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2. Thermal transmittance - Wikipedia

   en.wikipedia.org/wiki/Thermal_transmittance

   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)

3. Surface power density - Wikipedia

   en.wikipedia.org/wiki/Surface_power_density

   where Pd is the power density in watts per square meter (one W/m 2 is equal to 0.1 mW/cm 2), H 2 = the square of the value of the magnetic field in amperes RMS squared per meter squared, E 2 = the square of the value of the electric field in volts RMS squared per meter squared. [6]

4. Cooling load temperature difference calculation method

   en.wikipedia.org/wiki/Cooling_load_temperature...

   These variables include, building material of the envelope, thicknesses of the building materials, day of the year, time of day, orientation of the surface (e.g. wall or roof, 90 degrees or 180), and wall face orientation (cardinal directions, i.e. N, NW, S, SE, etc.), to name a few.

5. Domestic roof construction - Wikipedia

   en.wikipedia.org/wiki/Domestic_roof_construction

   Building codes in the U.S. specify ventilation rates as a minimum of 1 sq ft (0.093 m 2) of opening per 150 sq ft (14 m 2) (1:150) with a ratio of 1:300 in some conditions. [8] Warm air rises, so ceiling insulation is designed to have a higher r-value and the insulation is often installed between the ceiling joists or rafters.

6. R-value (insulation) - Wikipedia

   en.wikipedia.org/wiki/R-value_(insulation)

   If the interior of a home is at 20 °C and the roof cavity is at 10 °C then the temperature difference is 10 °C (or 10 K). Assuming a ceiling insulated to RSI 2.0 (R = 2 m 2 ⋅K/W), energy will be lost at a rate of 10 K / (2 K⋅m 2 /W) = 5 watts for every square meter (W/m 2) of ceiling. The RSI-value used here is for the actual insulating ...

7. Roof pitch - Wikipedia

   en.wikipedia.org/wiki/Roof_pitch

   Roof pitch is the steepness of a roof expressed as a ratio of inch(es) rise per horizontal foot (or their metric equivalent), or as the angle in degrees its surface deviates from the horizontal. A flat roof has a pitch of zero in either instance; all other roofs are pitched .