11.4   Building Indoor Air Quality and Ventilation Requirements

This section addresses the requirements for indoor air quality (IAQ) and ventilation in multifamily buildings and is organized as shown in Table 11-20. Sections 11.4.1 through 11.4.5 discuss IAQ and ventilation requirements for dwelling units, and Section 11.4.6 discusses ventilation requirements for common use areas, including corridors, community rooms, common laundry rooms, exercise facilities, and other areas outside of dwelling units.

Table 11-20: Overview of Indoor Air Quality and Ventilation Requirements in the Energy Code and Compliance Manual Organization

Source: California Energy Commission

Heating and cooling requirements for multifamily dwelling units are provided in Section 11.5.

11.4.1      What’s New for the 2022 Energy Code

The following is an overview of the new multifamily IAQ and ventilation requirements for the 2022 Building Energy Efficiency Standards (Energy Code).

11.4.1.1    Mandatory Features and Devices

For dwelling units:

•    Unitary energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs) (one unit serving each dwelling unit) are required to meet a maximum fan efficacy of 1.0 W/CFM.

•    If a vented range hood is used for the exhaust system in the dwelling unit kitchen, the range hood must either meet a minimum capture efficiency or airflow dependent on the range fuel and the floor area of the dwelling unit to ensure adequate removal of cooking-related pollution.

•    Central ventilation duct systems that provide continuous ventilation airflow or serve as part of dwelling units’ balanced ventilation must be sealed to ensure leakage does not exceed:

o  10% of the central (e.g., rooftop) fan airflow rate at 50 Pa (0.2 inches w.c.) for central ventilation duct serving more than six dwelling units

o  6% of the central fan airflow rate at 25 Pa (0.1 inches w.c.) for central ventilation duct serving six or fewer dwelling units

•    Updated ventilation requirements based on applicable sections of 2019 ASHRAE 62.2 and added clarification language.

•    Filter racks or grilles must use a gasket or sealing to prevent air from bypassing the filter.

For common use areas:

•    Common use areas are required to have occupant sensing ventilation controls if the space conditioning zones are permitted to have ventilation air reduced to zero or if occupant sensors are used to comply with lighting requirements. Occupant sensor ventilation control devices must comply with §160.2(c)E.

•    Filter racks or grilles must use a gasket or sealing to prevent air from bypassing the filter.

11.4.1.2    Prescriptive Requirements

For dwelling units:

•    In Climate Zones 4-10, if the ventilation system is a balanced system without heat or energy recovery, the fan efficacy must be 0.4 W/CFM or less.

•    In Climate Zones 1-2 and 11-16, for projects following the balanced ventilation path, the prescriptive approach requires an ERV or HRV.

o  Unitary ERV or HRV equipment (one unit serving each dwelling unit) must be field verified to have a sensible heat recovery efficiency of at least 67% and fan efficacy less than or equal to 0.6 W/CFM.

o  Central ERV or HRV equipment (one unit serving multiple dwelling units) must be field verified to have a minimum sensible heat recover effectiveness of 67%, have minimum fan efficacy as required in §170.2(c)4a, and include a bypass or free cooling function whereby the intake air bypasses the heat exchanger during favorable outdoor air temperatures.

For common use areas:

•    Common use areas using a dedicated outdoor air system (DOAS) to condition, temper, or filter 100% outdoor air separate from local or central space-conditioning systems serving the same space must meet new criteria specified in §170.2(c)4N. This includes requirements for heat recovery, an energy recovery bypass or control to directly economize with ventilation air, modulating fan speed control capabilities, fan efficacy requirements, and (for airflows > 1,000 cfm) demand control ventilation requirements.

•    Common use area fan systems that operate to criteria shown in Table 170.2-I or Table 170.2-J need to include an exhaust air heat recovery system that meet the requirements in §170.2(c)4O

11.4.1.3    Additions and Alterations

New to the Energy Code, there are explicit triggers for whole-dwelling unit mechanical ventilation system alterations including ventilation fans, air filters, and local mechanical exhaust systems.

There are no new requirements common use areas for additions or alterations. Additions to the common use area should follow the nonresidential building requirements. Any newly installed space conditioning system must meet the ventilation requirements in §120.1|topic=SECTION 120.1 – REQUIREMENTS FOR VENTILATION AND INDOOR AIR QUALITY (Requirements for Ventilation and Indoor Air Quality) for both the prescriptive and performance approaches.

11.4.2      Dwelling Unit IAQ and Mechanical Ventilation

As multifamily buildings have been tightened to improve energy performance, the dilution of indoor air through natural ventilation has been significantly reduced. As a result, the importance of controlling indoor pollutants generated by kitchen ranges during food preparation and (where applicable) from gas stoves. Cleaning products, furniture, dry cleaning, personal care products, and other sources may have increased. Without local exhaust to remove pollutants from areas such as kitchens and bathrooms, and dwelling unit ventilation to dilute pollutants throughout the dwelling unit, IAQ will be poor. This can negatively impact occupant health and (due to high relative humidity) the integrity of the building.

This section covers typical design solutions, energy consumption issues, and other requirements specified by ASHRAE Standard 62.2 as amended in the Energy Code.

11.4.2.1    Dwelling Unit Mandatory Requirements

A.    Overview of Requirements

Multifamily dwelling units must meet the requirements of ASHRAE Standard 62.2-2019 including Addenda v and d subject to the amendments specified in §160.2(b)2A. A copy of this version of ASHRAE Standard 62.2 may be obtained at the following link: www.techstreet.com/ashrae/standards/ashrae-62-2-2019?product_id=2087691 

As part of mandatory requirements, all dwelling units must have mechanical ventilation, Minimum Efficiency Reporting Value (MERV) 13 air filtration on space conditioning systems, and ventilation systems that provide outside air to the occupiable space of a dwelling. Opening and closing windows and continuous operation of central fan-integrated ventilation systems are not allowable options for meeting dwelling unit ventilation requirements. The requirements of ASHRAE Standard 62.2 focus on providing continuous whole-dwelling unit mechanical ventilation, as well as local exhaust ventilation at known sources of pollutants or moisture, such as kitchen, bathroom, and laundry. The key mandatory requirements for mechanical ventilation for most newly constructed multifamily buildings are:

•    A whole-dwelling unit mechanical ventilation system must be provided. Typical solutions are described in Section 11.4.2.10 Dwelling Unit Ventilation Strategies

•     section below. The airflow rate provided by the system must be confirmed through field verification and diagnostic testing in accordance with the applicable procedures specified in Reference Residential Appendix RA3.7.

•    Dwelling units must either use balanced ventilation or meet a compartmentalization (dwelling unit air sealing) requirement.

•    Kitchens and bathrooms must have local exhaust systems vented to the outdoors.

•    Clothes dryer exhaust must be vented to the outdoors.

The following additional IAQ design mandatory requirements apply:

•    Ventilation air mustmust come from outdoors and must not be transferred from adjacent conditioned spaces, garages, or unconditioned spaces.

•    Combustion appliances must be properly vented, and exhaust systems must be designed to prevent back drafting.

•    Walls and openings between the dwelling unit and adjacent spaces, such as adjacent units, a common corridor, trash chute, parking garage, or other spaces must be sealed or gasketed.

•    Mechanical systems, including ventilation systems, that supply air to habitable spaces mustmust be designed to filter recirculated air and outdoor air through a MERV 13 filter or better and mustmust be designed to accommodate the rated pressure drop of the system air filter at the designed airflow rate.

•    Dedicated outdoor air inlets that are part of the ventilation system design mustmust be located away from known sources of outdoor contaminants.

•    A carbon monoxide alarm mustmust be installed in each dwelling unit in accordance with NFPA Standard 720.

•    Air-moving equipment used to meet the whole-dwelling unit ventilation requirement and the local exhaust requirement, including kitchen local mechanical exhaust, mustmust be rated by HVI or AHAM, which provides ratings for kitchen local mechanical exhaust, for airflow and sound:

o  Whole-dwelling unit ventilation and continuously operating local exhaust fans must be rated at a maximum of 1.0 sone (measurement of sound).

o  Demand-controlled local exhaust fans must be rated at a maximum of 3.0 sone.

o  Kitchen exhaust fans must be rated at a maximum of 3.0 sone at one or more airflow settings greater than or equal to 100 CFM. (As described in Section 11.4.2 0, the Standard requires kitchen range hoods to have a higher airflow than 100 CFM, but the range hoods must be tested for sound at a minimum of 100 CFM.)

o  Remotely located air-moving equipment (mounted outside habitable space, bathrooms, toilets, and hallways) is exempt from the sound requirements provided there is at least 4 ft. of ductwork between the fan and the interior grille. Kitchen range hoods are also exempt from the sound requirements provided they have a minimum airflow setting exceeding 400 cfm.

•    For central ventilation systems serving multiple dwelling units, ducts must be sealed, balanced, and (for some systems) tested for leakage.

11.4.2.2    Summary of Field Verification and Testing Requirements by a HERS Rater or ATT

Compliance with the Standard requirements must be verified by the enforcement agency, except for the following requirements. Table 11-21 shows the ventilation and IAQ HERS Verifications that must be conducted by either a HERS Rater or ATT, where “stories” refers to habitable stories. As shown, the Energy Code generally requires that some HERS raters verify some features and that ATTs verify others. NA1.9 allows ATTs to serve as HERS raters in multifamily buildings with four or more stories. The builder is free to choose either a HERS Rater or ATT to perform the eligible HERS verifications, but that choice must be approved by the enforcement agency (NA1.9.1).

Table 11-21: Ventilation and IAQ Field Verification and Testing Requirements by a HERS Rater or ATT

Source: California Energy Commission

For HERS verification requirements, HERS raters must follow procedures in Residential Appendix RA3.7 and ATTs must follow procedures in Nonresidential Appendix NA2.1. Section 11.4.8 provides more detail on compliance and enforcement.

11.4.2.3    Differences between Energy Code and ASHRAE Standard 62.2

The Energy Code mandatory requirements include the adopted 2019 ASHRAE Standard 62.2 with amendments. The key differences in the Energy Code compared to the 2019 ASHRAE Standard 62.2 include the following:

•    While ASHRAE Standard 62.2 requires compartmentalization but does not require balanced ventilation, the Energy Code provide two options for compliance with dwelling unit ventilation: 1) installation of a balanced ventilation system or 2) installation of an exhaust or supply-only system accompanied by compartmentalization: sealing to a leakage rate of not more than 0.3 CFM50 per square feet of dwelling unit enclosure surface area.

