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Assessment of Energy Savings from Proposed Revisions to Oregon Residential Specialty Code

Ben Larson 2 November 2010. Assessment of Energy Savings from Proposed Revisions to Oregon Residential Specialty Code. b en @ecotope.com 4056 9 th Avenue NE, Seattle, WA 98105 (206) 322- 3753. Background and Goals. Background:

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Assessment of Energy Savings from Proposed Revisions to Oregon Residential Specialty Code

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  1. Ben Larson 2 November 2010 Assessment of Energy Savings from Proposed Revisions to Oregon Residential Specialty Code ben@ecotope.com 4056 9th Avenue NE, Seattle, WA 98105 (206) 322-3753

  2. Background and Goals • Background: • New Oregon residential energy code proposal analysis. The OR-BCD has asked the RTF and Ecotope to produce a savings estimate. • Last Meeting: • Presented methodology • Goals Today: • Present analysis findings & recommendations • Obtain approval of predicted savings

  3. Oregon Residential Specialty Code • Code revision goal is to reduce whole-house energy use by 10% over the 2008 code. • Code covers single family detached and multi-family dwellings 3 stories or less.

  4. Modeling Steps • Determine representative characteristics of housing population including: • Climates • Single Family (SF) and Multifamily (MF) occupancies • HVAC systems • Prototype buildings • Compile base case and proposed code requirements • Calculate annual energy use for the representative housing population. End uses considered include: • Heating, Cooling, Ventilation, Lighting, and DHW • Weight calculation outputs together based on housing population data

  5. Review: Housing Characteristics Weightings

  6. Updated: Prototype Weightings • Single Family unchanged from 28 September: • 1344ft2 – Single story over crawl space • 2688ft2 – Like 1344, but over a conditioned basement • 2200ft2 – 1.5 story split level with garage and bonus room (over crawl) • Updated: Multifamily prototype is a single unit in an eight unit townhouse complex. • Prototype used in previous OR analysis (at least as early as 1990) • 952ft2 conditioned area per unit (stacked units, 4 on bottom, 4 on top) • Both slab-on-grade and crawl space modeled • Net result: 51 different house types resulting from combination of climates, prototypes, and heating systems.

  7. Oregon Code Proposal • Code proposal uses the existing core prescriptive requirements from 2008 • (but does add provision for heat pump aux heat outdoor temperature lockout) • The new code savings come from a revised set of additional measure tables. The code will require the selection of two measures. • The measures are divided into two categories with one measure being selected from each category. • Envelope Enhancement Measures (6 options) • Conservation Measures (7 options)

  8. A High efficiency HVAC system: • AFUE of 90% gas furnace • HSPF of 8.5 heat pump (SEER 13) • B Ducted HVAC systems within conditioned space • C Ductless heat pump: • DHP in primary zone with HSPF 8.5 (resistance heat allowed in secondary zones). • PTHP with comparable efficiency ratings (no supplemental zonal heaters installed in the building) and integrated backup resistant heat is allowed in a PTHP. • D High efficiency water heating & lighting: • Gas tankless EF of 0.80, and 75% CFLs • E Energy management device & duct sealing: • Performance tested duct systems , and 75% CFLs • F Solar photovoltaic: • Minimum 1 Watt / ft2 conditioned floor space • G Solar water heating: • Minimum of 40 ft2 of gross collector area • 1 High efficiency walls & windows: Exterior walls – U-0.047 / R-19+R-5 (sheathing) Windows-U-0.30   • 2 High efficiency envelope: Exterior walls – U-0.058 / R-21 Flat ceilings – U-0.025 / R-49 Framed floors – U-0.025 / R-38 Windows – U-0.30 Doors- All U-0.20, or Add’l 15% high-efficacy lamps • 3 High efficiency ceiling, windows & duct sealing: Flat ceilings – U-0.025 / R-49, and Windows-U-0.30, and Performance tested duct systems • 4 High efficiency thermal envelope UA: Proposed UA is 15% lower than the Code UA • 5 Building tightness testing, ventilation & duct sealing: A mechanical system providing ventilation rates specified in Table 1101.1(3), or ASHRAE 62.2. Blower door testing to 6.0 air changes per hour. Performance tested duct systems. • 6 Ducted HVAC systems within conditioned space

