THICKNESS is the dimension between two surfaces of an object, usually the dimension of smallest measure.
WEIGHT for energy analysis purposes, is measured in pounds per square foot of wall surface area, or lb/ft 2. In practice, the total wall weight is divided by the wall area to obtain the average wall weight. This weight is influenced by the wall construction and by the density of the materials in the wall.
Light Mass: Heat Capacity < 7 Btu/ft.²-°F
Medium Mass: Heat Capacity >= 7 and <15 Btu/ft.²-°F
Heavy Mass: Heat Capacity >= 15 Btu/ft²-°F
GROUT is a thin mortar used to fill cracks and crevices in masonry or cells of hollow units or spaces between wythes of solid unit masonry and increases the compressive, shear, and flexural strength of the masonry element. Grout is also used to bond steel reinforcement and masonry together.
U-FACTOR is the overall coefficient of thermal transmittance of a construction assembly, in Btu/(hr x ft² x ºF), including air film resistance at both surfaces.
C-FACTOR (also known as C-value) is the time rate of heat flow through unit area of a body induced by a unit temperature difference between the body surfaces, in Btu (hr. x ft.2 x °F). It is not the same as K-value or K-factor.
HEAT CAPACITY (HC) is the amount of heat necessary to raise the temperature of all the components of a unit area in an assembly by 1°F. It is calculated as the sum of the average thickness times the density times the specific heat for each component, and is expressed in Btu per square foot per °F.
R-VALUE (also known as thermal resistance) is the resistance of a material or building component to the passage of heat in (hr. x ft.² x ºF)/Btu.