PREFERRED STRATEGIES

The sections below outline preferred and acceptable ventilation strategies.  The strategies are arranged as follows:

  1. Apartment or in-unit ventilation strategies
    • Apartment source control ventilation
    • Apartment background ventilation
  2. Common Area ventilation strategies
    • Common area source control ventilation
    • Common area background ventilation

All ventilation system designs will be subject to review by Design & Building Performance.  Use of strategies other than the preferred strategies will require explicit approval from the Design & Building Performance Departments.

 

apartment VENTILATION

APARTMENT BACKGROUND VENTILATION:

Balanced ventilation with recovery

Balance energy recovery ventilation (ERV) or heat recovery ventilation (HRV) is preferred in all climates excepting Climate Zone 2a. There are three different general approaches to providing this kind of background ventilation to apartments:

  • Individual apartment ERV or HRV
  • Floor-by-floor (or other sub-section of the building) ventilation with direct ventilation supply to each apartment
  • Central ERV or HRV system with direct supply to apartments

Individual apartment ERV or HRV

Individual apartment ERV/HRV offers the advantage of apartment-level control, off-the-shelf products and minimized risk of cross-contamination between apartments.  It brings the challenges of distributed in-unit equipment that requires periodic maintenance.  Ventilation using a separate ERV/HRV for each apartment will require at least one through-wall penetration per apartment for the fresh air intake and stale air vent.  However, this approach supports compartmentalization as vertical shafts between floors and penetrations through interior separations are not needed for general apartment ventilation.

SAMPLE PRODUCTS:

 
  Lunos

Lunos

Reversing flow non-ducted ERV: 
This type of product uses one or more reversing flow non-ducted exchanges to alternately exhaust stale air and supply fresh outdoor air.  This type of ventilation unit is installed through the exterior wall (note exterior wall penetrations) and requires a minimum wall thickness.  Because it is non-ducted, it does not require space other than wall space within the apartment.  Given the limited ventilation flow provided by these units, typically on unit would be required per bedroom.  The unit is not able to also provide bathroom source control ventilation.  The product shown is Lunos.

 
  RenewAire

RenewAire

Ducted ERV/HRV with cross-flow or counter-flow enthalpy/heat exchange core:
These systems will require one or more exterior wall penetrations per apartment.  The ducting allows for distribution of ventilation air and can provide a degree of air mixing (to prevent stagnation) within the apartment.  The ventilation may also be integrated with heating and cooling ductwork provided proper design and controls to minimize air handler fan energy and to allow ventilation distribution and prevent short-circuiting of the ventilation supply to the stale air exhaust.  If sized properly, these systems can provide bathroom source control ventilation.  Typically installation of these systems will soffits or a ceiling plenum in which to run ductwork as well as an area (e.g. upper part of closet) where the equipment could be located.  The product shown is RenewAire.

On the horizon: 
As of Spring 2017, two manufacturers are beginning to offer heat pump heat recovery units to the US market.  These units offer ventilation and dehumidification with the ability to provide a modest amount of heating and cooling.  Once these products achieve a successful track record, they will offer an interesting solution for complete apartment-side conditioning and ventilation for low load buildings.

Floor-by-Floor ERV/HRV

This approach can reduce or eliminate the need for vertical ventilation ducts in a building.  Economies of scale can be achieved by sharing ventilation equipment among several apartments.  These economies may afford the installation of high quality and highly efficient equipment.  Some ventilation equipment may offer economizer capabilities to provide free cooling.  This approach may present challenges in balancing the ventilation airflows to each apartment.  If sized properly, these systems can provide bathroom source control ventilation.  Maintenance requirements of the ventilation system are met without the need for access to apartments.  This approach entails a challenge of routing ductwork horizontally through corridors (above the ceiling) and of crossing fire separation assemblies with ductwork.  In existing buildings, the deck-to-deck height may not be able to accommodate horizontal ductwork along corridors.

Central ERV/HRV

This approach may be most suitable for existing buildings with existing exhaust and ventilation supply risers through the building.  This approach allows for minimizing the number of penetrations through the exterior enclosure but will require many penetrations through assemblies within the enclosure.  Economies of scale can be achieved by sharing ventilation equipment among several apartments.  Larger and more sophisticated equipment may offer useful functionality such as enthalpy economizer functionality, variable speed demand control, etc.  Typically, commercial-sized ERV/HRV equipment offers only modest recovery efficiency (note the exception of Ventacity with its exceptional performance). Maintenance and controls may require specialized skills.  A central ERV/HRV will require vertical shafts through the building. This approach will present challenges in balancing the ventilation airflows to each apartment.  In existing buildings, the deck-to-deck height may not be able to accommodate horizontal ductwork along corridors.

  • Bathroom exhaust risers should be connected to the ERV/ HRV.
  • Rangehood kitchen exhaust risers should NOT be connected to the ERV/ HRV due to grease buildup.

