Ching Dictionary of Architecture: Heat Basics

Ching Dictionary of Architecture: Heat Basics

British thermal unit (BTU) = The quantity of heat required to raise the temperature of one pound (0.4 kg) of water 1 deg F.

Calorie (cal) = A unit of heat equal to the quantity of heat required to raise the temp. of one gram of water 1 deg C at a pressure of one atmosphere, equivalent to 4.186 joules. Also called gram calorie, small calorie

Kilocalorie (Cal) = A unit of heat equal to the quantity of heat required to raise the temp. of one kilogram of water 1 deg C at a pressure of one atmosphere, equivalent to 1000 small calories. Also called kilogram calorie, large calorie. (note the capitalized C in the abbreviation)

Fahrenheit scale (F) = A temp. scale in which 32 deg F represents the freezing point and 212 deg F the boiling point of water under standard atmospheric pressure.

Convert Fahrenheit to Celsius = Subtract 32 from Fahrenheit number then multiply by 5/9 to find degrees Celsius.

C = (F-32) x 5/9 OR C = (F-32) x .5555555555...

Celsius scale (C) = A temp scale divided into 100 degrees, in which 0 deg C represents the freezing point of water under standard atmospheric pressure. Also called the Centigrade scale.

Convert Celsius to Fahrenheit = Multiply Celsius number by 9/5 an then add 32 to find degrees Fahrenheit.

F = (C(9/5)) + 32 OR F = (C x 1.8) +32

Kelvin scale = An absolute scale of temp. having a zero point of -273.16 deg C

Absolute scale = A temp. scale based on absolute zero with scale units equal in magnitude to centigrade degrees.

Absolute zero = The hypothetical lowest limit of physical temp. characterized by complete absence of heat, equal to -273.16 deg C or -459.67 deg F.

Absolute temperature = Temperature as measure on absolute scale

Kelvin (K) =The base SI unit of temp. equal to 1/273.16 of the triple point of water.

Triple point = The particular temp. and pressure at which the liquid, gaseous and solid phases of a substance can exist in equilibrium.

Heat capacity = the quantity of heat required to raise the temp. of a substance by one degree.

Specific heat = Heat capacity per unit mass of substance: the number of Btu required to raise the temp. of one pound of a substance 1 deg F, or the number of calories per gram per degree centigrade.

Latent heat = The quantity of heat absorbed or released by a substance during a change in phase at constant temp. and pressure.

Phase change = point at which a substance changes from a gas to liquid, liquid to gas, liquid to solid, also applies in reverse (caused by temp., no change in chemical composition)

Sensible heat = The quantity of heat absorbed or released by a substance during a change in temp. without a change in phase.