Manufactured Homes Calibration: Existing and New Homes Josh Rushton & Mohit Singh-Chhabra RTF Update...

Manufactured Homes Calibration: Existing and New Homes

Josh Rushton & Mohit Singh-ChhabraRTF Update

June 16, 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

Calibration Timeline, Existing MHs• August 2014: RTF approved MH Calibration (Phases I & 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

• June 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 bottom-line calibrated savings estimates to actual program-billing data

• Preview: Things look pretty good for weatherization in homes with electric-resistance heat. Heat pumps are a problem.


Phase I Curve: Review

• Phase I adjustments based trend in differences between SEEM.69 and VBDD that were observed in RBSA – SEEM.69: Heating kWh estimated by SEEM (given

standardized inputs, such as 69/64 ⁰F day/night t-stat)– VBDD: 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)

• Weak link: RBSA not a pre-/post- data set!


Phase I Curve: Review7 – 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: Review8 – Existing MH Calibration

Will the trend carry through pre/post?

Answer affects how saving estimates should use calibration:• Adjustment factors

that change pre-/post-

• Adjustment factor(s) that don’t change pre-/post-

• Something else?

MH RBSA Homes

Phase I Comparison: Data

Idea: Compare calibration curve to actual pre-/post- program data. Data: From 2011-12 Idaho Power (IDP) low-income weatherization assistance programs • Includes both Wx and heat pump conversion measures• Initial sample: n = 106 homes with...

– Complete pre-/post- audit data (with blower door 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 IDP site, pre- and post-weatherization


Apples to apples: SEEM inputs (1)

Many SEEM inputs come directly from IDP audit data…• Location (for climate)• Square footage (floor area as well as windows/doors/walls)• U-factors, pre and post, for each shell component

– Based on auditor estimates of nominal R-value and U-factor table from DOE Low-Income WAP

– Mapping from building characteristics to U-factors differs from that used in RBSA (and the SEEM calibration)• Some noticeable differences: For most vintage cohorts, pre-case IDP window- and door-U

somewhat higher, and ceiling-U somewhat lower, than in RBSA.• Little net difference: Uo values very similar between IDP pre-cases and RBSA (true for all

vintage cohorts up to mid-1990s; see additional slides)

• Infiltration, pre- and post, from blower-door tests – RBSA infiltration rates also based on blower door tests (values for homes w/o tests

were imputed based on values for homes with tests)• Equipment type (electric resistance furnace or heat pump)

– For SEEM HP parameters, used same efficiency levels (HSPF 7.9 / SEER 13.0), and same iterative sizing technique, as the calibration


Apples to apples: SEEM inputs (2)

Duct tightness inputs not taken directly from audit data• IDP data indicates some duct sealing activity for many sites

– Data not available for all sites– 69% of sites with complete entries indicate some form of duct sealing

• IDP entries for pre/post duct efficiency are based on visual inspection and a BPI table relating observable characteristics to efficiency levels– CAT didn’t use these reported efficiency values in SEEM inputs

• Values not likely to be consistent with measured leakage values in RBSA• For the record, reported efficiency levels averaged 62% (pre) and 87% (post)

– CAT’s analysis assumes 9% heating energy savings (based on Avista evaluation of prescriptive MH duct sealing program) for all homes that received duct sealing

• For SEEM inputs, used RBSA averages for duct tightness – Separate averages for pre-92 and post-92 homes (same as RBSA missing-value imputation) – Duct tightness inputs do not change pre/post– Post-case calibrated-SEEM values reduced by 0.69*0.09 = 6.2% to account for duct sealing.

• Detail: Reduced post-case uncalibrated SEEM until post-case calibrated SEEM was 6.2% lower • Result: Graphs below look exactly as they would if we’d found post-case duct leakage values that reduce

calibrated SEEM by 6.2%


0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%

(SEEM-VBDD)/SEEM (pre)

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30

(SEEM-VBDD)/SEEM (pre)

Initial Comparison: Phase 1 Trend12 – Existing MH Calibration

Differences SEEM.69 – VBDD for IDP sample versus trend captured in RBSA

Phase I curve values

SEEM.69/ft2

0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%

(SEEM-VBDD)/SEEM (post)

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30

(SEEM-VBDD)/SEEM (post)



All but two of these had HPs installed Phase I curve values

SEEM.69/ft2

0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%

(SEEM-VBDD)/SEEM (post) (SEEM-VBDD)/SEEM (pre)

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30




All but two of these had HPs installed

SEEM.69/ft2

0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%(Cal.SEEM-VBDD)/Cal.SEEM (post) (Cal.SEEM-VBDD)/Cal.SEEM (pre)

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30

(Cal.SEEM-VBDD)/Cal.SEEM (post) (Cal.SEEM-VBDD)/Cal.SEEM (pre)

Initial Comparison: Residuals15 – Existing MH Calibration

IDP differences SEEM.69 – VBDD after Phase I adjustment

• Mean difference much closer to zero for most x-value ranges.

