Solar Attic Fan Terms

ACH- Air Changes per Hour. Refers to the number of times indoor air is replaced by outdoor air in one hour.

AHU- Air Handling Unit. An electronic device that moves air from place to place in a controlled fashion.

Air Exchange Rate- Rate at which indoor air is replaced by outdoor air in a building or space. Usually measured by CFM or cubic feet per minute.

Ambient Temperature- Commonly referred to as room temperature.

Anemometer- Device used to measure air velocity.

ANSI- American National Standards Institute. An organization that publishes consensus standards on ventilation and the recirculation of air.

Atmospheric Pressure- The measurement of force exerted by the weight of the atmosphere on a given space or area.

Attic Fans- Fans designed for residential properties. Attic fans pull or exhaust hot air from attics to help regulate total home temperature.

Basket Fan- So named because the guard that surrounds the blades of this circulation fan resemble a basket.

Belt Drive- Belt Drive refers to a type of fan where the fan wheel or blades are driven by a belt and motor pulley which is connected to the motor shaft. This type of fan is the opposite of a direct drive fan. (See Direct Drive)

Breathing Zone- Level or area of a space in which occupants breathe during normal activity.

BTU- British Thermal Unit. Used to measure cooling or heating capacity.

Capacity- Comparative term used to describe the ability or capability of a heating or cooling system. Often referred to in BTUs. (See BTU.)

Ceiling Fan- Fan designed to redistribute warmer air from the ceiling area  downward while pulling the cooler air upwards.

CFM- An abbreviation or acronym for Cubic Feet per Minute. A unit of measurement for air flow.

Circulation Fans- Fans that re-circulate air but have no effect on the static pressure within a building or space.

Condensation- The change of vapor to water that occurs when warm, moist air meeting a cool surface.

Conditioned Air- Air that has been treated or ‘conditioned’ by cooling, heating, humidifying or dehumidifying before being supplied to a designated space or area. Also referred to as Tempered Air.

Contaminant- Foreign material in a normal atmosphere. Usually harmful or irritating.

Dampers- Mechanized controls that vary airflow through outlets, inlets or ducts.

Dehumidification- Process where excess water vapor is removed from the air reducing humidity.

Density- Density is the weight of a unit volume of a substance. Specifically:Air = 0.075 pounds per cubic foot (1.2 kg/cubic meter)Water = 62.3 pounds per cubic foot (1 kg/liter)

Diffusers- Component of a ventilation system that distributes or “diffuses” air to promote circulation in a designated space or area.

Direct Drive- Direct Drive refers to a type of fan where the fan wheel or blades are attached directly to the motor shaft. This is in opposition to the belt drive fan. (See belt drive.)

Duct- A pipe or tube that circulates air within a building or space.

Exhaust Air (EA)- Indoor air leaving a building.

Exhaust Fans- Fans blowing air out of a building creating negative pressure that is equalized to static pressure by air inlets.

Fan- An electronic device or machine used to move air.

General Ventilation- A system designed to maintain acceptable indoor air by mixing indoor air with fresh outdoor air.

HEPA Filter- High Efficiency Particulate Air filter. A filter designed to remove contaminants from the air.

Humidity- See Relative Humidity.

HVAC- A generic term that abbreviates Heating, Ventilation and Air Conditioning.

IAC- Acronym for Indoor Air Quality.

Industrial Fans- General term for fans that either assist in the control of hazards and contaminants or provide a comfortable workplace for industrial workers. Can be ventilation, exhaust or circulation fans.

Industrial Ventilation- Within an industrial setting, the supply or exhaust of air by natural or mechanized means to control occupational hazards and contaminates.

Make-Up Air- Air entering a space to replace air that has been exhausted or removed. Also known as Replacement Air.

Manometer- An instrument used for measuring the pressure of liquids and gases.

Misting Fan- Fan that propels water vapor through its airflow path to cool the surrounding atmosphere.

Negative Pressure- A condition where more air is exhausted from a space than supplied creating a vacuum effect. Under these conditions air can be pulled into the space through air inlets providing air circulation.

NEMA- National Electrical Manufacturers Association.

Odor Threshold- Term referring to the lowest concentration of a contaminant the can be detected by smell.

Oscillating Fans- Fans that are designed to turn from side to side to better circulate and redistribute air.

OSHA- Federal agency that sets requirements for ventilation.

Outside Air (OU)- Outside air brought into a building in its natural state.

Pedestal Fans- Free-standing fans that are raised above floor level to improve circulation. Often these fans will have adjustable height adjustments to further aid in proper air circulation.

Positive Pressure- A condition where more air is supplied to a space than exhausted so the air pressure is greater than the surrounding space. Under this condition air can be pushed from the space through air outlets providing air circulation.

Pressure Gauge- Instrument used to measure pressure relative to atmospheric pressure. Can show whether air pressure as either positive (greater than the atmospheric pressure) or negative (less than atmospheric pressure).

Relative Humidity- Ratio of the amount of water vapor in a volume of air to the greatest amount of water vapor that could be held in this same volume of air at the same temperature and pressure. Expressed as a percentage.

Replacement Air- Air entering a space to replace air that has been exhausted or removed. Also known as Make-Up Air.

Return Air- Air that is returned to a fan or mechanized system for re-circulation.

RPM- Acronym for Revolutions Per Minute. Measurement used to define speed of a motor.

Service Factor- The rate or measurement of periodically overload capacity at which a motor can operate without overload or damage. The NEMA standard service factor for totally enclosed motors is 1.0.

Shutter Fans- Fans designed with shutters that allow the total fan aperture to be closed when not in use.

Shutters- Mechanized openings that allow for either air intake or air exhaust in a building or space.

Solar Attic Fan- A solar-powered fan that exhausts hot air from an attic, thereby reducing the heat entering a home and helping reduce energy used for air conditioning.

Solar Energy- The radiant energy from the sun

Static Pressure- Static pressure refers to the condition of equilibrium when the amount of air supplied and exhausted from a designated space is equal. Measured with a manometer.

Sone- A unit for the measurement of the loudness of sound.

Tempered Air- Make-up or replacement air that has been either heated or cooled to obtain a specific desired temperature. Also known as Conditioned Air.

Thermal Effect- The natural property or process where warm air rises and cool air falls. Also know as Thermal Buoyancy.

Tunnel Ventilation- Called this because of the similarities of the system to a wind tunnel. In a tunnel ventilation system a series of exhaust fans installed on the short end of a rectangular building pull air through the building and it is expelled through air outlets on the opposite end.

Vacuum- A space or area where air has been removed to a point below the atmospheric pressure.

Ventilation- Controlled introduction of outside, untreated air into a building that corresponds to an equal amount of exhaust air.

Ventilation Fan- Fan blowing air into a building creating positive pressure that is equalized to static pressure by exhaust openings or outlets.

Ventilation Rate- Rate at which air is either entering or leaving the building. Measured in cubic feet per minute.

Wall Mount Fans- Circulating fans that are permanently mounted or attached to the wall of your space.