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This presentation discusses the calibration process and results of the AJLC Annex Sunroom Model in Oberlin, Ohio. The objective is to accurately predict the temperature of the sunroom based on building specifications, irradiance, and outside temperature. The presentation covers data collection, calibration methods, and validation results. Future research suggestions for improving the model are also provided.
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Calibration of the AJLC Annex Sunroom Model in Oberlin, Ohio Samina Ali, Kristin Braziunas, Lora DiFranco Systems Modeling Final Presentation Spring 2007
Background • AJLC Annex history • Original model by John Petersen & Alfredo Fernandez (AS5) • Focus on winter months • Building characteristics • Now that the sunroom is completed… • Test the model! • Temperature sensors
Objectives Main question: Does the current model correctly predict the temperature of a sunroom given building specifications, irradiance, and outside temperature? • Compare new and observed data • Calibrate & perform sensitivity analysis • Validate using April data • Sunroom as a heat source
SunRoom Air Temperature Slab Temperature Model Structure:Major Stocks and Flows
Assumptions • No solar gain through west- or east-facing windows • Trial and error • No interaction with the house • “door open” problem
Methods: Data Collection • 6 Temperature Sensors • 2 measure sunroom air temperature • 4 measure slab temperature
Methods: CalibrationMarch 2007 Initial run without variable changes Sunroom Air Temperature Difference Range: -30 to +35 degrees F
Methods: Calibration March 2007Initial run without variable changes Slab Temperature Difference Range: -23 to +57 degrees F “Upper” Slab Temperature used for calibration
Methods: Calibration March 2007Initial run without variable changes Sunroom Temperature, predicted by Upper Slab Temperature Difference Range: -27 to +10 degrees F Conclusion: problems in predicting slab temperature
Methods: Calibration Calibrating the Slab, Main Stocks and Flows • Values added • Solar Heat Gain Coefficient • Values to mess with • Diurnal Heat Capacity Slab • Solar Gain to Slab • Pct Solar to Slab • South Shading
Methods: Calibration Calibrating the Slab, Physical Characteristics • Values Added • Passive Solar Enhancement • “depth of slab”
Methods: Calibration March 2007 Calibrating the Slab Difference Range: -15 to +18 degrees F
Methods: Calibration March 2007Calibrating the Sunroom Air Difference Range: -25 to +24 degrees F, mostly due to outliers
Validation Results • April 1st – 5th: Heater Off • slab temperature Difference range: 2 to 14 deg F
April 1st – 5th: heater offSunroom temperature Difference range: -4 to 16 deg F
April 7th- 30th: Heater Onslab temperature Difference range: 5 to 21 deg F
April 7th- 30th: Heater Onsunroom temperature Difference range: -5 to 7 deg F • Noise: The days with the sunroom door open
Take home points • If predicted slab temp oscillation > actual slab temp oscillation, use dampening variables- - increase slab volume - decrease the inflow to the slab from the sun • West and East heat gain may not be very significant
Future Research • Heat exported into the house (ex – fan) • Standard model: Include east and west component for heat gain and loss • Increase Heat flow into the slab (ex- fan) • What if there are different kinds of thermal mass? - DHC - Volume - Position of the mass (trombe wall, water bed, water drums) • Plants in the sunroom - plant volume * plant conversion coefficient etc. • Improving the sunroom: South overhang, Reflectors
Future Audience • Future Systems Modeling students • Modelers, designers - to evaluate the performance of their sunrooms or greenhouses, using the standard model • Designers - to better design a sunroom before it has been built. We are the best calibration crew!!! EVER!