VS 1 ADU Energy Calcs2018 Washington State Energy Code Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path Single Family 2018WashingtonStateEnergyCode-R 1
Project Information Contact Information
Instructions: This single-family 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
n/a n/a
Ceiling e 49 j 0.026
Wood Frame Wall g,h 21 int 0.056
Floor 30 0.029
Below Grade Wall c,h 10/15/21 int + TB 0.042
Slab d,f R-Value & Depth 10, 2 ft n/a
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 compressed 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.
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.
These requirements apply to all IRC building types, including detached one- and two-family
dwellings and multiple single-family dwellings (townhouses).
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.
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
d R-10 continuous insulation is required under heated slab on grade floors. See Section R402.2.9.1.
e
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.
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.
Single Family New & Additions (effective February 1, 2021)
DetachedADU
2018 Washington State Energy Code Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path Single Family 2018WashingtonStateEnergyCode-R 2
2.Medium Dwelling Unit: 6 credits
All dwelling units that are not included in #1 or #3
3.Large Dwelling Unit: 7 credits
Dwelling units exceeding 5,000 sf of conditioned floor area
4.Additions less than 500 square feet: 1.5 credits
All other additions shall meet 1-3 above
Before selecting your credits on this Summary table, review the details in Table 406.3 (Single Family), on page 4.
Summary of Table R406.2
Heating
Options Fuel Normalization Descriptions Credits - select ONE
heating option User Notes
4 DHP with zonal electric resistance per option 3.4 0.5
5 All other heating systems -1.0
Energy
Options Energy Credit Option Descriptions
Credits - select ONE energy option from each category d
1.3 Efficient Building Envelope 0.5
1.5 Efficient Building Envelope 2.0
1.6 Efficient Building Envelope 3.0
1.7 Efficient Building Envelope 0.5
2.1 Air Leakage Control and Efficient Ventilation 0.5
2.2 Air Leakage Control and Efficient Ventilation 1.0
2.3 Air Leakage Control and Efficient Ventilation 1.5
2.4 Air Leakage Control and Efficient Ventilation 2.0
3.1a High Efficiency HVAC 1.0
3.2 High Efficiency HVAC 1.0
3.3a High Efficiency HVAC 1.5
3.4 High Efficiency HVAC 1.5
3.5 High Efficiency HVAC 1.5
3.6a High Efficiency HVAC 2.0
4.1 High Efficiency HVAC Distribution System 0.5
4.2 High Efficiency HVAC Distribution System 1.0
1.2 Efficient Building Envelope 1.0
1 Combustion heating minimum NAECAb 0.0
1.1 Efficient Building Envelope 0.5
1.4 Efficient Building Envelope 1.0
2 Heat pumpc 1.0
3 Electric resistance heat only - furnace or zonal -1.0
1.Small Dwelling Unit: 3 credits
Dwelling units less than 1,500 sf in conditioned floor area with less than 300 sf of fenestration area.
Additions to existing building that are greater than 500 sf of heated floor area but less than 1,500 sf.
Single Family New & Additions (effective February 1, 2021)
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) to achieve the following minimum number of
credits. To claim this credit, the building permit drawings shall specify the option selected and the
maximum tested building air leakage, and show the qualifying ventilation system and its control sequence
of operation.
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2018 Washington State Energy Code Residential
Prescriptive Energy Code Compliance for All Climate Zones in Washington
Prescriptive Path Single Family 2018WashingtonStateEnergyCode-R 3
Summary of Table R406.2 (cont.)
Energy
Options Energy Credit Option Descriptions (cont.)
Credits - select ONE energy option from each category d User Notes
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 1.5
5.5 Efficient Water Heating 2.0
5.6 Efficient Water Heating 2.5
6.1e Renewable Electric Energy (3 credits max) 1.0
7.1 Appliance Package 0.5
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)
d.You cannot select more than one option from any category EXCEPT in category 5. Option 5.1 may be combined
with options 5.2 through 5.6. See Table 406.3.
c.Equipment listed in Table C403.3.2(1) or C403.3.2(2)
e. 1.0 credit for each 1,200 kWh of electrical generation provided annually, up to 3 credits max.
See the complete Table R406.2 for all requirements and option descriptions.
Single Family New & Additions (effective February 1, 2021)
Please print only pages 1 through 3 of this worksheet for submission to your building official.
