Baltimore’s summer humidity and winter chill make carefully planned ventilation a must in our area, but not all types of home ventilation work equally well. Some provide only a bare minimum of fresh air. Others clean the air throughout your home while also helping to maintain your preferred temperature and humidity levels. By understanding your options, you can more easily find the ideal ventilation method for your home.
Good Ventilation Means Better Health for You and Your Home
If you’ve ever entered a home with lingering odors, whether from cooking, mildew, pets or another source, you’ve experienced firsthand how unpleasant a lack of ventilation can be. Simply from day-to-day living, odors like these can build up before you realize it and begin to sink into the drapes, carpet and other soft furnishings.
Eventually, your whole house and even your clothes can take on a certain smell. Almost all types of home ventilation remove stale, odor-laden air and leave you with fresh, clean air that makes your home more comfortable and enjoyable.
Ventilation also protects your health. Mold spores, pollen, car exhaust fumes and other pollutants blow in through windows, doors and air leaks around your house. Pest debris, chemical fumes from certain materials and carbon monoxide (CO) from fuel-burning appliances are produced right inside your home. All of these can adversely affect your health.
Mold spores, pollen and particles of pest debris like mouse and cockroach droppings irritate your airways, aggravating allergies and asthma, and increasing your risk of respiratory problems even if you’re otherwise healthy.
Volatile organic compounds (VOCs) also affect your health, even if you can’t always smell them. These are gaseous forms of chemicals such as benzene, xylene and styrene that are given off by household materials such as paint and varnish, carpeting, and pressed wood and upholstered furniture. Exposure to VOCs is associated with “sick building syndrome.” Whole-house types of home ventilation help remove these airborne chemicals from all your rooms.
Sufficient airflow protects your home, too. High indoor humidity creates favorable conditions for mold growth. If mold develops inside the walls, under floors or in the attic, it can do serious damage to your home’s structure before you even realize it’s there. Ventilation removes excess humidity, protecting both you and your home from mold.
Natural Ventilation: Relying on the Weather
Natural ventilation relies on natural phenomena to provide airflow. Wind-driven ventilation uses natural wind currents, while buoyancy-driven ventilation takes advantage of convection or the tendency for warm air to rise. These types of home ventilation don’t require fans, so they operate without electricity.
Open a few windows on a mild, breezy day, and you have a reasonably effective form of natural ventilation. The cross breeze blowing through your home carries away the stale air while bringing in fresh outdoor air. The problem is it also lets in outdoor air pollutants and humidity. More advanced forms of natural ventilation minimize these issues.
- Trickle ventilation – Trickle vents are narrow plastic vents of around 12 to 18 inches long that are typically installed above windows to provide wind-driven ventilation. The vents let air in as the wind blows through them, but slow and redirect the airflow to prevent drafts. They also reduce the amount of pollutants that enter. These vents provide a minimum amount of fresh air and reduce condensation on the windows.
- Passive stack ventilation (PSV) – These systems combine trickle vents installed at various locations in the house with roof vents and ductwork. Warm indoor air naturally rises out through the roof vents, and as it does so, it pulls in cool outdoor air through the trickle vents. Although PSV provides airflow throughout the house, the amount varies greatly depending on the weather.
Spot Ventilation: Helpful But Limited
Other types of home ventilation use mechanical means to move air. One of the simplest types is known as spot ventilation, which is designed to clear out contaminated or humid air produced within a small area. Examples include kitchen and bathroom exhaust fans, range hood fans and vents for appliances such as clothes dryers.
These fans and vents serve an important purpose and should be used as necessary. Running the range hood fan while you cook removes humid air and particles of grease and smoke. Turning on the exhaust fan for a few minutes after cooking or showering gets rid of built-up odors and humidity.
Handy as it is, though, spot ventilation can affect only a small area. It does next to nothing to draw out the pollen, mold spores and VOCs that may be lingering in other parts of your home. Letting the fans run longer isn’t a solution. Run the fans for more than a few minutes, and you’ll let in more humidity and air pollutants than you vent out, especially in summer.
Running exhaust fans too long can also create negative air pressure in your home. This increases the rate at which outdoor air enters through leaks around your doors, windows, utility line penetrations and other places. This incoming outdoor air carries pollutants and moisture that raises the risk of mold growth in the walls.
Exhaust fans can also cause back-drafting, a situation in which exhaust fumes from fuel-burning appliances, such as the gas stove, are pulled back into the room instead of flowing up the exhaust vents as they should.
Whole-House Ventilation: Fresh Air Everywhere
If you’re looking for types of home ventilation that improve air quality in all your rooms, whole-house ventilation is the type to look for. These systems use mechanical fans to draw in fresh air, remove stale or both. The fan system is connected either to the heating and cooling system’s ducts or to its own ducts, which allows it to affect the air all throughout your home.
Three types of whole-house ventilation are used:
- Supply-only – This type uses fans to bring in fresh air while relying on open windows, air leaks and a few exhaust fans to let out stale air.
- Exhaust-only – This ventilation style uses fans to draw out stale air, but fresh air must enter through windows and air leaks.
- Balanced – Balanced ventilation uses both supply and exhaust fans to bring in and draw out air in equal amounts.
Balanced systems provide the most thorough and reliable ventilation while solving some of the problems of supply- or exhaust-only systems. They don’t rely on air leaks, so they let in fewer air contaminants. They don’t create negative air pressure indoors, so they don’t draw in appliance exhaust fumes.
Heat recovery ventilation (HRV) and energy recovery ventilation (HRV) have even greater benefits. These types of home ventilation systems contain heat exchangers. In winter, the heat exchanger takes heat from the outgoing warm indoor air and moves it to the cold incoming airstream. In summer, it does the reverse. This helps keep your indoor temperature stable. An ERV moves moisture as well as heat, helping to maintain your indoor humidity level.
Lack of Ventilation Presents Serious Risks
Funny smells and allergy-aggravating pollen aren’t the only things you’ll have to worry about if you let stale air build up in your home. The greatest threat comes from air pollutants that can cause you immediate harm, such as carbon monoxide.
Even with well-vented and well-maintained fuel-burning appliances, a small amount of carbon monoxide can enter your air. Without good airflow, the CO will accumulate and potentially cause headaches, tiredness and a general feeling of illness. If you notice you feel less well at home than outside or at work, the cause could be insufficient ventilation. In addition to installing ventilation, installing carbon monoxide detectors helps keep you safe from CO.
Exhaust-only ventilation systems need air leaks to supply fresh air, but a poorly designed system can exacerbate leaks enough to cause serious moisture problems. This is a particular problem in summer when the warm humid air entering hits the cool surfaces of your air conditioned home and causes condensation. The excess moisture alone is enough to damage wood and drywall.
Worse yet, damp and dark areas offer the perfect growing conditions for mold, which further decays your home’s structure and surfaces. Depending on the degree of damage, you may not be able to clean up the mold. Severe damage could mean having to replace wall studs, beams and other parts of your home. Ensuring good ventilation throughout your home can prevent this while also protecting you from exposure to harmful mold spores.
For help choosing from among the types of home ventilation on the market, contact us at Griffith Energy Services, Inc. We proudly serve homeowners in Baltimore, Manassas, and Westminster, as well as in Dover, Delaware and Martinsburg West Virginia.
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