Sebastopol Residence
Context:
This new house is designed for a narrow west-facing hillside lot near the town of Sebastopol. The site is bordered by the road to the east, a creek to the west, and wooded neighboring properties to the north and south. Between the house site and the road is a grove of eucalyptus, acacia and pine trees, which are being selectively thinned to support regrowth of a native oak forest. From the house site, an expansive view opens to the west across the valley, to a wooded hillside. Near the creek are the remains of a former homestead and small apple orchard. To minimize impact to this site, the house was designed as a single long bar, parallel to the contours of the hillside. The existing driveway is being improved to allow for fire truck access, and minimal additional site grading is being done to provide walkable pathways across the site.
Program/Scope:
The family of four requested a four-bedroom house with a focus on a large great room where the family can spend quality time together throughout the day. Smaller storage/service spaces are tucked into a lower roofed section at the east side of the house, built with earth masonry blocks and covered with a green roof. The larger gathering spaces are located in the higher sloped roof portion of the home, opening to the west. The great room connects to the landscape directly through the west-facing terrace, with stairs leading out to the native meadow. A hallway/library provides quieter workspace for the children, who may be homeschooled in the future. Bedrooms are kept minimal in size, with views out to the native landscape.
Utilities/Systems:
When the family purchased the property, it had no existing utilities on it. The design calls for a new well and septic system to support the house. Power is being brought to the site, but a ground-mounted PV system will also be installed on site. The home is designed to be all-electric and net-zero energy with battery back-up for additional resilience and avoidance of peak load emissions. The home is served by an electric heat-pump that serves the radiant in-floor heating system, and the domestic hot water needs. No cooling system is being installed – thermal modeling was used to refine the design of the overhangs, windows and shutters to provide a comfortable space through the hottest days of the year. An energy-recovery ventilation system is being installed, with careful attention to air filtration due to the air quality issues during fire season.
Design Challenge
Special Challenges:
While the program is straight forward, the site presents a number of challenges including:
- How to best deal with a western exposure that is also the main view from the house.
- How to position the house to maintain privacy, views, and minimize grading.
- How to address a changing climate, longer fire seasons, and unpredictable utilities.
Solution:
The site slopes at a fairly constant rate from the road above to a small creek below. Entering the site from the road, you first encounter a small recording studio, located in the dense trees near the road, allowing clients access without entering the more private portions of the site. The house is located just beyond the dense grove of trees that protect the house from the roadway, while still being high enough on the site to maintain distant views to the west. The house is a simple, narrow bar that runs parallel to the contours, minimizing grading.
The volume of the house is comprised of a lower earth masonry block portion along the east side that retains the hillside and creates an entry path along contour, and a higher simple shed roof portion that opens the house to the expansive views to the west. The shed roof extends well beyond the house to the west to shade the decks and to the north to connect to the garage. The owners don’t like air conditioning, so passive design solutions were carefully studied. The western sun is controlled with lightweight metal shutters at the western edge of the deck that the owners are willing to deploy when needed to ensure that the house stays cool passively on sunny summer days.
Ample operable windows on the long sides of the house optimize daylighting and cross-ventilation, while shading prevents excess heat gain. Combined with the thermal mass of the high-slag concrete floors, earth masonry blocks, green roof, and a high performance, tightly sealed building envelope, the house will stay cool passively.
To address the impact that a growing fire season has on all of our lives, the family was focused on a home that could be functional and comfortable when the grid is down. A large PV array with battery backup ensures that the house will be habitable, allowing the filtered ventilation system to run. The PV system is designed to run the house on battery power during peak load times, reducing carbon emissions.
The materials palette consists of simple, durable, low embodied carbon materials that are fire-resistant. Watershed Block (reduced cement and recycled materials) form retaining walls and the fireplace. CLTs provide efficient use of materials for the roof and keep the roof plane thin. FSC certified lumber is used for framing and siding. And exposed high-slag concrete flooring provides thermal mass. The metal roof, green roof, shutters, and plaster walls all are resistant to fire-spread.
Physical Context
The Sebastopol Residence is designed to provide a home that connects to a beautiful rural site, focusing on expansive views to the west, while also minimizing impacts on the site and the larger environment.
The house is a narrow bar stretched along the contours of the site, minimizing grading and providing views and daylight on two sides for all of the principal living spaces. The deep overhanging roof to the west shelters the main outdoor living space and shades the house from sun and glare. Movable Corten steel shutters can be deployed along the western edge of the deck to protect against low angle sun on hot days.
The thermal mass of the concrete floor, which is also the finished floor, is cooled with natural ventilation at night, helping to stabilize daily temperature fluctuations.
Minimal landscape is proposed for the site, consisting of simple pathways leading through native meadows connect the house uphill past food-producing gardens and into the grove of trees near the road, and downhill to the orchard and creek beyond. Through selective thinning and careful attention, the family expects to help restore a more native oak forest uphill of the house, while replenishing and expanding the former apple orchard near the creek.
To connect to the native hillside, the main living space opens to a terrace that steps down into the meadow. On the uphill side, a small stairway is carved into the hill providing access to the gardens and studio uphill. The native plants of the site find their way onto the low roof over the earth block volume. High hopper windows in the clerestory provide a pathway for air flow carrying the fragrance of the wildflowers and herbs planted nearby.
By keeping the parti simple, focused on capturing views and air flow while minimizing impact to the site, the majority of the site can stay or be restored to a more native state, ranging from the riparian creek near the orchard, to the native meadows by the house, and the protective oak forest near the roadway.
