Residential Duct Insulation New Deemed Measure Proposal – A Second Look

Regional Technical Forum May 4 th , 2010

• • •

At the April RTF Meeting…

Look into the ETO’s evaluation numbers in more detail and determine whether/how the RTF should apply them Recommend changing a few assumptions, requirements – 75% of ducts in crawlspace, vs 90%; 150 square foot minimum duct area, vs 250.

Recommendation to run model with 50% duct insulated, 50% un-insulated Measure Duct Insulation (Existing <3/4" 100%, install R11)

Duct Insulation (Existing <3/4" 50% / R11 50%, install R11) Duct Insulation (Existing <3/4" 50% / R4.2 50%, install R11 on uninsulated)

Heating Zone 1 2 3

1 2 3 1 2 3

Measure Life (years) 18

18 18

Measure Cost Energy Savings Levelized Cost (kWh/yr) (mils/kWh) $662 805 1,542 2,236

401

7 -29 -41

7 $331 768 1,115 397 -29 -41 8 $331 761 1,104 -29 -41

B/C 1.7

3.2

4.7

1.7

3.2

4.7

1.7

3.2

4.7

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• • •

Another Look at ETO’s In-House Evaluation Numbers

Savings convert to about 400 kWh/year PTCS Duct Sealing was required, but may not have always occurred Median linear feet: 182 Number 1 2 2006-2007 ETO study Duct Sealing Duct Insulation Measure counts 388 285 3 4 5 6 Overlap Duct Insulate+duct sealing Only Duct Insulation Only Duct sealing Only Duct Seal + Duct insulate 191 9 31 13 3

Thoughts?

• • •

Is this Deemable?

–

Early sunset date with a required evaluation effort?

Savings metric?

–

Per house? Per linear foot? Other?

Savings Calculation?

–

Use 50/50 savings?

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Residential Duct Insulation New Deemed Measure Proposal

Regional Technical Forum April 6 th , 2010

Proposed Deemed Measures

Measure Flex Duct Replacement (Existing R4.2 or less; install R8) Duct Insulation (Existing <1.5", install R11) Duct Insulation (Existing <3/4", install R11) Heating Zone 1 2 3 1 2 3 1 2 3 Measure Life (years) 18 18 18 Measure Cost $839 $662 $662 Energy Levelized Savings Cost (kWh/yr) (mils/kWh) 155 423 297 431 212 189 109 216 404 587 805 1,542 2,236 81 34 7 -29 -41 B/C 0.3

0.5

0.7

0.4

0.9

1.2

1.7

3.2

4.7

• • • Savings and costs are “per house” Insulation of flex duct not allowed Cooling Zone 1 shown. Zones 2 and 3 are very similar (slightly larger savings) 6

• • • • • •

Savings Methodology & Inputs

SEEM Modeling 3 Site Built Prototypes (1344 ft 2 , 2200 ft 2 , 2688 ft 2 ) – 1344 and 2200 prototypes: supply ducts in crawl; return in attic – 2688 prototype: basement, so not included in final numbers Fully Weatherized (Package 8) with Sealed (PTCS) Ducts – Attic: R38, Floor: R30, Windows: u-0.30, Walls: R-13, ACH: 0.35

Modeled both electric FAF and Heat Pump – Heat Pump = 8.0 HSPF (HPA3) • Used the 5 baseline heat pump control strategies Duct Insulation Options – Flex Duct • Replace R-4.2 flex duct with R-8 flex duct – (R-11 flex duct was not analyzed because of high cost) – Hard Duct • Uninsulated (3/4” or less) to R-11 • R-4.2 (1.5” or less) to R-11 Used “True R-Values”, assuming round ducts & R-2.8/inch – Assumed R-2 for “uninsulated” ducts case 7

“True R-Values of Round Residential Ductwork”

Larry Palmiter and Erin Kruse, Ecotope, Inc. ACEEE Summer Study 2006 8

Prototype Small (1344) Medium (2200) Large (2688) Average Size (sqft)

More Inputs

Regional Mix 75% 16% 9% 1,602 Duct Insulation 82% 18% 0% 1,495 Foundation Area (ft2) 1344 1584 not used 1386 Modeled Duct Area (ft2) 290 380 not used 306 Important Assumption: Savings between Small and Medium prototypes varies by a factor of ~ 2.

Heat Pump FAF Heating System 80% 20% AC No AC Cooling System 80% 20% Nominal Duct Dia. (in) 6 8 14 18 Supply Duct in Unconditioned Space lin. Feet sq. feet 49% 32% 16% 3% 35% 31% 28% 6% Return Duct in Unconditioned Space lin. Feet sq. feet 0% 0% 100% 0% 0% 0% 100% 0% 9

Intermediate Savings Calculation Results

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ETO Impact Evaluation Results

• Equivalent kWh (assuming 80% gas efficiency): – ranges from 400 to 1050 kWh/year.

