built for two
One couple avoids “marital Armageddon” by striking a balance between sustainable design and comfortable livability.
Walking into our friend’s house, I find myself wondering: Why didn’t they put in low-water landscaping? Is there enough roof overhang to shield the south-facing windows from the summer sun? Is that a single-pane window in the kitchen? What’s that unusual stain on the ceiling? Do the walls have enough insulation? Then I feel a sharp elbow in my ribs as my wife, Leslie, whispers, “You’re off duty. We’re here to visit and have a nice dinner.”
As a building scientist for more than 30 years, these are the types of issues I’m asked to assist clients with all week, so it’s difficult to unplug. Through my company, Environmental Building Sciences, I get to investigate problems of unsavory indoor air and environmental quality, poor temperature and humidity control, moisture and mold damage, and high energy usage. And when I’m not acting like Lieutenant Columbo, I’m teaching workshops, conducting research, and advising owners, builders, and architects on these concerns.
In 2002 when Leslie and I were planning to put up a new house and equine facility on ranch land near Las Vegas, New Mexico, I was presented with an opportunity and a dilemma. Despite years of consulting on energy efficiency, indoor air quality, sustainability, and other green-building issues, this time I would have to live with the decisions and the cost of the project. Did I want to do the green building full monty?
As an owner, I was drawn to the thought of paying small utility bills. As someone with sympathies for environmental issues, I found the notion of reducing environmental impacts and climate-change gases important. And as a building scientist, I was excited by the nerdy opportunity to do some of the cool things my fellow building scientists and I talk about over beers. I had visions of small and efficient windows, exotic wall construction, sophisticated heating systems, and lots of geeky gadgets. But in a collision with reality, it turned out my wife also wanted a say in the design and construction of our house. That’s when we both realized that, like so many other things in life, this would involve lots of compromise.
First, we had to select a piece of property that would meet our needs and interests. It had to be close enough to towns and airports to avoid unnecessary mileage and energy use for travel, but it had to be affordable and big enough to pasture horses. It should be protected from wind to reduce heating demand and improve comfort but open enough to satisfy our desire for expansive vistas, viewing of night skies and approaching storms, and so on. We spent many weekends and windshield hours over 10 years before finding land that met most of our criteria. Once we acquired the property, we had to compromise on the alignment of the house for optimum passive solar exposure and the orientation for beautiful views. We chose to adjust the house layout about 15 degrees east of due south and got the best of both.
As we started the design process, we understood the importance of involving a good and patient architect or designer. Just because you’re smart and work hard doesn’t mean you know how to design a building for people to live in, taking into account things like, “Oh, I guess you can see the toilet from the front door” or “I didn’t know that you had to open three doors in sequence to get into the laundry room.” An architect or designer would inject common sense, mediate different viewpoints, synthesize ideas, and ultimately help us avoid marital Armageddon. For these reasons, we turned to architect Roy L. Woods of Conron & Woods Architects in Santa Fe. We also eventually hired builder Leroy Vigil to manage construction.
In fact, the design phase turned out to be engaging and intellectually interesting as we blended Leslie’s aesthetic sense with my technical background. We pulled out our notes we had collected over the years about features we liked in the houses we had known. We agreed it would be a single-story structure with a northern New Mexico flavor and an open-format interior. It turned out that our main disagreement was on the number and size of windows (she wanted more and bigger; I wanted fewer and smaller). We successfully negotiated this so that neither of us was perfectly happy—in other words, a good compromise. After several changes to the building plans, the house had grown to about 2,700 square feet. This was larger than we had hoped but had well-designed space for two bedrooms, one large office/bedroom, two baths, a mud room, a large open kitchen/dining room/living room, and a wraparound portal. In the end, the limited size of our budget tempered all decisions.
Our home’s foundation and floors are a monolithic pigmented concrete slab on grade, which provides considerable thermal mass for the passive solar gain through the extensive south-facing windows. Because my calculations showed that existing and proposed requirements for insulating the slab were inadequate, particularly for floors with radiant heat, we boosted the insulation around the exterior edge of the slab (down to the footer) with R-20 rigid foam plus a radiant barrier. Two inches of rigid foam were also installed beneath the slab. To make the construction resistant to radon entry from the soil, four to six inches of clean, coarse gravel was placed beneath the foam board. We buried two 10-foot sections of perforated four-inch PVC vent pipe in the gravel layer to collect the radon and routed the pipe to the attic. If the home were found to have high radon levels after we moved in, these pipes could have been extended through the roof and connected to small fans to improve extraction of radon. As an additional radon-proofing measure, all cracks and gaps in the slab, including those around pipe and conduit penetrations, were sealed. The pigmented concrete was later scored with a wet saw to form grout lines, creating an attractive and durable surface for our less-than-pristine lifestyle. (At least we’d hoped it would be durable and easy to maintain. We’re still struggling to find an affordable low-emissions finish that is long-wearing and resists stains.)
Arguments over wall systems often dominate green-building discussions. Many people defend by duel their favorite approach: adobe, double stud, Rastra block, ICF, strawbale, etc. The fact is that many of today’s wall systems are extremely energy efficient and their selection depends more on personal preference and local availability of the materials and skilled labor to install them. I decided to use 10-inch-thick structural insulated panels (SIPs) with a thermal resistance of R-40-plus for the walls and roof/ceilings. SIPs are essentially a sandwich of oriented strand board (the bread) with a foam core (the filling) glued together to form long, wide, freestanding panels that require minimal structural reinforcement with studs or other support. From the architectural drawings, the panels were precut to size with door and window openings, numbered at the factory, and delivered on two tractor trailers. A small crew erected the panels and carefully sealed all joints over five days. Electrical wiring was installed in the panels as they were set up.
