Air quality in your home

Spiralling energy costs and the impact of energy consumption on our environment have brought about a marked improvement of construction techniques over the past twenty years. Air tightness has improved in most homes to the point of having a positive impact on homeowners' budgets. On the other hand, lack of adequate ventilation sometimes has negative repercussions on the health of a home's occupants. Pollutants and dampness trapped inside a house can cause serious respiratory problems and lead to the deterioration of the building's structure.
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The ventilation
The noise of the ventilation system
Heat recovery ventilators (HRVs)
Air exchangers
Bathroom fans
Range hoods
Attic ventilators (natural flow ventilation)
Air filtration

The ventilation

Whether you're building or renovating, whatever the ventilation system you choose, remember that the process of ensuring a supply of fresh air in a house entails additional heating expenses because new air has to be warmed up.

Natural ventilation, which occurs through doors, windows and other openings where air infiltrates buildings that are not perfectly airtight, constitutes an "accidental" ventilation system.

Mechanical ventilation uses mechanical power to control the evacuation of stale and damp air and the intake of fresh air. All new homes must be equipped with a ventilation system that meets local building code standards. The rate of evacuation is calculated in cubic feet per minute and varies in accordance with the total volume of the house.

You should question your distributor on the compatibility of any proposed system with the building in which it's going to be installed. Be sure your ventilation system is not going to cause smoke to accumulate in heating system ducts and back into the house. This is particularly important with wood stoves and fireplaces.

The noise of the ventilation system

Ventilation systems often generate noise that can become unpleasant. Noise levels are measured in sones. Product specifications provide information on the subject. By way of example, a refrigerator produces 1 sone.

Heat recovery ventilators (HRVs)

HRV's are without doubt the ultimate in central ventilation. They're the best way to counterbalance air tightness in new homes. Determination of the system best suited for a given house is based on the area that needs to be ventilated and takes into account the number of residents in the house. HRV's are more expensive to purchase than other systems but they represent an investment that can become profitable after a few years provided, of course, they're installed in an airtight house. HRV's use the heat from the air they expel to heat the new air they carry into the house, thus reducing energy consumption. They also filter the new air before circulating it through the house.

A number of variations of HRV's are available to suit different types of heating systems and buildings (bungalows, cottages, etc.). It's easier to install HRV's during original construction. That is why few are ever added to existing houses. However, your merchant will supply installation kits for existing houses on request.

*Please note that the model shown in the image is available only in big-box stores. The model sold in other RONA stores may vary from what is shown in the image.

Air exchangers

Less expensive to buy (from $750 to $1,500, approximately), air exchangers which are central ventilations systems, also control the level of humidity by evacuating stale air and replacing it with fresh air. They then heat the new air and distribute it through the house. However, their energy efficiency is less than other systems because they aren't able to recuperate as much of the evacuated air. If they're well installed, air exchangers can ensure a good supply of fresh air and can also solve condensation problems caused by humidity.

Bathroom fans

There are two types of bathroom fans: the propeller fan and the turbine fan. The latter is more expensive and performs better. In order to make the right choice, you should take into account the following technical factors:
  • Be sure the system evacuates humidity outside the house.

  • Also check the system's extraction capacity. It should be at least fifty cubic feet per minute. If you use the shower often, or if your bathroom is equipped with a whirlpool bath, choose a powerful ventilator.

  • Be sure the ventilator will fit in the available space.

  • Pay particular attention to the noise level. It should be below two sones (by way of example, a refrigerator generates about one sone).

Range hoods

There are range hood for every taste, every need and every pocket book. Prices vary in accordance with design and technical characteristics that can be very sophisticated on certain models. You need to make your choice between propeller and turbine fan models in keeping with your budget and your proposed use of the hood. The turbine models are quieter, more powerful, more effective and, as you might expect, more expensive.

Whatever the model you choose, your hood should extract steam, smoke, household smells and any flying particle released when you cook. Here's what you should look for:
  • Be sure your hood generates sufficient suction. We recommend an average capacity of between 100 and 200 litres per second (200 to 400 cubic feet per minute).

  • Be sure the hood can be operated at varying speeds, to suit different cooking needs.

  • See if the model features light intensity adjustments.

  • Get information on the level of noise the hood generates. Generally, range hoods generate between 3 and 8 sones.

  • And make sure you buy a hood that is easy to maintain.

Certain models are especially designed for gas ranges.

If you don't have the necessary ducts to evacuate stale air, you can buy a hood fitted with a charcoal filter that can treat stale air without evacuating it. Needles to say, this type of hood is a less effective substitute.

Attic ventilators (natural flow ventilation)

In order to avoid condensation and humidity problems in the attic as well as the mildew problems that often follow, it's important that the attic be able to replace stale air with new air. Soffit air intakes are generally inadequate because they're all installed at the same height, which stops them from generating sufficient draft. An intake in the higher part of the soffit causes a chimney effect and brings about sufficient ventilation. But, that intake must, at the same time, prevent infiltration by water, snow and ice. That's what an attic ventilator is designed to do.

There is a number of models of attic ventilators on the market. The slope of the roof and the area to be ventilated are among the criteria that will dictate your choice. Attic ventilators are made of a base on which sits a turbine that is activated either by hot air trying to escape the house or by the wind. Some are motorized. However, they're not recommended for winter use because they can cause air and humidity trapped in the house to escape through cracks in ceilings thus causing humidity problems in the attic. For double-sloped roofs, a gable vent that can cause a chimney effect through the soffit holes is often adequate in providing good ventilation.

Ventilator ducts that are not airtight or badly installed often cause humidity and condensation problems. In such situations, rather than evacuating the humid air outside, they expel it in the attic. Perform all necessary checks before installing your ventilator.

Air filtration

Air cleaning may achieve an additional reduction in the levels of certain pollutants when source control and ventilation do not result in acceptable pollutant concentrations. However, air cleaning alone cannot be expected to adequately remove all of the pollutants present in the typical indoor air environment.

Air cleaners are usually classified by the method employed for removing particles of various sizes from the air. There are three general types of air cleaners on the market: mechanical filters, electronic air cleaners, and ion generators. Hybrid units, using two or more of these removal methods, are also available. Air cleaners may be in-duct units (installed in the central heating and/or air-conditioning system) or stand-alone portable units.

Portable air cleaners vary in size and effectiveness in pollutant reduction capabilities. They range from table-top units to larger, more powerful console units. In general, units containing either electrostatic precipitators, negative ion generators, or pleated filters, and hybrid units containing combinations of these mechanisms, are more effective than flat filter units in removing tobacco smoke particles.

Pollutants in indoor air may be divided, for convenience, into three groups: particles, gaseous pollutants, and radon and its progeny. Some air cleaners, under the right conditions, can effectively remove small particles which are suspended in air. However, controversy exists as to the efficacy of air cleaners in removing larger particles such as pollen and house dust allergens, which rapidly settle from indoor air.
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