A one-of-a-kind passive and active solar home was always in the cards; Jack and Juanita Clay just needed to come home.

Both seasoned educators originally from suburban Connecticut, the Clays had spent more than two decades teaching abroad. From Iran to Romania, Switzerland to Ecuador, the couple embraced a nomadic international lifestyle, jumping from one boarding school to the next—somehow raising two kids in the process. However, having grown up hiking and skiing stateside, in Vermont, the Clays decided to make their homestead in the Green Mountain State.

They sought mountain views, enough land to provide hardwood for heat, clearings with plenty of sunshine, and flexibility to build a home “outside of the box.” In the 1980s, they purchased an 18-acre farm in Middletown Springs that filled the bill—ample space with breathtaking views, west of Rutland, Vermont.

Their extensive travels and familiarity with living with less and traveling lightly in combination with riding out the oil crisis of the 1970s fueled a growing desire to establish a lighter environmental footprint. In Juanita’s words, “Why burn oil when the sun’s out there? Building a solar home seemed like the obvious thing to do.” They were betting that the long-term economics would be worth the challenges and costs of researching, designing, and building a solar home.

The challenge was efficiently heating and cooling a home in the Northeast, which can experience wide temperature fluctuations—wintertime temperatures can drop below zero and summertime temperatures can be upwards of 90°F. Their research showed the best way to mitigate high heating and cooling costs was to use the earth to help regulate the home’s temperature.

However, they didn’t want to live in a windowless box or a cave; they preferred the house to be aboveground for the views, and wanted some unique architectural angles and lots of light—ideally available in every room. It took about 20 years for the Clays to slowly build their solar residence.

The Home

With an exquisite piece of land in hand, the Clays set upon finding a home design that balanced form and function. While they admired the thick, more organic wall shapes associated with handbuilt homes—strawbale with plaster, earth-sheltered concrete, or cob/rammed earth—they had their doubts about long-term moisture resistance and structural integrity, especially in the Northeast. The home had to be able to withstand the New England weather, but also reduce external energy input—electricity, heating oil, and propane.

The home needed to be livable and fit the Vermont landscape. In addition to ample daylight, they wanted exposed wooden beams and a spacious garage for two vehicles and storage. It had to accommodate family, yet be small and efficient enough to make sense for just two. After much deliberation and research, they settled on a unique “active” solar design by solar home designer Norman Saunders.

Aiming for 100% Solar

The selected design, as featured in books such as Super Solar Houses: Saunder’s 100% Solar, Low-Cost Designs (Shurcliff, 1983), pairs passive solar with fans and thermostats to move heat to different thermal storage locations. Common features include both high and low thermal mass (a “heat sandwich”); and an almost full-length south wall/roof greenhouse. The goal is to meet heating needs solely with solar energy. This strategy is not for everyone, though, as it requires a lot of space for thermal mass, as well as more controls and homeowner involvement than conventional homes.

The Clays’ three-level, 2,300-square-foot home features a gambrel barn shape with locally sourced post-and-beam framing and superinsulated (R-40+) 8-inch structural insulated panels (SIPs). The SIPs provide a contiguous thermal barrier, reducing thermal bridging. The south wall’s glass façade is enormous, spanning the whole width of the house, and rising from the foundation floor to the upper section of the gambrel roof. From straight-on, it almost appears as though the entire house is made of glass. Upon first glance, one might think anyone living inside would be uncomfortable; that there is so much south-facing glazing that overheating in the warmer months is a given, and freezing during colder months is inevitable.

However, that glazing is actually an integrated greenhouse. About 6 feet from the outside greenhouse wall, there is another three-layered, custom-constructed glass wall, with sliding doors. Amidst the drying laundry, a scattering of succulents bask in the hot, dry air—that is, before the heat gets convected up the middle channel of glass to the thermal storage in the attic. The greenhouse collects some heat itself, but since most of the heat is redirected before entering the living space, it also acts as a temperate buffer zone for the home.

