Super-Efficient ADU Complete in Portland

The accessory dwelling unit (ADU) market is alive and well in the Concordia neighborhood of Portland, Oregon.  People like these tiny structures — sometimes referred to as backyard cottages, granny flats, or laneway houses — because they can be leased out or used to accommodate an expanding family situation.  And, as these structures grow in popularity, they’re getting greener, too.  For instance, check out this high-performance ADU built by Hammer & Hand and designed by Departure Design.

This 800 square-foot structure won’t obtain Passive House certification, but Hammer & Hand used the Passive House Planning Package to plan the most energy-efficient and cost-effective approach to materials and construction.

The ADU is expected to be about 60% more efficient than a code-built home, and that’s because of details like airtight construction, insulation, and efficient ventilation.  Footers rest on geofoam and the foundation slab was poured over type II EPS.  The walls have a layer of seam-sealed plywood, 2″ of type II EPS, and 5.5″ of high-density cellulose insulation.

Inside, the backyard ADU is ventilated with a Panasonic ERV system in the kitchen.  In the same area, all of the appliances are Energy Star or better and the total project cost came in at $125,000.  It has a kitchen, two bedrooms, and one bathroom.

[+] More info on this high-performance ADU with a small footprint.

Credits: Bright Designlab.

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  • Tammy

    I’m curious – Panasonic ventilation fans?

    • Fred L. McGhee

      Panasonic makes some of the best ventilation fans our there. I have four in my own home.

  • Sophie Tresxia Collin

    If one is eyeing to have an energy efficient design like this property, you have to start from choosing an energy efficient construction materials and appliances. Simply because this will make up most of your home and this is where having an energy efficiency home will start. Aside from the Panasonic ventilations and green star certified appliances, using window tints can also be added. Why? Because films
    can stop up to 80% of all solar energy coming through windows which means for each degree you raise or lower your thermostat, you can save anywhere from 1 to 5 percent on your cooling or heating bills depending on where you live. If interested, you can ask and seek help about your tinting needs at They provide free technical support to homeowners and businesses. Getting the “right window tint” is not only practical but also eco-friendly.

  • Thomas – EV

    for the price its great! I would buy it

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