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# Lec 8 - Principles of Heat Flow 1 There is a difference...

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Principles of Heat Flow 1. There is a difference between heat and temperature. 2. Heat flows from hot area toward the cold 3. Insulation slows down heat flow. R-value measure of resistance to heat flow. Quality insulation needed varies with climate. 4. Warm air holds more moisture than cold air. 5. Moisture vapor can move through building materials. Rot Timber Ruin some types of Insulation 6. Heat production must equal heat loss or the temperature changes. Heat Loss Q Bldg + Q vent = Q Pigs + Q Supp. Q Bldg = Ceiling + Walls + Floor + Foundation In uninsulated sidewall over 30% building heat loss is from floor + foundation. Often an area to be improved. In a well insulated building over 50% - up to 60-70% of the total heat loss is from the ventilation system. Q = Heat loss BTU = Area, ft 2 * Temp F 0 /R BTU hr/sow CFM/sow Humidity R10 R20 R30 20 67 1300 810 650 30 50 2220 1560 1400 40 40 2770 2320 2160 20 CFM/crate, 20 crates FIGURE 1 Example: 24' x 36' Farrowing House 12 crates A. Temperature difference 70 F° inside B. Building Heat Loss Ceiling (R=15) Walls (R=12) Foundation (R=1.33) Floor Perimeter (R=1.23) 3,500 BTUs/hr. 3,600 BTUs/hr. 10,800 BTUs/hr.

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