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 Compare new and observed data Calibrate & perform sensitivity analysis Validate using April data Sunroom as a heat source Main question: Does the current model correctly predict the temperature of a sunroom given building specifications, irradiance, and outside temperature?

Model Structure: Major Stocks and Flows SunRoom Air Temperature Slab Temperature

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: Calibration March 2007 Initial run without variable changes Sunroom Air Temperature Difference Range: -30 to +35 degrees F

“Upper” Slab Temperature used for calibration Methods: Calibration March 2007 Initial run without variable changes Slab Temperature Difference Range: -23 to +57 degrees F

Sunroom Temperature, predicted by Upper Slab Temperature Conclusion: problems in predicting slab temperature Methods: Calibration March 2007 Initial run without variable changes Difference Range: -27 to +10 degrees F

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 2007 Calibrating the Sunroom Air Difference Range: -25 to +24 degrees F, mostly due to outliers

Validation Results April 1 st – 5 th : Heater Off slab temperature Difference range: 2 to 14 deg F

April 1 st – 5 th : heater off Sunroom temperature Difference range: -4 to 16 deg F

April 7 th - 30 th : Heater On slab temperature Difference range: 5 to 21 deg F

April 7 th - 30 th : Heater On sunroom 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!