Some of the direct solar irradiance hits the living space, but the majority is directed to the attic. Oversized posts and beams were used in the structure to allow the option of adding additional thermal mass (barrels full of water) to the attic, although the Clays never did due to concerns about leaks and excessive weight above their bedroom.

During the colder winter months, temperature-controlled fans pull the warmed attic air through large ducts to the thermal mass in the basement—18 tons of water, mostly contained in about eighty 55-gallon reclaimed juice-storage drums. Despite the voluminous, somewhat unwieldy footprint of all the water, it has superior thermal conductivity compared to sand or stone. While the Clays’ home doesn’t achieve its goal of relying exclusively on solar energy for its heating needs, the mass of the water, combined with a well-insulated envelope, create a comfortable baseline. On a few occasions during multiday winter power outages, the temperature inside the house never dipped below 55°F, with no sun or backup heat source. During the warm summer months, the stored heat in the attic is released to the outdoors by opening large gable-end temperature-controlled air vents.

The home and its construction were not without challenges. The Clays will attest to the frustration of entrusting contractors with successfully implementing unfamiliar building methods, such as the three-layered glass wall and extensive venting and controls. In the absence of regular oversight, mistakes were common and sometimes costly to remedy. Some contractors reverted to standard practices and ignored guidance when faced with new architectural methodologies. And the Clays acknowledge their own shortcomings with the Saunder design—most notably forgoing the thermal mass in the attic. In Jack’s words, “Despite the extra-strong framing, the thought of 10 tons of water above our bedroom spooked us a little bit regarding the weight and somewhat inevitable leak potential with steel drums.”

For the first few years after the home was completed, a variety of thermostatically controlled switches combined with a custom software program operated the many fans and vents to keep air moving to the desired locations. The Clays worked directly with Saunders for about 10 years, sending him collected data for him to analyze and update the software appropriately. However, the main control board was eventually damaged from a power surge, and a combination of difficult-to-find replacements, in addition to the realization that no control is “smart” enough, led to a more involved approach for the Clays—manual operation of the fans and vents to suit their comfort levels.

Adding Renewable Electricity

The Clay home effectively captures solar energy to help with heating, but until recently, they had not addressed their electrical usage. The home consumes about 420  kWh per month—less than half the regional residential average. Jack and Juanita rounded out their solar endeavors with a batteryless grid-tied, 4.2 kW PV system that meets 100% of their annual electrical needs. The home and surrounding land had a generous solar window, but there were design challenges when planning the solar-electric system.

Despite the standing-seam, south-facing gambrel roof, the Clays decided against a roof-mounted system to give better access to the array for maintenance and snow removal. They also had concerns about the long-term effects of snow and ice from a rooftop array sliding onto the southern glass wall. The grounds around the home were open fields, but the fairly steep slope away from the house would have made a contiguous ground mount difficult.

The home’s septic tank and leachfield, as well as the “million-dollar” southern view, also made siting an array more challenging. To avoid altering the landscape and the view, a pole-mounted array was sited downhill to the west of the house. Fifteen 280-watt modules was the largest array that could be installed on a single static pole (the Clays had no interest in a tracking array and its associated moving parts), and just so happened to be a great match for their needs. To assist in seasonally tilting the very large pole mount, a custom cable was fabricated and attached to the upper strongback of the rack for greater control during the tilting process. To meet National Electrical Code requirements regarding DC conductor accessibility, vinyl-coated mesh screening was attached to the lower portion of the array

AC conduit from the inverter in the garage was run on the outside of the home—and under the front steps and behind the siding trim to be out of sight—because the basement was nearly full of water drums. Interconnection was made with a ConnectDER, a connection device installed in-line between the utility net meter and its socket (see “Methods” in HP167), allowing the utility interconnection point to be outside of the house.

To accommodate the 15-module array—a less-common single-pole configuration, a transformerless inverter with dual-channel maximum power point tracking (MPPT) was specified. This can better handle the two differently sized source circuits (one with seven modules; another with eight modules) and their lower-than-typical operating voltages.

Now that their solar home is complete, the Clays are exploring the possibility of adding cold-weather heat pumps and, to deal with occasional power outages, battery backup for their PV system.