Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-51 - State Building Code adoption and amendment of the 2021 edition of the International Residential Code › Section 51-51-1505 - Section M1505-Mechanical ventilation

Current through Register Vol. 24-14, July 15, 2024
M1505.1
General.
Where local exhaust or whole-house mechanical
ventilation
is provided, the ventilation system shall be
			 designed in accordance with this section.
EXCEPTION:
Alternate balanced whole-house
ventilation
systems and local exhaust systems designed and commissioned in
						  accordance with ASHRAE 62.2 are permitted.
M1505.4
Whole-house mechanical ventilation system.
Each dwelling unit
			 shall be equipped with a ventilation system. The whole-house mechanical
			 ventilation systems shall be designed in accordance with Sections M1505.4.1
			 through M1505.4.4.
M1505.4.1
System
			 design.
The whole-house ventilation system shall consist of one or more
			 supply fans, one or more exhaust fans, or an ERV/HRV with integral fans,
			 associated ducts and controls. Whole-house mechanical ventilation system supply
			 and exhaust fans shall meet the requirements of Sections M1505.4.1.2,
			 M1505.4.1.3, M1505.4.1.4, and M1505.4.1.5. Local exhaust fans are permitted to
			 serve as part of the whole-house ventilation system when provided with the
			 proper controls in accordance with Section M1505.4.2. The systems shall be
			 designed and installed to exhaust and/or supply the minimum outdoor airflow
			 rates required by Section M1505.4.3 as modified by whole-house ventilation
			 system coefficients in Section M1505.4.3.1 where applicable. The whole-house
			 ventilation system shall operate continuously at the minimum ventilation rate
			 required by Section M1505.4.2 unless configured with intermittent off controls
			 in accordance with Section M1505.4.3.2.
M1505.4.1.1
Whole-house system
			 component requirements.
Whole-house ventilation supply and exhaust fans
			 specified in this section shall have a minimum efficacy as prescribed in the
Washington State Energy Code
. Design and installation of the
			 system or equipment shall be carried out in accordance with manufacturers'
			 installation instructions. Whole-house ventilation fans shall be rated for
			 sound at no less than the minimum airflow rate required by Section M1505.4.3.1.
			 Ventilation fans shall be rated for sound at a maximum of 1.0 sone. This sound
			 rating shall be at a minimum of 0.1 in. w.c. (25 Pa) static pressure in
			 accordance with HVI procedures specified in Sections M1505.4.1.2 and
			 M1505.4.1.3.
EXCEPTION:
HVAC air handlers, ERV/HRV units, and remote mounted
						  fans need not meet the sound requirements. To be considered for this exception,
						  a remote mounted fan must be mounted outside the habitable spaces, bathrooms,
						  toilets, and hallways, and there must be at least 4 feet (1.3 m) of ductwork
						  between the fan and the intake grille.
The whole-house supply fan shall provide ducted outdoor
				ventilation air to each habitable space within the residential unit.
EXCEPTION:
Interior joining spaces provided with a 30 cfm
						  whole-house transfer fan or a permanent opening with an area of not less than 8
						  percent of the floor area of the interior adjoining space but not less than 25
						  square feet do not require ducted outdoor ventilation air to be supplied
						  directly to the space. Whole-house transfer fans shall meet the sone rating of
						  Section M1505.4.1.1 and shall have whole-house ventilation controls that comply
						  with Section M1505.4.2.
M1505.4.1.2
Exhaust fans.
Exhaust fans required shall be ducted directly to the outside. Exhaust air
			 outlets shall be designed to limit the pressure difference to the outside and
			 equipped with backdraft dampers or motorized dampers in accordance with the
Washington State Energy Code
. Exhaust fans shall be tested and
			 rated in accordance with the airflow and sound rating procedures of the Home
			 Ventilating Institute (HVI 915, HVI Loudness Testing and Rating Procedure, HVI
			 916, HVI Airflow Test Procedure, and HVI 920, HVI Product Performance
			 Certification Procedure, as applicable). Exhaust fans required in this section
			 may be used to provide local ventilation. Bathroom exhaust fans that are
			 designed for intermittent exhaust airflow rates higher than the continuous
			 exhaust airflow rates in Table M1505.4.3.2 shall be provided with occupancy
			 sensors or humidity sensors to automatically override the fan to the high speed
			 airflow rate. The exhaust fans shall be tested and the testing results shall be
			 submitted and posted in accordance with Section M1505.4.1.6.
