|
Rebecca F. Bundy, Design for Sustainable Living, LLC |
|
Ketchum, Idaho: New Residence, Passive Solar Design, 2002 |
|
Home, garden and renewable energy systems featured in variety of publications including: ◄ Sun Valley Magazine, Fall 2007 online version ◄ Sun Valley Magazine, Fall 2007 as printed, pp 94-95 ◄ Sun Valley Guide, Winter 2006 |
|
The clients were looking for a passive & active solar house that would also be a beautiful, casual home in which to raise their family. The house needed to accommodate three bedrooms, two home offices, a guest suite and an informal great room for living and entertaining.
The great room, bedrooms and offices all orient to the south, while garage, utility rooms, bathrooms and the less frequently used guest suite are located on the north side of the house. Eight foot tall windows and French doors grace the south and east façades. West windows were avoided, except to frame a view of the dramatic butte to the west. North windows are smaller and few. The roof and deck overhangs were calculated to admit low winter sun for passive solar heating and to keep the high summer sun off the glazing.
|
|
The 4” thick stained concrete floors, the 2 1/2” concrete countertops and the central stone chimney provide thermal mass for winter heat storage and heat mitigation in summer. The programmable thermostats are set at 60 degrees, so the radiant floor heat comes on only on the coldest winter nights. Bathroom thermostats are set a bit higher for comfort.
The thermal mass also helps keep the house cool and comfortable in summer. Even when temperatures have been in the high 90’s for a couple of weeks, the house interior has never exceeded 76 degrees. Operable windows located low and high in the wall provide for excellent cross ventilation and stack effect. They are left open on summer evenings and then closed when the sun comes up, keeping the interior exquisitely cool.
A Rais woodstove, clad in soapstone, is used to provide backup heat mornings before the sun rises and on cloudy days. The soapstone absorbs heat and radiates it long after the fire has burned out. |
|
The house was framed using standard stick framing techniques, with custom site-built trusses and knee braces that express the roof structure. The walls were insulated with R-21 blown-in recycled content cellulous. The ceiling insulation is R-30 pre-vented SIPs panels that provide a continuous insulation over the entire roof. The slab on grade floor is insulated with R-20 rigid board below to encourage the solar warmth to radiate back into the living spaces as they cool down on winter evenings.
The active solar panels are located on the south facing roof at the rear of the house. The UniSolar photovoltaic panels (PV) are “building integrated” and are laminated directly to the Kynar standing seam metal roof. The dark gray roof color was chosen to closely match the almost black color of the solar panels, which makes them almost invisible on the roof. Two Thermomax evacuated tube solar thermal racks are centered above the doors and decks below to resemble skylights.
|
|
The home’s PV system was one of the first legal grid-tied systems in the state of Idaho. The electrical meter spins backwards when the sun is shining, banking electrical credits for nighttime and cloudy days. The PV panels produce about 75% of the home’s electrical requirements. In order to achieve this, the client had to make intelligent choices in appliances: all are Energy Star compliant. Compact fluorescent lighting fixtures were used throughout the house, with the exception of the pendants above the dining table, where fully dimmable incandescent provide better mood lighting.
The solar thermal panels produce about 80% of the home’s domestic hot water. A high-efficiency, wall-mounted Monitor boiler provides backup radiant floor heat and hot water in the dead of winter and during extended cloudy periods.
The xeriscaped garden is now fully established and needs irrigation only when the weather has been dry for a few weeks. Most plants used are native species—the lawn is high prairie Buffalo Grass, the conifers various pine varieties, a favorite shrub is the evergreen Mountain Mahogany and flowers include flax, penstemmon, salvia, lupine and wild geranium. |