•    The Energy Code require MERV 13 filtration for all recirculated air and outdoor air, including outdoor air provided by supply air ventilation systems or the supply side of balanced ventilation systems, while ASHRAE Standard 62.2 requires MERV 6 filtration for HVAC systems with at least 10 ft. of ductwork. The additional filtration requirements in the Energy Code are important for reducing particulate matter which can pose a health to residents.

•    Both standards require kitchen exhaust systems vented to the outdoors and allow three systems for kitchen exhaust systems in multifamily dwelling units: 1) demand-controlled range hood, 2) downdraft exhaust or 3) continuous kitchen exhaust for enclosed kitchens only.

o  For demand-controlled range hoods, the Energy Code require that they either meet a minimum airflow or capture efficiency that depends on the type and dwelling unit floor area as shown in Table 11-22. There are no capture efficiency requirements in ASHRAE Standard 62.2. Additionally, the required minimum hood airflows are higher in the Energy Code, as shown in Table 11-22, than the requirement in ASHRAE Standard 62.2, which is 100 CFM for all demand-controlled range hoods.

Table 11-22: Minimum Capture Efficiency (CE) or Airflow (CFM) for Demand-Controlled Range Hoods

Source: California Energy Commission

o  For downdraft and continuous kitchen exhaust requirements, the Energy Code and ASHRAE Standard 62.2 are the same.

The verification protocol for kitchen exhaust systems remains the same. Kitchen range hood fans are required to be verified by a HERS Rater. The verification protocol requires comparing the installed model to ratings in the Home Ventilating Institute (HVI) or Association of Home Appliance Manufacturers (AHAM) directory of certified ventilation products to confirm the installed range hood is rated to meet the required airflow in the Energy Code, as well as the sound requirements specified in ASHRAE Standard 62.2. See the section, Requirements for Kitchen Exhaust below for more detail. Kitchen range hood fans that exhaust more than 400 CFM at minimum speed are exempt from the sound requirement.

Limiting the sources of indoor pollutants is an important method for protecting IAQ. The United States Environmental Protection Agency (EPA) provides information and resources on improving IAQ. For more information, see the EPA’s Indoor Air Quality webpage: /www.epa.gov/indoor-air-quality-iaq.

11.4.2.4    Dwelling Unit Ventilation Strategies

This section provides typical strategies for providing outdoor air for whole-dwelling unit ventilation. Local exhaust systems, which provide spot ventilation to remove polluted air from areas such as bathrooms and kitchen, are described in the section 11.4.2.1 0 Dwelling Unit Local Exhaust .

Multifamily projects can use either of the following strategies:

•    Unitary ventilation system, in which each dwelling unit has its own ventilation system. These are often simpler designs and use packaged equipment, but present more systems to maintain, may require maintenance by the resident (or at least their cooperation to provide access), and can require more wall penetrations.

•    Central ventilation systems, in which a centrally located (typically rooftop) fan and centralized ductwork serves multiple dwelling units. These can streamline maintenance and reduce exterior wall penetrations. For ERVs and HRVs, centralized equipment provides economies of scale for features such as bypass, which provides significant energy savings during the cooling season. However, centralized ventilation systems reduce the occupiable square footage in a building and can increase penetrations between units, which should be sealed for IAQ concerns.

There are generally three system types available for meeting the mandatory whole-dwelling unit ventilation requirements:

1.    Exhaust ventilation: air is exhausted from the dwelling unit and replaced by infiltration—i.e., air entering the dwelling unit through cracks and leaks in the dwelling unit air barrier.

2.    Supply ventilation: filtered outdoor air is supplied directly to the dwelling unit

3.    Balanced ventilation: combination of exhaust and supply in which air is exhausted from a dwelling unit and outdoor air is supplied directly to the dwelling unit at the same rate (within 20%).

For the mandatory requirements of the Energy Code, §160.2(b)2Aivb requires the whole-dwelling unit ventilation system to either be a balanced system or a supply or exhaust system with compartmentalization testing. See section 11.4.2.10 for details on compartmentalization testing. Multifamily buildings must use one approach for compliance (either balanced ventilation, or supply or exhaust-only ventilation with compartmentalization throughout the entire building, per §160.2(b)2Aivb. Multifamily projects could implement both balanced ventilation and compartmentalization for best practice but are not required to do so.

Natural ventilation does not satisfy requirements for dwelling unit ventilation. All dwelling unit ventilation systems need to have a mechanical fan.

A.    Exhaust-only

In an exhaust-only system, air is drawn from the dwelling unit and exhausted to the outdoors. Outdoor air enters the unit through infiltration. This infiltration air will include both outdoor air, as well as air from adjacent spaces in the building (e.g., corridor, adjacent units). While not prohibited, exhaust-only ventilation systems are not good practice in dwelling units that will have difficulty drawing adequate outside air due to limited exterior wall area.

Exhaust ventilation is typically provided using a continuously operating ceiling-mounted fan. Projects may use intermittent fans for meeting the dwelling unit ventilation rate, but these must be on a schedule to ensure that the minimum ventilation rate is met. Examples of intermittent ventilation systems can be found in ASHRAE 62.2 Section 4.5. Intermittent ventilation systems must be certified to the Energy Commission.

All fans must meet sound requirements: maximum of one sone for continuously operated and 3 sones for intermittent. Remotely located fans (fans mounted outside habitable spaces, bathrooms, toilets, and hallways) are exempt from the sound requirements if there is at least four feet of ductwork between the fan and the interior grille. For larger units, more than one fan may be needed to meet ventilation air requirements. The same fan can be used to meet dwelling unit and local (bathroom or laundry) exhaust ventilation requirements. Inline fans (fans mounted in line with ductwork) can be used to exhaust air from one or more bathrooms.

While not required, some multifamily units include passive air inlets, such as Z-ducts or trickle vents, to increase the rate of fresh air that enters the unit beyond natural infiltration. Since there is no filter in an exhaust-only dwelling unit ventilation system, MERV 13 filtration is not applicable to exhaust-only ventilation or air that enters via passive air inlets. However, MERV 13 filtration is still required in the dwelling unit for the separate space conditioning (heating or cooling) system, if it is a forced air system with ductwork exceeding 10 feet in length. Figure 11-26 provides an example of an exhaust-only ventilation strategy. While this example is shown for a garden style unit, the same approach could be used for a dwelling unit on a common corridor (in a building with a common entry).

Figure 11-26: Exhaust Ventilation Example

Bathroom exhaust fans may serve a dual purpose to provide whole-dwelling unit ventilation operating at a low constant airflow rate and to provide local demand-controlled ventilation at a higher airflow rate, or boost, when needed. For these system types, the continuous whole-dwelling unit airflow operation must have an ON/OFF override, which may be located in the bathroom or in a remote accessible location. The boost function is controlled by a separate wall switch located in the bathroom or by a motion sensor or humidistat located in the bathroom.

A kitchen exhaust fan in an enclosed kitchen may also serve a dual purpose of whole-dwelling unit ventilation and kitchen ventilation if it meets both the minimum dwelling unit ventilation rate and the minimum requirement for kitchen exhaust (described in the Section Dwelling Unit Local Exhaust).

B.    Supply Ventilation

Supply ventilation systems draw outdoor air into the unit using a dedicated supply fan. Indoor air escapes through leaks in the building envelope (exfiltration). Space conditioning system air handling units cannot be used to provide supply ventilation, unless they meet the Central Fan-Integrated Ventilation approach described in Section 11.4.2.10D.

Continuously operating ventilation fans must meet mandatory sound requirement of one sone or less. For larger dwelling units, more than one fan may be used. Remotely located fans (fans mounted outside habitable space, bathrooms, toilets, and hallways) are exempt from the sound requirements if there is at least four feet of ductwork between the fan and the interior grille.

§160.2(b)1 requires that outside air be filtered using MERV 13 (or greater) particle removal efficiency rated air filters. The filters must be accessible to facilitate replacement. Supply systems may locate the MERV 13 air filter either upstream or downstream of the fan as long as the incoming outdoor air is filtered prior to delivery to the dwelling unit’s occupiable space. An example of MERV 13 filter placement in air handling units is shown in Figure 11-27. Fans may be located in dropped ceiling spaces, mechanical closets, or other spaces dedicated for installation of mechanical equipment. As required in §10-103(b), builders must provide information to building operators and occupants for the operation of any equipment that requires filter replacement.

Figure 11-26: MERV 13 Locations for Ventilation and Space Conditioning Air Handler Unit

in Example Scenario

The outdoor air inlet should be located to avoid areas with contaminants such as smoke produced in barbeque areas, products of combustion emitted from gas appliance vents, and vehicle emissions from parking lots or garages. Air may not be drawn from attics or crawlspaces.

To minimize drafts and optimize distribution, supply air can be ducted directly to bedrooms and living areas using an appropriately sized and sealed ventilation-only duct system or by connecting to the HVAC supply plenum. However, distribution of supply air is best practice but not required.

C.    Balanced Ventilation

Balanced systems use an exhaust fan and a supply fan to move approximately the same volume of air into and out of the dwelling. To be considered a balanced ventilation system, the total supply airflow and the total exhaust airflow must be within 20 percent of each other. Specifics on measuring airflows to determine compliance are found in RA3.7.4.1.2. Balanced ventilation may be a single packaged unit containing supply and exhaust fans that moves approximately the same airflow, or it may use separate fans. In both cases, air supplied from outdoors must be filtered. (See Section 11.4.2.10: Dwelling Unit Air Filtration for air filter requirements.) Balanced ventilation can incorporate heat recovery. As described in Section 11.4.2.2, heat recovery is required in certain climate zones under the prescriptive path.

§160.2(b)2Aivb requires the whole-dwelling unit ventilation system to either be a balanced system or a supply or exhaust system with compartmentalization testing. The Energy Code encourage the use of balanced ventilation in §160.2(b)2Aiv, since exhaust-only systems bring in air from adjacent spaces, which can negatively impact IAQ.

Some balanced systems are small HRVs or ERVs that are packaged systems. HRVs and ERVs temper incoming air with outgoing air, which reduces the thermal effect of ventilation on heating and cooling loads, but the dual fans increase electrical energy use. HRVs and ERVs are discussed in Section 11.4.2.2.

Like supply ventilation systems, balanced systems are required to be equipped with MERV 13 or better filters to remove particles from the intake airflow prior to delivery to the dwelling unit’s occupiable space per §160.2(b)1.

Balanced systems must comply with the same minimum separation distance between intake and exhaust as supply-ventilation systems. The outdoor air inlet should be located to avoid areas with contaminants such as smoke produced in barbeque areas, products of combustion emitted from gas appliance vents, and vehicle emissions from parking lots or garages. Air may not be drawn from attics or crawlspaces.

