How to Control Your Home's Ventilation and Maintaining Good Indoor Air Quality

With today's newer building technology to make houses more energy-efficient, your home is now more insulated... "sealed"....to the point of being considered "airtight", and because of that, ventilation becomes critical in maintaining good indoor air quality. 

To achieve good ventilation conditions, stale, humid, contaminated and oxygen-depleted air, needs to be exchanged with fresher outdoor air. This is difficult to achieve and to control by simple ventilation, opening windows or depending on small permanent vents for exhausting stale indoor air. Wind conditions may vary, and some exterior surfaces will be exposed to face positive winds, blowing against the house.  At the same time, sheltered surfaces cause negative pressure, creating a suction effect. When this occurs, chimneys get a downdraft and could create smoke fumes. This draft of air in rooms with open fires in fireplaces, boilers or heating appliances, if not sealed against indoor air, when ignited, combust indoor oxygen and deplete the room of oxygen. Worse yet, it can create a build-up of carbon monoxide to dangerous levels.

Radioactive radon gas levels can also increase indoors, by open chimneys, drawing warm air up and out. This can happen in circumstances where there’s a lack of ventilation vents. The interior spaces can create a negative air pressure with the ground, thereby vacuuming radon up from below the ground and trapping it within the interior environment of the house. 

Odors from toilets, grease and fumes from cooking, all create health problems. However, the most common health damage caused by poor ventilation is a build-up of humidity and condensation.

High relative humidity conditions are now quite common in homes, especially since the fitting of draft-sealed windows and closing of permanent vents. Can you imagine the amount of vapor you create in your home, from washing, cooking, breathing, and even perspiring....being sealed within your home during the cold and therefore, long heating season, sometimes lasting several months? Therefore, you need quality ventilation, without giving discomfort to you and your family and without causing a heat loss from uncontrolled cold drafts. 

Asthma has increased tremendously over the last twenty years and much of this increase is triggered from high humidity, producing condensation and molds, and favoring conditions for dust-mites to multiply.

An effective solution to ventilation for airtight homes, is fitting a Heat Recovery Ventilation System. This is to prevent warm interior air that’s heated during the cold days of winter, from driving through the exterior building elements, to balance with the outside ambient colder air. The warmer, interior air typically suspends more water vapor then the outside colder air, causing a differential vapor pressure. This pressure drives the warm air to the outside, to balance the vapor pressure with the outside environment. It is therefore critical to
prevent this vapor-packed air from driving through permeable materials like plasterboard and timber that are fitted on the inside of insulation. This is achieved by laying a vapor-resisting, airtight membrane, ‘smart-ply’ OSB boards or by applying coats of wet plaster rendering. It is also important to eliminate all small gaps at joints and junctions that leak moist, warm, interior air to the colder air outside, which contains much less water vapor. This is achieved by hermetically sealing all joints and junctions.