3.0 CLEAR FORM
·
Simple Heating System Size: Washington State
Project Information Contact Information
Heating System Type:
To see detailed instructions for each section, place your cursor on the word "Instructions"
Design Temperature
Instructions Design Temperature Difference (∆T)41
∆T = Indoor (70 degrees) - Outdoor Design Temp
Area of Building
Conditioned Floor Area
Instructions Conditioned Floor Area (sq ft)865
Average Ceiling Height Conditioned Volume
Instructions Average Ceiling Height (ft)9.0 7,785
Glazing and Doors U-Factor X Area =UA
Instructions 0.280 125 35.00
Skylights U-Factor X Area =UA
Instructions 0.50 ---
Insulation
Attic U-Factor X Area =UA
Instructions 0.026 865 22.49
Single Rafter or Joist Vaulted Ceilings U-Factor X Area UA
Instructions ---________
Above Grade Walls (see Figure 1)U-Factor X Area UA
Instructions 0.056 1,099 61.54
Floors U-Factor X Area UA
Instructions 0.025 865 21.63
Below Grade Walls (see Figure 1)U-Factor X Area UA
Instructions 0.028 ________
Slab Below Grade (see Figure 1)F-Factor X Length UA
Instructions 0.303 ---
Slab on Grade (see Figure 1)F-Factor X Length UA
Instructions ---________
Location of Ducts
Instructions Duct Leakage Coefficient
1.10
Sum of UA 140.66
Envelope Heat Load 5,767 Btu / Hour
Sum of UA x ∆T
Air Leakage Heat Load 3,447 Btu / Hour
Volume x 0.6 x ∆T x 0.018
Building Design Heat Load 9,214 Btu / Hour
Air leakage + envelope heat loss
Building and Duct Heat Load 10,136 Btu / Hour
Ducts in unconditioned space: sum of building heat loss x 1.10
Ducts in conditioned space: sum of building heat loss x 1
Maximum Heat Equipment Output 12,670 Btu / Hour
Building and duct heat loss x 1.40 for forced air furnace
Building and duct heat loss x 1.25 for heat pump
This heating system sizing calculator is based on the Prescriptive Requirements of the 2018 Washington State Energy Code (WSEC) and ACCA Manuals J
and S. This tool will calculate heating loads only. ACCA procedures for sizing cooling systems should be used to determine cooling loads.
Please complete the green drop-downs and boxes that are applicable to your project. As you make selections in the drop-downs for each section, some values
will be calculated for you. If you do not see the selection you need in the drop-down options, please contact the WSU Energy Program at
energycode@energy.wsu.edu or (360) 956-2042 for assistance.
Detached ADU
Above Grade
Below Grade
Figure 1.
All Other Systems Heat Pump
(07/01/13)
Window, Skylight and Door Schedule
Project Information Contact Information
Width Height
Ref.U-factor Qt.Feet Inch Feet Inch Area UA
Exempt Swinging Door (24 sq. ft. max.)0.0 0.00
0.0 0.00
Vertical Fenestration (Windows and doors)
Component Width Height
Description Ref.U-factor Qt.Feet Inch Feet Inch Area UA
0.28 1 3 0 6 8 20.0 5.60
0.28 1 3 0 1 0 3.0 0.84
0.28 1 2 6 3 6 8.8 2.45
0.28 1 5 0 4 0 20.0 5.60
0.28 1 5 0 4 0 20.0 5.60
0.28 1 6 0 1 0 6.0 1.68
0.28 1 6 0 6 8 40.0 11.20
0.28 1 2 0 4 0 8.0 2.24
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.28 0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
Exempt Glazed Fenestration (15 sq. ft. max.)
bed 2
bed 1
great rm
great rm
kitchen
Detached ADU
entry door
entry door transum
bath
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
Sum of Vertical Fenestration Area and UA 125.8 35.21
Vertical Fenestration Area Weighted U = UA/Area 0.28
Overhead Glazing (Skylights)
Component Width Height
Description Ref.U-factor Qt.Feet Inch Feet Inch Area UA
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
0.0 0.00
Sum of Overhead Glazing Area and UA 0.0 0.00
Overhead Glazing Area Weighted U = UA/Area 0.00
125.8 35.21Total Sum of Fenestration Area and UA (for heating system sizing calculations)