
| <500 | 30 | 38 | 45 | 53 | 60 |
| 501-1000 | 45 | 53 | 60 | 68 | 75 |
| 1001-1500 | 60 | 68 | 75 | 83 | 90 |
| 1501-2000 | 75 | 83 | 90 | 98 | 105 |
| 2001-2500 | 90 | 98 | 105 | 113 | 120 |
| 2501-3000 | 105 | 113 | 120 | 128 | 135 |
| 3001-3500 | 120 | 128 | 135 | 143 | 150 |
| 3501-4000 | 135 | 143 | 150 | 158 | 165 |
| 4001-4500 | 150 | 158 | 165 | 173 | 180 |
| 4501-5000 | 165 | 173 | 180 | 188 | 195 |
Effective Annual Average Infiltration
Rate (Qinf) shall be calculated using
Equation E605.1.3.2:
Where:
* Replace 7.3 with 1.44 for metric units. [ASHRAE 62.2:4.1.2(e)]
Qinf(cfm) = (NL x wsf x Afloor) / (7.3)*
[Equation E605.1.3.2]
Where:
| NL | = | normalized leakage |
| wsf | = | weather and shielding factor from ASHRAE 62.2. |
| Afloor | = | floor area of residence, ft2 (m2) |
Required Mechanical Ventilation
Rate (Qfan) shall be calculated using Equation E605.1.3.3:
Where:
Qfan = Qtot - (Qinf x Aext)
[Equation E605.1.3.3]
Where:
| Qfan | = | required mechanical ventilation rate, cfm (L/s) |
| Qtot | = | total required ventilation rate, cfm (L/s) |
| Qinf | = | may be not greater than 2/3 x Qtot |
| (see ASHRAE 62.2 for exceptions for existing buildings) | ||
| Aext | = | 1 for single-family detached homes, or the ratio of exterior envelope surface area that is not attached to garages or other dwelling units to total envelope surface area for single-family attached homes. [ASHRAE 62.2:4.1.2(f)] |
Table
E605.1.3.1 and Equation E605.1.3.1 assume two
persons in a studio or one-bedroom dwelling unit
and an additional person for each additional bedroom.
Where higher occupant densities are known,
the rate shall be increased by 7.5 ft3/min (0.003 m3/s)
for each additional person. Where approved by the
Authority Having Jurisdiction, lower occupant densities
shall be permitted to be used. [ASHRAE
62.2:4.1.3]
The dwelling-unit mechanical ventilation system shall consist of one or more supply or exhaust fans and associate ducts and controls. Local exhaust fans shall be permitted to be part of a mechanical exhaust system. Where local exhaust fans are used to provide dwelling-unit ventilation, the local exhaust airflow shall be permitted to be created towards the whole dwelling-unit ventilation airflow requirement. Outdoor air ducts connected to the return side of an air
handler shall be permitted as supply ventilation where
manufacturer's requirements for return air temperature
are met. See ASHRAE 62.2 for guidance on selection of
methods. [ASHRAE 62.2:4.2]
The dwelling-unit mechanical ventilation system shall consist of one or more supply or exhaust fans and associated ducts and controls. Local exhaust fans shall be permitted to be part of a mechanical exhaust system. Where local exhaust fans are used to provide dwelling-unit ventilation, the local exhaust airflow shall be permitted to be credited towards the whole dwelling-unit ventilation airflow requirement. Outdoor air ducts connected to the return side of an air
handler shall be permitted as supply ventilation where
manufacturer's requirements for return air temperature
are met. See ASHRAE 62.2 for guidance on selection of
methods. [ASHRAE 62.2:4.2]
The airflow
required by this section shall be the quantity of outdoor
ventilation air supply, indoor air, or both exhausted by
the mechanical ventilation system as installed and shall
be measured according to the ventilation equipment manufacturer's
instructions, or by using a flow hood, flow
grid, or other airflow measuring device at the mechanical
ventilation fan's inlet terminals/grilles, outlet terminals/grilles, or in the connected ventilation ducts.
Ventilation airflow of systems with multiple operating
modes shall be tested in all modes designed to be in
accordance with this section. [ASHRAE 62.2:4.3]
A readily accessible
manual ON-OFF control, including but not limited
to a fan switch or a dedicated branch-circuit overcurrent
device, shall be provided. Controls shall include text or
an icon indicating the system's function.
Exception: For multifamily dwelling units, the manual
ON-OFF control shall not be required to be readily
accessible. [ASHRAE 62.2:4.4]
Dwelling-unit mechanical ventilation systems designed
to provide variable ventilation shall comply with Section
E605.1.7.1 or Section E605.1.7.2 or Section E605.1.7.3.
Section E605.1.7.2 and Section E605.1.7.3 also require
compliance with ASHRAE 62.2 and require verification
with supporting documentation from the manufacturer,
designer, or specifier of the ventilation control system that the system meets the requirements of these sections.
Where the dwelling-unit ventilation rate varies based on
occupancy, occupancy shall be determined by occupancy
sensors or by an occupant-programmable schedule.
[ASHRAE 62.2:4.5]
To comply with this section, a variable ventilation
system shall be installed to provide an average
dwelling-unit ventilation rate over any three-hour
period that is greater than or equal to Qfan as determined in accordance with Section E605.1.3.3. [ASHRAE 62.2:4.5.1]
This section
shall only be allowed to be used where one or more
fixed patterns of designed ventilation are known at the
time compliance to Section E605.0 is being determined.
Such patterns include those both clock-driven
and driven by typical meteorological data. Compliance
with this section shall be in accordance with
either Section E605.1.7.2.1 or Section E605.1.7.2.2.
[ASHRAE 62.2:4.5.2]
An annual schedule of ventilation complies
with this section when the annual average relative
exposure during occupied periods is not
more than unity as calculated in accordance
with ASHRAE 62.2. [ASHRAE 62.2:4.5.2.1]
The schedule
of ventilation complies with this section
when it is broken into blocks of time and each
block individually has an average relative exposure
during occupied periods that is not more
than unity as calculated in ASHRAE 62.2. [ASHRAE 62.2:4.5.2.2]
A real-time ventilation
controller complies with this section when it
is designed to adjust the ventilation system based on
real-time input to the ventilation calculations so that
the average relative exposure during occupied periods
is not more than unity as calculated in ASHRAE
62.2. The averaging period shall be not less than one
day but not more than one year and shall be based on
simple, recursive or running average, but not extrapolation.
[ASHRAE 62.2:4.5.3]
A dwelling-unit
ventilation system shall be designed and operated in such
a way as to provide the same or lower annual exposure as
would be provided in accordance with Section E605.1.3.
The calculations shall be based on a single zone with a
constant contaminant emission rate. The manufacturer,
specifier, or designer of the equivalent ventilation system
shall certify that the system is in accordance with
this intent and provide supporting documentation.
[ASHRAE 62.2:4.6]
Except where a whole
house energy recovery system is used, a mechanical exhaust
fan vented to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The
ventilation rate shall be not less than 50 ft3/min (0.02 m3/s) for
intermittent operation and 20 ft3/min (0.009 m3/s) for continuous operation. Fans shall comply with the Energy Star Program.
Heating and air conditioning filters shall
have a MERV rating of 6 or higher. The air distribution system
shall be designed for the pressure drop across the filter.