Balanced ventilation systems may be either unitary (each dwelling unit has own ventilation system) or central systems. Examples of unitary and central balanced systems are provided below.

Unitary Balanced Ventilation

An example of a balanced ventilation system which couples a continuous exhaust fan with an in-line fan that directly supplies outdoor air is shown in Figure 11-28.

Figure 11-27: Example of Balanced Ventilation Without Heat Recovery: Discrete Supply In-Line Fan with Continuous Bath Exhaust

Strategies other than an inline fan for providing outdoor air include packaged terminal unit (or packaged terminal air conditioning - PTAC) or supply fans.

An ERV or HRV balanced ventilation is shown in Figure 11-29.

Figure 11-29: Example of Balanced Ventilation with Heat Recovery: Unitary ERV

Central Balanced Ventilation

A central balanced ventilation system provides supply-air to and exhaust air from multiple dwelling units. A central balanced ventilation approach could use a dedicated outdoor air system (DOAS) for supplying outdoor air to units and unitary bathroom exhaust. Figure 11-30 shows an example schematic of DOAS; note, the unitary bathroom exhaust is not shown. Because the building in this diagram assumes that the bottom floor is

commercial space, the system does not serve this floor.

Figure 11-30: Dedicated Outdoor Air System (DOAS) for Supplying Fresh Air to Dwelling Units

Alternatively, balanced ventilation could be provided by a rooftop HRV or ERV. For the prescriptive path in Climate Zones 1, 2, and 11- 16, the Energy Code require that a central HRV or ERV include a bypass or free cooling function that enables the HRV or ERV to bring in fresh air from the outdoors. This function allows incoming air to bypass the heat or energy recovery component when the enthalpy of the outdoor air is within certain temperature and relative humidity limits.

Figure 11-31: Central Balanced Ventilation Strategies: DOAS and Central ERV

As shown in the figures above, each rooftop supply fan, HRV, or ERV would connect (via rooftop ductwork) to vertical shafts. In the example, six vertical shafts serve two dwelling unit from each floor, and one vertical shaft serves one dwelling unit per floor. While not shown in the figure for simplicity, each shaft would need a short horizontal run-out to the dwelling units on each floor and fire smoke dampers (FSDs) at the entry of this duct to the dwelling unit.

Alternatively, central ERVs or HRVs could be located throughout the building (such as one on each floor or for each wing) and serve a cluster of units.

D.    Central Fan-Integrated Ventilation

A central fan integrated (CFI) ventilation system is a configuration where the ventilation ductwork is connected to the space conditioning duct system, to enable distribution of ventilation air to the dwelling unit when the space conditioning system air handler is operating. This strategy mixes the outdoor air with the large volume of return air from the dwelling unit before being distributed. CFI ventilation systems consume a relatively high amount of energy compared to the other ventilation types because it uses the air handler fan. The Energy Code includes the following requirements specific to CFI ventilation systems:

1.    Continuous Operation is Prohibited – The continuous operation of a space conditioning air handler is prohibited in providing whole-dwelling unit ventilation.

2.    Outdoor Air Damper(s) – A motorized damper must be installed on any ventilation duct that connects outdoor air to the space conditioning duct system and must prevent airflow into or out of the space conditioning duct system when the damper is in the closed position.

3.    Damper Control – The outdoor air damper must be controlled to be in the open position only when outdoor air is required for whole-dwelling unit ventilation and must be in the closed position when outdoor air is not required. The damper must be in the closed position when the air handler is not operating. If the outdoor airflow is fan-powered, then the outdoor air fan must not operate when the outdoor air damper is in the closed position.

4.    Variable Ventilation Control – CFI ventilation systems must have controls that track outdoor air ventilation run time, and either open or close the motorized damper depending on whether the required whole-dwelling unit ventilation airflow rate is being met. During periods when space conditioning is not called for by the space conditioning thermostat, the controls must operate the air handler fan and the outdoor air damper(s) when necessary to ensure the required whole-dwelling unit ventilation airflow rate is met. This control strategy must be in accordance with ASHRAE 62.2 section 4.5 which requires controls to operate the fan at least once every three hours, and the average whole-dwelling unit ventilation airflow rate over any 3-hour period must be greater than or equal to the required whole-dwelling unit ventilation airflow rate.

Figure 11-32: Example of Central Fan-Integrated (CFI) Ventilation with MERV 13 Filtration

§160.2(b)1 requires that outside air be filtered using minimum MERV 13 particle removal efficiency rated air filters. Filters must be accessible to simplify replacement. For CFI systems, the filters must be installed upstream of the cooling or heating coil; thus, the filter rack provided at the inlet to the air handler may be used. In this case, it is not necessary to provide another MERV 13 or greater filter within the outdoor air duct. Otherwise, filters must be provided at the return grill(s) for the central fan, and another filter must be provided in the outside air ductwork before the point the outside air enters the return plenum of the central fan.

For a CFI ventilation system, both the central forced-air system fan total airflow and the much smaller outdoor ventilation airflow rate must be verified by a HERS Rater.

CFI ventilation systems, devices, and controls may be approved for use for compliance with the HERS field verification requirements for whole-dwelling unit mechanical ventilation in accordance with RA3.7.4.2. CFI ventilation systems are considered intermittent mechanical ventilation systems and must be certified to the Energy Commission that the CFI ventilation system will meet the minimum whole-dwelling unit ventilation requirements.

A listing of certified CFI ventilation systems is posted at the following URL:

http://www.energy.ca.gov/title24/equipment_cert/imv/

The outside air ducts for CFI ventilation systems are not allowed to be sealed/taped off during duct leakage testing. However, CFI outdoor air ductwork that uses controlled motorized dampers that open only when outdoor air ventilation is required and close when outdoor air ventilation is not required may be closed during duct leakage testing.

Because CFI ventilation systems can use a large amount of electricity annually compared to other ventilation system types, the air handlers used in CFI ventilation systems are required to meet the fan watt draw requirements given in Section 150.0(m)13B in all climate zones.

11.4.2.5    Dwelling Unit Ventilation Rate

This section discusses calculation of ventilation rates and necessary ventilation control systems to meet mandatory requirements.

E.     Total Ventilation Rate (Q_tot)

The total ventilation rate Q_tot is the volume of ventilation air provided by mechanical ventilation provided from multifamily dwelling units fans, as follows:

Equation 11-1

Where:

Dwelling units cannot use a building infiltration credit to reduce the required whole-dwelling unit mechanical ventilation rate, since it is difficult to determine whether that infiltration is truly outdoor air, or it comes from adjacent spaces in the building.

F.     Continuous, Scheduled, and Smart Ventilation Systems

Dwelling unit ventilation systems may operate continuously or on a short-term basis. If fan operation is not continuous, the average ventilation rate over any three-hour period must be greater than or equal to the ventilation rate calculated using Equation 11-1.

The Energy Code allows for scheduled ventilation and real-time control. A control method must be chosen so that the relative exposure does not exceed specified peak and average relative exposure limits of ASHRAE Standard 62.2. Normative Appendix C provides direction on calculating the relative exposure and provides standardized calculations for complex ventilation controls implemented by use of digital controls that rely on the manufacturer's product-specific algorithms or software. Users installing any type of intermittent ventilation control system (scheduled or real-time) must submit an application to the Energy Commission to have the control approved. The manufacturers must provide documentation that the system will perform to provide the required whole-dwelling unit mechanical ventilation. Listings of systems approved by the Energy Commission and certified by the manufacturer are located at the following link: www.energy.ca.gov/rules-and-regulations/building-energy-efficiency/manufacturer-certification-building-equipment-6

Designers should calculate the value for F_an as shown in Equation 11-1 and record it on the certificate of compliance. The compliance software approach uses Equation 11-1. in the calculation

Time-of-day timers or duty-cycle timers can be used to control intermittent/variable dwelling unit ventilation. The system must operate automatically without intervention by the occupant. Some controls look back over a set time interval to determine if the CFI system air handler has already operated for heating or cooling before it turns on the air handler for ventilation-only operation.

G.    Control and Operation

While dwelling unit ventilation systems should operate (i.e., be in the ON position) in almost all circumstances, the Energy Code require a manual ON-OFF control, with the purpose of allowing occupants or staff to temporarily turn off the system for extreme events, such as during wildfires. The dwelling unit ventilation system dilutes pollutants that can worsen IAQ such as particulate matter; combustion gases due to imperfect exhaust systems; volatile organic compounds from personal care products, dry cleaning, and other sources; and other pollutants. The dwelling unit ventilation system also reduces relative humidity, which can cause mold or damage the building.

In alignment with ASHRAE Standard 62.2, while the Energy Code require that the manual ON-OFF control be accessible to the occupants in single-family units, there is an exception for multifamily units; it is not required to be readily accessible to the dwelling unit occupants. For multifamily buildings, manual ON-OFF control may be accessible to occupants or only to building maintenance staff. The control strategy where it is only accessible to maintenance staff may be appropriate for multifamily buildings that use central ventilation systems and possibly unbalanced (supply-only or exhaust-only) system types (for which the Energy Code require that all the ventilation systems in the building operate continuously). Continuous operation of all ventilation fans in the building tends to minimize ventilation fan-induced pressure differences between adjoining dwellings, thus, reducing the leakage of transfer air between dwelling units. However, designers should consider the possibility of wildfire smoke or other outdoor air pollution events that could impact the IAQ of dwelling units and ensure there is a means for occupants or maintenance staff to quickly turn off dwelling unit ventilation systems in the circumstances when these systems may inadvertently degrade IAQ. The ventilation system should be returned to the ON position after the extreme event passes.

11.4.2.6    Dwelling Unit ERV/ HRV Fan Efficacy and Heat Recovery

There is a mandatory requirement that all HRVs and ERVs serving a single dwelling unit must have a fan efficacy of one W/CFM or less. HRVs and ERVs meeting the prescriptive path for multifamily dwelling units using balanced ventilation in Climate Zones 1, 2 and 11-16 must meet more stringent fan efficacy, as described in Section 11.4.2.2.

Fan efficacy is calculated as the Power Consumed in Watts divided by the Net Airflow in CFM. Sensible recovery efficiency is directly reported in the HVI database. If the HVI database or other CEC approved directories do not list the fan energy for the installed model or the proposed product is a large central ERV/HRV whose airflow rate exceeds the maximum listed in the HVI database, use information from the manufacturer's published documentation.