Acceptable Strategies for Existing Building Rennovation and Dry Mild Climates (e.g. Zone 3B):

Exhaust-Only Ventilation

Exhaust only ventilation systems are prevalent in the portfolio.  Exhaust only systems are problematic for a few reasons. 

  1. They create a negative pressure inside the building which allows air from the exterior and neighboring units to enter apartments. 
  2. Outdoor air leaking directly into the apartment is likely to contribute to comfort problems. colder, warmer and/or more humid so the heating and cooling systems have to work harder to temper that air. 
  3. Air from neighboring units is likely to have odors that are unpleasant to residents. There is also the opportunity for contaminants to enter the building (i.e. Radon) if an exhaust only system in used. Exhaust systems are typically installed in bathrooms and kitchens. See below for more information and preferred products on both.

Exhaust-only apartment general background ventilation is typically provided by one of three means:

  • Continuous bathroom exhaust with a shared exhaust riser and a roof-top fan
  • Continuous bathroom and kitchen exhaust with shared exhaust risers and a roof-top fans
  • Bathroom exhaust with a continuously operating or cycling in-unit bath fan

Continuous bathroom exhaust with shared exhaust riser and roof-top fan

Where a shared exhaust riser and roof-top fan are used to provide continuous exhaust from apartment bathrooms, POAH prefers the following measures:

  • Seal the shaft to 5cfm per floor or less (measured at 50 Pascals)
  • Install constant air flow regulators (CARs)  for each exhaust intake grille to control exhaust flow rate provided
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure within parameters for CAR operation.
 
 

Continuous bathroom and kitchen exhaust with shared exhaust risers and a roof-top fan

This approach is discouraged if separate range hood exhaust is not provided.  Where separate range hood exhaust is provided, the shared kitchen exhaust riser might be re-purposed for ventilation supply after thorough duct cleaning and sealing.  Such reconfiguration would require careful evaluaton.

Bathroom exhaust with a continuously operating or cycling in-unit bath fan

  • Fans should be low noise. Sone (measurement of sound) should be 0.9 max.
    • Please evaluate ductwork. The low sone cannot be achieved if ductwork is loose, or uninsulated. Exhaust ductwork should also be as short and straight as possible, minimizing the number of bends and angles. If flexible duct is used, the flexible duct shall be pulled taught and excess duct length shall be eliminate. 
    • A mock-up must be completed to measure sone level of new fans + existing ductwork.
  • Bathroom exhaust fans should run continuously at a low CFM (~30) and be capable of boosting to higher CFM when switched on. The low speed setting is typically set at the fan. By running the fan at a low speed continuously the humidity can be controlled in the space without resident intervention. Excessive humidity leads to mold.
    • The boost capability shall include a delay so that the fan can run for an additional ~15 minutes after the boost is turned off.
    • In order to provide separate background and boost capabilities, there must be two wires to the fan. If the project is a simple fan replacement with no re-wiring, the separate boost capability may be achieved through a special wall switch or controller at the switch box. Contact POAH Design + Building Performance for other options.
  • The cost to run a bath fan continuously cost less than $3 dollars a month at ¢10 cents a kWh.  
  • There are add-on modules for the Panasonic fan that can be used instead of continuously running.  Occupancy sensors and timers can be programmed to help manage humidity and insure long term durability and good IAQ.
  • Airtightness measures:
    • Use foam or tape to seal any gaps between the ductwork and/or fan housing before installing fan or grill.
  • After installation the fan should be measured to confirm appropriate draw. 

MAINTENANCE:

  • Fan should be cleaned every year at minimum:
    • Grill only: Remove register and clean.  Clean inside reachable ductwork.
    • Fan: Remove dust and dirt from the fan body using a vacuum, a dirty fan can cause noise issues and loss of efficiency.

SAMPLE PRODUCTS:

Panasonic
WhisperGreen Select
CFM: 30 - 110
Sone: 0.3 - 0.8
CFM/Watt: 11.5 - 15.1
Manufacturer Number:
FV-05-11VKS1

Panasonic
WhisperSense
Motion/Humidity Sensor
CFM: 80
Sone: 0.3
CFM/Watt: 5.1
Manufacturer Number:
FV-08VQC5

Supply-Only Ventilation

General background ventilation may also be provided at the apartment level through a supply-only system.  This will require an outdoor air intake and a fan to draw outdoor air.  If the fan is not designed or needed to run continuously, the system should also include a motorized damper.

A central-fan integrated supply (CFIS) ventilation system may be appropriate for apartments with a forced-air heating/cooling system.  This system involves an outdoor air intake that is ducted to the return air plenum of the air handler and includes an outdoor air intake, a motorized damper and a controller to operate the motorized damper and energize the air handler fan as needed to provide the desired ventilation rate.  If this system is used, the air handler fan should have an ECM motor to minimize fan energy impact.

