When we get into cars, one of the first things we do is either open a window or turn on the heat, air conditioner or fan. We want the air to move and we want it to be fresh. What is the thing you hear people say when they walk into an old building or room that has been closed up and shut down for a long time? We hear them say, “Let’s get a window open or open the door and get some fresh air in here.” We want the air to be clear and immediately available. Humans don’t like “stuffy” air.
Ventilating bad air out and getting good air in has been one of the goals of ventilation for centuries. This type of ventilation is a process of changing or replacing air in a space to control factors such as temperature, pressure, humidity, and quality. Ventilation in a space is concerned with the air that flows inside the dwelling and air that travels from the inside to the outside.
The scientific study of the principles of physics, air flow, and mechanical engineering has divided ventilation into two different kinds. These kinds or methods are natural and mechanical.
Natural ventilation has to do with the cracks, small holes, and seals that are broken in the envelope of an office building or home. Older homes will usually have more openings in the places where joints are made, in spaces in the attic and roof, and around windows. This kind of ventilation is not systematic and cannot be predicted or centrally controlled. Natural ventilation depends on the quality of the dwelling’s tightness, environmental conditions, wind, and other factors. If these factors are not consistent, the quality of the indoor air and the percentage of pollutants will be unstable.
Natural ventilation is further divided into two types. One type is wind driven ventilation and the other is buoyancy-driven. Wind driven ventilation is impacted and controlled by two factors to include local air pressures and holes in the envelope of your home/office. Buoyancy-driven ventilation is a result of a directional buoyancy force that results from temperature differences between the exterior and interior of the dwelling.
Homes, offices and buildings are also impacted by the body heat that humans bring into the room and wind currents that naturally flow through the area. Because of these variables dwellings are said to ‘breathe.’
Mechanical ventilation is also known as ‘forced’ ventilation and calls into play various kinds of mechanical and electrical machines. These machines such as an air handler, ceiling and floor fans, and others impact the amount and direction of air in a structure.
Mechanical ventilation serves the purpose of keeping the air inside a structure rotated, moving, and clean. Fresh air, moisture, odors and contaminants are consistently pushed/directed to ducts and air handlers that force the air through filters keeping it clean.
Ventilation provides three primary benefits:
Mechanical ventilation systems may be categorized into four different kinds.
Supply Ventilation Systems: Air is drawn in through an air intake vent and funneled to different areas by the force of a fan and traveling through a duct system. This system allows the air to be conditioned and/or dehumidified before entering key living areas.
Exhaust Ventilation Systems: In this system, indoor air is being forced from the inside of a space to the outside through the use of fans.
Balanced Ventilation Systems: Equal amounts of air are brought into and released from a structure. This is often done with the use of two fans. One fan compels the air to come into the structure and the other fan forces the air outside the structure.
Energy Recovery and Heat Recovery Ventilation Systems:
These types of systems reduce the cost of energy required to both heat and cool air. These systems are divided into heat-recovery ventilators(HRV) and energy-recovery ventilators(ERV). Each system involves a heat exchanger and fans to force air through the system. This is usually a whole house distribution system.
The differences in the way these systems function can be localized around the work of the heat exchanger. HRVs transfer heat from exhaust air to incoming air during the colder seasons and from incoming air to exhaust air in the warmer season to reduce the heating and cooling load and improve comfort. An ERV transfers heat and moisture between the exhaust air and incoming air. Savings are gained by the reduction of moisture which would have required the use of a dehumidifier and cooling equipment. During the winter, ERVs add moisture from the outgoing air to the incoming air which reduces the degree of dry indoor air.
The use of well thought out and appropriate ventilation systems are needed to produce sufficient indoor air quality and comfort levels for everyone concerned. It is estimated by the World Health Organization that 30% of all buildings suffer from ‘Sick Building Syndrome’ due to the lack of competent ventilation design. Standardization organizations such as ASRAE have arrived at protocols and guidelines for appropriate ventilation installation. Specifically, standard 62 outlines installation and maintenance procedures for professional ventilation installers.
Should you have questions or concerns related to your indoor air quality or the ventilation system installed in your dwelling, call Freedom Heating and Cooling at 205 444 4444!