HVAC part 2-MANSUR.pptx - Energy Management in HVAC Systems Part 2 Heating Cooling Ventilation niversity of Jordan UJ Loads Outline • Introduction to

HVAC part 2-MANSUR.pptx - Energy Management in HVAC Systems...

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niversity of Jordan - UJ Energy Management in HVAC Systems Part 2: Heating, Cooling, & Ventilation Loads
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niversity of Jordan - UJ Outline Introduction to cooling, heating, and ventilation loads. Heating and cooling load calculations: People Solar radiation Conduction Lighting Air Ventilation requirements. Degree-days calculations.
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niversity of Jordan - UJ Introduction One of the easier ways to reduce costs in HVAC systems is to reduce the amount of energy that must be added to or extracted from an area to bring the area to the desired temperature range. Two major strategies for accomplishing this are available: (1) reduce the heating or cooling load ; (2) change the targeted temperature range. The amount of cooling needed in an area can be reduced by reducing the amount of heat brought into the area through the walls , by reducing the number of people present , by reducing the number of heat sources such as lighting , or by modifying the energy consumption characteristics of the industrial processes.
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niversity of Jordan - UJ Introduction The amount of heating needed can be reduced by increasing the amount of machinery located indoors, by capturing some of the heat from lights , by reducing infiltration of cold outside air , or by insulating roofs or ceilings so that less heat escapes. In any of these examples, the cooling or heating load is being changed. The second strategy is to change the temperature range that is considered to be desirable. This means changing the temperature limit above which air cooling occurs—the upper set point, and the temperature limit below which heating occurs—the lower set point.
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niversity of Jordan - UJ Introduction If heating does not start until the temperature is 12°C or lower, less heat will be used than if the threshold temperature for heating is 18°C. Similarly, an upper control limit of 30°C is more economical than a limit of 24°C. Changing these temperatures has the effect of changing the heating or cooling load imposed upon the HVAC system, although none of the heat sources are changed.
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niversity of Jordan - UJ Heating & Cooling Load Calculations The heating and cooling loads in a building occur because of: Heat given off by people Radiant energy from the sun that enters through windows, is absorbed by furniture, walls, and equipment, within the building, and is later radiated as heat within the building; Heat conducted through the building envelope (walls, roofs, floors, and windows) to or from the environment around the building; Waste heat given off by processes and machinery within the building; Heat given off by lighting; and Heat or cooling lost to ventilation or infiltration air.
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niversity of Jordan - UJ Heating & Cooling Load: People People give off heat, and the amount they give off depends on the type of work they are doing , the temperature of their surroundings , and whether they are men or women.
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