For guidance on application of CFIS, consult BSC Information Sheet 610:
https://basc.pnnl.gov/resources/central-fan-integrated-ventilation-systems.

SAMPLE PRODUCTS:

 

Example of controller and motorized damper for central-fan-integrated supply ventilation.  Product shown is AirCycler® G1. 

Apartment Source Control Ventilation:

Bathroom Exhaust

  • Every bathroom must exhaust to exterior by using one of the following systems:
    • exhaust fan in the ceiling vented to exterior
    • or, exhaust grill connected to a roof top fan that exhausts to exterior

Local Bath Fan

  • Fans should be low noise. Sone (measurement of sound) should be 0.9 max.
    • Please evaluate ductwork. The low sone cannot be achieved if ductwork is loose, or uninsulated. Exhaust ductwork should also be as short and straight as possible, minimizing the number of bends and angles. If flexible duct is used, the flexible duct shall be pulled taught and excess duct length shall be eliminate. 
    • A mock-up must be completed to measure sone level of new fans + existing ductwork.
    • Local bath fans should be capable of “delay-off” operation whereby the fan continues to operate for a prescribed amount of time after a user exits the bathroom or turns off the fan.

Bathroom Exhaust through Shared Exhaust Riser and Roof-top Fan

This approach generally employs continuous exhaust flow to achieve source control of excess humidity and odors. Where a shared exhaust riser and roof-top fan are used to provide continuous exhaust from apartment bathrooms, POAH prefers the following measures:

  • Seal the shaft to 5cfm at 50 Pascals per floor or less
  • Install constant air flow regulators (CARs)  for each exhaust intake grille to control exhaust flow rate provided
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure within parameters for CAR operation.
 
 

KITCHEN EXHAUST

Building codes allow for kitchen exhaust ventilation to be either 1) intermittent or 2) continuous.  Intermittent kitchen exhaust is preferred as it 1) provides for more effective source control (capture efficacy) and 2) results in less aggregate ventilation load.

Codes also allow for kitchen exhaust through either a capture hood over the cooking appliance or through a general area exhaust grille located in the cooking area.  The capture hood is prefered as this approach has the potential for reasonably effective capture efficacy of cooking effluent.  The general area exhaust is not effective[KSN1] .

Antiquated code provisions that allow for a kitchen window to serve as kitchen ventilation are right out.

  • Every kitchen must exhaust to exterior by using one of the following systems:
    • Range hood with integral fan exhausted directly to exterior
    • Range hood connected to a shared exhaust riser served by a rooftop fan

Fan Powered Range Hood

The following requirements apply for fan power range hoods in apartment kitchens.

KITCHEN EXHAUST

  • Every kitchen must exhaust to exterior by using one of the following systems:
    • exhaust fan in wall or ceiling vented to exterior (least effective)
    • or, a range hood with integral fan exhausted directly to exterior
    • or, a range hood connected to a mechanized rooftop fan exhausted to exterior
    • Do not use recirculating range hoods as the sole source of kitchen ventilation
  • Sone sound should be maximum 7. 
  • Kitchen exhaust fan ductwork should never terminate into attic space.
  • Kitchen exhaust fan should include back draft damper.
  • CFM rating should be minimum 100.
  • Assist capacity required for buildings 3 stories and above. May be accomplished using an In-line fan or a roof top unit (RTU).
  • Range hood should be deep enough that Range Queen, when installed, is not visible.  Range Queen Product information below.

MAINTENANCE:

  • Range hood should be cleaned every year at minimum:
    • Clean grille.
    • Clean filter.

SAMPLE PRODUCTS:

See sample products located in the APPLIANCES category:

Where apartment kitchen range hood exhaust is connected to a shared riser with roof-top fan assist, POAH prefers the following measures:

  • Seal the shaft to 5cfm per floor or less (measured at 50 Pascals)
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure as needed to prevent backflow of kitchen exhaust through connected range hoods.
  • Adjust barometric control setting such that incidental exhaust drawn through a range hood when off does not exceed 30 cfm.  Spring dampers may be needed.

Acceptable Strategies for Existing Building RENOVATION:

Range hood connected to a shared exhaust riser served by a rooftop fan

Where a shared exhaust riser and roof-top fan are used to provide exhaust from apartment kitchens, POAH prefers the following measures:

  • Range hood should be deep enough that Range Queen, when installed, is not visible. 
  • Seal the shaft to 5cfm per floor or less (measured at 50 Pascals)
  • Install constant air flow regulators (CARs)  for each exhaust intake grille to control exhaust flow rate provided
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure within parameters for CAR operation.

