1 Residential Weatherization Calculator Deriving Realistic Savings Estimates for the “Uninsulated” House

2 What Is The Issue? All prior evaluations have measured “average” savings for the mix of ResWX measures installed in programs The “average” house already was partially weatherized Savings from the installation of individual measures has been estimated using engineering simulation models “calibrated” to an average package of measures.

3 Simulation Model Assumptions Historically, all “cost-effectiveness” analysis has held “consumer behavior” (i.e., thermostat set- point) constant across all thermal integrity levels –65 F weighted average set point 70 F – 8 hours/day 62 F – 16 hours/day This assumes that consumers in very poorly insulated homes would prefer to be just as comfortable as those in well insulated homes

4 Prior Modeling Assumption Justification Experience in the Hood River Conservation Project showed that once houses were “super-weatherized” consumers: –Stopped burning as much wood –Set up the thermostat on their electric heat BPA ResWX evaluations have shown that “net” savings increased over time as comparison group use “rebounded” after the rate increases of the early 1980’s dissipated If they can afford it, people will keep their homes warmer

5 Re-Calibration Process Compared Simulated Space Heating Use with Sub- metered Space Heating Use Sample – 617 SGC Homes w/Zonal Heat (Sample contains only sub-metered homes with space heating use of at least 1.0 kWh/sq/ft/yr.) Some homes had wood heat & used it Average Use = 3.48 kWh/sq.ft./yr Average Size = 1596 sq.ft. Weather – Portland & Seattle

6 Approach Fit Regression Line Through Sub-metered Use vs. Building Heat Loss Rate Adjusted SUNDAY Simulation Set-point Temperature, Thermal Mass and Internal Gains to Match “Heating Slope” of SGC Data Set

7 SGC Sub-metered Use vs. Building Heat Loss Rate

8 Simulations Results Compared to SGC Submetered Data – Total UA

9 Simulations Results Compared to SGC Submetered Data – UA/Sq.Ft.

10 Sample Results Zone sq.ft. Home w/Zonal Heat

11 Recommendation Use Standard Modeling Input Assumptions for purposes of determining “cost-effectiveness” Use “Modified” Modeling Input Assumptions for purposes of estimating “realizable” savings from weatherization –Thermostat set-point decreases by 0.1 F for every 15 Btu-F Increase in Heat Loss Rate for non-basement house and 0.15 F for homes with basements –3000 Btu/hr Internal Gains (Inefficient Appliances)