1. REM as a Compliance Tool Infiltration Trade-off REMRate vs. SEEM February 19th, 2014 1

2. Presentation Objectives To approve REM Rate for use as a compliance tool with infiltration as a trade-off measure. o Infiltration has been tested for trade-off with heating system efficiency.  Most frequent request for trade off  Presented at July 2013 meeting; RTF concluded infiltration not ready for use in trade-offs and requested further analysis NW REM Rate has been approved for use as a compliance tool, allowing a rater to trade off or combine any number of measures to create a home that meets or beats the BOP home on annual energy use. The caveats that were applied during the initial approval: o No use of infiltration as a trade-off component. o No use of slab insulation as a trade-off component (so an R-60 passivehaus slab or an R-5 BOP slab both have to be modeled as BOP-level) o No specifying heat pumps above 9.0 hspf 2

3. Compliance Modeled home achieves equivalent or better energy performance than the reference design home o Reference design home is a home that meets the minimum standards for Energy Star. REM Rate qualifies as a compliance tool if it provides the same results as SEEM for compliance tests. o i.e. both tools agree on which trade-off scenarios provide compliance. 3

4. What is REM Rate? REM Rate – Seasonal proprietary modeling simulation tool designed for users trained in RESNET standards. “Northwest” REM Rate has been modified for closer alignment with SEEM outputs (see July presentation and decision) and Northwest ENERGY STAR Homes’ specific modeling guidelines. o No significant changes were made to REMRate’s engine since last RTF presentation 7/16/2013 o Analysis was expanded 4

5. Initial analysis/presentation Sensitivity Analysis 5

6. Initial analysis/presentation Sensitivity Analysis 6

7. Initial analysis and presentation CLEAResult team also analyzed 4 scenarios in which multiple trade-offs were applied, according to frequently requested/currently available options Envelope upgrade – improved walls and windows Wall/Ceiling U-value trade-off Ducts inside vs. wall U-value trade-off Infiltration vs. Heating efficiency Discrepancies in the Infiltration vs Heating efficiency trade-off prompted a request for further analysis 7

8. Current Analysis – REM Rate and SEEM Simulations Conducted. RTF prototype homes 1344 2688 (basement runs only) Two heating fuels/systems Gas furnace with AC Heat Pump Multiple foundation types Post + pier Vented crawlspace Slab on grade Conditioned basement Three climate locations: Boise Kalispell Seattle Two duct locations Attic Conditioned space 8

9. Scenarios Simulated: 9

10. REM Rate vs SEEM – Matching Inputs REM Rate allows user to assign ductwork to multiple locations. (half can be located in the attic and the other half the conditioned basement, for example.) For Conditioned basement runs, 50% of the supply and 50% of the return were allocated to the attic and conditioned space. So for the basement homes, we have models with the following duct locations: Conditioned space Conditioned space/Attic SEEM only allows one duct location for supply and one for return. For the SEEM runs, the “Conditioned space/Attic” duct location run results are an average of two identical runs: one with 100% of the ductwork in the Attic and one with 100% of the ductwork in Conditioned space 10

11. REM Rate & SEEM Matching Inputs (Contd.) REM Rate has an auto setback of 2 degrees. SEEM thermostat set-points and schedule were changed to match REM Rate inputs Set up temps as defined by calibration from May, 2013. Described here: Tstat setpoints HeatingCooling SEEMREMSEEMREM Set UpSetbackSet UpSetbackSet UpSetbackSet UpSetback IDBoise3 70.3 68.370.3Auto (-2F) 75.0 77.0 75.0 Auto (+2F) WASeattle3 70.3 68.370.3Auto (-2F) 75.0 77.0 75.0 Auto (+2F) MTKalispell3 67.0 65.067Auto (-2F) 75.0 77.0 75.0 Auto (+2F) 11

12. REM Rate & SEEM Matching Inputs (Contd.) REM Rate auto-calculates internal gains. SEEM internal gains inputs were adjusted to match REM Rate via HERS formulae. 12

13. Compliance Comparison Scenario are said to “Agree” when REM Rate and SEEM both indicate compliance or non-compliance for the same scenario. o Agreement for almost all HP scenario o 72 % of the Furnace scenario agree. 13

14. Compliance Comparison – Heat Pump The following scenario’s do not show agreement In each case, REM Rate estimates compliance; SEEM does not. o Difference in estimated heating energy consumption vary between 55 to 223 kWh. o This is manifestation of the difference in slope presented in slide 6. To get a complete understanding of agreement between HSPF and ACH trade-off, more scenarios need to be modeled. Staff recommend that REM Rate be used for HP trade-off for only those scenarios that show agreement with SEEM. 14

15. Compliance Comparison- Furnace. 17 of the 24 disagreements between REM Rate and SEEM are 3 ACH – 90 AFUE tradeoff. o Estimates of consumption between SEEM and REM Rate vary from 50 kWh and 160 kWh for this tradeoff. o No consistent pattern in difference in consumption. i.e. SEEM consumption not always higher than REM Rate, or vice-versa. o For 10 of the 24 disagreements, REM Rate shows no change in heating energy consumption (between baseline and scenario run); SEEM shows a potentially large change (~500 kWh). 15

16. Presenter Proposal We need to be able to allow Raters to use infiltration as a potential trade-off component as part of their analysis. We suggest a range of 1.5-5.0 ACH50. Heating system efficiency was used as the other trade off component because this is one of our more frequent requests. This was what was modeled as one of the “scenarios” for the original analysis 16

17. Staff Recommendation REM Rate be used for compliance only for those scenarios that show agreement with SEEM as per CLEAResult analysis reviewed by staff. As per slides 5 & 6, there is a difference in the way SEEM and REM Rate model infiltration. o No changes have been made to the infiltration engine since the last presentation. o This trend manifests itself in the comparison analysis conducted. 17

18. RTF Proposed Motion “I _________ move that the RTF: (Pick one) 1.Allow use of infiltration as a knob for all possible trade off for testing compliance. 2.Allow use of infiltration trade offs with heating efficiency for Heat Pumps and Furnaces for testing compliance. 3.Allow use of infiltration tradeoffs for Heat Pumps and Furnaces for only those cases that showed a compliance match with SEEM for testing compliance.” 18