ENERGY 1-BLDG 1-Multifamily Prescriptive Worksheet 2018_BLDG 12018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 1
Project Information Contact Information
Instructions: This multifamily project will use the requirements of the Prescriptive Path below and
incorporate the minimum values listed. Based on the size of the structure, the appropriate number of
additional credits are checked as chosen by the permit applicant.
Authorized Representative Date
a
R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity that is less
than the label or design thickness of the insulation, the compresse d R-value of the insulation from Appendix Table
A101.4 shall not be less than the R-value specified in the table.
b The fenestration U-factor column excludes skylights.
c
"10/15/21 +5TB" means R-10 continuous insulation on the exterior of the wall, or R-15 continuous insulation on
the interior of the wall, or R-21 cavity insulation plus a thermal break between the slab and the basement wall at
the interior of the basement wall. "10/15/21 +5TB" shall be permitted to be met with R-13 cavity insulation on the
interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the wall. "5TB" means R-
5 thermal break between floor slab and basement wall.
d R-10 continuous insulation is required under heated slab on grade floors. See Section R402.2.9.1.
e For single rafter- or joist-vaulted ceilings, the insulation may be reduced to R-38 if the full insulation depth extends
over the top plate of the exterior wall.
f
R-7.5 continuous insulation installed over an existing slab is deemed to be equivalent to the required perimeter
slab insulation when applied to existing slabs complying with Section R503.1.1. If foam plastic is used, it shall meet
the requirements for thermal barriers protecting foam plastics.
g For log structures developed in compliance with Standard ICC 400, log walls shall meet the requirements for
climate zone 5 of ICC 400.
h
Int. (intermediate framing) denotes framing and insulation as described in Section A103.2.2 including standard
framing 16 inches on center, 78% of the wall cavity insulated and headers insulated with a minimum of R-10
insulation.
All Climate Zones (Table R402.1.1)
R-Value a U-Factor a
Fenestration U-Factor b n/a 0.30
Skylight U-Factor b n/a 0.50
Glazed Fenestration SHGC b,e
Provide all information from the following tables as building permit drawings: Table R402.1 - Insulation and
Fenestration Requirements by Component, Table R406.2 - Fuel Normalization Credits and 406.3 - Energy Credits.
Multifamily (effective February 1, 2021)
These requirements apply to Group R-2 buildings three stories or less in height above grade plane.
Other Group R-2 buildings must comply with the commercial energy code.
n/a n/a
Ceiling e 49 0.026
W ood Frame W all g,h 21 int 0.056
Floor 30 0.029
Below Grade W all c,h 10/15/21 int + TB 0.042
Slab d,f R-Value & Depth 10, 2 ft n/a
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Multifamily R2 Dw elling Unit: 4.5 credits
Before selecting your credits on this Summary table, review the details in Table 406.3 (Multifamily), on page 3.
Summary (Table R406.2)
Heating
Options Fuel Normalization Descriptions Credits - select ONE
heating option User Notes
1 Combustion heating minimum NAECAb 0.0
3 Electric resistance heat only - furnace or zonal -1.0
4 DHP with zonal electric resistance per option 3.4 na
5 All other heating systems -0.5
Energy
Options Energy Credit Option Descriptions
Credits - select ONE
energy option from each
category d
1.1 Efficient Building Envelope 0.5
1.2 Efficient Building Envelope 1.0
1.4 Efficient Building Envelope 1.0
1.5 Efficient Building Envelope 1.5
1.6 Efficient Building Envelope 2.0
1.7 Efficient Building Envelope 0.5
2.1 Air Leakage Control and Efficient Ventilation 1.0
2.2 Air Leakage Control and Efficient Ventilation 1.5
2.3 Air Leakage Control and Efficient Ventilation 2.0
2.4 Air Leakage Control and Efficient Ventilation 2.5
3.3a High Efficiency HVAC 1.0
3.4 High Efficiency HVAC 2.0
3.6a High Efficiency HVAC 3.0
4.1 High Efficiency HVAC Distribution System 0.5
5.1d Efficient Water Heating 0.5
5.2 Efficient Water Heating 0.5
5.3 Efficient Water Heating 1.0
5.4 Efficient Water Heating 2.0
5.5 Efficient Water Heating 2.5
5.6 Efficient Water Heating 3.0
6. 1e Renewable Electric Energy (3 credits max) 1.0
7.1 Appliance Package 1.5
Total Credits
a. An alternative heating source sized at a maximum of 0.5 W/sf (equivalent) of heated floor area or 500 W,
whichever is bigger, may be installed in the dwelling unit.
b. Equipment listed in Table C403.3.2(4) or C403.3.2(5)
with options 5.2 through 5.6. See Table 406.3.
e. 1.0 credit for each 1,200 kWh of electrical generation provided annually, up to 3 credits max. See Table R406.2 for
full requirements and complete option descriptions.
