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In the United States, U-value is expressed as British thermal units (Btu) per hour-square feet-degrees Fahrenheit: Btu/(h⋅ft 2 ⋅°F) Within this article, U-values are expressed in SI unless otherwise noted. To convert from SI to US customary values, divide by 5.678. [2] [3] Most governments in several countries offer tax breaks or rebate to ...
Equivalence of direct radiation (EDR) is a standardized comparison method for estimating the output ability of space-heating radiators and convectors.. Measured in square feet, the reference standard for EDR is the mattress radiator [1] invented by Stephen J. Gold in the mid 19th century.
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)
U = Overall heat transfer coefficient in Btu/(ft2-hr-deg F) A = Area in square feet T1 = outdoor temperature in degrees F T2 = indoor temperature in degrees F For heat gains due to people, equipment (hooded and unhooded), and lighting
Btu per hour (Btu/h) is sometimes used in North America and the United Kingdom - the latter for air conditioning mainly, though "Btu/h" is sometimes abbreviated to just "Btu". [18] MBH—thousands of Btu per hour—is also common. [19] 1 W is approximately 3.412142 Btu/h [20] 1,000 Btu/h is approximately 0.2931 kW; 1 hp is approximately 2,544 Btu/h
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The unit is operated 120 days each year for 8 hours per day (960 hours per year), and the electric energy cost is $0.10 per kilowatt-hour. What is its annual cost of operation in terms of electric energy? First, we convert tons of cooling to BTU/h: (4 tons) × (12,000 (BTU/h)/ton) = 48,000 BTU/h. The annual cost of the electric energy is:
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