2021 Energy Code Notes

Last updated October 11, 2024
By Emma Howland

General Notes and Terms:

  • Variable Capacity Heat Pumps: new generation heat pumps are Variable (speeds) for energy efficiency and WA code is encouraging “cold climate”* heat pumps.
    • Heating and Cooling loads are decreasing in residential new construction because of better envelope construction. Most homes being built are now under 3 ton systems
    • VCHPs have lots of different options for distribution- (traditional ductless wall heads, 4-way cassettes(typ. commercial), flush mount one-way cassette (becoming more popular), slim/horizontal ducted system, and floor mount (typ. commercial)

Design Temps: Seattle/Bellevue/Tacoma/Edmonds => 24F (right on the cusp of cold climate heat pump requirement)

Kirkland/Redmond/Everett/Marysville/Kent =>23F (Cold Climate Heat pumps required)

Main Takeaways from Code Changes:

403.5.7- Heat pump water heating is becoming a requirement going forward in most homes, except ADU’s or Dwelling units under 1,000 SF

402.1.6 Insulation: Continuous exterior Rigid Foam may be required unless you can prove that your wall meets or exceeds the code through UA trade-off, alternative calculations (usually Advanced framing + high performance windows, raised heel trusses)

R402.1.3 Vertical fenestration U values are reduced– ex. Option 1.3 (Vertical Fenestration U = 0.28, Floor R-38, Slab on Grade R-10 perimeter…for 0.5 credits is now 1.2 U=0.25, Floor R-38, Slab on grade R-10 perimeter for 1 credit)

Option 2- Air Leakage control and Efficient Ventilation Options

  • Option 2.1 (formerly 2.2, former 2.1 was removed) 2.0 ACH @ 50pascals

Option 3: High Efficiency Heating/Cooling System

Option 3.3: Central heat pump 9.6 HSPF- design temps at or less than 23 degrees require NEEP certified cold-climate VCHP

Option 3.5: 10 HSPF min. ductless mini split and electric resistance (most cost-effective)

Option 3.6: 11 HSPF min. heat pump or 10 HSPF NEEP cold-climate VCHP

Option 3.7: 10 HSPF min. Ductless split system with no supplemental heating, or for small homes/ townhomes with heating loads at or under 24,000 BTUs, 9 HSPF min.

Option 3.11: .5 energy credits available for using ENERGY STAR smart thermostat, which is great for a lower efficiency heat system like gas furnace/ one or two speed heatpump, but newer VCHPs do not function better with smart thermostats.

  • Northeast Energy Efficiency Partnerships: NEEPS Cold Climate air source Heat Pump List
    • know that not all cold-climate heat pumps that are NEEP certified do not need supplemental heating

Option 4: High Efficiency HVAC Distribution

  • Option 4.1 is removed- all ductwork must be in conditioned space in order to claim 0.5 credits

Option 5: Efficient Water Heating Options

  • NEEA Tier I Heat pump Water Heater no longer an option- Option 5.6 Electric water heater meets Tier III – 2 credit points
  • New Compact Water system (min. 1.5 bathrooms)- Option 5.2: Easy option for small homes/ townhomes

Option 6 Renewable Energy Option:

  • Solar- you can get .5 credit for 600 kWh instead of 1 credit for 1200 kWh

Option 7: Appliance Package

  • Code no longer specifies ventless ENERGY STAR dryer (but pretty much every dryer on the required list are ventless…)

Townhome considerations:

  • cost-effective options for limited footprints:
    • Option 3.5- mini split in living area, mini split in main bedroom, then electric resistance in other rooms. (1.5 credits + 2.0 Fuel normalization)
    • Compact water system (0.5 credits)
    • 600 watts for solar panels is probably 2 panels, so it’s more incentive to use this credit on smaller projects (0.5 credits)