Here we have the preliminary design and construction photos of a new cabin in the Okanagan Highlands. This 1,100 square foot cabin sits on a west-facing slope in high desert second-growth fir, Ponderosa pine and tamarack forest near Wauconda, WA. Our clients have been camping on the site for several years, getting to know the site and its seasons. (A strategy we commend!) The cabin will be a year-round weekend and vacation retreat for the family for now, and may become a full-time home after retirement.

Like almost all second homes, this one carries the inherent contradiction between our and our clients' interest in making the cabin itself as energy intelligent as possible and the necessity of driving four or five hours to spend time in it--effectively wiping out any reduction in carbon emissions afforded by the design. We have all agreed to acknowledge that contradiction and move on. The cabin will use 70% less total energy than it would if it were built to the 2009 Washington State energy code, one of the most rigorous energy codes in the United States. There are also many benefits for us as the architects: The "cabin" format allows us to further explore the design of a smaller, more compact house, as well as the application of the Passivhaus standard to a more extreme climate. If we can make it work here, making it work anywhere in the western foothills of the Cascades will be a piece of cake. Please click the "Green Features" tab above for more information on the technical aspects of the project.

The parking area will be some distance from the cabin. The approach will be from the north, along a footpath though the forest. Coming into a clearing around the cabin (for fire prevention, solar access on the south and for view on the west) you will walk up a set of steps onto a covered porch, a door onto the screen porch on your right, a fully glazed entry door on your left. The entry has an eight-foot bench with boot storage below, hanging hooks for wet coats and scarves as well as a closet. Stepping into the main room, the ceiling rises to the south to a full wall of windows, and the view opens Bonaparte Mountain to the west through a bank of 8'-0" windows and a wide lift and slide door that opens onto the deck. Set into the western windows is a solid block of wood and stone that contains the wood stove and a wide-screen TV. The simple galley kitchen is to the right, with an efficient 24" wide refrigerator, big sink with a window to the entry, induction cooktop and recirculating range hood. A door at the far end of the kitchen leads out onto the screen porch. Ahead and to the left is a bank of storage that includes the entry closet with a stacked washer and condensing dryer, a pantry, and further on, a niche for an electronic piano and bookshelves. Peeking out from that wall of storage, all of which (like the kitchen bank) is covered in a thin plywood paneling, is a short run of three stairs that lead up into the bedroom wing. The two bedrooms are about 10' x 13'--just enough room for a queen-size bed. Both bedrooms have fully-glazed doors that lead out to a patio on the east side of the cabin. The south bedroom has a built-in writing desk. The bathrooms are simple, with long vanities, built-in cabinets, and modest showers. (The showers supplement the outdoor shower....) Sliding doors allow each bedroom to have an ensuite bath. The sound-insulated mechanical room is tucked between the two baths.

We are thinking fiber-cement siding on the more solid bedroom/entry wing with its punched windows, and vertical reclaimed Wyoming snow fence siding on the mostly transparent main room. Floors will be reclaimed pine, except entry and bath, which will be ceramic or stone tile. Ceilings will either be painted drywall or T&G fir. Trim will be minimal, also fir.

To give readers in Washington an idea of the climate, with an elevation of 4,250 feet above sea level, the cabin site is close to the elevation of Stevens Pass. With 7,894 Heating Degree Days (number of days below 68ºF x the degrees below 68ºF on each of those days), a latitude of 48.77º North (almost to Canada), and solar radiation 8.2 kBtu/SF/month during December (not very sunny)...it is a challenging site on which to build a cabin that meets the Passivhaus standard.

As of this writing, we have modeled the cabin in the Passive House Planning Package (PHPP) and achieved a heating demand of 4.70 kBtu/SF/year, and a Primary Energy Use of our energy use targets with the following levels of insulation:

Walls: R-75 (2x6 structural wall with a 16" TJIs on the outside, both filled with dense-pack cellulose insulation.)

Roof: R-102 (prefabricated parallel chord trusses, ~34" of loose-fill cellulose)

Floor: R-108 (prefabricated parallel chord trusses, ~30" of dense-pack cellulose)

Windows: Pazen Enersign from Quantum Builders, U-0.13 with a solar heat gain coefficient of .52. By virtue of their incredible performance, these windows contribute more heat to the cabin over the course of a year than they lose, allowing us to have a glazing area of 50% of the floor area, even in this extremely cold climate.

Onsite Energy

A small photovoltaic panel system will be integrated into the roof of the screened porch. Batteries will supply mainly emergency lighting and power the well pump. Solar Hot Water will come from a vaccum tube array mounted vertically on the south elevation, to the right of the master bedroom window.

Mechanical System

A Zehnder ComfoAir 200 Heat Recovery Ventilator (HRV) will provide filtered fresh air and exhaust stale air while transferring 92% of the warmth of the exhausted air back to the incoming fresh air through an air-to-air heat exchanger. A small electric coil on the fresh air supply will bring the fresh air up to near-ambient temperature. Annual heat demand is 4,800 kBtu. Normal heating will come from a small in-wall electric convection heater (not the squirrel cage type!) in each of the two bedrooms, and electric heating mats in the floors of the entry and both bathrooms. When first arriving after being away for a time during the winter, a small fire in an efficient wood-burning stove will bring the cabin up to temperature. The stove will also provide supplementary heat during long periods of cold and no sun. There will be no furnace as such.

Owners: Anonymous

Design Team: Rob Harrison, Matt Wasse, Geoff Briggs

Passive House Consultants: Rob Harrison, Matt Wasse

Structural Engineer: Carissa Farkas Structural Engineering

General Contractor: Mark Gerrish, Bonaparte Builders