Lago Vista resident Juergen Koehn became interested in hogans � Navajo Indian dwellings, often made of logs and mud with an east-facing door � during summers spent working on the Colorado River while on hiatus from his mechanical engineering business. The more Koehn learned, the more intrigued he became about the simple structures.
�It always fascinated me how they worked it out,� Koehn says. �So, I got interested in passive solar.�
According to the U.S. Department of Energy, passive solar or climatic design is achieved by designing windows, walls and floors to collect, store and distribute solar energy in the form of heat in the winter and reject solar heat in the summer.
Koehn eventually became so engrossed with the idea of passive solar that he hired New Mexico-based architect Mark Chalom to help him design a house that would not only keep the heat and cold at bay but also keep the electric bill below $100. The 3,000-square-foot house, where he has now lived with wife, Kate, for about 21 years, resembles a modern-style adobe more than a hogan (it includes a guest suite), but even on the steamy, hot day of our visit, it was cool and comfortable inside.
The designing and building phases for the house took two years.
�Building something yourself is a true test of matrimony,� Koehn jokes. That said, Koehn admits that if he had it to do all over again, he would have taken on the job of contractor. �There is no one that has better interest in the end product than you, the owner.�
The end product is a cinder-block structure covered with a combination of plastic foam, plastic mesh and a fiberglass paste, then coated with a paint containing stone flecks. This low-maintenance exterior treatment is much better-suited to the humid Central Texas climate than typical adobe coverings such as stucco.
Inside, hexagonal Saltillo tile and white walls provide a backdrop for the Koehns� collection of teak Scandinavian furniture. But the most striking part of the interior is the absence of corners. All of the rooms are curvilinear and spill into one another.
�I didn�t want anything square,� Koehn says. �I wanted easy flow. To me, it�s pleasing.�
Because of the curving walls, windows and cabinetry were custom-built, and several spaces, such as a niche for the hutch, were designed to fit pieces of furniture that the couple already owned. There are also several cubby holes built into the walls in the hallway and in the kitchen, perfect for wine storage.
To allow for additional ventilation, there is a vent under each window and a wind chimney, which creates a gentle draft when opened, hidden in the kitchen pantry.
The main part of the house includes the kitchen and dining areas, a sunken living room, the master bedroom and bathroom, a second bathroom with a cedar sauna and a sun room connecting to the guest suite. There are three fireplaces, and the back wall of the house is nearly all windows, offering a breathtaking view of Lake Travis.
Additional exterior features that help combat the heat and moisture are deep overhangs, shielding the windows from sun and rain, plus the roof, which is overlaid with reflective aluminum strips. Landscaping includes native plants, and the Koehns have a rainwater collection system that supplies water for the pool.
And if it gets too hot or cold for lounging in the backyard, the Koehns can go inside, where the climate is just right.