Prescriptive Path – Multifamily 2018 Washington State Energy Code-R 2
d. You cannot select more than one option from any category EXCEPT in category 5. Option 5.1 may be combined
3.1a High Efficiency HVAC 1.0
2 Heat pumpc 1.0
Each dwelling unit in a residential building shall comply with sufficient options from Table R406.2 (fuel
normalization credits) and Table 406.3 (energy credits) so as to achieve the following minimum number of credits:
Multifamily (effective February 1, 2021)
c. Equipment listed in Table C403.3.2(1) or C403.3.2(2)
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 3
Table 406.3 – Energy Credits (Multifamily)
Option Description Credits: MF
1. EFFICIENT BUILDING ENVELOPE OPTIONS
Only one option from Items 1.1 through 1.7 may be selected in this category.
Compliance with the conductive UA targets is demonstrated using Section R402.1.4, Total UA alternative, where
[1-(Proposed UA/Target UA)] > the required %UA reduction.
1.1 Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.24 0.5
1.2 Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.20 1.0
1.4
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.25
Wall R-21 plus R-4 ci
Floor R-38
Basement wall R-21 int plus R-5 ci
Slab on grade R-10 perimeter and under entire slab Below grade slab R-10 perimeter and
under entire slab or
Compliance based on Section R402.1.4: Reduce the Total conductive UA by 15%
1.0
1.5
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.22
Ceiling and single-rafter or joist-vaulted R-49 advanced
Wood frame wall R-21 int plus R-12 ci
Floor R-38
Basement wall R-21 int plus R-12 ci
Slab on grade R-10 perimeter and under entire slab Below grade slab R-10 perimeter and
under entire slab or
Compliance based on Section R402.1.4: Reduce the Total conductive UA by 30%
1.5
1.6
Prescriptive compliance is based on Table R402.1.1 with the following modifications:
Vertical fenestration U = 0.18
Ceiling and single-rafter or joist-vaulted R-60 advanced
Wood frame wall R-21 int plus R-16 ci
Floor R-48
Basement wall R-21 int plus R-16 ci
Slab on grade R-20 perimeter and under entire slab Below grade slab R-20 perimeter and
under entire slab or
Compliance based on Section R402.1.4: Reduce the Total conductive UA by 40%.
2.0
1.7
Advanced framing and raised heel trusses or rafters
Vertical Glazing U-0.28
R-49 Advanced (U-0.020) as listed in Section A102.2.1, Ceilings below a vented attic and
R-49 vaulted ceilings with full height of uncompressed insulation extending over the wall
top plate at the eaves.
0.5
Multifamily (effective February 1, 2021)
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 4
Table 406.3 – Energy Credits (Multifamily)
Option Description Credits: MF
2. AIR LEAKAGE CONTROL AND EFFICIENT VENTILATION OPTIONS
Only one option from Items 2.1 through 2.4 may be selected in this category.
2.1
Compliance based on R402.4.1.2:
Reduce the tested air leakage to 3.0 air changes per hour maximum at 50 Pascals or
For R-2 Occupancies, optional compliance based on Section R402.4.1.2: Reduce the
tested air leakage to 0.3 cfm/sf maximum at 50 Pascals and
All whole house ventilation requirements as determined by Section M1507.3 of the
International Residential Code or Section 403.8 of the International Mechanical Code
shall be met with a high efficiency fan(s) (maximum 0.35 watts/cfm), not interlocked
with the furnace fan (if present). Ventilation systems using a furnace including an ECM
motor are allowed, provided that they are controlled to operate at low speed in
ventilation only mode.
To qualify to claim this credit, the building permit drawings shall specify the option being
selected and the maximum tested building air leakage, and shall show the qualifying
ventilation system and its control sequence of operation.