11.4.2.7    Dwelling Unit Local Exhaust

The Energy Code specify local exhaust requirements, but do not adopt ASHRAE Standard 62.2 Section 5 (Local Exhaust). However, the Energy Code are based on the local exhaust requirements in ASHRAE Standard 62.2 Section 5, with the exception of kitchen exhaust. This section provides an overview of demand-controlled local exhaust, continuous local exhaust, and special requirements for kitchen exhaust in the Energy Code. The Energy Code follows the ASHRAE 62.2 definitions for kitchens and bathrooms for these ventilation requirements. Kitchens are any rooms containing cooking appliances, and bathrooms are any rooms containing a bathtub, shower, spa, or other similar source of moisture. A room containing only a toilet is not required to have an exhaust fan; ASHRAE 62.2 assumes there is an adjacent bathroom with local exhaust.

H.    Demand Controlled Local Exhaust

Local exhaust (sometimes called spot ventilation) has long been required by building codes and ASHRAE standards for bathrooms and kitchens to remove moisture, odors, and (for kitchens) particulate matter and combustion gases (from gas ranges) at the source.

The Energy Code require bathroom fans with a minimum exhaust airflow of 50 CFM and a sound rating of no more than three sone. To reduce exposure to cooking contaminants, the Energy Code require that kitchen range hoods be capable of exhausting between 110 and 280 CFM depending on dwelling unit size and range type (gas or electric).

The Energy Code require that local exhaust fans be designed to be operated by the occupant. This usually means that a wall switch or some other control is readily accessible. There is no requirement to specify where the control or switch needs to be located, but bathroom exhaust fan controls are generally located next to the light switch, and kitchen exhaust fan controls are generally integrated into the range hood or mounted on the wall or counter adjacent to the range hood.

Bathrooms can use a variety of exhaust strategies, including ceiling-mounted exhaust fans or remotely mounted fan ducted to two or more exhaust grilles. Demand-controlled local exhaust can be integrated with the dwelling unit ventilation system to provide both functions.

The control can be a manual switch or automatic control like an occupancy sensor. Some exhaust fans have multiple speeds, and some fan controls have a delay-off function that operates the exhaust fan for a set time after the occupant leaves the bathroom. Title 24, Part 11 (CALGreen) specifies additional requirements for the control and operation of demand-controlled local exhaust. For example, §4.506 requires bathroom exhaust fans to be ENERGY STAR compliant and (unless functioning as a component of a whole house ventilation system) to be controlled with a humidity control.

I.      Continuous Local Exhaust

The airflow requirements from ASHRAE Standard 62.2 for continuous exhaust are adopted into the Energy Code and shown in Table 11-23.

Table 11-23: Continuous Local Ventilation Exhaust Airflow Rates (Table 160.2F from the Energy Code)

Source: California Energy Commission

The Energy Code allows the designer to install a local exhaust system that operates without occupant intervention continuously and automatically. Continuous local exhaust is generally specified when the local exhaust ventilation system is combined with a continuous dwelling unit ventilation system. For example, if the dwelling unit ventilation is provided by a continuously operating exhaust fan located in the bathroom, this fan may also satisfy the local exhaust requirement for that bathroom, provided the fan provides airflow greater than or equal to the minimum continuous local ventilation airflow rate. Many builders install a two-speed fan that runs at low speed continuously to satisfy the dwelling unit ventilation system requirement, but that can increase to a higher speed to meet the demand-controlled bathroom exhaust requirement using a wall switch. A continuous local exhaust system may also include a pickup, which refers to an interior grille that is ducted to a remote fan, which could be ducted to an HRV or ERV.

Continuously operating bathroom fans must operate at a minimum of 20 CFM and a sound rating of no more than one sone. Continuous kitchen exhaust fans must operate at a minimum of five kitchen air changes per hour (ACH).

J.      Requirements for Kitchen Exhaust

Kitchen exhaust is important to remove pollution created during cooking processes, including fine particles (PM2.5) and relative humidity; combustion gases such as nitrogen dioxide (NO2) and carbon monoxide (CO) from natural gas and propane-fueled cooktops and ovens; and odors. The most effective method in removing pollutants generated from cooking is to use a vented kitchen range hood, which removes pollutants above the cooking surface before they mix with the air in the rest of the home. The 2022 Energy Code incorporates a new metric for local exhaust called capture efficiency. Capture efficiency is determined in accordance with ASTM E3087 as the fraction of emitted tracer gas that is directly exhausted by a range hood.

The Energy Code allow different options for kitchen exhaust including intermittent (typically demand-controlled) range hoods, a continuously operating fan in the kitchen, or a downdraft fan. For the demand-controlled option, the Energy Code allow the traditional airflow (in cubic feet per minute, or CFM) path for compliance or a capture efficiency path.

Under the Energy Code, dwelling units can use any one of the following options for kitchen exhaust:

•    A demand-controlled, vented range hood with at least one setting with a capture efficiency (CE) that meets or exceeds the values shown in Table 11-24.

•    A demand-controlled, vented range hood with an airflow that meets or exceeds the exhaust rates shown in Table 11-24.

•    A demand-controlled, vented downdraft kitchen exhaust fan (not represented in the table below) in enclosed kitchens with a minimum airflow of 300 cfm or a capacity of 5 air changes per hour. In a nonenclosed kitchen, the fan must have a minimum airflow of 300 cfm (no air changes per hour option).

•    For enclosed kitchens only: Continuous exhaust system with a minimum airflow equal to five kitchen air changes per hour.

Table 11-24: Kitchen Range Hood Airflow Rates (CFM) and ASTM E3087 Capture Efficiency (CE) Ratings
According to Dwelling Unit Floor Area and Kitchen Range Fuel Type

Source: from Table 160.2-G in the Energy Code

The capture efficiency path (Option 1) is specific to the Energy Code. The minimum capture efficiency or airflow requirement for the range hood is the minimum required to adequately capture the moisture, particulates, and other products of cooking and/or combustion. While many products do not have published capture efficiency results as of the time of the publication of this manual, Option 1 is intended to be a forward-looking approach and will support future listings.

While capture efficiency is the metric that directly measures pollutant removal, the airflow path (Option 2) is provided because capture efficiency generally increases with airflow, and the HVI and AHAM databases list airflow for kitchen exhaust appliances. ASHRAE Standard 62.2 includes a similar path as Option 2, but with lower required airflows (minimum 100 CFM). Because there is less air available for dilution in small dwelling units, the Energy Code set higher minimum requirements for smaller dwelling units. Because gas ranges emit NO2 and CO, in addition to the PM2.5 released from cooking processes, the capture efficiency and airflow requirements are higher for hoods over gas ranges. 

The vented downdraft compliance option (Option 3) and continuous kitchen exhaust option (Option 4) are taken directly from ASHRAE Standard 62.2. The definition of an “enclosed kitchen”, which must be met to use continuous kitchen exhaust, is also taken from ASHRAE Standard 62.2, and is defined as “permanent openings to interior adjacent spaces do not exceed a total of 60 square feet”. Only in enclosed kitchens, the exhaust requirement can also be met with either a ceiling or wall-mounted exhaust fan or with a ducted fan or ducted ventilation system that can provide at least five air changes of the kitchen volume per hour.

Recirculating range hoods that do not exhaust pollutants to the outside cannot be used to meet the Energy Code requirements, unless paired with an exhaust system exhausting to the outside that can provide at least one of the following:

1.    Continuous or demand-controlled operation in an enclosed kitchen providing five air changes of the kitchen volume per hour, or

2.    Demand-controlled operation in an enclosed or unenclosed kitchen providing at least 300 cfm of exhaust.

Generally, HRV/ERV manufacturers do not recommend that kitchen exhaust pass through HRV or ERV equipment, because the heat, moisture, grease, and particulates could damage heat exchange core.

The Energy Code do not explicitly specify a static pressure at which range hoods should be measured for airflow. However, the Energy Code require that range hoods be listed in the HVI or AHAM product directories, and both of those directories list range hood airflows at 0.1” w.c. (and some at 0.25” w.c.), since 0.1” is the basic rating point for range hoods in HVI Standard 920. Note that some product airflows are listed at working-speed at lower static pressures, but working-speed airflows can only be used for compliance with the sound requirement, not airflow requirement.

The Energy Code require either field-measurement of kitchen exhaust airflow or meeting prescriptive duct sizing requirements. When complying using prescriptive duct sizing requirements, the Energy Code require range hood airflow at a static pressure of 0.25” of w.c. Section 11.4.4.3 Duct Sizing provides more detail.

The Energy Code require verification that range hoods are HVI- or AHAM-certified to provide at least one speed setting at which they can deliver at least 100 CFM at a sound level of 3 sones or less. (This rating point of 100 CFM is lower than the minimum air flow required for pollutant removal.) Verification must be in accordance with the procedures in Reference Residential Appendix RA3.7.4.3. Range hoods that have a minimum airflow setting exceeding 400 CFM are exempt from the sound requirement. HVI listings are available at: https://www.hvi.org/hvi-certified-products-directory. AHAM listings are available at: https://www.aham.org/AHAM/What_We_Do/Kitchen_Range_Hood_Certification.

The Energy Code limits exhaust airflow when atmospherically vented combustion appliances are located inside the pressure boundary. The demand-controlled range hood airflow and capture efficiency requirements will often exceed this exhaust airflow limit for typical multifamily dwelling units. Therefore, most multifamily dwelling unit with atmospherically vented appliances will need a makeup air fan. Refer to Section 11.4.5.3 for more information.

The verification protocol for kitchen exhaust systems remains the same compared with the 2019 Energy Code procedures. The only difference is that an option of using capture efficiency (instead of airflow) has been added to verify the kitchen exhaust system.

•    Manufacturers must test the range hood air flow and/or capture efficiency, which will be available in the HVI or AHAM database to reference for verification.

•    Kitchen exhaust systems are required to be verified by a HERS Rater or ATT, depending upon the number of habitable stories in the building. The verification protocol requires comparing the installed model to ratings in the HVI or AHAM directory of certified ventilation products to confirm the installed range hood is rated to meet the required capture efficiency or airflow in the Energy Code. The HERS rater or ATT should also confirm the range hood meets the sound requirements specified in the Energy Code.

11.4.2.8    Dwelling Unit Ventilation Airflow Measurement

K.    Whole-dwelling Unit Ventilation System

§160.2(b)2Avii requires airflow measurement of the whole-dwelling unit ventilation system. The purpose is to ensure that the specified ventilation rate is delivered to the unit.

All whole-dwelling unit ventilation systems must demonstrate compliance by direct airflow measurement using a flow hood (such as shown in Figure 11-33), flow grid, or other approved measuring device. HERS verification of whole-dwelling unit ventilation airflow is required for newly constructed buildings and existing buildings with additions greater than 1,000 sq. ft or an increase in the number of dwelling units.