• All but one of these had HPs installed

SEEM.69/ft2

Apples to apples: Phase II

“Calibrated SEEM” means Phase I and Phase II adjustments have been made. • All figures and graphs describe “okay-VBDD”

homes • For these homes, Phase II reduces electric

heating kWh by about 5.5%, pre and post• For unfiltered homes, the Phase-II adjustment

would be about twice as large.


Initial Comparison: Averages17 – Existing MH Calibration

85 “okay-VBDD” sites VBDDCalibrated

SEEM(RTF-

approved)

Constant-factor*

Calibrated SEEM**

Uncalibrated SEEM.69**

Heating kWh (Pre) 9,936 10,418 10,418 18,157

Heating kWh (Post) 6,851 6,463 5,224 9,065

Difference 3,085 3,956 5,194 9,091

* Constant-factor Calibrated SEEM applies the base-case Phase I adjustment factor to raw SEEM output pre and post.

** To account for duct sealing, Constant-factor Calibrated SEEM and Uncalibrated SEEM.69 both use SEEM.69*(1 - 0.062) for post-case SEEM output.

0

2,500

5,000

7,500

10,000

Ave

rage

sav

ings

(kW

h)

Initial Comparison: Averages18 – Existing MH Calibration

0

2,500

5,000

7,500

10,000

VBDD CalibratedSEEM

(approved)

Constant -factor

calibratedSEEM

UncalibratedSEEM

Aver

age

savi

ngs

(kW

h)

0

2,500

5,000

7,500

10,000

VBDD CalibratedSEEM

(approved)

Constant-factor cal.

SEEM

VBDD CalibratedSEEM

(approved)


SEEM

VBDD CalibratedSEEM

(approved)


SEEM

83 homes with base-case furnaces 47 Wx-only homes 37 HP-install homes

Estim

ated

sav

ings

(kW

h)

A Closer Look19 – Existing MH Calibration

Sites with ER heat pre and heat pump post (many have Wx measures in addition to HP conversion)

Sites with electric-resistance heat pre and post

Excludes 2 homes that had HPs prior to program participation

0

2,500

5,000

7,500

10,000

VBDD CalibratedSEEM

(approved)


SEEM

VBDD CalibratedSEEM

(approved)


SEEM

VBDD CalibratedSEEM

(approved)


SEEM


Estim

ated

sav

ings

(kW

h)





0

2,500

5,000

7,500

10,000

VBDD CalibratedSEEM

(approved)


SEEM

VBDD CalibratedSEEM

(approved)


SEEM

VBDD CalibratedSEEM

(approved)


SEEM


Estim

ated

sav

ings

(kW

h)





0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%


-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30


A closer look: Weatherization

Based on Wx-only portion of IDP sample…• Approved calibration

estimates savings about 9% lower than VBDD

• Difference is not statistically significant

• Approved Phase I trend looks reasonable against pre-/post- data


47 weatherization-only sites, pre and post

CAT Recommendation (part 1)

• Recommendation: Accept the current electric-resistance calibration for existing MH– Reasoning: Results are consistent with pre-/post-

Wx data shared by Idaho Power– Consequence: Would allow proven savings for

weatherization in homes with electric resistance heat

• Decisions on actual measures taken separately.


A Closer Look: Heat pump retrofits24 – Existing MH Calibration

0

5,000

10,000

15,000

20,000

pre

post

pre

post

UA x HDD.65 VBDD.ht.kWh UA x HDD.65 VBDD.ht.kWh

Wx-only sites HP-install sites

kWh

32% lower 28% lower


0

5,000

10,000

15,000

20,000

pre

post

pre

post

pre

post



kWh

32% lower 28% lower

30% lower

0

5,000

10,000

15,000

20,000

pre

post

pre

post

pre

post

pre

post



kWh


32% lower 28% lower

30% lower

32% lower ?!?

