Single Family New Construction Measure: Slab Insulation Mohit Singh-Chhabra Regional Technical Forum April 19 th, 2016

Overview Today, we are seeking from the RTF: Change the Measure Category to Small Saver Approve the updated analysis, energy savings estimates for this measure 2

Measure Overview Measure DevelopersMohit Singh- Chhabra CAT ReviewReviewed with CAT Tech Sub-Com ReviewNo R&E Sub-Com ReviewNo Notes Measure being updated to reflect new MT building energy codes Measure only applies to Heating Zone 3, Montana Per Mission Valley Power (MVP), 34 total homes with a combined slab insulated area of 47,860 square feet from As per CAT prelim. research only MVP offers this measure; measure not included in BPA measure list Measure being updated as MT state code was updated; now using IECC 2012 with modifications 3

Measure Background Measure Name:Res. New Construction Slab Insulation Current Measure Category: Proven Proposed Measure Category: Small Saver Current Measure Status:Active Proposed Measure Status:Active Measure Sector:Residential End Use:Whole Building Current Sunset Date:December,

Measure is Proposed as Small Saver Measure applies to MT – HZ3 only Technical potential for annual (first year) savings is approx. 0.1 aMW; this implies 2 aMW over the next 20 years in first year savings – Based on (1) Council projections for SF NC in MT, (2) population distribution among HZ, (3) distribution of gas and electric homes in MT, (4) average measure savings, and (5) the assumption that all new SF homes qualify for the measure Alternatively, if RTF requests Proven measures, the HP measure applications will have to be developed as Planning. This is because of knowledge gap in baseline CC&S practices – Research Strategy for CC&S and affected measures already developed 5

Current Montana Code for Slab Insulation If foundation is slab-on-grade, and slab is less than 12 inches below grade: – Code requires R-10 slab insulation on perimeter – Insulation needs to extend 4 ft. by any combination of vertical and horizontal placement (see next slide for illustration) 1 If slab is greater than 12 inches below grade (e.g. full basement), no slab insulation is required – Code does specify basement wall insulation level at U value of 0.05 (~ R20) 6 1 Applies to slabs without in-floor heat. Heated slabs required R-15 slab insulation by MT code.

Current Montana Code for Slab Insulation (continued) 7 Slab-On-Grade Code Options Vertical caseHorizontal case Combination horizontal and vertical case

Baseline and Efficient Cases Modeled Slab homes: Baseline (Code): Edge insulation R10, 4 ft (horizontal and vertical) Efficient Case: Continuous R10 under slab, R5 thermal break at the edges Basement Homes Baseline (Code): Basement walls insulated per code Efficient Case: Continuous R10 under slab in addition to basement walls insulated per code 8

Updates Made to the Measure Although MT building codes updated to IECC 2012, MT amendments to IECC undo most updates. Significant changes include: – Reduced max. allowable infiltration (6  4 ACH50) – Reduced window U value (U33  U31) Overall effect is lower consumption and less savings to be had (for most measures) 9

Annual Energy Savings (kWh/ s.f.) Comparison 10

Incremental Cost: No Change Incremental cost is $0.90 / s.f. in 2012$ – Based on correspondence from Lyle Neiss, Mission Valley Power Lyle Neiss confirmed that they are still seeing similar incremental cost – CAT back of the envelope calculation using insulation costs per internet search (Home Depot) produced costs in a similar range 11

Regional Benefit Cost Analysis Test Results 12

Proposed Motion “ I, _________, propose that the RTF adopt New Construction Slab Insulation measure analysis and set: Change Measure Status to Small Saver Keep Measure Category as Active Sunset Date to April, 2019” 13