Residential Appendix RA3.7.4 (for multifamily buildings up to three habitable stories) and Nonresidential Appendix NA2.2.4.1.1 (for multifamily buildings four or more habitable stories) provide guidance for measurement of supply, exhaust, and balanced system types. These measurement procedures are applicable when there is a fixed airflow rate required for compliance, such as for systems that operate continuously at a specific airflow rate or systems that operate intermittently at a fixed speed (averaged over any three-hour period), according to a fixed programmed pattern that is verifiable by a HERS Rater on site. (Refer to ASHRAE Standard 62.2 Section 4.5.1 Short Term Average Ventilation.)

For exhaust-only systems, measurement of the whole-dwelling unit ventilation airflow should be done by measuring airflow of the exhaust fan(s). While this approach will over-represent the airflow from the outdoors, it is difficult to determine the fraction of the infiltration from the outdoors versus adjacent spaces in the building.

For whole-dwelling unit ventilation systems that use scheduled ventilation or real-time controls, the Energy Commission may consider the ventilation system for approval, if the manufacturer provides a method that can be used by a HERS Rater or ATT to verify that an installed system is operating as designed. Figure 11-33 shows examples of an airflow rate measuring devices.

Figure 11-33: System Airflow Rate Measurement Using Flow Capture Equipment

Source: California Statewide CASE Team

11.4.2.9    Local Exhaust System

Local exhaust systems also require airflow measurement, similar to the whole-dwelling unit ventilation system. For local exhaust systems, there are two ways to demonstrate compliance with airflow requirements of §160.2(b)2Avie:

•    Test the ventilation system using an airflow measuring device after completion of the installation to confirm that the delivered ventilation airflow meets the requirement using same process as airflow measurement of whole-dwelling unit ventilation system.

•    Use a fan that has a certified airflow rating that meets or exceeds the required ventilation airflow, and ventilation ducts that meet either the fan manufacturer’s published duct design specifications or the duct design requirements given in Table 11-25.

11.4.2.10  Dwelling Unit Air Filtration

Air filtration is used in forced air systems to protect the equipment from dust accumulation that could reduce the capacity or efficiency of the system. Preventing dust buildup may also prevent the system from becoming a host to biological contaminants such as mold, especially if dust is deposited on cooling coils that become wet from water condensation during comfort cooling operation. Air filter efficiencies of Minimum Efficiency Reporting Value (MERV) 6 remove approximately half of PM10 (Particulate Matter 10 microns or smaller), which includes these large airborne dust particles.

Air filter efficiencies of at least MERV 13 are needed to protect occupants from exposure to the smaller airborne particles that are known to adversely affect health. These smaller particles are often referred to as PM 2.5 which refers to particulate matter of 2.5 microns or smaller. PM2.5 can travel into the lungs and bloodstream, causing respiratory and cardiovascular impacts. PM2.5 is produced from several sources including combustion from cooking and exhaust from motor vehicles that enters a dwelling through ventilation openings and infiltration.

§160.2(b)1 requires that all recirculated air or outdoor air supplied to the occupiable space is filtered with MERV 13 filtration prior to being supplied to the occupiable space. The requirement applies to all ventilation systems with supply-side ventilation, including supply-only systems, ERVs, HRVs, and the supply side of other balanced systems with ductwork greater than 10 feet. This requirement does not apply to exhaust-only ventilation systems since those systems do not have dedicated supply air. However, since §160.2(b)1 applies to both recirculated and outdoor air, a dwelling unit with an exhaust-only ventilation system and forced air furnace will still need MERV 13 filtration in the furnace air handling unit with ductwork greater than 10 feet in length.

§160.2(b)1 also imposes air filtration requirements to address pressure drop and ensure minimum delivered airflow. These are detailed in Section 11.6.4.10.

Any gaps around an air filter allows air to bypass the filter. The Energy Code requires that filter racks and grilles use gaskets, sealing, or other means to close gaps around inserted filters and prevent air from bypassing the filter. Filter racks and grilles include any device that houses the air filter used to satisfy the air filtration requirements. 

11.4.2.11  Dwelling Unit Compartmentalization, Adjacent Spaces and Transfer Air

Compartmentalization (i.e., sealing of the dwelling unit air barrier) is important for maintaining the indoor air quality of multifamily dwelling units because it limits transfer air. Transfer air is the airflow between adjacent dwelling units or between a dwelling unit and other nearby spaces (e.g., garage or crawlspace) in a multifamily building, that can be a major contributor to poor IAQ in the dwelling units. Transfer airflow is caused by differences in pressure between adjacent spaces that force air to flow through leaks in the dwelling unit enclosure. The pressure differences may be due to stack effects (hot air rising in taller buildings when outside air temperature is low, leading to air pressing upward and exiting the building through upper floors) and wind effects, but unbalanced mechanical ventilation is also a contributor. Compartmentalization minimizes leaks in all the dwelling enclosures in the building to prevent pollutants such as tobacco smoke, pollution generated from food preparation in the kitchen, odors, and other pollutants from being transferred to adjacent dwellings in the building. Drawing ventilation air from the garage could introduce carbon monoxide or volatile organic compounds into the indoor air. Drawing ventilation air from an unconditioned crawlspace could cause elevated allergen concentrations in the dwelling. In addition to maintaining good IAQ, compartmentalization provides energy benefits, by reducing leakage of conditioned air to the exterior.

The Energy Code in §160.2(b)2Aiv provide two compliance paths for mandatory mechanical ventilation which improve indoor air quality in multifamily buildings:

•    Install a balanced ventilation system for all dwelling units.

•    Compartmentalize each dwelling unit by sealing each dwelling unit envelope and verify that the dwelling unit leakage is not greater than 0.3 CFM per sq. ft of dwelling unit enclosure area using the procedures in RA3.8 (blower door test for multifamily buildings with up to three habitable stories) or NA2.3 (blower door test for multifamily buildings with four or more habitable stories) as applicable. Sampling is allowed for the blower door testing, according to RA2.6 and NA1.6. If the sampled dwelling units in the multifamily building pass this blower door test, use of continuously operating supply-only ventilation systems, or continuously operating exhaust-only ventilation systems is allowed.

If the balanced ventilation path (#1) is used, air sealing to 0.3 CFM per sq. ft and blower door testing is not required. Both balanced ventilation and compartmentalization provide IAQ benefits. Balanced ventilation ensures that outdoor air is provided at the required rates, and compartmentalization reduces pollutant transfer between dwelling units. If compartmentalization (#2) is used, air sealing and blower door testing must be conducted. Note the Energy Code deviates from ASHRAE Standard 62.2, which requires compartmentalization in multifamily dwelling units, but does not require balanced ventilation as a mandatory requirement.

To compartmentalize the unit, project teams should seal areas that include, but are not limited to the following:

•    Vent and pipe penetrations, including those from water piping, drain waste and vent piping

•    HVAC piping and sprinkler heads

•    Electrical penetrations, including those for receptacles, lighting, communications wiring, and smoke alarms

•    HVAC penetrations, including those for fans and for exhaust, supply, transfer, and return air ducts

In addition, project teams should seal leaks and gaps in the dwelling-unit air barrier, including but not limited to the intersections of baseboard trim and floor, the intersections of walls and ceilings, around window trim and dwelling-unit doors, and the termination points of internal chases in attics, between floors, and crawlspaces.

11.4.2.12  Dwelling Unit Prescriptive Requirements

A.    Balanced Ventilation

If a balanced system is used to satisfy mandatory requirements, the prescriptive requirements of §170.2(c)3Biv requires multifamily units to install HRVs or ERVs in Climate Zones 1, 2, and 11-16. Multifamily units that do not trigger this requirement may still choose to use an HRV or ERV.

For multifamily buildings up to three stories in Climate Zones 4-10, balanced ventilation systems without heat or energy recovery are required by §170.2(c)3 to have a fan efficacy of 0.4 W/CFM or less. For example, if the balanced ventilation system includes a bathroom exhaust fan and an in-line supply fan, the total rated fan efficacy must be less than 0.4 W/CFM. The total fan efficiency for the ventilation system is calculated using the parameters in the following equation.

Compliance with the fan efficiency requirements for ventilation can be verified by reviewing product certification data from the HVI database or the AHAM Certified Range Hood Directory. Linear interpolation of rated performance parameters may be used when calculating the fan efficacy at the required outdoor airflow rate as described in Reference Residential Appendix RA3.7.4.4. The HVI database can be found at the following link: www.hvi.org/hvi-certified-products-directory. The AHAM Directory can be found at the following link: https://www.aham.org/AHAM/What_We_Do/Kitchen_Range_Hood_Certification.

B.   CFI Ventilation Systems Fan Watt Draw

When using the prescriptive approach, the fan efficacy of CFI systems must be verified by a HERS Rater (for multifamily dwelling units in buildings up to three habitable stories) or an ATT (for multifamily dwelling units in buildings four or more habitable stories) using the same methods as required for furnaces and air handlers. (See Reference Residential Appendix RA3.3.) For verification, the central system air handler must be operating in ventilation mode with the outdoor air damper open and with outdoor ventilation air flowing into the return plenum from the supply duct. Furthermore, the airflow that must be measured is the total airflow through the air handler (system airflow), which is the sum of the return airflow, and the outside air ducted to the return plenum (ventilation airflow).

The watt draw must be less than or equal to 0.45 W/CFM for furnaces, 0.58 W/CFM for air handlers that are not gas furnaces, and 0.62 W/CFM for small duct, high-velocity systems. If not, the performance approach must be used.

C.   ERV/HRV Fan Efficacy and Heat Recovery

For Climate Zones 1, 2, and 11-16, in addition to requiring heat recovery for ventilation, the prescriptive requirements require that HRVs and ERVs serving a single dwelling unit must have a fan efficacy of 0.6 W/CFM or less per §170.2(c)3Biv.

Central ERVs or HRVs (serving multiple dwelling units) must meet fan efficacy requirements per §170.2(c)4A using the fan power allowance formula below. For ERVs and HRVs, the fan power allowance must be separately calculated for the supply and return airflows, and then summed.

Where:

•    FPA_adj = The corrected fan power allowance for component in W/CFM

•    Q_comp = The airflow through component in CFM

•    Q_sys = The system airflow

•    FPA_comp = The fan power allowance of the component from Table 170.2-B or Table 170.2-C.

ERVs and HRVs meeting the §170.2(c)3Biv prescriptive requirements must also meet a minimum sensible recovery efficiency or effectiveness of 67%, rated at 32°F.

