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AHU 1Chris TriggChris TriggJune 3, 2009System OverviewSource: Haak and Maile, ‘Data Manual for Stanford’s Y2E2 Building’, 2009Data Summary: AHU1 was studied for the month of April with particular at tention paid to temperature sensors, valve positions as well as pressure and flow interactionsas well as pressure and flow interactions.Number219 221 222 1107 1108NameCool Coil Valve PositionBypass Valve PositionHeating Coil Valve PositionSupply Flow Supply PressureUnit%%%cfmin wcLocationAHU 1 AHU 1 AHU 1 AHU 1 AHU 1Count39272 39268 39284 39278 39276Min0 0 0 18739 15Max68 100 26 34651 21Avg7.70 83.50 3.27 26023.66 17.00Std17.95 37.12 6.37 4609.63 0.15CoV2.33 0.44 1.95 0.18 0.01First4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00Last4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59ClassificationSys Response Sys Response Sys Response Func. Setpoint Func. SetpointNumber1110 1123 1128 1105 1106NameSupply Temp Outdoor Temp Exhaust (Building) TempHR Exit Exhaust TempHR Supply TempUnitºF ºF ºF ºF ºFLocationAHU 1OutdoorsInteriorHR UnitHR UnitLocationAHU 1OutdoorsInteriorHR UnitHR UnitCount39275 39281 39284 39284 39279Min53.1 37.8 69 49.5 50.9Max70.6 93.4 74.7 84.5 83.8Avg65.96 56.42 70.94 62.04 62.60Std1.77 10.93 1.14 6.94 5.84CoV0.03 0.19 0.02 0.11 0.09First4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00 4/1/2009 0:00Last4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59 4/30/2009 23:59ClassificationFunc. Setpoint Exogeneous Outcome Behv. Outcome Behv. Func. SetpointFunctional Requirements‐ Temperature setpoint (65F) is the same over the entire month. Daily temps were approximately +/‐25F of setpointof setpoint.901008090Outdoor 70mp (F)Setpoint60Tem4050304/1/2009 0:00 4/6/2009 0:00 4/11/2009 0:00 4/16/2009 0:00 4/21/2009 0:00 4/26/2009 0:00 5/1/2009 0:00Functional Requirement ‐ Supply pressure , while not given, has assumed setpoint of 17 in wc. Flow varies between occupied (≈30,000 cfm) and unoccupied (≈20 000 cfm)35000unoccupied (≈20,000 cfm).310003300022242700029000fm)1820in wc)Fl2300025000Flow (cf16Pressure (FlowPressure19000210001214170004/21/2009 0:00 4/22/2009 0:00 4/23/2009 0:00 4/24/2009 0:00 4/25/2009 0:00 4/26/2009 0:00 4/27/2009 0:00 4/28/2009 0:0010System Response‐ Pressure deviates from assumed setpoint for 3‐7 minutes in response to changes in flow from occupied to unoccupied modemode.35000310003300022242700029000fm)1820in wc)Fl2300025000Flow (cf16Pressure (FlowPressure19000210001214170004/21/2009 0:00 4/22/2009 0:00 4/23/2009 0:00 4/24/2009 0:00 4/25/2009 0:00 4/26/2009 0:00 4/27/2009 0:00 4/28/2009 0:0010System Response‐ Cooling coil valves open when outdoor temp > 65 degrees (setpoint and heating coil valves when outdoor > 55 degrees . The valves are never simultaneously open and valve position isThe valves are never simultaneously open, and valve position is proportional to magnitude of temperature difference.90100 100708090905060Position (%)7080emp (F)Cool CoilHeating CoilOutside Temp3040Valve P60TeOutside TempSet10205004/21/2009 0:00 4/22/2009 0:00 4/23/2009 0:00 4/24/2009 0:00 4/25/2009 0:00 4/26/2009 0:00 4/27/2009 0:00 4/28/2009 0:0040System Response‐ Heating coil valves are only at appropriate times, however they fluctuate open/closed rapidly in small time increments.6070Setpoint T50(%)Outdoor T40d Valve Position 2030Temp (F) andHeat Coil Valve Position1004/3/2009 0:00 4/3/2009 2:24 4/3/2009 4:48 4/3/2009 7:12 4/3/2009 9:36 4/3/2009 12:00 4/3/2009 14:24 4/3/2009 16:48 4/3/2009 19:12 4/3/2009 21:36 4/4/2009 0:00701System Response‐ HR unit operates in coordination with heating and cooling coils.60700.91HR HeatingHR Cooling500.70.8Cooling Coil Valve Position40e Position (%)0.50.6On/Off2030Valve0.30.4Heating Coil Valve Position100.10.204/6/20090:004/6/20092:244/6/20094:484/6/20097:124/6/20099:364/6/200912:004/6/200914:244/6/200916:484/6/200919:124/6/200921:364/7/20090:000System Performance‐ Supply temp varies +/‐ 5F from setpoint. Days with outdoor temps significantly higher than setpoint show larger daily range of supply temp (often with temps > 5F below setpoint) from large100of supply temp (often with temps > 5F below setpoint) from large cooling load.8090Outdoor T70p (F)Setpoint TSupply T60Temp4050303/30/2009 0:00 4/4/2009 0:00 4/9/2009 0:00 4/14/2009 0:00 4/19/2009 0:00 4/24/2009 0:00 4/29/2009 0:00Recommendations –(In ref erence to previous plots)Proper ResponseAir supply flow and pressure show proper correlation and operate at or near the assumed setpoints.Cool coil valve is operating properly both in terms of when it is open and closed and the magnitude of its position.HR Unit operates in coordination with the heating and cooling coils.Improper ResponseHeating coil valves, while operating correctly in response to theHeating coil valves, while operating correctly in response to the outdoor air temp, fluctuate on and off over small timescales when a sustained opening would be expected. Facilities should check and repair any problems for smoother operation of the valveany problems for smoother operation of the valve.Measured and Simulated Data Comparison Common IssuesSetpoints in all offices fluctuate throughout the day in the simulations but are measured as constant. Potential occupant behavior issue.Supply temperature to the active chilled beam hot/cold water loops and radiative heater hot water loops significantly different (up to 5‐40 degrees) between simulations and measured datadegrees) between simulations and measured data. Measured (blue) vs Simulated (purple)666870145 SpaceTempSetpoint [Degrees F]145 Zone/Sys Thermostat Heating SetpointGenerally similar trends in space temperatures, although typically off by 35 degrees6264Unittypically off by 3‐5 degrees.58604/5/20090:004/6/20090:004/7/20090:004/8/20090:004/9/20090:004/10/20090:004/11/20090:004/12/20090:004/13/20090:004/14/20090:00Time StepBIM GuideModelExterior Walls (Revit and E+)Wall‐linked Windows and Doors (Revit and E+)Walllinked Windows and Doors (Revit and E+)Roof and Ceilings (Revit and E+)Shading Devices (E+ some difficulty in interface transfer from Revit)Shading Devices (E+, some difficulty in interface transfer from Revit)Tagged Spaces with Type (Revit and E+)2ndLevel Space Boundaries (E+)HVAC Equipment/Configuration (E+)BIM ModelRules1. Utilize the data’s granularity. Trends over a period of minutes often point to problems while encompassing longer trends can be


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Stanford CEE 243 - Lecture Notes

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