14N-R4-R403 Systems.

The provisions of Section R403 of IECC-RE are adopted by reference with the following modifications:

1.   Throughout the body of each provision of this section, reset the singular and plural forms of the following terms in italic type: "building thermal envelope," "cavity insulation," "duct system," "dwelling unit," "on-site renewable energy," "thermostat," and "water heater."

2.   Revise Section R403.3.3 by deleting item 3.

3.   Revise Section R403.3.4 to read:

"Ducts, air handlers and filter boxes shall be sealed. Joints and seams shall comply with the Chicago Mechanical Code."

4.   Revise the last sentence of Section R403.3.5 to read: "A written report of the results of the test shall be signed by the party conducting the test and made available to the building official."

5.   Revise the numbered items in Section R403.3.6 to read:

"1.   Rough-in test: The total leakage shall be less than or equal to 4.0 cubic feet per minute (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area where the air handler is installed at the time of the test. Where the air handler is not installed at the time of the test, the total leakage shall be less than or equal to 3.0 cubic feet per minute (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

Exception: Where the duct system is serving less than or equal to 1,500 square feet (139.4 m2) of conditioned floor area, the allowable duct leakage with the air handler installed shall be less than or equal to 60 cubic feet per minute (1699 L/min).

2.   Postconstruction test: Total leakage shall be less than or equal to 4.0 cubic feet per minute (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

Exception: Where the duct system is serving less than or equal to 1,500 square feet (139.4 m2) of conditioned floor area, the allowable duct leakage shall be less than or equal to 60 cubic feet per minute (1699 L/min).

3.   Test for ducts within thermal envelope: Where all ducts and air handlers are located entirely within the building thermal envelope, total leakage shall be less than or equal to 8.0 cubic feet per minute (226.6 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

Exception: Where the duct system is serving less than or equal to 750 square feet (69.7 m2) of conditioned floor area, the allowable duct leakage shall be less than or equal to 60 cubic feet per minute (1699 L/min)."

6.   Revise the last two sentences of R403.5.1 to read: "Access to automatic controls, temperature sensors and pumps shall be provided. Ready access to manual controls shall be provided."

7.   Revise Section R403.6 and its subsections to read:

"R403.6 Mechanical ventilation.

Buildings and dwelling units shall be provided with mechanical ventilation that complies with the requirements of the Chicago Building Code and Chicago Mechanical Code. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.

R403.6.1 [Reserved.]

R403.6.2 Whole-house mechanical ventilation system fan efficacy.

Fans used to provide whole-house mechanical ventilation shall meet the efficacy requirements of Table R403.6.2 at one or more rating points. Fans shall be tested in accordance with HVI 916 and listed. The airflow shall be reported in the product listing or on the label. Fan efficacy shall be reported in the product listing or shall be derived from the input power and airflow values reported in the product listing or on the label. Fan efficacy for fully ducted HRV, ERC, balanced, and in-line fans shall be determined at a static pressure of not less than 0.2 inch w.c. (49.85 Pa). Fan efficacy for ducted range hoods and bathroom and utility room fans shall be determined at a static pressure of not less than 0.1 inch w.c. (24.91 Pa).

TABLE R403.6.2
WHOLE-HOUSE MECHANICAL VENTILATION SYSTEM FAN EFFICACY a

 

SYSTEM TYPE	AIRFLOW RATE (CFM)	MINIMUM EFFICACY (CFM/WATT)
HRV, ERV, or balanced	Any	1.2 cfm/watt
Range hood	Any	2.8 cfm/watt
In-line supply or exhaust fan	Any	3.8 cfm/watt
Other exhaust fan	< 90	2.8 cfm/watt
	≥ 90	3.5 cfm/watt
Air-handler that is integrated to tested and listed HVAC equipment	Any	1.2 cfm/watt

 

For SI: 1 cubic foot per minute = 28.3 L/min.

a.    Design outdoor airflow rate/watts of fan used.

R403.6.3 Testing.

Mechanical ventilation systems shall be tested and verified to provide the minimum ventilation flow rates required by Section R403.6. Testing shall be performed according to the ventilation equipment manufacturer’s instructions, or by using a flow hood or box, flow grid, or other airflow measuring device at the mechanical ventilation fan’s inlet terminals or grilles, 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 made available to the building official.

Exception: Kitchen range hoods that are ducted to the outside with 6-inch (152 mm) or larger duct and not more than one 90-degree (1.57 rad) elbow or equivalent in the duct run.

R403.6.4 Local exhaust.