Compliance with the requirements for unitary equipment can be verified by reviewing product certification data from the HVI database at the URL below. See Reference Residential Appendix RA3.7.4.4 for more information on verification of unitary equipment performance parameters.

https://www.hvi.org/hvi-certified-products-directory

Central equipment must have a bypass function for free cooling, in which the incoming outdoor air bypasses the heat exchanger when the outdoor air temperature is below the cooling set point. This allows the ventilation system to operate in economizing mode taking advantage of cool outdoor temperatures. The bypass mode is an important feature, particularly in mild climates where heat recovery without bypass can increase cooling loads. The controls must meet the air economizer high limit shut off control requirements in Table 170.2-G.

For ERVs or HRVs that are not meeting the prescriptive requirements, including in Climate Zones 3-10, the fan efficacy need only meet the mandatory requirement of 1.0 W/CFM or less. 

11.4.2.13  Dwelling Unit Performance Approach

B.    Ventilation Systems without Heat Recovery

The performance approach allows the option of default minimum dwelling unit ventilation airflow rate and a watt draw value of 0.25 W/CFM, which is typical of continuous exhaust fans that meet the 1 sone requirement. If the installed fan has a different airflow and fan efficacy, the actual airflow rate and fan watt draw of the fan must be used.

Values for airflow and fan W/CFM information may be available from the HVI directory at the following link: www.hvi.org/hvi-certified-products-directory/.

If HVI does not list fan energy for the installed model, use information from the manufacturer's published documentation. Note that fan energy may sometimes be listed as CFM/W rather than W/CFM, so must be converted to the Energy Code’ fan efficacy units of W/CFM. Installation of a dwelling unit ventilation system with a fan watt draw greater than 1.2 W/CFM of ventilation airflow will increase the proposed design energy. Values less than 1.2 W/CFM are compliance-neutral (standard design = proposed design).

11.4.2.14  ERV/HRV Fan Efficacy and Heat Recovery

For the performance approach, the proposed equipment recovery efficiency, fan efficacy, and bypass condition are used in the compliance software. The compliance software assumes values for the standard design that align with the prescriptive requirements for ERVs/HRVs.

11.4.3      Central Ventilation Duct Systems Serving Dwelling Units

Central ventilation systems serving multiple dwelling units are often used, particularly in tall buildings, to provide supply air (such as in a DOAS system), exhaust, or balanced ventilation (such as a central ERV or HRV). These systems reduce the number of fans that must be maintained and the number of envelope penetrations for supply intakes or exhaust discharges.

The central ventilation system is typically comprised of a central fan (often located at the rooftop), a central ventilation duct (shaft) that runs between floors, horizontal branches to connect the dwelling units to the shaft, and in-unit connection points such as grilles to deliver (for supply) or remove (for exhaust) air from each dwelling unit. Figure 11-33 illustrates an example with no horizontal branches.

Figure 11-33: Diagram of Central Exhaust Ventilation Duct System Components

Source: Center for Energy and Environment 2016

11.4.3.1    Central Ventilation Mandatory Requirements

When a supply or exhaust system provides dwelling unit ventilation to more than one dwelling unit, the airflows in each dwelling unit must be equal to or greater than the specified ventilation rate, and the airflows for each dwelling unit must also be balanced to be no more than 20% greater than the specified rate, per §160.2(b)2Av. The specified rate for the systems that share a common fan/shaft may be the minimum rate required for compliance, in which case each of the dwellings receiving airflow from a common fan/shaft must have ventilation airflow no more than 20% greater than the minimum dwelling unit ventilation airflow required. If the lowest airflow provided to any of the dwellings served by the common fan/shaft is a specific percent value greater than the minimum required for compliance, then each of the dwellings receiving airflow from that common fan/shaft must have ventilation airflow no more than 20% greater than that lowest dwelling unit ventilation airflow. For example, if the lowest ventilation airflow among all dwellings served by the common fan/shaft is 2% greater than the minimum required for compliance, then all dwellings served by the common fan/shaft must be balanced to have ventilation airflow that is no more than 22% greater than the minimum ventilation airflow required for compliance

These systems must use balancing devices to ensure the dwelling-unit airflows can be adjusted to meet this balancing requirement. These system balancing devices may include, but are not limited to, constant air-regulation devices (often referred to as “CAR dampers”), orifice plates, and variable-speed central fans.

In addition, for multifamily buildings with four or more habitable stories, the Energy Code include a mandatory sealing and leakage testing requirement for central ventilation systems providing continuous airflow or an airflow to meet the balanced ventilation path in §160.2(b)2Aiv. An ATT must conduct a fan pressurization test to show that central shaft leakage is no greater than 6% compared to a nominal airflow rate of the central fan at 0.2 inches water column (inch w.c.) (50 Pa) for ducts serving more than six dwelling units. For ducts serving six or fewer dwelling units, the maximum leakage is the same, but the test must be conducted at 0.1 inches w.c. (25 Pa), since these systems typically have a lower operating pressure. As described in the NA1.6 procedures, sampling may be used for this duct testing requirement, and the ATT may conduct the leakage test at rough-in. Central ventilation systems providing intermittent flows, such as demand-controlled exhaust from kitchens, bathrooms, or driers, are exempt from this testing requirement, although careful sealing is still recommended.

The airflow, sealing, and leakage testing requirements work in tandem to provide better control of airflow to each unit so that units are not overventilated (which would waste energy) or under-ventilated (which would degrade IAQ).

11.4.4      Air-Moving Equipment - Mandatory Requirements (Section 7 of ASHRAE Standard 62.2)

Equipment used to meet the dwelling unit ventilation requirements or the local exhaust ventilation requirements must have been tested and rated by manufacturers to ensure that the equipment meets the requirements of this section.

11.4.4.1    Fan Selection and Installation

The Energy Code require that equipment used to comply with the standard be selected based on tested and certified ratings of performance for airflow and sound. The HVI and AHAM products directories list certified ratings of performance for airflow and sound. The directories can be used to verify compliance with Energy Code requirements. The HVI-Certified Products Directory can be viewed at the following link: www.hvi.org/hvi-certified-products-directory.

The AHAM-Certified Products Directory can be viewed at the following link: www.aham.org/AHAM/What_We_Do/Kitchen_Range_Hood_Certification.

In addition, the Energy Code require that the fans be installed in accordance with the manufacturer’s instructions.

11.4.4.2    Fan Sound Ratings

Dwelling unit occupants may choose not to operate ventilation equipment, particularly local exhaust fans, due to the noise the fans may create. To address this, the Energy Code require that certain fans be rated for sound, and installed fans must have ratings below specified limits.

§160.2(b)2Avif requires kitchen range hoods to be rated for sound in accordance with Section 7.2 of ASHRAE Standard 62.2, and it provides an exception to allow kitchen range hoods to be rated for sound at a static pressure determined at working speed as specified in HVI 916 Section 7.2. The static pressure at working speed may be lower than 0.1 inch w.c.

Because of the variables in length and type of duct and grille, there is no clearly repeatable way to specify a sound level for ventilation devices that are not mounted in the ceiling or wall surface. Consequently, air handlers and remote fans are exempted from the sound rating requirements that apply to surface-mounted fans. However, to reduce the amount of fan and/or motor noise that could come down the duct to the grille, the Energy Code sets a minimum of four ft. of ductwork between the grille and the ventilation device. This may still produce an undesirable amount of noise for the occupant, especially if hard metal duct is used. A sound attenuator will reduce the transmitted sound into the space.

C.    Continuous Ventilation Fans (Surface-Mounted Fans)

Continuously operated fans must be rated at 1 sone or less. This 1 sone requirement applies to continuous dwelling unit ventilation fans and to continuous local exhaust ventilation fans.

D.    Intermittent/Variable or Demand Controlled Fans (Surface-Mounted Fans)

Intermittently/variably operated dwelling unit ventilation fans must be rated at 1 sone or less. Demand-controlled local exhaust fans must be rated at a maximum of 3 sones unless the minimum rated airflow is greater than 400 CFM.

The Energy Code extend the fan sound requirements to include range hoods and bath exhaust fans. Dwelling unit ventilation fans or systems that operate continuously must be rated 1 sone or less. Demand-controlled local exhaust fans, including demand-controlled bathroom fans, must be 3 sones or less. Range hood exhaust fans must also be rated at 3 sones or less at a minimum required speed of 100 CFM.

The 3 sone requirement is measured at a minimum required speed of 100 CFM that is different from the minimum airflow requirements of the Energy Code for kitchen range hoods. The Energy Code require range hoods to have a minimum airflow between 110 CFM and 280 CFM when using airflow rating for compliance, dependent on the size of the dwelling unit and kitchen fuel used. The requirements for the minimum airflow for a sound rating and the minimum airflow for an airflow rating are different to allow sound ratings of previously tested range hoods to be used. The Energy Code previously permitted testing at “working speed”.

11.4.4.3    Duct Sizing

For local exhaust systems, there are two ways to demonstrate compliance with airflow requirements of §160.2(b)2Avie:

•    Test the ventilation system using an airflow measuring device after completion of the installation to confirm that the delivered ventilation airflow meets the requirement discussed in Section 11.4.2.1.

•    Use a fan that has a certified airflow rating that meets or exceeds the required ventilation airflow and ventilation ducts that meet the duct design requirements given in Table 11-25 (Table 160.2-H). This option is limited to ventilation systems with a total duct length less than or equal to 25 ft (8m), with no more than three elbows, and has exterior termination fitting with a hydraulic diameter greater than or equal to the minimum duct diameter and not less than the hydraulic diameter of the fan outlet.

When using the duct sizing table or manufacturer's design criteria for compliance, the certified airflow rating of the fan must be based on tested performance at the 0.25 inches water column (w.c.) static pressure. The airflow rating of a fan is available from the HVI Certified Products Directory at the HVI website (www.hvi.org/hvi-certified-products-directory).

If the manufacturer's duct system design specifications are used for compliance, the enforcement agency may require that the manufacturer's published system design documentation be provided for use for inspection of the installation(s).

The duct design criteria provided in Table 11-25 identifies the minimum exhaust duct diameter based on airflow. The higher the airflow, the larger the required diameter. Smooth rigid duct can be used to reduce pressure losses for longer duct runs. Interpolation and extrapolation of Table 11-25 are not allowed. To use the table for kitchen exhaust, first determine the required airflow based on unit floor area and range type (gas or electric) using Table 11-22 (from Table 160.2-G in the Standards). Then select the column that lists an airflow equal to or greater than the required airflow and use the duct Table 11-25: size listed for rigid duct. If the duct is rectangular, calculate the equivalent diameter using footnote a.

