Ventilation is a process of movement of fresh air around the room. Ventilation includes exchange of fresh outside air and circulation of inside air. Good ventilation accounts for the comfort and safety of the inhabitants and it also suffices a legal requirement.
Ventilation methods can be classified into mechanical, natural and hybrid. Mechanical ventilation is used to control the quality of indoor air. Odor, excessive humidity and other contaminants can be replaced with fresh outside air. Energy requirement increases during humid climates in order to remove the excess moisture. Kitchens and bathrooms consist of exhaust fans to control humidity and odor.
Kitchen ventilation helps in resolving problems rising from smoke and grease. Ceiling fans reduce the temperature arising due to perspiration of the people inside the room.
Natural ventilation is achieved by open vents/windows in the building. The warm air of the building flows out of the vents and the cooler air is brought inside the building through the openings in the building. In warm months, thermal comfort is created by natural ventilation through open spaces.
Hybrid /Mixed mode of Ventilation is a combination of natural and mechanical form of ventilation. The mechanical and natural components of ventilation may be used separately or together at different hours
of the day. The natural ventilation component may not provide adequate ventilation during extreme weather conditions. Then the mechanical component is utilized to meet the desirable internal temperature and to make the room a comfortable place to live.
The rate of ventilation is denoted by the volume of air flowing outside that is brought inside the building. The rate is measured in the units of cubic feet per minute (CFM) or liters per second (L/s).
Spray foam insulation and Ventilation
Spray foam insulation is a popular measure over several years as it is affordable and an effective energy saving solution on a long – term basis. The insulation creates an envelope around the building and restricts the passage of air. It diminishes the natural ventilation of air through the building. Insulated
homes without ventilation become humid.
Natural ventilation reduces the effects of pollutants at home. The absence of natural ventilation gives rise to dangerous levels of dust, moisture, allergens and other pollutants which result in health problems. The natural ventilation replenishes the level of oxygen in the room and thus helps in maintaining a good quality of indoor air.
Therefore an important feature of a spray foam house is the provision of mechanical fresh air ventilation.
The best ways to provide mechanical fresh air ventilation are listed below:
a) Exhaust Ventilation system: These systems pull out the indoor stale air and create an air leakage the structures. The electrical energy cost is lowest and it can be used with any heating system.
b) Balanced Ventilation systems comprise of one fan too brings air inside the home and another to take out the stale indoor air. They are generally classified into Energy Recovery Ventilators and Heat Recovery Ventilators.
c) Supply ventilation Systems push outside air into the home and provide air to exit from kitchen hoods and bathroom fans. It comprises of 2 components – controlled mechanical damper and whole house ventilating dehumidifier.
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