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Ventilation Air Inlet Locations

Scope

Ventilation air inlets located ≥10 ft. of stretched-string distance from known contamination sources such as stack, vent, exhaust hood, or vehicle exhaust
Ventilation air inlets located ≥10 ft. of stretched-string distance from known contamination sources such as stack, vent, exhaust hood, or vehicle exhaust

Install fresh air ventilation inlets away from contamination sources.

  • Install air inlets at least 10 feet away from all contamination source terminations. Install air inlets in the wall at least 3 feet away from dryer exhausts and contamination sources that exit through the roof (as required by ENERGY STAR Single-Family New Homes).
  • Install air inlets at least 2 feet above grade or above the roof deck (as required by ENERGY STAR Single-Family New Homes). Note: it is easier to install an air inlet at the gable end of the house than to try to lift it off the roof 2 to 4 feet.
  • Ensure that ventilation air comes directly from outdoors and not from adjacent dwelling units, garages, crawlspaces, or attics.
  • Install the air inlet duct in a location with the shortest, most direct path possible to the air handler unit, HRV, or ERV. 
  • Stretch the duct tight and support it adequately to minimize sagging and kinks. 
  • Air seal around the intake duct termination and seal the duct to the HRV/ERV or return side of the air handler with mechanical fasteners and metal tape or mastic. 
  • Install a ≤ 0.5-in.-mesh screen on all air inlets to keep out rodents, insects, and debris, except use a louvered damper rather than a mesh screen on clothes dryer vents.

See the Compliance Tab for links to related codes and standards and voluntary federal energy-efficiency program requirements.

Description

When a home has a balanced ventilation system that uses a heat recovery ventilator (HRV), energy recovery ventilator (ERV), or central-fan-integrated supply ventilation, fresh air is brought into the home through a ventilation air inlet. To ensure good air quality, the inlet should be placed in a location away from possible sources of contamination, and where it has unobstructed access to clean air. 

Possible contamination sources include bathroom exhaust fans, plumbing vent pipes, kitchen exhaust fans, dryer exhaust vents, furnace exhaust vents, water heater exhaust vents, fireplace flues, and whole-house fans. The locations for these outlets and inlets should be specified on plans. In addition, the HVAC contractor should coordinate with other subcontractors, including the framers, plumbers, and electricians, at the beginning of construction to determine the proper placement of both air inlets and contamination source terminations.

The air inlet should be located high enough above the ground, or roof surface, to prevent accumulated snow from piling up over it, rainwater from splashing into it, and plants from growing into it. It should be located outside, not in an attic, crawlspace, garage, or attached dwelling. The inlet should be covered with a mesh screen to prevent animal and insect entry. Ideally, it should be placed in a location where the home owner can check and clean it regularly.

Where to Install Ventilation Air Inlets 

1. Verify locations of all contamination source terminations.

2. Install fresh air inlets so that they are

  • at least 10 feet away from all contamination source terminations
  • at least 3 feet away from dryer exhausts and contamination sources exiting through the roof
  • at least 2 feet above grade or above the roof deck

* Note: it is easier to install an air inlet at the gable end of the house than to try to lift it off the roof 2-4 feet.

3. Install the air inlet duct in a location with the shortest, most direct path possible to the air handler unit, HRV, or ERV. Stretch the duct tight and support it adequately to minimize sagging and kinks. Air seal around the intake duct termination and seal the duct to the HRV/ERV or return side of the air handler with mechanical fasteners and metal tape or mastic. 

4. Install a ≤ 0.5-in.-mesh screen on all air inlets to keep out rodents, insects, and debris, except clothes dryer vents which should have a louvered damper instead. See the guide Proper Clothes Dryer Venting for more information.

On the diagram of a house below, which has central-fan-integrated supply ventilation, the fresh air intake is located more than 4 feet above grade level and away from other contaminant sources such as other flue or exhaust pipe outlets on the house.

Fresh air inlet on side of house.
Figure 1. Fresh air inlet on side of house.

 

The metal frame for the fresh air intake duct grille has been installed in the ceiling of a covered porch of this home under construction. 

Fresh air inlet located in ceiling of covered porch.
Figure 2. Fresh air inlet located in ceiling of covered porch.

 

The intake and duct have been installed for the fresh air inlet in the eave of the roof of this home under construction. The grille has not yet been installed.