Table 11-25: Prescriptive Ventilation System Duct Sizing (from Table 160.2-H in the Energy Code)

Source: California Energy Commission

Relevant footnotes to table:

a.     For noncircular ducts, calculate the diameter as four times the cross-sectional area divided by the perimeter.

f.      When a vented range hood utilizes a capture efficiency rating to demonstrate compliance with 160.2(b)2Avic2, a static pressure greater than or equal to 0.25 in. of water at the rating point must not be required, and the airflow listed in the approved directory corresponding to the compliant capture efficiency rating point must be applied to Table 160.2-G for determining compliance.

The first restriction is that if more than one exhaust fan in the same dwelling unit shares a common duct, then each fan must be equipped with a backdraft damper, so air exhausted by one fan is not allowed to go into another space.

The other restriction applies to remote fans serving more than one dwelling unit. Sometimes a single remote fan or HRV/ERV will exhaust air from several dwelling units in a multifamily building. The Energy Code require that either the shared exhaust fan operate continuously, or each unit be equipped with a backdraft damper so that air cannot flow from unit to unit when the fan is off. Note these requirements are also in the California Mechanical Code §504.1.1.

Additionally, §160.2(b)2Ci requires central ventilation system ducts serving multiple dwelling, providing continuous airflows, or part of a balanced ventilation system to be balanced and sealed according to the California Mechanical Code §603.10 and tested in accordance with procedures in Reference Appendix NA7.18.3.

11.4.4.4    Supply Ducts

Supply outlets to more than one dwelling unit may be served by a single fan upstream of all the supply outlets if the fan is designed to run continuously or if each supply outlet is equipped with a backdraft damper to prevent cross-contamination when the fan is not running.

11.4.5      Other Mandatory Requirements (Section 6 of ASHRAE Standard 62.2 and California Mechanical Code)

All dwelling units must meet the requirements of ASHRAE Standard 62.2, Ventilation and Acceptable Indoor Air Quality in Residential Buildings subject to §160.2(b)2A ventilation requirements. These additional requirements are described below.

The following sections of ASHRAE Standard 62.2 are not required for compliance: Section 4.1.1, Section 4.1.2, Section 4.1.4, Section 4.3, Section 4.6, Section 5, Section 6.1.1, Section 6.5.2, and Normative Appendix A.

11.4.5.1    Instructions and Labeling

Building on the requirements for labeling in ASHRAE Standard 62.2, the Energy Code Section §10-103(b)4 requires the builder to leave in the building for the building owner at occupancy:

•    A description of the quantities of outdoor air that the whole-dwelling unit ventilation system(s) are designed to provide and instructions for proper operation and maintenance of the ventilation system.

•    Instructions for proper operation and maintenance of local exhaust systems, including instructions for conditions for any occupant-controlled systems such as kitchen range hoods and bathroom exhaust fans that should be used.

For systems in buildings or dwelling unit spaces that are not individually owned by the dwelling unit occupants, the building’s owner or their representative should provide:

•    A copy of the ventilation system information to dwelling occupants at the beginning of their occupancy.

For systems in buildings or dwelling unit spaces that are centrally operated, the builder should provide:

•    All applicable ventilation system information to the person(s) responsible for operating and maintaining the feature, material, component, or mechanical ventilation device installed in the building. This information must be in paper or electronic format.

The Energy Code require that ventilation system controls be labeled as to their function. An acceptable option is to affix a label to the electrical panel that provides some basic system operation information.

11.4.5.2    Clothes Dryers

All dryers in dwelling units must be ducted to the outdoors, with the exception of condensing dryers. Devices that allow the exhaust air to be diverted into the indoor space to provide extra heating are not permitted.

In multifamily buildings, multiple dryer exhaust ducts can be connected to a common exhaust only when dampers are provided to prevent recirculation of exhaust air from one dwelling unit to another.

11.4.5.3    Combustion and Solid-Fuel Burning Appliances

The Energy Code require that the ventilation system for combustion appliances including furnaces and gas water heaters to be properly installed, as specified by the instructions from the appliance manufacturer and by the California Building Code. Compliance with the venting requirements involves determining the type of vent material to be used, the sizing of the vent system, and vent routing requirements.

The Energy Code require compensating outdoor air (makeup air) when atmospherically vented appliances are installed inside the pressure boundary if the two largest exhaust fans have a combined capacity that exceeds 15 CFM/100 sq. ft of floor area. Use of atmospherically vented appliances in new multifamily buildings is rare or nonexistent, but observation of this ASHRAE requirement will improve combustion even if atmospherically vented appliances are not installed.

The two largest exhaust fans are normally the kitchen range hood and the clothes dryer. In many cases, the range hood airflow/capture efficiency requirements result in the range hood alone exceeding the 15 CFM/100 sq. ft limit. Thus, many units with atmospherically vented appliances will require makeup air fan. Example 4-13 discusses an example of a multifamily unit using an atmospherically vented water heater.

A supply fan can be used to balance the exhaust airflow, but from an equipment, operating cost, maintenance cost, comfort, and safety standpoint, atmospherically-vented appliances are not recommended inside dwelling units, as illustrated in the example below.

11.4.5.4    Ventilation Opening Area

While this section of ASHRAE Standard 62.2 requires that single-family homes have ventilation openings (typically operable windows) for all habitable spaces, multifamily dwelling units are exempt from this requirement. There are no requirements for ventilation openings areas for multifamily units in the Energy Code. It is best practice to design multifamily units to meet this design practice, if possible, to provide adequate ventilation during circumstances where high levels of contaminants are released into the space. Operable windows are the most likely means of providing additional ventilation. Additional ventilation can also be provided by operable skylights; through-the-wall vents; or similar devices that are readily accessible to the occupant. An operable skylight should have some means of being operated while standing on the floor: a push rod, a long crank handle, or an electric motor.

Ventilation openings should have openable area equal to at least 4% of the space floor area (but not less than five sq. ft).

11.4.5.5    Air Inlets

When the ventilation system is designed with outdoor air inlets, the inlets must be located away from locations that can be expected to be sources of contamination. The minimum separation is 10 ft. Inlets include not only inlets to ducts, but windows that are needed to achieve the minimal opening area.

For residential buildings, typical sources of outdoor air contaminants include:

1.  Vents from combustion appliances

2.  Fireplace chimneys.

3.  Exhaust fan outlets.

4.  Barbeque grills.

5.  Driveways or any location where vehicles may be idling.

6.  Any other locations where outdoor air contaminants are generated.

The Energy Code also requires that air intakes be placed so that they will not become obstructed by snow, plants, or other material. Forced air inlets must also be equipped with insect/rodent screens with mesh is no larger than 1/2 inch.

11.4.6      Common Use Area Ventilation Requirements

This section provides an overview of the Energy Code requirements for ventilation  and ventilation systems serving common use areas of the building, such as community rooms, corridors, fitness areas, common laundry rooms, and parking garages. This section also discusses whether the Energy Code or California Mechanical Code (CMC, or Title 24 Part 4) takes precedent, for areas where both standards provide requirements.

Since there are similar requirements for ventilation systems serving common use area and systems serving nonresidential occupancies, more detailed discussion of the applicable requirements can be found in Chapter 4.3 for the applicable requirements.

Requirements for systems serving nonresidential occupancies in mixed occupancy buildings are in Section 120, 130, 140 and 141 of the Energy Code.

11.4.6.1    Common Use Area Ventilation Prescriptive Requirements

Applicable Prescriptive requirements for common use area ventilation system include:

Common Use Area Space Conditioning Systems, which includes requirements for space conditioning as well as ventilation - §170.2(c)4

11.4.6.2    Performance Approach

Applicable Performance approach requirements for common use area ventilation systems include:

11.4.6.3    Common Use Area Ventilation Performance Approach

§170.1 specifies the performance approach for common use area ventilation.

11.4.7      Additions and Alterations

This section describes dwelling unit and common use area ventilation requirements for additions and alterations, including the scopes that trigger these requirements.

For both additions and alterations, when HERS field verification is required, buildings with up to three habitable stories should use the applicable procedures in the Residential Appendices. All HERS forms must be registered online with a HERS Provider. (See Section 2.5 and Appendix A.) Buildings with four or more habitable stories should use the applicable procedures in Nonresidential Appendices NA1 and NA2.

11.4.7.1    Additions

11.4.7.2    Dwelling Unit

For additions to existing buildings, local mechanical exhaust should comply with all applicable requirements specified in §160.2(b)2Avi (Local Mechanical Exhaust) and §160.2(b)2B (Dwelling Unit HERS Field Verification and Diagnostic Testing).

For whole-dwelling unit mechanical ventilation, the following requirements apply:

For additions to an existing dwelling unit that increase conditioned floor area by more than 1,000 sq. ft, the mechanical ventilation airflow must be in accordance with §160.2(b)2Aiv or §160.2(b)2Av. (Central Ventilation System Airflow Rate Tolerance), as applicable. The mechanical ventilation airflow rate should be based on the conditioned floor area of the entire dwelling unit including the existing and additional conditioned floor area.

For new dwelling units that are additions to an existing building, mechanical ventilation must meet §160.2(b)2Aiv or §160.2(b)2Av., as applicable. The mechanical ventilation airflow rate should be based on the conditioned floor area of the new dwelling unit.

•    Dwelling units do not have to meet the whole-dwelling unit ventilation airflow requirements of §160.2(b)2Aiv or §160.2(b)2Av.if the addition increases the existing dwelling unit conditioned floor area by less than or equal to 1000 sq. ft.

11.4.7.3    Common Use Area

Additions to the common use area should follow the nonresidential building requirements. Any newly installed space conditioning system must meet the ventilation requirements in §120.1|topic=SECTION 120.1 – REQUIREMENTS FOR VENTILATION AND INDOOR AIR QUALITY (Requirements for Ventilation and Indoor Air Quality) for both the prescriptive and performance approaches.

11.4.7.4    Alterations

11.4.7.5    Dwelling Unit

If the ventilation system is entirely new or a complete replacement, the ventilation system should comply with all applicable requirements in §160.2(b)2 (Ventilation and Indoor Air Quality Requirements for Attached Dwelling Units). An entirely new ventilation system includes a new ventilation fan component and an entirely new duct system, where an entirely new duct system should be at least 75% new duct material. Up to 25% of the duct system may be made up of reused parts of the existing duct system.

For altered ventilation system components or newly installed ventilation equipment serving the alteration, requirements are dependent on the component and requirements under the previous building permit.

