In recent years new standards have required that homes be built to a higher standard of energy efficiency. In large part, this means a more air tight home with less air infiltration. The result has been an ever-increasing concern over indoor air quality, and dealing effectively with pollutants that are trapped in the home. This is a particular issue in cities like Ottawa where the heating season is long and the home is closed up tight for a large portion of the year. This leads to challenges with to several indoor air quality issues, including a lack of ventilation.
What Causes Indoor Air Quality Problems?
Indoor air pollutants enter your home a variety of ways. Sources like building materials from the home itself, and furniture release gases that can be hazardous to our health. These are commonly know and “Volatile Organic Compounds” (VOC’s). Other pollutants such as particles enter the home through traffic from outdoors. Other materials degrading the indoor air quality in your home include particulates, such as fibers from carpets, pet hair and dander, to name just a few. Insufficient ventilation and poor air filtration can allow these to build up over time resulting in indoor air quality levels that can be harmful to the occupants of your home. High temperature and humidity levels can also increase concentrations of some pollutants, leading to poor indoor air quality.
In addition to the most obvious indoor air quality pollutants, there are numerous other sources of air pollution that decrease the indoor air quality in any home. These include combustion sources such as oil, gas, kerosene, coal, wood, and tobacco products. Others indoor air quality pollutants are as diverse as deteriorated, insulation, products for household cleaning and maintenance. Poorly maintained central heating and cooling systems, including cooling coils and humidifiers can be a source of mould. Outdoor sources such as radon and pesticides can also be harmful.
The comparative importance of any one source on your homes indoor air quality is dependent on how much pollutant it gives off, as well as how hazardous those emission can be. In some cases, factors such as how old the source is and whether it is properly maintained are significant. A common example of a serious, but often overlooked risk to your indoor air quality, would be an improperly adjusted gas stove, which can emit significantly more carbon monoxide than it would if it were adjusted correctly. Older mid-efficiency gas furnaces as well as oil furnaces are a very common source of poor indoor air quality.
Some sources, such as building materials, furnishings, and household products like air fresheners, release pollutants on what is essentially continuous basis. Other sources, can be more closely related to regular activity in the home. These release pollutants more intermittently. This could include smoking, malfunctioning stoves, furnaces, or space heaters. Other sources are from solvents for cleaning or hobby activities, paint strippers, or cleaning products and pesticides. High concentrations of pollutants can remain in the air for a long time.
How Does Outdoor Air Enter a House?
Under normal circumstances, outdoor air enters and leaves a house by: infiltration, natural ventilation. More recent building codes have implemented a requirement for mechanical ventilation. With infiltration, outdoor air enters the house through a multitude of openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors. Natural ventilation is when air moves through opened windows, doors or intentional opening in the home. With both infiltration and natural ventilation air flow is created by air temperature differences between indoors and outdoors as well as wind. There here are a number of devices used to create mechanical ventilation. Fans that intermittently remove air from bathrooms and kitchens are the most commonly known. The air exchange rate is the rate that outdoor air is exchanged with indoor. Pollutant levels can increase when there is too little infiltration natural ventilation, or mechanical ventilation.
Amount of Ventilation
If too little outdoor air enters a home, pollutants can accumulate to levels that can pose health and comfort problems. Because some conditions can drastically reduce the amount of outdoor air that enters a home naturally, pollutants can build up even in older homes that are not as tightly built as modern homes Without a mechanical means of ventilation, homes that are designed and constructed to higher energy efficiency standards, minimizing the amount natural air infiltration are likely to have higher pollutant levels than other homes.