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NORA Advanced Efficiency

Typical Transmission Heat Loss Factors the region of the country. The Outdoor Design National Oilheat Research Alliance 39 Temperature is the temperature it will not be colder than for more than 2.5% of the time during the coldest month of the year for a specific location, so it is the average temperature on the coldest day of the year. Transmission Heat Loss, Insulation The transmission loss is the quantity of heat (Btuh) flowing through one square foot of wall, ceiling, floor, roof or glass for every degree temperature difference between inside and outside air. Transmission Heat Loss Factor is the rate of heat flow through the insulation and material that makes up the walls, ceilings, windows, and doors. To determine the Transmission Heat Loss, find the Surface Area (square feet) of all the surfaces in the building that separate the heated space from outdoors and the unheated spaces in the building. Multiply the square feet of surface area by the Heat Loss Factor for each surface. The heat loss factor is a number that describes how fast heat travels through the materials the walls, ceilings, and floors are made of. The next step is to multiply the answer by the Design Temperature Difference. The better the insulation, the smaller the factor and the slower the heat loss. This equals the Transmission Losses. Infiltration Loss—Air Leaks Infiltration Heat Loss Factors measure the energy required for heating the cold air that infiltrates in through the walls and cracks around windows and exterior doors. It is the number of times each hour that the total cubic feet Windows & Doors: Single pane glass—1.14 Double glass—0.65 Storm windows—0.56 Walls not insulated: Wood frame—0.24 Brick, cement—0.31 Walls insulated: 2" batts (R-7) —0.10 4" batts (R-11) —0.08 6" batts (R-19) —0.02 Ceiling: Uninsulated—0.30 2" batts—0.11 4" batts—0.07 6" batts—0.05 8" batts (R-28) —0.03 12" batts (R-40) —0.02 Cold Floor: Over cold basement Uninsulated —0.15 2" —0.05 4" —0.04 Vented Crawl space: Uninsulated— 0.36 2" —0.09 4" —0.06


NORA Advanced Efficiency
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