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British Thermal Unit (BTU)
The amount of heat required to raise the temperature of 1 pound of water by 1 degrees F.
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Coefficient of heat Transmission
the overall rate of heat flow through any combination of materials.
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Conductance
the number of BTU per hour that pass through 1 sqft of material of a given thickness when temperature difference is 1 degree F.
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Conductivity
the number of BTU per hour that pass through 1 sqft of material 1 inch thick when the temperature differential is 1 degree F.
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Dew Point
the temperature at which water vapor in the air becomes saturated and condenses into water drops.
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Dry-bulb Temperature
the temperature of the air-water mixture as measured with a standard dry-bulb thermometer.
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Enthalpy
the total heat in a substance, including latent and sensible heat.
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Insolation
the total solar radiation on a horizontal surface.
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Latent Heat
heat that cuases a change in state and a change in temperature of a substance.
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Sensible Heat
heat that cause a change in temperature, but not a change of state of a substance.
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Resistance
number of hours need for 1 BTU to pass through 1 sqft of material or assembly of a given thickness when the temperature differential is 1 degree F.
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specific heat
the number of BTUS (joules) required to raise the temperature of a specific material by 1 degree F. Measure of a materials capacity to store heat as compared to water.
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wet-bulb temperature
the temperature of air as measured with a sling psychrometer.
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Convection
transfer of heat through movement of a fluid, either gas or liquid.
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Evaporation
moisture changes to a vapor
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Radiation
transfer of heat energy through electromagnetic waves from one surface to a cooler surface.
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Conduction
transfer of heat through direct contact between 2 objects of different temperature.
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Human Comfort
- Air Temperature
- humidity
- air movement
- surface temperature
- clothing
- ventilation
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lumen
a measure of the power of light perceived by the human eye. Quality of light.
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candlepower (candela)
now-obsolete unit which was used to express levels of light intensity in terms of the light emitted by a candle of specific size.
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footcandle
Illuminance. Density of illumination on a surface.
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footlambert
Luminance. A surface that emits 1 lumen per sqft.
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lumincance
L-leaving. Emitting light, giving off light.
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illuminance
il=in. Density of illumination on a surface.
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efficancy
the amount of light produced by a lamp (measured in lumens), as a ratio of the amount of power consumed to produce it, (measured in watts).
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amplificationi
increased intensity of sound by mechanical or electrical means.
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frequency
number of pressure fluctuations or cylces occuring in 1 sec.
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hertz
unit of frequency. one cycle per second = 1 Hz
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attenuation
the reduction of sound
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reverberation
the persistence of sound in a room after the scource has stopped producing the sound
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noise reduction coefficient (NRC)
sound absorption coefficient
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sound transmission class (STC)
sound absorption by a material
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3 ways to control sound in a space
- reduce the level of the sound scource
- modify absorption in the space (materials)
- introducing background sound to mask the sound
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reflection
return of sound waves from a surface.
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diffusion
random distribution of sound from a surface
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diffraction
bending of sound waves around an object or through an object.
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Ohm's Law
- the relationship between volts (V), amps (I) and ohms (R)
- V = I x R
- V=voltate, I=current, R=resistance
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