Impacts of Static Pressure Set Level on the HVAC Energy Consumption and Indoor Conditions

摘要

Air static pressure must be maintained at acertain level leaving the air-handing unit (AHU) toforce a suitable amount of air through the terminalboxes. However, an excessive static pressure level isoften used due to ( 1 ) lack of a control device in aconstant volume system (CV); (2) malfunctioningcontrol device in a variable volume (VAV) system;and (3) fear of failure to maintain room temperature.High static pressure often develops excessive damperleakage in older mixing boxes. This results in aninappropriate mixing of hot and cold air and anexcessive amount of air entering the space.Consequently, the actual fan power, heating andcooling energy consumption all become significantlyhigher than the design values. Even worse, the systemmay not be able to maintain room conditions due tounwanted simultaneous heating and cooling, and maybe noisy due to the excessive static pressure. Thispaper proposes to control the hot duct pressure andthe Variable Frequency Drives ( VFD's) to controlthe fan static i.e. the cold duct pressure. Both atheoretical analysis and a case study results arepresented in this paper.