Having conducted too many investigations of mold in houses with leaky flat roofs, I resolved that our house would have a pitched metal roof. While many good roofing contractors and materials produce high-quality flat roofs, why risk living beneath a swimming pool? Even the best of them can develop leaks within 25 years—all it takes is one thing to go wrong. On the other hand, I’ve seen daylight through steeply pitched, 90-year-old shake-shingle roofs with nary a leak into the attic. These roofs were designed and built by old-timers who knew that if they shed the rainwater fast enough, it was less likely to penetrate into the building. Although the metal roof can be noisy during a hailstorm, it also affords some protection (along with stucco-covered exterior walls) against wildfires.
air sealing and ventilation
With my motto of “build tight and ventilate right,” we conducted extensive air-leak sealing throughout the construction process, to the point that the crew kept track of the number of tons of sealant used and joked that the windows would blow out if anyone coughed. The air sealing resulted in a very low natural ventilation of less than 0.1 air changes per hour. To compensate for this, we installed an innovative ventilation system that continuously supplies sufficient fresh outdoor air to exceed the American Society of Heating, Refrigerating, and Air-Conditioning Engineers standard for residential indoor air quality and ventilation. This system uses a small fan to blow fresh air into a long pipe buried five feet below the driveway. The pipe enters the building in five locations to deliver the fresh air, which has been cooled in summer or warmed in winter to the temperature of the soil. It works very well in New Mexico’s comparatively dry climate. In more humid climates, moisture could condense in the cool pipe in the soil, encouraging the growth of mold or bacteria.
High-quality, high-performing windows are essential to a low-energy home. For homes with lots of windows, they are also one of the single most costly construction expenditures. I reviewed literature, inspected products, and considered the reputation of manufacturers, then purchased high-end windows from a well-known window-maker. Unfortunately, despite careful preparation and installation, after several months many of the window sashes began to twist, pulling away from the frame and weather strip, leaving large gaps and compromising all the air sealing we had done. Even after several attempts by the manufacturer’s service reps, the windows continue to have more air leakage than the manufacturer’s specifications, albeit reduced from before.
indoor air quality
Most but not all of our interior materials, finishes, and paints have low or no volatile organic compound emissions. Finishes with higher VOC content were allowed to outgas for at least six weeks before the house was occupied, greatly reducing their health risk. As a pragmatist, not a purist, I selected these products not solely for maintaining good indoor air quality but also for cost, availability, and their track record of performance.
electricity and water usage
Even though the house and barn are almost one mile from the nearest power line, the lack of tax incentives for alternative power generation and storage at the time of construction made this option cost prohibitive. We selected efficient lighting and appliances based on estimated payback at current and future electrical rates, and—more importantly—whether Leslie really liked them. Our poor-producing water well forced us to carefully select water-efficient appliances, to install low-water and xeric landscaping, and to divert rainwater from roofs to small flower gardens and other outdoor plantings. Because of reported problems with gray water systems and constructed wetlands in low-flow conditions, we opted for a traditional septic system with leach field.
heating and cooling
By now everyone on the planet should know that fireplaces are anathema to energy-efficient, environmentally responsible buildings. They are essentially gigantic holes in your building that waste more heat than they produce, can backdraft combustion gases and particles into tightly sealed homes, and are dirty, nasty things. But they are romantic. So I hang my head in faux shame to admit that I really lusted for a fireplace in my house. To mitigate this atrocity, we built a modified Rumford designed to improve smoke removal and heating efficiency and to reflect much of the fire’s heat back into the room.
Relying principally on passive solar gain, large thermal mass, and a well-insulated and sealed enclosure, only a small supplemental heating system was necessary for our home in a climate similar to Denver’s. Our heating subcontractor grumbled after looking over the building that it would probably “only need a candle to keep it warm.” In fact, when we intentionally turned off the supplemental heat during one midwinter week, indoor temperatures never dropped below 60 degrees. The supplemental heating system is built around a very high efficiency condensing hot water tank that acts as a boiler to provide hot water for sinks and showers, and for the radiant floor space heating. The system is designed so solar hot water collection can be incorporated. The thermal properties of the structure and well-designed roof overhangs mean there is no need for air conditioning. We’ve never seen indoor temperatures rise above 76 degrees.
how well does it work?
Eventually this boils down to a pair of questions: Do you enjoy living in your house? Was it worth the additional money and effort? While the house incorporates many innovations, it is not a fully tricked-out model demonstration project. We couldn’t afford to do everything, nor were we satisfied that technical problems for other features had been resolved.
But we really like our home. Because our businesses are based at home, we spend a lot of time here. We find the house to be attractive and comfortable. It perfectly suits our lifestyle. I enjoy Leslie’s aesthetic and practical contributions, and she appreciates the creative technical approaches and comfort features I contributed. The layout of spaces and arrangement of rooms works well for the two of us yet easily accommodates a busload of guests. We spend a lot of our summer evenings out on the portal. We also like the snug, secure feeling when the house is buttoned up in the winter and the way it naturally connects to the outdoors at all times of the year. “I’d pay to vacation here,” Leslie says, putting it simply and best.
Brad Turk is the principal of Environmental Building Sciences in Las Vegas, New Mexico, and can be contacted at firstname.lastname@example.org.