Fresh air inlet located in eave of roof.
Figure 3. Fresh air inlet located in eave of roof.

 

Ensuring Success

 Visually inspect the ventilation inlet to ensure that it is at least 10 feet from any known contamination sources, at least two feet above grade and above the roof deck. Make sure the inlet is not obstructed by any objects, that the ventilation air comes from outdoors—not from a garage, attic, crawlspace, or adjacent dwelling, and that the ventilation inlet is covered with a protective screen with ≤ 0.5–inch mesh. Dryer vents should have a louvered damper, not a mesh screen, covering the outside end.

Region

No climate specific information applies.

Training

Right and Wrong Images

Ventilation air inlet is too close to exhaust outlet
Ventilation air inlet is too close to exhaust outlet
Ventilation air inlet is too close to exhaust outlet
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Source
Courtesy Of
EPA
Ventilation inlet is greater than 10 ft. from known contamination source
Ventilation inlet is greater than 10 ft. from known contamination source
Ventilation inlet is greater than 10 ft. from known contamination source
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Source
Courtesy Of
EPA
Ventilation air inlet is too close to exhaust outlet
Ventilation air inlet is too close to exhaust outlet
Ventilation air inlet is too close to exhaust outlet
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Source
Courtesy Of
EPA
Ventilation inlet is greater than 10 ft. from known contamination source
Ventilation inlet is greater than 10 ft. from known contamination source
Ventilation inlet is greater than 10 ft. from known contamination source
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Source
Courtesy Of
EPA
Ventilation inlet is too close to exhaust outlets and does not extend at least 2 ft. above the roof deck
Ventilation inlet is too close to exhaust outlets and does not extend at least 2 ft. above the roof deck
Ventilation inlet is too close to exhaust outlets and does not extend at least 2 ft. above the roof deck
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Source
Courtesy Of
EPA
Ventilation inlet does not terminate high enough above the roof deck
Ventilation inlet does not terminate high enough above the roof deck
Ventilation inlet does not terminate high enough above the roof deck
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Source
Courtesy Of
EPA
Ventilation inlet is too close to the ground and is being blocked by the grass
Ventilation inlet is too close to the ground and is being blocked by the grass
Ventilation inlet is too close to the ground and is being blocked by the grass
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Source
Courtesy Of
EPA
Ventilation inlet is appropriately located above grade
Ventilation inlet is appropriately located above grade
Ventilation inlet is appropriately located above grade
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Courtesy Of
EPA
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
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Source
Courtesy Of
EPA
Mesh screen is correctly installed and gaps are less than 0.5 in.
Mesh screen is correctly installed and gaps are less than 0.5 in.
Mesh screen is correctly installed and gaps are less than 0.5 in.
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Source
Courtesy Of
EPA
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
Mesh screen is spaced wider than 0.5 in. allowing insects to enter
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Source
Courtesy Of
EPA
Air inlet is not convenient for cleaning and located next to exhaust outlets
Air inlet is not convenient for cleaning and located next to exhaust outlets
Air inlet is not convenient for cleaning and located next to exhaust outlets
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Source
Air inlet is located in a convenient place for homeowner to clean
Air inlet is located in a convenient place for homeowner to clean
Air inlet is located in a convenient place for homeowner to clean
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Source
Exhaust terminates inside of soffit and was just covered
Exhaust terminates inside of soffit and was just covered
Exhaust terminates inside of soffit and was just covered
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Source
Courtesy Of
EPA
Exhaust terminates to the outside away from air inlets
Exhaust terminates to the outside away from air inlets
Exhaust terminates to the outside away from air inlets
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Source
Courtesy Of
EPA
Kitchen exhaust properly installed and sealed with mastic
Kitchen exhaust properly installed and sealed with mastic
Kitchen exhaust properly installed and sealed with mastic
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Source
Courtesy Of
EPA
Ventilation duct is compressed because supporting strap is too small
Ventilation duct is compressed because supporting strap is too small
Ventilation duct is compressed because supporting strap is too small
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Source
Courtesy Of
EPA
Exhaust duct is well supported by framing and support straps
Exhaust duct is well supported by framing and support straps
Exhaust duct is well supported by framing and support straps
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Source
Courtesy Of
EPA
Right – A separately ducted HRV supplies fresh air to most rooms in the home.
Right – A separately ducted HRV supplies fresh air to most rooms in the home.
Right – A separately ducted HRV supplies fresh air to most rooms in the home.
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Source
Right – This plug-in sensor detects indoor air quality issues in a home, including elevated levels of humidity, VOCs, smoke, carbon dioxide, or small particulates; if detected, the sensor can switch on the nearest exhaust fan to remove the pollutants.
Right – This plug-in sensor detects indoor air quality issues in a home, including elevated levels of humidity, VOCs, smoke, carbon dioxide, or small particulates; if detected, the sensor can switch on the nearest exhaust fan to remove the pollutants.
Right – This plug-in sensor detects indoor air quality issues in a home, including elevated levels of humidity, VOCs, smoke, carbon dioxide, or small particulates; if detected, the sensor can switch on the nearest exhaust fan to remove the pollutants.
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Source
Right - The automated ventilation system has a sensor built in switch that can detect indoor air pollution; if it senses a rise in humidity, VOCs, smoke, carbon dioxide, or small particulates, the system will turn on the nearest fan to eliminate pollution
Right - The automated ventilation system has a sensor built in switch that can detect indoor air pollution; if it senses a rise in humidity, VOCs, smoke, carbon dioxide, or small particulates, the system will turn on the nearest fan to eliminate pollution
Right - The automated ventilation system has a sensor built in switch that can detect indoor air pollution; if it senses a rise in humidity, VOCs, smoke, carbon dioxide, or small particulates, the system will turn on the nearest fan to eliminate pollution
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Source
Right – This HRV is ducted separately from the home’s ductless heat pumps to provide filtered fresh air to sleeping and living areas and to exhaust stale air from the bathrooms and laundry.
Right – This HRV is ducted separately from the home’s ductless heat pumps to provide filtered fresh air to sleeping and living areas and to exhaust stale air from the bathrooms and laundry.
Right – This HRV is ducted separately from the home’s ductless heat pumps to provide filtered fresh air to sleeping and living areas and to exhaust stale air from the bathrooms and laundry.
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Source