Local exhaust systems shall be provided in kitchens, bathrooms and toilet rooms and shall have the capacity to exhaust the minimum airflow rate determined in accordance with Table 403.6.4.

TABLE 403.6.4
MINIMUM REQUIRED LOCAL EXHAUST RATES

 

AREA TO BE EXHAUSTED	EXHAUST RATE CAPACITY
Kitchens	100 cfm intermittent or 50 cfm continuous
Bathrooms and toilet rooms	50 cfm intermittent or 20 cfm continuous

 

For SI: 1 cubic foot per minute = 0.47 L/s.

R403.6.5 Exhaust discharge.

The air removed by every mechanical exhaust system shall be discharged outdoors at a point where it will not cause a public nuisance. The air shall be discharged to a location from which it cannot again be readily drawn in by a ventilating system. Air shall not be exhausted into an attic or crawl space.

Exceptions:

1.   Whole-house ventilation-type attic fans shall be allowed to discharge into the private attic of the dwelling unit served.

2.   Domestic ductless range hoods in accordance with the Chicago Mechanical Code.

R403.6.6 Ventilating equipment.

Fans providing exhaust or outdoor air shall be listed and labeled to provide the minimum required airflow in accordance with ANSI/AMCA 210-ANSI/ASHRAE 51.

R403.6.7 Whole-house mechanical ventilation systems.

Whole-house mechanical ventilation systems shall be installed in accordance with Sections R403.6.7.1 through R403.6.7.3.

R403.6.7.1 System design.

The whole-house mechanical ventilation system shall consist of one or more supply or exhaust fans, or a combination of such, and associated ducts and controls. Local exhaust or supply fans are permitted to serve as such a system. Outdoor air ducts connected to the return side of an air handler shall be considered to provide supply ventilation.

R403.6.7.2 System controls.

The whole-house mechanical ventilation system shall be provided with controls that enable manual override. Controls shall include text or a symbol indicating their function.

R403.6.7.3 Mechanical ventilation rate.

The whole-house mechanical ventilation system shall provide outdoor air at a continuous rate of not less than that determined in accordance with Equation 4-1.

Exceptions:

1.   The minimum mechanical ventilation rate determined in accordance with Equation 4-1 shall be allowed to be reduced by 30 percent where both of the following conditions apply:

1.1.   A ducted system supplies ventilation air directly to each bedroom and to one or more of the following:

1.1.1. Living room.

1.1.2. Dining room.

1.1.3. Kitchen.

1.2.   The whole-house mechanical ventilation system is a balanced ventilation system.

2.   The whole-house mechanical ventilation system is permitted to operate intermittently when the system has controls that enable operation for not less than 25 percent of each 4-hour segment and the ventilation rate prescribed in Equation 4 or Exception 1 is multiplied by the factor determined in accordance with Table R403.6.7.3.

CFMtotal = 0.03CFA + 7.5(Nbr + 1)      (Equation 4-1)

where:

CFMtotal   =   total required ventilation rate (cfm)

CFA      =   conditioned floor area of dwelling unit (ft2)

Nbr      =   number of bedrooms (not less than 1)

TABLE R403.6.7.3
INTERMITTENT WHOLE-HOUSE MECHANICAL VENTILATION RATE FACTORS a, b

 

RUN-TIME PERCENTAGE IN EACH 4-HOUR SEGMENT	25%	33%	50%	66%	75%	100%
Factor a	4.0	3.0	2.0	1.5	1.3	1.0

 

a.   For run-time percentage values between those given, the factors are permitted to be determined by interpolation.

b.   Extrapolation beyond the table is prohibited.

R403.6.7.3.1 Different occupant density.

Equation 4-1 assumes two persons per dwelling unit and an additional person for each additional bedroom. Where higher occupant densities are known, the airflow rate shall be increased by 7.5 cfm (3.5 L/s) for each additional occupant. When approved by the building official, lower occupant densities may be used.

R403.6.7.3.2 Airflow measurement.

The required ventilation rate is the quantity of outdoor ventilation air supplied or indoor air exhausted by the whole-house mechanical ventilation system installed, and shall be measured using a flow hood, flow grid, or other airflow measuring device. Ventilation airflow of systems with multiple operating modes shall be tested in all modes designed to meet Section R403.6.4.3. A written report of the results of the test, indicating the verified airflow rate, shall be signed by the party conducting the test and made available to the building official."

8.   Revise the first sentence of Section R403.10.2 to read:

"Access to an on-off switch controlling electric power to heaters shall be provided. The on-off switch shall be an integral part of the heater mounted on the exterior of the heater or external to and within 3 feet (914 mm) of the heater."