For whole-dwelling unit mechanical ventilation:

For an altered or replaced whole-dwelling ventilation system, if a previous building permit required compliance with whole-dwelling unit airflow requirements in §160.2(b)2, the whole-dwelling unit mechanical ventilation airflow must meet or exceed requirements specified in §160.2(b)2Aiv or §160.2(b)2Av. Otherwise, compliance is not required.

•    Whole-dwelling unit replacement ventilation fans should be rated for airflow and sound in accordance with requirements in ASHRAE Standard 62.2 Section 7.1 and 7.2. If a specified airflow is required for compliance, the fan should be rated at an airflow no less than airflow rate required for compliance.

•    For an altered or replaced air filtration device, if a previous building permit required air filtration requirements in §160.2(b)1, the altered or replacement filtration device must comply with air filtration requirements in §160.2(b)1. Otherwise, compliance is not required.

For local mechanical exhaust systems:

•    Altered bathroom local mechanical exhaust systems should comply with applicable requirements specified in §160.2(b)2Avi.

•    For a kitchen local ventilation fan that is altered or replaced, if a previous building permit required compliance with local exhaust requirements in §160.2(b)2Avi, the applicable airflow and capture efficiency must meet or exceed requirements in §160.2(b)2Avi. If a previous building permit required installation of a vented kitchen range hood or other kitchen exhaust fan, the replacement fan must have an airflow that meets or exceed requirements of the previous building permit, or 100 CFM, whichever is greater. Otherwise, compliance is not required.

•    New or replacement local mechanical exhaust fans should be rated for airflow and sound in accordance with requirements of ASHRAE Standard 62.2 Section 7.1 and §160.2(b)2Avif. If a specified exhaust airflow is required for compliance, the fan should be rated at not less than the required airflow.

For alterations to space conditioning systems in existing buildings that have all or portions of the forced air ducts, plenums or air-handling units in the garage, there are leakage requirements discussed in “Duct System Sealing and Leakage Testing” in Section 11.6.4 of the Building Space Conditioning Systems section. Note that for the central ventilation system duct sealing test, the sampling group consists of no more than three central ventilation duct systems.

11.4.7.6    Common Use Area

Alterations to the common use area should follow the nonresidential building requirements. Any altered components of space conditioning systems or newly installed space conditioning systems must meet the ventilation requirements in §120.1|topic=SECTION 120.1 – REQUIREMENTS FOR VENTILATION AND INDOOR AIR QUALITY (Requirements for Ventilation and Indoor Air Quality) for both the prescriptive and performance approaches.

11.4.8      Compliance and Enforcement

Compliance with the Standard requirements must be verified by the enforcement agency, except for the requirements listed in Table 11-10, which must be verified by a HERS Rater or ATT. As a summary, HERS raters:

•    Conduct dwelling unit air leakage testing (compartmentalization / blower door test).

•    Verify ERV/HRV listing in the HVI directory, nominal airflow, and (in dwelling units in buildings up to three habitable stories) sensible recovery efficiency and fan efficacy.

•    Verify kitchen exhaust range hood listing in the HVI or AHAM directory, compliance based on nominal airflow or capture efficiency, and sound rating.

ATTs:

•    Verify ERV/HRV sensible recovery effectiveness and fan power allowance in dwelling units in buildings four or more habitable stories.

•    Conduct functional bypass testing for central ERVs /HRVs.

•    Conduct an air leakage testing measurement in central ventilation ducts.

11.4.8.1    Design-Phase Documentation Requirements

This subsection describes design-phase documents for multifamily buildings.

The performance approach allows compliance credit for special additional features to be quantified. The certificate of compliance lists features for which special compliance credit was taken using the performance approach. They require additional visual verification by the enforcement agency to ensure proper installation. Some require field verification and diagnostic testing by a HERS Rater or ATT. These will be listed in a separate section.

The mechanical ventilation rate (Qfan) must be manually calculated using the applicable equations in §160.2(b)2Aiv. The value for Qfan is required to be reported on the certificate of compliance. The performance certificate of compliance will report the:

•    Minimum mechanical ventilation airflow rate (calculated value) that must be delivered by the system.

•    Type of ventilation system (exhaust, supply, balanced, CFI).

•    Fan efficacy (W/CFM) for the selected system.

•    Recovery efficiency (%) (applicable to HRV/ERV system types only)

•    For CFI systems--HERS verification of air handler fan efficacy is required.

The installed dwelling unit ventilation system must conform to the performance requirements on the certificate of compliance.

The enforcement agency may require additional information/documentation describing the ventilation systems be submitted along with the certificate of compliance at plan check.

11.4.8.2    Construction-Phase Documentation

This subsection describes construction-phase documents for multifamily buildings up to three stories. For multifamily buildings with four or more stories, the equivalent processes must be followed using nonresidential forms.

During construction, the general contractor or specialty subcontractors must complete all applicable certificate of installation documents for the building design special features specified on the certificate of compliance. The builder/installer must complete certificates of installation for the dwelling.

Like the certificate of compliance, registration of the certificate of installation is required, except for multifamily buildings with four stories and more. For all other buildings, the licensed contractor responsible for the installation must submit the certificate of installation information that applies to the installation to a HERS Provider Data registry using procedures described in §10-103 and Section RA2 of the Reference Residential Appendix. Certificate of installation documents corresponding to the list of special features requiring HERS Rater or ATT verification are required. For buildings with four or more stories, the licensed contractor responsible for the installation must complete and submit the certificate of installation to the building department or jurisdiction having authority.

E.    Certificate of Installation

The following information must be provided on the certificate of installation to identify each ventilation system/fan in the dwelling that will require HERS verification.

For dwelling unit ventilation systems:

•    Ventilation system name or identification

•    Ventilation system location

•    Ventilation system control type (i.e., continuous, variable)

•    Ventilation system type (i.e., exhaust, supply, balanced).

•    Ventilation system target airflow rate (may be less than Q_fan if using multiple systems/fans to comply)

•    Ventilation system manufacturer name

•    Ventilation system model number

•    Control system manufacturer (if applicable)

•    Control system model number (if applicable)

•    Energy Commission certification number for variable system/control (if applicable)

•    ERV or HRV manufacturer name (if applicable)

•    ERV or HRV model number (if applicable)

•    ERV or HRV location (if applicable)

•    ERV or HRV type (i.e., unitary or central, if applicable)

•    Presence of bypass recovery bypass or free cooling function (if applicable)

•    Duct system name or identification

•    Dust system description of area served

•    Supply duct location

•    Return duct location

•    Sealing materials used for duct system (if applicable)

For kitchen exhaust ventilation systems:

•    Kitchen exhaust control type (i.e., demand-controlled, continuous)

•    Kitchen exhaust system type (i.e., range hood, over-the-range microwave, downdraft, local exhaust, other)

•    Kitchen exhaust system required airflow rate or capture efficiency for demand-controlled or downdraft, and minimum kitchen air exchange rate (ACH50) for continuous systems

•    Kitchen exhaust system manufacturer name

•    Kitchen exhaust system model number

The following additional information must be provided on the certificate of installation to document compliance with §160.2 and 170.2(c)3B. Refer also to the procedures in RA 3.7.4 for dwelling units in buildings up to three habitable stories, and sections including NA 1.1 for dwelling units in buildings four or more habitable stories.

For dwelling unit ventilation systems:

•    Measured airflow rate of the installed dwelling unit ventilation system. For balanced systems, exhaust and supply airflows must be measured and recorded.

•    Installed ERV or HRVs’ nominal sensible recovery efficiency and fan efficacy, if applicable.

•    Installed exhaust or supply dwelling unit ventilation efficacy, if applicable.

•    Installed dwelling unit ventilation system fan sone rating for fans that are not remotely mounted.

•    Confirmation installed ERV or HRV has a sensible recovery efficiency and fan efficacy greater than those specified in standards.

•    If a central ERV or HRV is installed, confirmation that the installed ERV or HRV includes a bypass or free cooling function.

For kitchen exhaust ventilation systems:

•    Confirmation the installed system is rated by HVI or AHAM to meet the required airflow or capture efficiency and sound requirements

•    The rated airflow value or rated capture efficiency listed in the HVI or AHAM directory

•    The sound rating listed in the HVI or AHAM directory

•    Confirmation the value for the rated airflow or capture efficiency given in the HVI directory is greater than or equal to those specified in the standards, and the value for the sone rating given in the directory is less than or equal to the sone rating requirements in specified standards.

For central ventilation systems that provide dwelling unit ventilation or operates continuously:

•    Confirmation an ATT has performed a duct leakage field verification

•    Documentation of duct leakage field verification showing flow rate measurement that meets requirements of specified standards

For all ventilation systems:

•    Confirmation that the other applicable requirements given in Sections 6 and 7 of ASHRAE Standard 62.2 as amended in 160.2 have been met (see Sections 11.4.4 and 11.4.5)

11.4.8.3    Field Verification and Diagnostic Testing

This subsection describes field verification and diagnostic testing for multifamily buildings.

Table 11-10 lists special features requiring HERS Rater or ATT field verification or diagnostic testing for multifamily buildings. For buildings for which the certificate of compliance requires HERS or ATT field verification for compliance with the Energy Code, a HERS Rater or ATT must visit the site to perform field verification and diagnostic testing to complete the applicable heating and cooling system certificates of field verification and diagnostic testing. Certificate of verification documents corresponding to the list of special features requiring HERS Rater or ATT verification are required.

Field verification for nonmandatory features is necessary only when performance credit is taken for the feature. Some field verifications are for mandatory requirements and will occur in all multifamily buildings unless they are exempt from the requirement.

Like the certificate of compliance and certificate of installation, registration of the certificate of verification is required. The HERS Rater must submit the field verification and diagnostic testing information to the HERS Provider Data Registry as described in RA2 of the Residential Appendix and NA2 of the Nonresidential Appendix. For features requiring ATT verification, the ATT must follow the procedures described in NA1.9.

For multifamily buildings up to three habitable stories: verification, testing, and sampling procedures should follow the Residential Appendix requirements for these features, which are primarily located in RA2.6 (sampling) and RA3.7 (Field Verification and Diagnostic Testing of Mechanical Ventilation Systems). For multifamily buildings four or more habitable stories: verification, testing, and sampling procedures should follow the Nonresidential Appendix requirements for these features, which are primarily found in sections NA1.6 (sampling), NA2.2 (Field Verification and Diagnostic Testing of Mechanical Ventilation Systems), and NA7.18 (Multifamily Building Acceptance Tests). The central ventilation duct sealing test has unique sampling requirements, in that the ATT’s sampling group may consist of no more than three central ventilation duct systems in the building.