1.0
2.2
Compliance based on Section R402.4.1.2:
Reduce the tested air leakage to 2.0 air changes per hour maximum at 50 Pascals or
For R-2 Occupancies, optional compliance based on Section R402.4.1.2: Reduce the
tested air leakage to 0.25 cfm/sf maximum at 50 Pascals and
All whole house ventilation requirements as determined by Section M1507.3 of the
International Residential Code or Section 403.8 of the International Mechanical Code
shall be met with a heat recovery ventilation system with minimum sensible heat
recovery efficiency of 0.65. 1
1.5
2.3
Compliance based on Section R402.4.1.2:
Reduce the tested air leakage to 1.5 air changes per hour maximum at 50 Pascals or
For R-2 Occupancies, optional compliance based on Section R402.4.1.2: Reduce the
tested air leakage to 0.25 cfm/sf maximum at 50 Pascals and
All whole house ventilation requirements as determined by Section M1507.3 of the
International Residential Code or Section 403.8 of the International Mechanical Code
shall be met with a heat recovery ventilation system with minimum sensible heat
recovery efficiency of 0.75. 1
2.0
2.4
Compliance based on Section R402.4.1.2:
Reduce the tested air leakage to 0.6 air changes per hour maximum at 50 Pascals or
For R-2 Occupancies, optional compliance based on Section R402.4.1.2: Reduce the
tested air leakage to 0.15 cfm/sf maximum at 50 Pascals and
All whole house ventilation requirements as determined by Section M1507.3 of the
International Residential Code or Section 403.8 of the International Mechanical Code
shall be met with a heat recovery ventilation system with minimum sensible heat
recovery efficiency of 0.80. Duct installation shall comply with Section R403.3.7. 1
2.5
1 To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall
specify the maximum tested building air leakage and shall show the heat recovery ventilation system.
Multifamily (effective February 1, 2021)
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 5
Table 406.3 – Energy Credits (Multifamily)
Option Description Credits: MF
3. HIGH EFFICIENCY HVAC EQUIPMENT OPTIONS
Only one option from Items 3.1 through 3.6 may be selected in this category.
3.1 2
Energy Star rated (U.S. North) Gas or propane furnace with minimum AFUE of 95% or
Energy Star rated (U.S. North) Gas or propane boiler with minimum AFUE of 90%. 3
1.0
3.3 2
Closed-loop ground source heat pump; with a minimum COP of 3.3 or
Open loop water source heat pump with a maximum pumping hydraulic head of 150
feet and minimum COP of 3.6. 3
1.0
3.4
Ductless mini-split heat pump system, zonal control: In homes where the primary space
heating system is zonal electric heating, a ductless mini -split heat pump system with a
minimum HSPF of 10.0 shall be installed and provide heating to the largest zone of the
housing unit.
To qualify to claim this credit, the building permit drawings shall specify the option being
selected and shall specify the heating equipment type and the minimum equipment
efficiency.
2.0
3.6 2
Ductless split system heat pumps with no electric resistance heating in the primary living
areas. A ductless heat pump system with a minimum HSPF of 10 shall be sized and
installed to provide heat to entire dwelling unit at the design outdoor air temperature.
To qualify to claim this credit, the building permit drawings shall specify the option being
selected, the heated floor area calculation, the heating equipment type(s), the minimum
equipment efficiency, and total installed heat capacity (by equipment type).
3.0
2 An alternative heating source sized at a maximum of 0.5 W /sf (equivalent) of heated floor area or 500 W ,
whichever is bigger, may be installed in the dwelling unit.
3 To qualify to claim this credit, the building permit d rawings shall specify the option being selected and shall
specify the heating equipment type and the minimum equipment efficiency.
4. HIGH EFFICIENCY HVAC DISTRIBUTION SYSTEM OPTIONS
4.1
All supply and return ducts located in an unconditioned attic shall be deeply buried in
ceiling insulation in accordance with Section R403.3.7.
For mechanical equipment located outside the conditioned space, a maximum of 10
linear feet of return duct and 5 linear feet of supply duct connections to the equipment
may be outside the deeply buried insulation. All metallic ducts located outside the
conditioned space must have both transverse and longitudinal joints sealed with mastic.
If flex ducts are used, they cannot contain splices.
Duct leakage shall be limited to 3 cfm per 100 square feet of conditioned floor area.
Air handler(s) shall be located within the conditioned space.
0.5
Multifamily (effective February 1, 2021)
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 6
Table 406.3 – Energy Credits (Multifamily)
Option Description Credits: MF
5. EFFICIENT WATER HEATING OPTIONS
Only one option from Items 5.2 through 5.6 may be selected in this category. Item 5.1 may be combined with any option.
5.1
A drain water heat recovery unit(s) shall be installed, which captures waste water heat from
all and only the showers, and has a minimum efficiency of 40% if installed for equal flow or a
minimum efficiency of 54% if installed for unequal flow. Such units shall be rated in
accordance with CSA B55.1 or IAPMO IGC 346-2017 and be so labeled.