  9. Analysis Outputs • 43 possible combinations of additional measures (after excluded combinations removed) • 2394 independent simulation and calculation runs

  10. Measure Combinations Summary • The savings for each measure is a weighted sum of all the house types across the state • Analysis estimates of measure combinations: • 14 achieve 6-9% savings • 3 achieve 9-10% savings • 26 achieve 10-39% • high savings due to certain DHP measure combinations • without DHP, savings is 10-17% • Next slide shows the savings for each measure combination. Solar measures left off the table but are included in the overall analysis.

  11. *Excludes Solar Measures

  12. Sensitivity Analysis • In practice, housing market will be built with an uneven selection of these measure combinations • Therefore, the overall savings will be a set of the measure combinations. • Selection likely to be driven by cost and minimum perturbation to existing practices. Some emerging technologies, however, (DHPs, tankless & heat pump water heaters) may alter market dynamics. • Due to (obvious) lack of data of future market behavior, we conducted a sensitivity analysis examining different possible scenarios of measure combination selections

  13. Measure Selection Scenarios: • Equal – combinations selected with equal likelihood (not realistic) • HVAC – furnace, ducted heat pump, and ductless heat pumps upgrade options widely selected • DHW – tankless gas water heater preferentially selected • Middle– middle of the road scenario • Low – lowest (worst case) likely savings scenario where builders select options that save the least • All scenarios bounded by some constraints such as known population of ducted houses, basements, etc.

  14. Sensitivity Analysis Outputs

  15. Sensitivity Analysis Findings • The explored scenarios deliver a savings range from 8.8% to 10.5%. The middle scenario shows savings of 9.6% • A savings of at least 9.5% generally holds for other scenarios and combinations (not shown here) • Savings are still short of 10% target, but there is another source…

  16. Additions and Remodels • Proposed code changes include provisions for improving house addition and remodel energy performance. • 2008 version additions: • <400ft2 core requirements only • >400ft2 core requirements plus one additional measure (like new construction) • Proposed changes for additions: • <200ft2 core requirements only • 200-600ft2 core requirements plus one additional measure • >600ft2 core requirements plus two additional measures (like new construction) • Remodel changes not modeled but there are significant changes • Windows: U-0.65  U-0.35 • Doors: R-2  R-5 • Flat ceilings: R-38  R-49 • Slab perimeter: R10  R-15 • Underfloor: ≥2x10 Joist R-21R-30, ≤2x8 Joist R-21R-25

  17. Contribution of New Additions • Share of single family new construction based on floor area • Data from Construction Monitor for Clackamas, Columbia, Marion, Multnomah, Polk, Tillamook, Washington, and Yamhill Counties in 2009 • Additional permit activity not counted in table: remodels (1516), additions with no reported square footage (815), and change of occupancy (617). • There is an extensive set of possible combinations for constructing a code-compliant addition. The savings contribution will be small but likely not entirely insignificant.

  18. Savings from Additions & Remodels • An in-depth analysis not conducted because the population is small and extremely challenging to characterize • A general analysis suggests an additional 0.2-0.5% savings is possible from the most promising sources. • Includes the window upgrade for remodels and the effect of additions shown in the table below.

