Ventilating Your Home – Prevent Ice Dams
Proper ventilation of your home is important for your families health and comfort. Your home can become a repository for moisture, smoke, cooking odors and indoor pollutants. To control the levels of these substances in your home you have to have fresh air entering your home to replace these pollutants. In your typical home air movement is controlled mainly by infiltration, natural ventilation and mechanical ventilation.
Infiltration – This is the amount of fresh air that enters your home through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors . Newer homes are becoming tighter which reduces the amount of natural infiltration of fresh air into your house.
Natural Ventilation – Opening windows and doors is a common method of natural ventilation. I think we all can remember when our mothers used to “air out” rooms even in the middle of winter.
Mechanical Ventilation – New homes all have mechanical ventilation in kitchen, bathrooms and laundry rooms. This rooms have exhaust fans that discharge air to the exterior of the home. Kitchen exhaust fans that just re-circulate air through a metal grease filter can be quite a collector of grease, odors and airborne pollutants. Bathrooms that have peeling paint on ceiling from moisture is a sign of extremely poor ventilation. Exhaust only ventilation systems are only designed to work in the room in which they are installed.
Attic Ventilation – Having the proper insulation and adequate ventilation can protect your attic from mould and wood rot. If air cannot circulate from your soffits and pass through the attic area exiting through upper vents, heat and moisture will collect in the attic area causing extensive problems. When upgrading your insulation it is always a good idea to increase your attics ventilation by adding additional soffit baffles. One sure sign of poor attic ventilation and/or lack of insulation is the formation of ice dams on eaves of roof in the winter. Heating cables are another sign of problems in attics.
Heat Recovery Ventilators (HRV’s) – HRVs are efficient devices that provide good ventilation without a big energy cost for heating the outside air. The HRV uses the air being exhausted to preheat incoming air. Many municipalities now require a HRV unit to be installed if you have a wood burning appliance. This is to prevent negative pressure building up in your home creating a back draft problem. In energy efficient homes there can be a shortage of fresh air entering the home which can cause what was termed the “sick building syndrome”. This is basically when there is more air leaving the home through various sources, such as; fireplaces, furnaces, exhaust fans, hot water tanks and wood stoves. Some of the common symptoms were; back drafting of combustion appliances, mold, mildew and condensation on walls, lack of fresh air with musty and stale odors and a noticeable rush of air into the house when opening a door or window.
If you are contemplating installing a HRV unit for your home it is recommended that you consult and expert to have unit custom designed to work in tandem with your proposed HVAC system. Better results can be obtained when HRV’s are installed as part of new home construction as they can be added to your bathrooms, kitchen and laundry area. HRV’s can be an added option to an existing home but will not function as efficiently. CMHC and ASHRAE both have some excellent articles on home ventilation if further knowledge is required.
Martin Jennings contributed this great piece of information which I thought was worth adding so that everyone could benefit.
Home Services Sales Consultant | The Home Depot
Good advice about keeping your home well ventilated!
I’d like to expand on your attic section which is probably one of the most important sections of the home. A well balanced attic is one that breathes freely during all seasons. Here in Florida, I’ve seen roofing shingle temperatures of 170 degrees only to find the attic temperatures to be 165 degrees; a sure sign of an unbalanced ventilation system. The major culprit is insufficient soffit to ridge vent airflow due to improperly installed insulation.
Most homeowners think that piling up their attic floor with a huge blanket of blown in fiberglass (by themselves) is really saving them money. Get this done by the professionals that will install baffles between EVERY joist and ensure there is adequate ridge ventilation. Allowing the proper convective airflow will result in a cooler attic, better energy conservation, and extended roof life.
A good rule of thumb to determine if your attic is properly balanced:
If the asphalt shingle temperature on a 90 degree sunny day is 170 degrees, your attic should be NO MORE THAN 120 degrees. Achieving this balance will pay off in both the short and long runs!