To qualify to claim this credit, the building permit drawings shall include a plumbing diagram
that specifies the drain water heat recovery units and the plumbing layout needed to install
it. Labels or other documentation shall be provided that demonstrates that the unit
complies with the standard.
0.5
5.2 Water heating system shall include one of the following: Energy Star rated gas or propane
water heater with a minimum UEF of 0.80. 4 0.5
5.3
Water heating system shall include one of the following:
Energy Star rated gas or propane water heater with a minimum UEF of 0.91 or
Solar water heating supplementing a minimum standard water heater. Solar water heating
will provide a rated minimum savings of 85 therms or 2000 kW h based on the Solar Rating
and Certification Corporation (SRCC) Annual Performance of OG-300 Certified Solar W ater
Heating Systems or
Water heater heated by ground source heat pump meeting the requirements of Option 3.3.
To qualify to claim this credit, the building permit drawings shall specify the option being selected
and shall specify the water heater equipment type and the minimum equipment efficiency and,
for solar water heating systems, the calculation of the minimum energy savings.
1.0
5.4
Water heating system shall include one of the following:
Electric heat pump water heater meeting the standards for Tier I of NEEA's advanced water
heating specification or
For R-2 Occupancy, electric heat pump water heater(s), meeting the standards for Tier I of
NEEA's advanced water heating specification, shall supply domestic hot water to all units. If
one water heater is serving more than one dwelling unit, all hot water supply and
recirculation piping shall be insulated with R-8 minimum pipe insulation. 4
2.0
5.5
Water heating system shall include one of the following:
Electric heat pump water heater meeting the standards for Tier III of NEEA's advanced water
heating specification or
For R-2 Occupancy, electric heat pump water heater(s), meeting the standards for Tier III of
NEEA's advanced water heating specification, shall supply domestic hot water to all units. If
one water heater is serv ing more than one dwelling unit, all hot water supply and
recirculation piping shall be insulated with R-8 minimum pipe insulation. 4
2.5
5.6
Water heating system shall include one of the following:
Electric heat pump water heater with a minimum UEF of 2.9 and utilizing a split system
configuration with the air-to-refrigerant heat exchanger located outdoors. Equipment shall
meet Section 4, requirements for all units, of the NEEA standard Advanced Water Heating
Specification with the UEF noted above or
For R-2 Occupancy, electric heat pump water heater(s), meeting the standards for Tier III of
NEEA's advanced water heating specification and utilizing a split system configuration with
the air -to-refrigerant heat exchanger located outdoors, shall supply domestic hot water to
all units. If one water heater is serving more than one dwelling unit, all hot water supply and
recirculation piping shall be insulated with R-8 minimum pipe insulation. 4
3.0
4 To qualify to claim this credit, the building permit drawings shall specify the option being selected and shall
specify the water heater eq uipment type and the minimum equipment efficiency.
Multifamily (effective February 1, 2021)
2018 Washington State Energy Code – Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path – Multifamily 2018 W ashington State Energy Code-R 7
Table 406.3 – Energy Credits (Multifamily)
Option Description Credits: MF
6. RENEWABLE ELECTRIC ENERGY OPTION
6.1
For each 1200 kW h of electrical generation per housing u nit provided annually by on-
site wind or solar equipment a 1.0 credit shall be allowed, up to 3 credits. Generation
shall be calculated as follows:
For solar electric systems, the design shall be demonstrated to meet this requirement
using the National Ren ewable Energy Laboratory calculator PVW ATTs or approved
alternate by the code official.
Documentation noting solar access shall be included on the plans. For wind generation
projects designs shall document annual power generation based on the following
factors:
The wind turbine power curve, average annual wind speed at the site,
frequency distribution of the wind speed at the site and height of the tower.
To qualify to claim this credit, the building permit drawings shall specify the option being
selected and shall show the photovoltaic or wind turbine equipment type, provide
documentation of solar and wind access, and include a calculation of the minimum
annual energy power production.
1.0
7. APPLIANCE PACKAGE OPTION
7.1
To qualify to claim this credit, the building permit drawings shall specify the option being
selected and shall show the appliance type and provide documentation of Energy Star
compliance. At the time of inspection, all appliances shall be installed and connected to
utilities. Dryer ducts and exterior dryer vent caps are not permitted to be installed in the
dwelling unit.
1.5
Multifamily (effective February 1, 2021)
All of the following appliances shall be new and installed in the dwelling unit and shall
meet the following standards:
Dishwasher – Energy Star rated
Refrigerator (if provided) – Energy Star rated
Washing machine – Energy Star rated
Dryer – Energy Star rated, ventless dryer with a minimum CEF rating of 5.2