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• • Cost ($/house) ETO Bruce M.

Average

Measure Cost

Flex Duct Replacement R4.2 to R8 n/a $839 $839 Duct Insulation R4.2 to R11 $372 n/a R0 to R11 $601 $723 $662 $662 ETO Data – Based on 522 duct insulation jobs – All started at R-2 or lower • While it’s possible to calculate a cost for the R-4.2 to R 11 case ($372), it’s probably way too low. So, it was assumed to have the same cost as the uninsulated case (same installation cost, same R-11 batt) – Median Cost • $535 per job • $0.29/linear foot/∆ R-value – Median Job Size: 182 linear feet • Note on Savings – this compares well with what was modeled in SEEM (assuming 30% duct area in contact with floor or attic insulation) Bruce Manclark Data – Based on calls to installers – R8 flex duct = $4 - $5 per linear foot • includes removal/disposal of old, installation of new – R-11 on hard ducts: $1.50 to $1.65 per square foot of material • Material needed is 1.5 times uninsulated duct area $2,000 $1,500 $1,000 $500 $ $1.00 $0.75 $0.50 $0.25 $-

ETO Data

1 51 101 151 201 251 301 351 401 451 501

Job Number

1

ETO Data

51 101 151 201 251 301 351 401 451 501

Job Number

12

• • • •

Proposed Measure Requirements

Measure Definitions – Flex Duct Replacement • Existing supply flex duct shall be rated R-4.2 or lower. Replacement flex duct shall be rated R-8 or higher.

– Hard Duct: Existing <1.5” thick, install R-11 • Existing supply duct insulation shall be 1.5” thick or less. Supply and return ducts in unconditioned spaces shall be insulated to a nominal value of R-11 or higher.

– Hard Duct: Uninsulated (existing <3/4” thick), install R-11 • Existing supply ducts shall have less than 3/4” of insulation. Supply and return ducts in unconditioned spaces shall be insulated to a nominal value of R-11 or higher.

Measure Requirements – Only applies to houses where a significant portion of the supply ducts are located in a vented, unconditioned crawlspace or attic, or in an unconditioned garage. – Significant means: no less than 90% (by area) or 250 square feet, which ever is less.

– – – Ducts shall be sealed for air-leaks to PTCS standards prior to insulating.

Insulation installations shall follow the RTF’s Weatherization Specifications.

Flex duct installations shall follow manufacturer’s instructions.

Reporting Requirements – Crawlspace Foundation Area – House Square Footage – Amount of Insulation Installed • Length of flex duct • Total area of duct insulation – Project Cost Sunset Date – In 2 years, the measure savings will be re-visited by the RTF.

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• • • • •

How Should Savings be Reported?

By House + Simple, can’t get it wrong The assumed averages may not match what gets reported What about houses with some insulation already existing?

By House Square Footage + An attempt at normalizing House square footage doesn’t necessarily correspond to duct insulation area (two stories, basements, etc.) (Partial insulation?) By Foundation Area + Better normalization More complex; not intuitive; (partial insulation?) By Linear Feet of Duct + Even better normalization More complex; less intuitive; reporting errors are common Doesn’t take into account different duct sizes By Duct Area + Good normalization Difficult to determine and verify; complex The proposal is by House. Whole house, or nothing.

Discussion Encouraged, Implementers Should Also Discuss 14

Some More Things to Think About…

• • • Do we have adequate confidence to deem these measures?

– Modeling assumptions • Existing & replacement R-values don’t account for “real world” installations • House size and duct location both have a significant impact on the savings results – How should existing insulation levels be verified?

Should the measures be designed in a different way?

– – Higher insulation levels for colder climates?

More/less options for existing insulation levels/types?

Should the RTF attempt to deem additional duct-related measures?

– Duct Repairs (replacing damaged flex duct) – Duct Re-Design (to increase airflow for heat pumps) 15

Proposed Deemed Measures (again)

Measure Flex Duct Replacement (Existing R4.2 or less; install R8) Duct Insulation (Existing <1.5", install R11) Duct Insulation (Existing <3/4", install R11) • • • Heating Zone 1 2 3 1 2 3 1 2 3 Measure Life (years) 18 18 18 Measure Cost $839 $662 $662 Energy Levelized Savings Cost (kWh/yr) (mils/kWh) 155 423 297 431 212 189 109 216 404 587 805 1,542 2,236 81 34 7 -29 -41 Savings and costs are “per house” Insulation of flex duct not allowed Cooling Zone 1 shown. Zones 2 and 3 are very similar (slightly larger savings) B/C 0.3

0.5

0.7

0.4

0.9

1.2

1.7

3.2

4.7

Next Steps: Thoughts?

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