Compliance

ENERGY STAR New Homes and Apartments

DOE Zero Energy Ready Home

Air Conditioning Contractors of America (ACCA)

American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 62.2

Retrofit

SCOPE

Guidance for the measures described in this guide is applicable to both new and existing homes.

For more information on assessing ventilation systems see the assessment guide on ventilation.

For more information on installing outdoor air inlets in existing homes see the U.S. Department of Energy’s Standard Work Specifications. Follow safe work practices as described in the Standard Work Specifications section on ventilation worker safety.

More Info

References and Resources

*For non-dated media, such as websites, the date listed is the date accessed.

Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

Pacific Northwest National Laboratory

Sales

Building Science-to-Sales Translator

Balanced Ventilation = Fresh Air Balanced System

Image(s)

Technical Description

Fresh air balanced systems supply and filter outdoor air while exhausting an equal amount of indoor air. This type of system maintains a neutral balance in air pressure that minimizes moisture risks and optimizes mixing. These systems are often equipped with heat and moisture exchangers that optimize efficiency and comfort. This is achieved by exchanging heat and moisture between the incoming and outgoing air streams. This captures heat before it leaves the home in winter, heat before it enters the home in summer, moisture before it enters the home in summer, and moisture before it leaves the home in winter.

Alternate Terms

Fresh Air Balanced Technology

Fresh Air Balanced System
Sales Message

Fresh air balanced systems help ensure adequate dilution of any indoor contaminants. What this means to your home is supplied with enough fresh air every day so your family can breathe better. Wouldn’t you agree protecting health is too important to ignore in new homes?

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This content is a work created with funding provided by the United States Department of Energy under Contract no DE-AC05-076RL01830 for the operation of Pacific Northwest National Laboratory. The information and guidance provided by Pacific Northwest National Laboratory (PNNL) in the content are intended solely for educational purposes only and do not constitute formal training or certification. It is provided with the explicit understanding that neither the United States Government nor the United States Department of Energy, nor the Contractor, nor any or their employees, nor any jurisdiction or organization that has cooperated in the development of these materials, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or any information, apparatus, product, software, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Viewers assumes full responsibility for all actions that they may take from information provided in this content including ensuring the safety, code compliance, and proper functionality of any products they choose to install. Installation and use of such products should be performed in accordance with local regulations and manufacturer instructions.