10923 2nd Avenue NW

The ''Underhill: Custom designed, energy-efficient, and sustainable house/design studio built in 1978. It is a passive solar, earth-sheltered, green-roof building explicitly configured to the topography of the hillside site. It features a zero-step main floor, is all-electric, and utilizes 100% renewable power from Consumers Energy (through the Green Generation program, Solar Gardens, etc.). There is a Jotul wood stove in the great room for heating the house during power outages. The very private lot is 2.3 acres overlooking a large wetlands area. The upper living level is 1870 sq ft. There are four bedrooms (or three bedrooms and an office), one full bathroom, and two half bathrooms. All doors are 3'0'' wide for barrier-free access on the living level. The lower-level studio/workshop is 1600 sq ft. There is a 400 sq ft double-stall attached garage. The 3,100 sq ft ''tray system" green roof (vegetative roof) with a pond was installed 12 years ago. The original 1978 green roof lasted 35 years. The new roof vegetation is an intentionally biodiverse mixture of plant species. With the pond water feature, the roof environment was designated a National Wildlife Federation certified wildlife habitat in 2013. There is easy access to the roof and seating by the pond. The earth sheltered poured concrete walls vary in height depending on the direction they face. The north wall is 2 stories underground, sheltering the building from cold winter winds. The south wood frame glazed wall is two stories high, with the upper level offering sweeping views of the wetland from the 2nd floor. This large south-facing solar wall creates a considerable winter-time passive solar heating aperture for the upper living level windows and nighttime solar energy storage in a "Trombe Wall" on the lower office, studio, and shop level. With a 54" deep south overhang, the building is fully shaded in the summer, minimizing the need for air conditioning. The overhang has removable slats to maximize solar gain in the winter months. This also increases natural light penetration during the shorter winter days. The yard has no turf-type grass. All yard vegetation consists of natural weeds cut to various lengths and at varying frequencies, depending on the location on the heavily wooded hillside site. There is a 160 sq ft attached 3-season screen porch off the kitchen, connecting to a bridge leading to a 100 sq ft deck in the south woods.