Manufactured Housing Duct Sealing Pilot - Independent Evaluation Results

Tom Eckhart, Howard Reichmuth, Jill SteinerRegional Technical ForumFebruary 3, 2009

Program Description Operated by UCONS, LLC from September 2005 to June 2006 Focused on sealing and repairing duct leaks in manufactured

homes with electric furnaces Provided other low-cost measures

Efficient showerheads and aerators Temperature reset on water heater Pipe insulation Compact fluorescent lights Furnace filter

Served 1,686 Snohomish customers – about 13% of manufactured homes with electric furnaces

Program Process

Pre-Treatment Duct

Pressurization Test and Visual

Inspection

Installation of Low-Cost

Measures

Post-Treatment Duct

Pressurization Test

B

C

A

Leve

l of D

uct T

reat

men

t as

Det

erm

ined

App

ropr

iate

Duct Sealing Protocols “A” sites – Ducts tested and sealed from the interior (boots, registers, end

caps). Cross-over duct are inspected and if determined to still be in good condition but air leaks were identified at the crossover duct connections to the collars, the collar connections to the main duct runs, or there were air leaks in the crossover duct that were repairable. The identified air leaks were sealed with mastic, and/or repairs were made to crossover duct as required. These were referred to as “exterior treatment of crossover ducts”.

“B” sites – Ducts tested and sealed from the interior (boots, registers, end caps). Cross-over duct inspected and if found to be damaged, would be replaced. Collars sealed with mastic, new R-8 crossover duct installed and crossover duct connections sealed with mastic.

“C” sites - Ducts tested and sealed from the interior (boots, registers, end caps). Cross-over duct would be inspected and if no air leaks were found, no further work would be conducted.

Expected SavingsMeasure Number

InstalledEst per unit savings kWh/yr

Percent of Homes Installed

Total kWh/yr savings

Low Flow showerhead

958 158 57.1% 151,364

Aerator 1876 60 111.7% 112,560

Temp reset, pipe wrap

915 360 54.5% 329,400

CFL 7978 33 475.2% 263,274

Floor insulation 270 2.4 16.1% 848

Furnace Filter 1167 70 69.5% 81,690

Duct inspect only “C”

581 830 482,462

Duct test/seal “A”

262 1044 273,580

Duct test/seal & Repair “B”

836 1151 962,236

Totals 1,679 2,657,215

Data Challenges

Bi-monthly billing data Sought 18-months pre- and post-data

Ideally, 2 years would be available for analysis For robust sample, included some sights with less than 18-

months post-data Of the 1,686 participants, analyzable data for 572

(~34%)

Methodology

Compared pre- and post-treatment consumption data Defined energy consumption as a function of average

outside temperatures for pre- and post-periods Calculated Normalized Annual Consumption (NAC) for

pre- and post-periods to determine normalized average savings

Energy Consumption Function

Model Fit

0

20

40

60

80

100

120

140

160

35 40 45 50 55 60 65 70 75

Mean Temperature, deg F

Ener

gy/d

ay, k

Wh

PreRejectModelPostRejectModel

Participant Pre- and Post-ConsumptionNormal Monthly Use

0

500

1000

1500

2000

2500

3000

jan feb mar apr may jun jul aug sep oct nov dec

Month

Elec

tric

Use,

kW

h/m

o

pre

post

Statistical Results

Sample Mean Savings kWh/yr

Std Dev N 95% Lower Bound

95% Upper Bound

Full Sample 1,463 2,631 572 1,247 1,679

A sites 1,369 2,469 168 993 1,745

B sites 1,717 2,709 321 1,419 2,014

C sites 671 2,500 83 126 1,218

>20,000 pre 2,673 3,372 169 2,161 3,186

Program Savings

Treatment Group Average Savings kWh/yr

Number of Sites in Program

Total Savings kWh/yr

A sites 1,369 262 358,678

B sites 1,717 836 1,435,412

C sites 671 581 389,851

Total Program 1,679 2,183,941

Summary Results

Total Number of Program Participants 1,679

Mean Savings per Participant 1,301 kWh/yr

Total Participant Savings, kWh/yr 2,183,941 kWh/yr

Savings as % of Average Participant Usage

8% based on analysis sample

Realization Rate of Projected Savings 82%

Savings by Treatment Group

0

200400

600

800

1,0001,200

1,400

1,6001,800

2,000

A sites B sites C sites

Annu

al kW

h Sa

vings

Realization Rates by Treatment Group

0%

20%

40%

60%

80%

100%

120%

A sites B sites C sites

Reali

zatio

n Ra

tes

Pre- and Post- Consumption

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

A B C

Treatment Category

Annu

al E

nerg

y U

se, k

Wh/

yr

pre

post

7.3%9.5% 3.8%

8% average savings overall 9.8% savings (> 2,600 kWh) for homes with pre-treatment consumption over 20,000 kWh

Savings DistributionNormalized Savings Distribution - blue is full sample,

red is participants with pre usage > 20,000 kWh/yr

0%

5%

10%

15%

20%

25%

-6500 -5500 -4500 -3500 -2500 -1500 -500 500 1500 2500 3500 4500 5500

Center of Savings Bin, kWh/yr

Frac

tion

of S

ampl

e

Program Cost-Effectiveness

Program Cost $800,000

PV Utility Benefits $2,000,291

PV Societal Benefits $2,217,253

UCT B/C 2.50

TRC B/C 2.77

Levelized Cost 3.7¢/kWh

Findings

Longer pre- and post-periods were needed to evaluate data because of bi-monthly billing cycles

More savings would have been realized with high-quality 2.0 GPM or less showerheads

Homes with greater than 20,000 kWh pre-treatment consumption yielded higher savings, but savings across all homes electric resistance central heat was significant and cost-effective

Questions? Comments?