Manufactured Homes Calibration: Existing and New Homes Mohit Singh-Chhabra & Josh Rushton RTF Update May 12, 2015

Presentation Objectives Approve existing manufactured homes calibration based on comparative analysis with program data Review applicability of existing manufactured home comparison to New Construction based on comparison with reported billing analysis of NEEM homes 2

EXISTING MANUFACTURED HOMES CALIBRATION 3

MH Existing Homes Calibration Timeline August 2014: RTF approved MH Calibration (Phase I and II) December 2014: CAT presented Wx savings based on calibration – Savings values much lower than expected – RTF directed CAT to review calibration, compare with program data March 2015: CAT summarized available data and proposed subcommittee approved methodology for evaluating applicability of existing home calibration – RTF gave head-nod on proposed methodology May 2015 (Today): – Review results of calibration-program data comparison 4 – Existing MH Calibration

Two comparisons Phase I curve comparison: Compare existing RBSA-based calibration curve to pre-/post- program data Savings comparison: Compare calibrated savings estimates to actual program-billing data 5 – Existing MH Calibration

Phase I Curve: Review Phase I adjustments based on observed trend in differences between SEEM.69, VBDD SEEM.69 is heating kWh estimated by SEEM (given standardized inputs, such as 69/64 ⁰F day/night t-stat) VBDD is heating kWh estimated from billing data (via Variable-Base Degree-Day algorithm) – Data set portion of MH RBSA with good VBDD fits and no wood fireplaces, hot tubs, etc. (n=140) Weakness: RBSA not a pre-/post- data set! 6 – Existing MH Calibration

Phase I Curve: Review 7 – Existing MH Calibration Average SEEM.69 too low for more efficient homes Average SEEM.69 too high for less efficient homes MH RBSA Homes

Phase I Curve: Review 8 – Existing MH Calibration Savings calc. options Adjustment factors that change pre- /post- Adjustment factor(s) that don’t change pre-/post-

Phase I Comparison: Data Idea: Compare calibration curve to actual pre-/post- program data. Data: From Idaho Power weatherization programs Mix of Wx and equipment conversion measures First-cut sample: n = 106 homes with... – Complete pre-/post- audit data (with blower door and duct test results) – At least one full heating season pre- and post- Analysis sample: n = 85 homes… – Filtered to have “okay” VBDD fits pre and post – Not able to identify/filter out fireplaces, hot tubs, etc First step: Generate SEEM.69 and VBDD values for each site, pre- and post-weatherization 9 – Existing MH Calibration

Phase I Comparison: Average results using Idaho Power Data 10 – Existing MH Calibration Uncalibrated SEEM.69 Phase I calibrated SEEM Phase I & II calibrated SEEM* VBDD Heating kWh (Pre)16,51310,0839,0489,936 Heating kWh (Post)8,017 6,7196,0006,851 Difference8496 3,3643,0483,085 * Based on RBSA-typical levels of off-grid fuels. Probably reduces kWh estimates too much for okay-VBDD-fit sample.

Phase I Comparison: Confidence bands 11 – Existing MH Calibration (Alternative methods discussed in Additional Slides) Alternative 1: single calibration factor for each site, based on pre-conditions Alternative 2: single calibration factor for each site, based on post-conditions

Phase I Curve Comparison: Visual 12 – Existing MH Calibration Idaho Power SEEM.69 - VBDD differences, with Phase I curve from MH RBSA (Agree reasonably well) Phase I curve value ID Power homes, pre and post:

Phase I Curve Comparison: Visual 13 – Existing MH Calibration Idaho Power SEEM.69 - VBDD differences, after Phase I adjustment (No residual trend) ID Power homes, pre and post:

CAT Recommendation The current calibration is consistent with the pre-/post- program data shared by Idaho Power The alternative approaches we explored were found to have inconsistencies Staff recommends the RTF accept the current calibration for existing MH 14 – Existing MH Calibration

RTF Decision Slide “I _______ move that the RTF accept the current calibration for existing manufactured homes.” 15 – Existing MH Calibration

