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Mechanical insulation is used to cover pipes, ducts, tanks, and equipment in commercial or industrial environments and is typically relied upon to control temperature for a much broader range of temperature variances that that of a typical home. Home or residential insulation is typically found in the exterior walls and attics and is used to keep the home environment a consistent, comfortable living temperature. The temperature differential in a home insulation environment is in most cases far less than that of a typical commercial or industrial application. As an example, a typical home application may be to maintain an interior air temperature of 76°F against an exterior temperature of 10°F in the winter and 100°F in the summer. Thus the temperature differential could range between 24°F to 66°F. In many commercial and industrial applications, temperature differentials range from 20°F to 600°F or more. Mechanical insulation is primarily used to limit heat gain or loss from surfaces operating at temperatures above or below ambient temperature. The opportunities to limit that gain or loss are far greater in the commercial and industrial sectors versus the residential sector.
Temperature is a property unto itself. It is not a measurement of the amount of heat present. For example, if you pour two cups of coffee, one to the brim, and the other only halfway, the temperature will be the same in both cups, but the partially filled cup will only contain half the heat (Btus) of the full one. Mean Temperature is the average of the sum of a hot surface temperature and a cold surface temperature. Insulation conductivity (K-Factor) is tested at a number of mean temperatures to develop conductivity curves that simulate actual service conditions under which insulation systems are used. All conductivity figures (K, C, R) must be qualified by a mean temperature. Ambient Temperature is the average temperature of the medium, usually air, surrounding the object under consideration.
K-Factor (Thermal Conductivity Factor) : The measure of heat that pass through a unit area of a homogeneous substance, through a unit thickness, in a unit of time, for each unit temperature difference. The lower the k-value, the higher the insulating value. Note: I-P units are Btu – in / hr – ft2 - °F and typical SI units are Watts / m - °C. Textbook definition: The time rate of steady heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area. C-Factor (Thermal Conductance Factor): The time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces. R-Value (Thermal Resistance Value): A measure of the ability to retard heat flow rather than the ability to transmit heat. R-value is the numerical reciprocal of “U” or “C,” thus R = 1/U or 1/C. Thermal resistance R-value is used in combination with numerals to designate thermal resistance values: R-11 equals 11 resistance units. The higher the “R,” the higher the insulating value. The I-P units are °F – ft2 – hr / Btu; the SI units are °C – m2 / W.
An insulation energy appraisal puts actual dollar savings to Btu losses and calculates greenhouse gas emissions such as CO2, NOx and CE (Carbon Equivalent). An appraisal is based on data supplied by a plant/energy manager and gathered during a facility walk-through.