Super-Efficient ADU SIP House Seattle WA

Location: Seattle, WA

Project Information

Project Type: Residential, < 3,000 sq. ft.
Manufacturer: Premier Building Systems
Builder: Abode Builders
Design Professional: Velocipede Architects
Year Built: 2023


High Performance: Yes
HERS/EUI Index Score: -2
ACH50 - Blower Test Results: 1.07
CO2 lbs./sq.ft./year:

Awards/Certifications: Building Excellence Awards

BEA: 2024 Building Excellence Award - High Performance Winner

Building use:
Replacing an existing 100 year old Dadu with a super efficient Dadu and a versatile outbuilding.

How did SIP construction help you get this job?
As the owner/builder of 3 other SIP buildings I won't build with anything else!

SIP wall thickness and core material: 6” EPS
SIP roof thickness and core material: 10” EPS

Describe the benefits of using SIPs on this project. Did SIPs help save time, labor, construction costs, or energy?
Ease of construction is great but it's all about low energy use.

Describe any innovative design elements or structural engineering involved:
Exterior 2" cork insulation increases r value and eliminates siding cost and is 100% natural!

HERS: -2
ACH50: 1.07
HVAC: Sanden CO2 radiant floor heat/hot water. Fantech ERV

Describe any other energy-saving materials used in the building envelope other than SIPs. List U-values of windows used and the U or R-value of any insulation materials:
Cork 2" exterior insulation, triple pane U-15 windows

Please list any energy-efficient products or design features, such as lighting, hot water heating, appliances, passive solar:
Sanden CO2 hot water heater/radiant floor heat. Energy star washer, dishwasher, dryer and induction range.

Were any solar panels installed on the project?
A total array of 16KW is installed on the adjacent building.

Please list any sustainable materials or design features not listed above, such as recycled materials, low-VOC finishes, landscaping, etc.:
All no VOC paint, polished concrete floor and low voc wood floors upstairs


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