Types Of Ventilation

Types of Ventilation

To help homes and buildings breathe, there are a variety of different ventilation systems available. We take a look at some of the most common and standard practices.

Common Ventilation Systems

When discussing types of ventilation, there are two distinct categories that need to be dissected. In simple terms, these two categories are the location, or the “where” of the ventilation system, and the process, or the “how,” of the ventilation system. First, we will discuss the where category of ventilation.

Natural Ventilation

This ventilation system, as the name implies, is the natural movement of air currents and flows through a home uninfluenced by human technology. Natural ventilation is “located” wherever openings in the home’s building envelope are located. You can think of this system as the air flow which is delivered to the indoors through open windows, screen doors, doggy doors, and other fenestrations that aren’t exclusively designed for ventilation but still inherently dictate the airflow of the building. Natural air ventilation is used in nearly all homes to some degree, although some older homes may be more reliant on it than more modern structures.

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Spot Ventilation

This ventilation system utilizes technology to provide ventilation to very specific “spots” throughout the home. Any form of ventilation which uses man-made technology instead of purely natural airflow methods is often referred to as mechanical ventilation. Most often, these forms of ventilation are located in basements, attics, and other moisture-prone areas of a home. Exhaust fans, often found in kitchens and bathrooms, are another form of spot ventilation, as they quickly remove polluted air from their isolated location. Spot ventilation, while effective, is rarely the sole form of ventilation in a home, and is best used as a supplement to additional ventilation systems.

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Whole-Home Ventilation

This ventilation system is the most common form of ventilation found in modern housing. Whole-home ventilation utilizes a series of exhaust ducts and vents throughout the home to provide man-made, deliberate ventilation and circulated air flow. These ventilation systems boast the ability to be managed, controlled, and modified entirely by the homeowner or a licensed contractor.

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Ventilation: An Important Part of the Healthy Home Equation

Adding ventilation after sealing and insulating may seem counter productive, but it’s a critical component to building an efficient, healthy-home solution. The goal is to keep the good stuff (cool, clean air) in, and move the bad stuff (heat, moisture, indoor air pollution) out.

Mechanical Ventilation System Methods

Now that we’ve covered where ventilation systems are utilized in the home, we can address how these systems work and keep healthy air flow functioning in the home.

Exhaust Ventilation

Most homeowners are familiar with exhaust ventilation whether they recognize it or not. This form of mechanical ventilation blows polluted or unwanted air out of a specific location in a building. Kitchens and bathrooms are the most common locations for exhaust ventilation fans. In these rooms, you will often find them above the stove/oven, or on the floor behind the door. In older homes, exhaust fans often have their own independent switch on the wall, and can make a lot of noise once started. If you’re a homeowner who is unsure whether specific vents are for exhaust ventilation or whole-home ventilation, try adjusting the thermostat. If the vent starts blowing out air, it’s part of a whole-home system.

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Supply Ventilation

Supply ventilation works as the yin to exhaust ventilation’s yang. Instead of sucking out air that homeowners do not want inside, supply brings fresh air in from the outside world. Supply ventilation intake locations are installed evenly throughout a building envelope. Occasionally, contractors will install additional or specific supply ventilation ports to areas which rarely receive natural ventilation, like the attic or basement. Cycling clean, fresh air from the outdoors is important for resolving hazards that arise from stagnant indoor air. Utilizing supply ventilation allows a home to avoid relying on open windows and doors for their air cycling, which may only be open for a brief period of time.

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Balanced Ventilation

A balanced ventilation system is the ideal “how” system for a home’s breathing options. When exhaust ventilation is used, it depressurizes a home by taking air out of its sealed enclosure; likewise, supply ventilation depressurizes the home. However, used in tandem and installed with each other in mind, the combination of supply and exhaust ventilation creates a home ventilation system that is designed for equal pressurization and consistent air cycling. Balanced ventilation system is often the mechanical side of the “how” behind a whole-home ventilation system. With assistance from natural airflow, a balanced ventilation system can bring constant clean air and good living conditions to rooms throughout the house. Utilizing a balanced ventilation system does not impede the ability for additional exhaust or supply ventilation systems elsewhere in the home. Oftentimes kitchens, bathrooms, basements, and attics will still have their own forms of supplementary ventilation to support their room-specific needs.

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Hazards of Poor Ventilation

Mold

The most common side effect of bad ventilation is mold. When a home lacks proper air flow, the moisture in the air is allowed to rest within the walls and hard surfaces, creating a suitable environment for mold cells to grow. This is why basements, sheds, and attics are so consistently riddled by mold issues — they often have the worst airflow.

Moisture Damage

Moisture can cause additional damage to the structures of the home itself. Siding, banisters, columns, and walls are all susceptible to moisture damage, with the amount of damage depending on the material used within the structure. Generally, moisture damage results in a weakened home structure, causing chips, decay, and eventual deterioration.

Radon

Radon is an odorless, colorless, radioactive gas that is emitted through the soil underneath a home over time. When exposed to humans, it can cause long-term damage to the respiratory system. Radon is the number one cause of lung cancer in the United States for non-smokers and is particularly prevalent in older homes.

Mechanical Vs. Natural Ventilation Systems

Mechanical Ventilation

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Pros
  • Reliable for controlling exact flow rates
  • Ventilation locations can be added/removed
  • Specific attention can be given to low-flow locations (attic, basement)
  • Filter systems can be installed within existing ventilation to combat bacteria and additional pollutants
  • Can operate automatically/on a schedule, allowing homes to be ventilated regardless of if they are occupied

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Cons
  • Repairs can be more difficult than natural ventilation, as most homeowners are more equipped to repair a window than an internal vent
  • Whole-system repairs/maintenance can have higher cost rates
  • More easily ignored/forgotten by homeowners, as the systems themselves are largely unseen

Natural Ventilation

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Pros
  • More easily maintained by the average homeowner
  • Provides natural sunlight, room atmosphere that is incorporated into most home designs
  • Less viable when homeowners are away, as open windows can be a safety hazard

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Cons
  • Less filtration opportunities, as screen doors/window barriers catch less pollutants than mechanical systems
  • Less immediate, direct control over airflow to specific rooms and locations throughout a building
  • Very seasonally dependent. In extreme cold or heat seasons, natural air is rarely a viable option without drastically reducing indoor comfort