M1505.4.1.3
Supply fans.
Supply
			 fans used in meeting the requirements of this section shall supply outdoor air
			 from intake openings in accordance with the
International Mechanical
			 Code
Sections 401.4 and 401.5. When designed for intermittent off
			 operation, supply systems shall be equipped with motorized dampers in
			 accordance with the
Washington State Energy Code
. Supply fans
			 shall be tested and rated in accordance with the airflow and sound rating
			 procedures of the Home Ventilating Institute (HVI 915, HVI Loudness Testing and
			 Rating Procedure, HVI 916, HVI Airflow Test Procedure, and HVI 920, HVI Product
			 Performance Certification Procedure, as applicable). Where outdoor air is
			 provided by supply fan systems the outdoor air shall be filtered. The filter
			 shall be accessible for regular maintenance and replacement. The filter shall
			 have a Minimum Efficiency Rating Value (MERV) of at least 8.
M1505.4.1.4
Balanced whole-house
			 ventilation system.
A balanced whole-house ventilation system shall
			 include both supply and exhaust fans. The supply and exhaust fans shall have
			 airflow that is within 10 percent of each other. The tested and balanced total
			 mechanical exhaust airflow rate is within 10 percent or 5 cfm, whichever is
			 greater, of the total mechanical supply airflow rate. The flow rate test
			 results shall be submitted and posted in accordance with Section M1505.4.1.7.
			 The exhaust fan shall meet the requirements of Section M1505.4.1.2. The supply
			 fan shall meet the requirements of Section M1505.4.1.3. Balanced ventilation
			 systems with both supply and exhaust fans in a packaged product, such as an
			 ERV/HRV shall meet the requirements of HVI 920, as applicable. Local exhaust
			 systems that are not a component of the whole-house mechanical ventilation
			 system are exempt from the balanced airflow calculation.
M1505.4.1.5
Furnace integrated
			 supply.
Systems using space heating and/or cooling air handler fans for
			 outdoor air supply distribution are not permitted.
EXCEPTION:
Air handler fans shall have multispeed or variable
						  speed supply airflow control capability with a low speed operation not greater
						  than 25 percent of the rated supply airflow capacity during ventilation only
						  operation. Outdoor air intake openings must meet the provisions of Sections
						  R303.5 and R303.6 and must include a motorized damper that is activated by the
						  whole-house ventilation system controller. The motorized damper must be
						  controlled to maintain the outdoor airflow intake airflow within 10 percent of
						  the whole-house mechanical exhaust airflow rate. The flow rate for the outdoor
						  air intake must be tested and verified at the minimum ventilation fan speed and
						  the maximum heating or cooling fan speed. The results of the test shall be
						  submitted and posted in accordance with Section M1505.4.1.7.
M1505.4.1.6
Testing.
Whole-house
			 mechanical ventilation systems shall be tested, balanced and verified to
			 provide a flow rate not less than the minimum required by Sections M1505.4.3
			 and M1505.4.4.1. Testing shall be performed 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, outlet terminals or grilles or in the connected ventilation ducts.
			 Where required by the building official, testing shall be conducted by an
			 approved third party. A written report of the results of the test shall be
			 signed by the party conducting the test and provided to the building official
			 and be posted in the dwelling unit per Section M1505.4.1.7.
M1505.4.1.7
Certificate.
A
			 permanent certificate shall be completed by the mechanical contractor, test and
			 balance contractor or other approved party and posted on a wall in the space
			 where the furnace is located, a utility room, or an approved location inside
			 the building. When located on an electrical panel, the certificate shall not
			 cover or obstruct the visibility of the circuit directory label, service
			 disconnect label, or other required labels. The certificate shall list the flow
			 rate determined from the delivered airflow of the whole-house mechanical
			 ventilation system as installed and the type of mechanical whole-house
			 ventilation system used to comply with Section M1505.4.3.1.