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Although the concept of U-value (or U-factor) is universal, U-values can be expressed in different units. In most countries, U-value is expressed in SI units, as watts per square metre-kelvin: W/(m 2 ⋅K) In the United States, U-value is expressed as British thermal units (Btu) per hour-square feet-degrees Fahrenheit: Btu/(h⋅ft 2 ⋅°F)
The first of the cooling load factors used in this method is the CLTD, or the Cooling Load Temperature Difference. This factor is used to represent the temperature difference between indoor and outdoor air with the inclusion of the heating effects of solar radiation. [1] [5] The second factor is the CLF, or the cooling load factor.
The U-value is used to refer to the amount of heat that can pass through a window, called thermal transmittance, with a lower score being better. [1] The U-factor of a window can often be found on the rating label of the window. Although the concept of U-value (or U-factor) is universal, U-values can be expressed in different units.
Architects and engineers call the resulting values either the U-Value or the R-Value of a construction assembly like a wall. Each type of value (R or U) are related as the inverse of each other such that R-Value = 1/U-Value and both are more fully understood through the concept of an overall heat transfer coefficient described in lower section ...
Download as PDF; Printable version; ... move to sidebar hide. From Wikipedia, the free encyclopedia. Redirect page. Redirect to: R-value (insulation)#U-value ...
calorie (International Table) cal IT: ≡ 4.1868 J = 4.1868 J: calorie (mean) cal mean: 1 ⁄ 100 of the energy required to warm one gram of air-free water from 0 °C to 100 °C at a pressure of 1 atm ≈ 4.190 02 J: calorie (thermochemical) cal th: ≡ 4.184 J = 4.184 J: Calorie (US; FDA) Cal ≡ 1 kcal = 1000 cal = 4184 J: calorie (3.98 °C ...
The main idea of a per unit system is to absorb large differences in absolute values into base relationships. Thus, representations of elements in the system with per unit values become more uniform. A per-unit system provides units for power, voltage, current, impedance, and admittance. With the exception of impedance and admittance, any two ...
The Debye–Waller factor (DWF), named after Peter Debye and Ivar Waller, is used in condensed matter physics to describe the attenuation of x-ray scattering or coherent neutron scattering caused by thermal motion. [1] [2] It is also called the B factor, atomic B factor, or temperature factor.