CAT Recommendation (part 2)• Recommendation: The RTF does not have reliable calibrated model

for estimating heating energy in manufactured homes with heat pumps. – Reasoning: IDP heat pump sample gives reason for doubt, but does not

provide sufficient insight for proven-worthy calibration• Provides little insight into HP savings in non-weatherized homes• May not generalize (it’s only 36 low-income sites in one program)

– Consequence: MH measures related to heat pumps (equipment conversion, duct sealing, and weatherization in homes with existing heat pumps) should become Planning measures. • Staff should develop a research strategy to improve consumption and savings

estimates for MH measures that are related to heat pumps• MH weatherization workbook should be split out into Proven measures (electric

resistance heat) and Planning measures (heat pumps), similar to single-family.

• Decisions on actual measures taken separately.


Decisions

“I, _______, move that the RTF’s currently approved calibration does reliably estimate heating energy and savings in manufactured homes with electric resistance heat.”

“I, _______, move that the RTF does not have a reliable calibrated model for estimating heating energy in manufactured homes with heat pumps.”


NEW HOMES CALIBRATION

29

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?• June 2015 (Today): – Review existing new construction manufactured homes

calibration based on comparison with reported billing analysis of NEEM homes

30 – New-Construction MH Calibration

New Construction: DataSEEM.69 models constructed as per NEEM spec and compared to average billing data• 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 )


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


How does this compare to our existing curve?


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

-150%

-100%

-50%

0%

50%

100%

150%

NEEM Electric Resistance NEEM Heat pump

-150%

-100%

-50%

0%

50%

100%

150%

NEEM Electric Resistance NEEM Heat pump

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 in

November!– 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

34

BACKUP SLIDES

35

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”

36 – Additional: Existing MH

0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%


Phase I Curve Comparison: Trend37 – Existing MH Calibration

Trend in the SEEM.69 - VBDD differences with pre/post data

Phase I curve value

ID Power homes, pre and post,

“okay-VBDD” sample

Wx-only sites:

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30


0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%

150%


Phase I Curve Comparison: Trend38 Additional: Existing MH

Phase I curve value



HP-install sites:

Trend in the SEEM.69 - VBDD differences with pre/post data

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30


0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%


Phase I Curve Comparison: Residuals39 Additional: Existing MH

Pre/post program data after Phase I adjustment



Wx-only sites:

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30


0 5 10 15 20 25 30

-150%

-100%

-50%

0%

50%

100%


Phase I Curve Comparison: Residuals40 – Existing MH Calibration

Pre/post program data after Phase I adjustment



HP-install sites:

-150%

-100%

-50%

0%

50%

100%

150%

0 5 10 15 20 25 30


pre

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

VBDD Calibrated SEEM

Constant-fac-tor Calibrated

VBDD Calibrated SEEM

Constant-fac-tor Calibrated

Wx-only (47 sites) HP-install (36 sites)

0

5,000

10,000

15,000

20,000

Estim

ated

hea

ting

kWh

0

5,000

10,000

15,000

20,000 p

re

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

pre

pos

t

VBDD CalibratedSEEM

Constant-factor

Calibrated

VBDD CalibratedSEEM

Constant-factor

Calibrated

Wx-only (47 sites) HP-install (36 sites)

Estim

ated

hea

ting

kWh

Consumption estimates, pre and post41 -- Additional: Existing MH

Comparing IDP and RBSA U-factors

• For each shell component, calculated RBSA averages by vintage cohort (pre-1977, 1977-85, 1986-92, 1993-99, post-1999)

• Compared to IDP pre-Wx values to check consistency between IDP and RBSA U-factor conventions

• IDP seems to be using higher U-factors for windows and doors, lower for ceilings, about right for Uo.

42 -- Additional: Existing MH

0.00

0.05

0.10

0.15

0.20

0.25

0.30

IDP Uo (pre) IDP Uo (RBSA cohort components)IDP Uo (post) 5 per. Mov. Avg. (IDP Uo (pre))

Comparing IDP and RBSA U-factors43 -- Additional: Existing MH

0.00

0.05

0.10

0.15

0.20

0.25

0.30

IDP Uo (pre) Moving average (IDP Uo (pre))IDP Uo (RBSA cohort components) IDP Uo (post)

Pre-case Uo values in the Idaho Power data set are similar to Uo values in the RBSA (see previous slide), and this is true of all vintage cohorts up to the mid-1990s.

A more detailed analysis found IDP window and door U-factors somewhat higher than RBSA figures (for most cohorts), and ceiling U-factors somewhat lower than those of the RBSA.

0.00

0.05

0.10

0.15

0.20

0.25

0.30

IDP Uo (pre) IDP Uo (RBSA cohort components)IDP Uo (post) 5 per. Mov. Avg. (IDP Uo (pre))

New Construction: Note on Phase I Curve Comparison

44 Additional: New Construction MH

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

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