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SEEM 94 Calibration to Single Family RBSA Data

SEEM 94 Calibration to Single Family RBSA Data. Regional Technical Forum January 23, 2013. Introduction. SEEM is used to estimate energy savings for most space-heating-effected residential UES measures Goal Ensure SEEM’s results are grounded in measured space heating energy use. Method

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SEEM 94 Calibration to Single Family RBSA Data

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  1. SEEM 94 Calibration to Single Family RBSA Data Regional Technical Forum January 23, 2013

  2. Introduction • SEEM is used to estimate energy savings for most space-heating-effected residential UES measures • Goal • Ensure SEEM’s results are grounded in measured space heating energy use. • Method • Run SEEM using characteristics data from billing analyses and/or metering reports to define inputs. • Compare SEEM’s heating energy use outputs to the reports’ findings. • Modify unknown characteristics data (usually T-stat setting) until a reasonable match is found. • Standardize the “calibration inputs” (from step 3) for use in RTF measure analyses.

  3. RTF Guidelines 3.3.3.2 Model Calibration In most cases, calibrated engineering procedures will involve at least one stage of modeling in which baseline and efficient case energy consumption are estimated for the measure-affected end use. For example, the heating load for single-family homes is estimated as part of the derivation of UES for ductless heat pump conversion. A simulation model is used to derive the heating end use for typical homes in different climate zones. Ideally, the model would be calibrated to measured heating end use for a sample of homes. If end use data are not available, the model should at least be calibrated to metered total use for the sample. Calibration should also be performed for samples that have adopted the measure, i.e., the efficient case. For measures that affect new buildings the calibration may be limited to the efficient case or to comparable buildings of recent vintage.

  4. History • 11/9/2009 • SEEM92 Single Family Calibration Approved • 70°F/64°F for Gas FAF and HP’s • 66°F for Electric FAF and Zonal • 12/13/2011 • RTF adopted SEEM 94 • Infiltration Calculation now physics-based (previously assumed at a steady rate) • SEEM94 Manufactured Home Calibration Approved • 69.4°F/61.9°F for all heating system types • 9/18/2012 • SEEM94 Multi-Family Calibration Approved • 68°F for walk-up and corridor buildings • 66°F for townhouses

  5. Data Sources • SF Data Sources used in previous calibration: • Data Source used in this calibration: • Underlying database** for the Single Family Residential Building Stock Assessment (2012) • RBSA study’s database offers recent billing analyses results and detailed house characteristics on 1404 houses in the Region. • This allows well-defined SEEM runs for each individual house. • *Sample size used in the calibration exercise (study sample size may have been larger). • ** Using a pre-release version of the database for this analysis .

  6. Non-Lighting Internal Gains • Equation: • Based loosely on Building America Benchmark* • Used the original equation and values (averaged) to determine average internal gains for RBSA homes. • Original equation also includes Number of Bedroom and Finished Floor Area terms • Set Number of Bedrooms and Finished Floor Area terms to zero and adjusted Number of People term to achieve same average internal gains for RBSA homes. • Building America Benchmark based on • “The appliance loads were derived by NREL from EnergyGuide labels, a Navigant analysis of typical models available on the market that meet current NAECA appliance standards, and several other studies. ” • “The general relationship between appliance loads, number of bedrooms, and house size, was derived empirically from the 2001 RECS. ” • *Hendron, Robert. "Building America Research Benchmark Definition, Updated December 20, 2007." NREL/USDOE EERE. January 2008. NREL/TP-550-42662

  7. Some Houses Unable (or unwilling) to Run with SEEM • Resulting House Count: 1011 • These issues overlap on some houses, so the sum of the counts cannot be subtracted from 1404 to get 1011.

  8. Data Filters • Gas Billing converted to kWh/year using reported AFUE • Resulting House Count: 289 • (The counts for each item overlap here, too)

  9. Results

  10. T-Stat Setting “Calibrated” to: • Electric Zonal and FAF based on results • Gas FAF and Heat Pump based on average from RBSA (n=1011 subset).

  11. Alternative Method • This is how the RTF has performed SEEM calibrations in the past • Results shown here for comparison; not intended to be used as part of calibration • Modeling each house is considered a better approach • Compare Averages: RBSA average billing data vs. SEEM runs with Average RBSA characteristics • Using only RBSA data from the report to define SEEM run characteristics for the 3 prototypes • Exception: Used database to determine how many R0 duct insulation cases had ducts inside • Note: Used T-stat setting per RBSA report • 68.7°F with 65% of homes using a setback to 62.2°F • Results…

  12. What are the Takeaways? • Key SEEM inputs RTF carries forward for future Single Family space heating modeling: • Tstat settings (see table) • Internal Gains Method • Non-lighting: Use modified equation with RBSA average # of people/house for each prototype • Lighting: Use RBSA average LPD & 1.5 hours/day • Baseline Ventilation • 2 hours/day at 50 cfm • Baseline Infiltration

  13. Remaining Issues • Wood/Other Heat • By ignoring the significant fraction of wood/other heated homes in this analysis, future RTF analyses will likely overstate the electric space heat savings. • From a cost-effectiveness perspective, this may be ok if we consider the value of wood/other fuels similar to the value of electricity. • From an electric savings perspective, it’s important to remember some fraction of the stated electric savings will actually be wood/other savings, not actual electric savings. • Unused Homes • By ignoring unused homes in this analysis, we have a similar issue as with wood/other heat (except there won't be wood/other savings in these cases).

  14. Some Options • Leave as is; note caveats regarding stated savings • Determine a “grid savings” and a “TRC savings” for each measure • Grid Savings • Savings would account for wood/other and unused houses. • This will take more work & discussion. • Used to report electric savings. • “TRC Savings” • Savings don’t include the effects of wood/other heat. • Savings would be based on the calibration presented today. • Used to report TRC • Value of electricity used as a proxy for value of wood/other heat

  15. Decision • Approve SEEM94 calibration for use in estimating space heating energy savings in single family homes.

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