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Mission Valley Power Energy Efficient Home ProgramDeemed Savings Analysis

August 5, 2008

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Background

• Mission Valley Power (MVP) request that the RTF review its specifications for a new residential construction program to establish a deemed savings value and cost-effectiveness

• MVP also provided an analysis of the potential savings from requiring R-10 full under slab insulation with an R-5 slab edge thermal break for RTF review and potential adoption as a deemed measure.

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MVP Deemed Savings Analysis – R-10 Full Slab w/R-5 Thermal Break

• Used WattSUN model w/Kalispell Weather• Assumed MT Code as baseline, then modeled full slab

insulation w/ thermal break (UA 549) vs UA 518)– Wall (Above Grade) = R-19– Wall (Below Grade) = R-11 (0.054 base/0.056 w/full slab)– Attic = R-38– Glazing = U- 0.35– Door = U-0.19– On grade slab – R-0 (F-0.73) & R-10 w/R-5 TB (F-0.36)– Below grade slab = R-0 (F-0.56) & R-10 w/R-5 TB (F-0.42)

• Savings = 1.5 kWh/sq.ft. of slab

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MVP Deemed Savings Analysis – Energy Efficient Home

• Used WattSUN model w/Kalispell Weather• Assumed MT Code as baseline, compared

to– EStar Home BOP 2 – MVP Home specifications

• Results– EStar Home BOP 2 = 32% savings– MVP Home = 36% savings

Savings Input Assumptions – Crawlspace Home, Zonal Electric

Component MT Code EStar BOP 2

MVP Home V. Crawl

MVP Home S. Crawl

MVP Home Slab only

MVP Home Basement

Floor R-21 R-30 N/A R-38 N/A R-38

Slab on grade R-13 per. N/A N/A N/A R-10 full R-10 full

Glazing U-0.35 U-0.30 U-0.32 U-0.32 U-0.35 U-0.32

Doors U-0.19 U-0.19 U-0.16 U-0.16 U-0.19 U-0.16

Wall (Above grade) R-21 Std R-23 Std R-26 Adv R-26 Adv R-21 Std R-26 Adv

Wall (Below grade)* R-11 Std R-23 Std N/A R-21 Adv R-11 Std R-21 Adv

Attic R-38 R-38 R-49 Adv R-49 Adv R-38 R-49 Adv

Infiltration 0.35 ach 0.20 ach w/HRV

0.30 ach w/o HRV

0.30 ach w/o HRV

0.35 ach 0.30 ach w/o HRV

Overall UA 543 474 387 483 502 461

*MT Code does not require below grade walls to be insulated until “finished.” EStar & MVP require R-21 insulation at time of construction.

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Issues

• Specifications – Perimeter insulation permitted in lieu of R-38 under floor (may not

produce equivalent energy savings)– Assumed duct leakage rate for forced-air systems not specified– MVP requires 25% of sockets w/EStar Lighting, EStar requires

50% - Net impact on savings not quantified in analysis– No HRV required, even though savings are claimed for reduce

infiltration

• Quality Assurance– Performance testing of ducts is not required – 0.30 ach Air tightness verified by random testing (same as EStar,

but EStar assumes 0.35 ach)

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Results of Review – R10 Full Slab

• SEEM Model used to estimate use and savings– Full R-10 Slab w/R-5 Thermal Break

• WattSun Savings = 1.5 kWh/sq.ft. slab (zonal electric)

• SEEM Savings = 1.0 kWh/sq.ft. slab (zonal electric)

• No Cost Data Yet to Determine Cost-Effectiveness

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Results of Review – MVP Home Savings

Case MT Code

EStar BOP 2

MVP Home V. Crawl

MVP Home S. Crawl

MVP Home Slab only

MVP Home Basement

Annual Use (kWh)

18710 13717 13787 17895 18268 15844

Savings over Code

- 4994 4923 816 443 2866

Percent Savings - 27% 26% 4% 2% 15%