SAMPLE PRODUCTS:

 

FloAire
DU-H High Speed Direct Drive Centrifugal Upblast Exhaust Fan

  • Use ECM motor option 

General Kitchen Area Exhaust

This is not a preferred approach but may be a necessary short-term concession.  Where this configuration exists, renovation activity should anticipate future installation of ductwork connecting a range hood to the ventilation shaft.  Intermediate renovation to the kitchen exhaust ventilation should include the following:

  • Seal the shaft to 5cfm per floor or less (measured at 50 Pascals)
  • Install constant air flow regulators (CARs)  for each exhaust intake grille to control exhaust flow rate provided
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure within parameters for CAR operation.

Preferred Measures for Existing Buildings

  • For renovation work, the shared ductwork should be cleaned an air sealed with a product like Aeroseal.
  • When installing new fans they should be direct drive with ECM motors.

Common Area Ventilation

The following address ventilation strategies for corridors.  Ventilation for community rooms, activity spaces, communal kitchens and other non-apartment ancillary spaces within residential buildings are subject to other guidelines and requirements.

Common Area/Corridor background Ventilation:

Preferred strategies will ventilate corridors as per the requirements of that space plus additional supply airflow commensurate with common area exhaust of spaces such as trash rooms, janitor closets, elevator machine rooms that are directly attached to the corridor.  The ventilation design for new and renovation projects shall not employ the corridor as a make-up air plenum for apartment exhaust (unless the project is over 54 ft in height and is in Chicago where physics of air are different – hence “Windy City”).

Hallway ventilation by ERV/HRV 

Providing hallway ventilation by ERV or HRV will significantly reduce the thermal load of the hallway ventilation air.  It will bring a slight increase in fan energy however this may be mitigated by high efficiency equipment.

  • NEW CONSTRUCTION: do not install combustion equipment with an efficiency rating below 83%
  • REHAB: do not install a new piece of equipment with an efficiency rating equal to or less than the efficiency rating of the unit it is replacing.[KSN1] 

MAINTENANCE:

  • The manufactures’ guide should be followed for ongoing maintenance.  Perform the following at least once a year:
    • Clean/replace filters regularly - typically 3 to 6 times a year depending on equipment.
    • Check belt drives for wear, tension, alignment, debris
    • Tension belt drives per manufacturer’s directions
    • Clean motor and lubricate if necessary
    • Clean heating / cooling coils
    • Clear burner orifices

HALLWAY SUPPLY 

  • Applies to buildings with corridors
  • Across the portfolio the fresh air systems simply supply air into corridors with the expectation that the air will move through the gap below the door.  This is against the code in most locations for fire and smoke reasons.  It is also ineffective in making up air lost in kitchen and bathroom exhaust systems. 
    • If replacing a make-up air unit, size only for the corridor ventilation and make-up of exhaust in directly attached building services such as laundry, trash rooms, elevator machine rooms, etc. This right sizing typically results in a significant reduction in capacity. Do not simply replace the MAU with an in-kind product.
    • Weather-strip all apartment doors.
  • The air provided to common spaces is should be tempered or pre-conditioned.
    • The hallway supply may be tempered or “pre-conditioned” by energy recovery from other common area or apartment exhaust
    • Cooling and dehumidification capacity should be provided for hallway supply ventilation systems in climate zones 5 or lower.   
  • Ideally ventilation system replacement work would not be completed on a component by component basis.  In most of our properties it is preferred that the following occurs to update and drastically improve the performance, both from an indoor air quality and energy efficiency perspective, at one time
    • Air seal the existing ductwork
    • Right size the roof top exhaust fans with direct drive, ECM fans
    • Install CAR dampers at register locations or branch take-offs (only after ductwork is sealed.  Applies to buildings 3 stories and above).
    • Right size the corridor MAU to the required hallway ventilation
    • Individual apartments shall be air sealed and compartmentalized (See Building Enclosure section).
    • Weather-strip all unit entrance doors.
      • SAMPLE PRODUCT:
 

Q-Lon
Door Weatherstripping
Polyethylene-clad urethane foam secured to a on a PVC carrier.

MAINTENANCE:

  • The manufactures’ guide should be followed for ongoing maintenance.  Perform the following at least once a year:
    • Clean/replace filters regularly – typically 3 to 6 times a year depending on equipment
    • Check belt drives for wear, tension, alignment, debris
    • Tension belt drives per manufacturer’s directions
    • Clean motor and lubricate if necessary
    • Clean heating / cooling coils
    • Clear burner orifices

Common Area Source Control Ventilation

The following preferred strategies apply to trash rooms, janitor closets, elevator machine rooms and other areas outside of apartments where airborne contaminants are generated.

  • Seal the shaft to 5cfm per floor or less (measured at 50 Pascals)
  • Install constant air flow regulators (CARs)  for each exhaust intake grille to control exhaust flow rate provided
  • Install direct drive exhaust riser fan with barometric control to maintain duct pressure within parameters for CAR operation.