  19. Summary Findings • New construction from code proposal is likely to see a reduction in site energy use of 9-10% based on the sensitivity analysis of probable measure selection. • The proposals to improve performance of remodels and additions is likely to provide extra savings (~0.5%). • Decision: The probability the Oregon residential code proposal willrealize the 10% target is ? • A. Very probable • B. Reasonably probable • C. Highly improbable

  20. Backup Slides

  21. Possible Improvements • Envelope Measures 1-3: Window from U-0.30 to U-0.28 or U-0.25 • Furnace AFUE from 90 to 92 • House Infiltration in Envelope Measure 5 from 6ach50 to 5ach50

  22. Energy Use Calculations • Heating and Cooling with SEEM • Ventilation with SEEM and side calculations • Building tightness measure requires mechanical ventilation • Lighting based on LPD and 1.5 hr/day on time • DHW use based on average SF and MF occupancy of 2.5 and 1.8 people per unit respectively • Energy of hot water used is ~1150 kWh/yr/person (~22 gal/day) • MELs excluded from the analysis per OR BCD request

  23. Additional Measure Set 1 • 1 High efficiency walls & windows: Exterior walls – U-0.047 / R-19+5 (insulation sheathing) / SIPS, and Windows – Max 15% of conditioned area; or Windows-U-0.30   • 2 High efficiency envelope: Exterior walls – U-0.058 / R-21 Intermediate framing, and Vaulted ceilings – U-0.033 / R-30, and Flat ceilings – U-0.025 / R-49, and Framed floors – U-0.025 / R-38, and Windows – U-0.30; and Doors- All doors U-0.20, or Additional 15 percent of permanently installed lighting fixtures as high-efficacy lamps • 3 High efficiency ceiling, windows & duct sealing: (Cannot be used with Conservation Measure E) Vaulted ceilings – U-0.033 / R-30, and Flat ceilings – U-0.025 / R-49, and Windows-U-0.30 Windows- U-0.30, and Performance tested duct systems • 4 High efficiency thermal envelope UA: Proposed UA is 15% lower than the Code UA when calculated in Table N1104.1(1) • 5 Building tightness testing, ventilation & duct sealing: A mechanical exhaust, supply, or combination system providing whole-building ventilation rates specified in Table 1101.1(3), or ASHRAE 62.2, and The dwelling shall be tested with a blower door and found to exhibit no more than: 1. 6.0 air changes per hour, or 2. 5.0 air changes per hour when used with Conservation Measure E, and Performance tested duct systems   • 6 Ducted HVAC systems within conditioned space: (Cannot be used with Conservation Measure B or C) All ducts and air handler are contained within building envelope

  24. Additional Measure Set 2 • A High efficiency HVAC system: Gas-fired furnace or boiler with minimum AFUE of 90% a, or Air-source heat pump with minimum HSPF of 8.5 or Closed-loop ground source heat pump with minimum COP of 3.0 • B Ducted HVAC systems within conditioned space: All ducts and air handler are contained within building envelope • C Ductless heat pump: Replace electric resistance heating in at least the primary zone of dwelling with at least one ductless mini-split heat pump having a minimum HSPF of 8.5. Unit shall not have integrated backup resistance heat, and the unit (or units, if more than one is installed in the dwelling) shall be sized to have capacity to meet the entire dwelling design heat loss rate at outdoor design temperature condition. Conventional electric resistance heating may be provided for any secondary zones in the dwelling. A packaged terminal heat pump (PTHP) with comparable efficiency ratings may be used when no supplemental zonal heaters are installed in the building and integrated backup resistant heat is allowed in a PTHP. • D High efficiency water heating & lighting: Natural gas/propane, on-demand water heating with min EF of 0.80, and A minimum 75 percent of permanently installed lighting fixtures as CFL or linear fluorescent or a min efficacy of 40 lumens per Watt as specified in Section N1107.2 • E Energy management device & duct sealing: Whole building energy management device that is capable of monitoring or controlling energy consumption, and Performance tested duct systems, and A minimum 75 percent of permanently installed lighting fixtures as high-efficacy lamps • F Solar photovoltaic: Minimum1 Watt / ft2 conditioned floor space • G Solar water heating: Minimum of 40 ft2 of gross collector area

  25. Characteristics - Portland

  26. Characteristics - Redmond

  27. Characteristics - Medford

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