Solar SIP House ADU Seattle WA

Location: Seattle, WA

Project Information

Project Type: Residential, Tiny House < 900 sq. ft.
Manufacturer: Premier Building Systems
Builder: Abode Builders
Design Professional: Velocipede Architects Inc
Year Built: 2022


High Performance: No
HERS/EUI Index Score:
ACH50 - Blower Test Results: 1.38
CO2 lbs./sq.ft./year:

Awards/Certifications: Building Excellence Awards

BEA: 2022 Winner Classic Homes Under 900 sq. ft.

This project was designed to reuse an existing foundation that an abandoned building was on in a tight building site. A place to live where a non-descript shed was. Now a beautiful super energy efficient backyard cottage! We already have two high performance SIP panel houses that use about a quarter of conventionally built structures. Being able to quickly and efficiently build on a tight site in a wonderful residential neighborhood allowed us to show the neighbors what they didn't know was possible. 

SIP wall thickness: 6" GPS
SIP roof thickness: 10" GPS

The building exceeds Net Zero and produces all our energy needs including TWO electric vehicles. More like energy positive.  We connected/power part of the existing building as well including the HVAC load for the offices in the front building.

The neighborhood response was overwhelmingly positive to this project and introducing hundreds of people (high pedestrian traffic street) to something they didn't know existed was amazing. What is it and how can it go up so fast were the most popular questions. Telling someone that a home can be so efficient that there are no energy bills is mind blowing to most passersby. Showing them how quickly it can be built is equally impressive. We showed this home on the NW Green home tour and were excited to show people an amazing product.

Being able to reuse the existing foundation as well as a protecting a large tree that would have prevented construction.  We didn't need to touch a branch or a root and still met Seattle's stringent earthquake requirements.

HERS index: n/a

Blower door test results (ACH50): 1.38

HVAC system:
We have a radiant concrete slab that is heated with an air to water heat pump water heater. The water heater uses carbon dioxide as its refrigerant which is Ozone friendly and doesn't contribute to global warming. Both domestic water and heat are produced by the same unit.

U-values of windows: triple pane windows U-15, U-17.

LED Lighting, Energy Star appliances

Adjacent building was covered in panels to completely offset all energy use.

All no VOC paints, siding is thermally modified wood which is rot and pest resistant. Never needs painting or staining and can be put into our cities compost and yard waste bins and made into compost or mulch!

We couldn't love this cottage any more than we do. The inside temperature is so even you really can't tell the heat is on. It's quiet and large window openings bring in tons of natural light. Maybe when I 'retire' I'll become a spokesman for SIPS!!


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