NEW HOMES CALIBRATION 16

New Construction Calibration Timeline August 2014: RTF approved MH Calibration (Phases I and II) October 2014: RTF directed staff to re-think the calibration for new construction – Do new construction home properties differ enough from existing to warrant a separate calibration? May 2015 (Today): – Review existing new construction manufactured homes calibration based on comparison with reported billing analysis of NEEM homes 17

New Construction: Data SEEM.69 models constructed as per NEEM spec and compared to billing data averages SEEM.69: NEEM specs provided basis for models – Note: NEEM specs do not cover all building properties required by SEEM MH calibration standardized inputs used for SEEM input fields not covered by NEEM specs Duct leakage and infiltration values from the 2006 NEEM MH study (Summary of 2006 NEEM MH: Field Data and Billing Analysis – Ecotope ) 18

New Construction: Data Contd. VBDD: Billing data studied for 78 homes across all 4 states in the same 2006 NEEM study – VBDD billing analysis results available for electric resistance and heat pump homes Authors of the report advised that the HP numbers may not be reliable 19

How does this compare to our existing curve? 20 Single SEEM model constructed with NEEM specs is used to generate all six data points across 3 heating zone and 2 heating system types A range of new construction efficiencies would provide better basis for comparison Although the new construction data points align well with existing calibration curve, we don’t have enough variety of data to conduct a good statistical comparison no pre post data possible for new construction measures

Staff Recommendation Insufficient data available to conduct reliable calibration – lack of data on homes with varying efficiencies to validate existing home calibration – Note: reliable calibration required to develop proven measures Final call for billing data; measures sunset next month! – More data analysis required before recommending proven for MH new construction measures In the absence of more data, staff will develop planning measures with a research strategy using existing MH calibration curve 21

BACKUP SLIDES 22

SEEM.69 Heating Energy Calculations Assumptions needed to generate SEEM.69 values for Idaho Power sample: Envelope (Component areas, U values) – Some parameters (e.g., effective R-value) vary somewhat from RBSA conventions HVAC system type. – Did not have exact efficiencies for Heat Pump. Assumed 8 HSPF heat pump Used standardized calibration inputs to fill in data gaps (same as with RBSA). Essential inputs included: – Internal gains – Occupancy – Thermostat set-points (69/64) 23 – Additional: Existing MH Calibration

VBDD Heating Energy Calculations Required minimum of 5 heating-season billing periods pre and post Most sites had significantly more – 91 of 106 had at least 8 pre and 8 post – 79 had at least 10 pre and 10 post Billing periods with at least 50 HDDs (under site-specific base) counted as “heating- season” 24 – Additional: Existing MH Calibration

Alternative Calibrations Alternative 1: For each site, calculate a single calibration factor based on pre-conditions; use this factor for both pre- and post- calibration – Overestimates savings in Idaho Power sample – 5,113 kWh versus 3,085 kWh from VBDD Alternative 2: For each site, calculate a single calibration factor based on pre-conditions; use this factor for both pre- and post- calibration. – Overestimates savings in Idaho Power sample – 7,462 kWh versus 3,085 kWh from VBDD Alternative 3: Use a single fixed calibration factor, (VBDD Savings)/(SEEM.69 Savings) = 3085/8496 = 0.363; apply to all sites, pre and post. – Yields savings that agree with VBDD exactly (by design) – Under-estimates both pre-kWh and post-kWh by about 4000 kWh 25– Additional: Existing MH Calibration

Existing Homes: Phase I Curve Comparison Starting point: Add new observations to this graph Use same filters as before Analysis to depend on what we see Is the existing trend consistent with program data? 26 Remember this?

New Construction: Note on Phase I Curve Comparison 27 Nothing compares, nothing compares… to pre-post NC points should fall somewhere in this region Would not be able to reproduce phase 1 filters for this. Only meaningful if SEEM input conventions consistent across types… – NC vs. RBSA points – Baseline NC vs. NEEM, etc. – Lots of assumptions here